Focal adhesion kinase: A promising regulator of colitis-associated healing

Abstract

Although the etiology of inflammatory bowel disease (IBD) remains unclear, compromised epithelial barrier integrity is believed to promote susceptibility to IBD and be associated with disease severity, suggesting that improving gut barrier integrity may palliate or treat IBD. Such a notion gets support from the clinical findings that mucosal healing in IBD patients is associated with improved prognosis, and reduced risk of relapse or colitis-associated cancer. It therefore becomes critical to understand the intracellular signals that regulate mucosal healing and gut barrier integrity. Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that critically modulates epithelial cell growth and mobility and has been associated with carcinogenesis. However, studies also suggest that FAK activation may promote mucosal healing under conditions of colitis, which should reduce the risk of colitis-associated cancer. These findings highlight a potentially transformative role for FAK in the context of IBD. Understanding the molecular mechanisms by which FAK influences gut barrier repair and mucosal integrity could offer novel therapeutic avenues for treating IBD and preventing its long-term complications. This review focuses on the potential role of FAK in promoting colitis-associated mucosal healing and the underlying molecular mechanisms driving these processes, offering critical insights into IBD pathogenesis and therapy.

Key Words: Focal adhesion kinase; Inflammatory bowel disease; Mucosal healing; Gut barrier integrity; Colitis pathophysiology

Core Tip: Focal adhesion kinase (FAK) plays a critical role in gastrointestinal mucosal healing via various key cellular processes. Small molecule FAK activators, such as ZINC40099027 or analogs, selectively enhance the activity of FAK to promote epithelial cell migration and wound closure. Therefore, ZINC40099027 and similar agents demonstrate promise in treating gastrointestinal mucosal injuries, such as ulcers or inflammatory bowel disease. Their two-fold approach in perpetuating repair mechanisms while minimizing oncogenic pathogenesis offers a therapeutic solution that is a safer, long-term treatment option for complex mucosal injuries.

INTRODUCTION

Inflammatory bowel disease (IBD) consists primarily of ulcerative colitis (UC) and Crohn’s disease (CD). CD may affect any part of the gastrointestinal (GI) tract, while UC affects only the colon and rectum[1-3]. IBD pathobiology includes inflammation and ulceration of the mucosal lining, leading to symptoms such as abdominal pain, diarrhea, rectal bleeding, and an urgent need to defecate[4]. IBD significantly impacts patients’ quality of life and affects approximately 1 million people in the United States and 2.5 million in Europe, with an increasing incidence globally[5,6].

The etiology of IBD is unclear. However, a prevailing theory is that dysregulation of the intestinal epithelial (barrier) integrity results in immune hyperactivation leading to the mucosal damage and ulceration[1-3,7]. Investigations examining this postulate have suggested that repairing intestinal epithelial injury/ulceration to reinstate the gut barrier integrity lessens disease severity and relapse in murine models of colitis[3,8]. Clinical data also supports a positive association between mucosal healing in IBD patients and improved prognosis, reduced risk of disease relapse, reduced hospitalization, and reduced risk of colitis-associated cancer (CAC)[9-11]. Current IBD therapies focus primarily on controlling inflammation without directly addressing mucosal healing, and sometimes are at the crossroads with signaling pathways that promote mucosal healing[3,12]. These limitations in the clinical management of IBD reflect our lack of knowledge about the molecular regulation of mucosal healing under conditions of colitis.

Focal adhesion kinase (FAK), also known as protein tyrosine kinase 2, is a 125 kDa non-receptor protein tyrosine kinase that plays a pivotal role in cellular processes such as adhesion, migration, survival, and proliferation in many cell types including intestinal epithelial cells (IECs)[13-15]. Although FAK has been linked to various types of cancer including colorectal cancer[16], FAK is also crucial for GI injury/repair and thus mucosal healing, which may have critical clinical ramifications for conditions like IBD. Recent studies suggest that expression of activated FAK is upregulated under the conditions of colitis, but that this is context-dependent and injury-mediated and thus limited to the healing of the mucosal injury[17,18]. Thus, novel therapies targeting FAK activation may bridge the current gap in IBD treatment, enhancing the healing process and provide better outcomes for IBD patients[19].

In this regard, the injury to the GI mucosa triggers a complex healing response involving dedifferentiation, migration, and proliferation of the IECs. FAK potentially orchestrates these cellular events, ensuring efficient wound closure and tissue repair through a process originally described as adoption of a migrating phenotype and more recently called “fetalization”, where injured crypt cells acquire fetal crypt like properties to promote healing[17,20,21]. Thus, specific activation of FAK through small molecule activators can promote crypt fetalization and wound closure, potentially offering a targeted approach to treat not only IBD but also other inflammatory GI disorders[22]. However, it is not well understood how FAK activation under the settings of colitis/IBD promotes mucosal healing. Understanding FAK’s molecular dynamics and its role in diseases like IBD opens new avenues for targeted therapies, offering hope for more effective and comprehensive treatment strategies[5,6,19,22].

Enhancing FAK activation in IBD may facilitate the restoration of the epithelial barrier by promoting mucosal repair, thus reducing inflammation[19]. Recent studies have demonstrated the potential of FAK activators in preclinical models of UC. In our studies, we have found remarkable increase in the expression of FAK phosphorylated at tyrosine 397 in the biopsies from IBD patients (Figure 1). Additionally, nuclear FAK has been found to stimulate vascular endothelial growth factor receptor 2 expression within endothelial cells, potentially pointing to its role within transcriptional regulation of angiogenesis-related genes[23]. After stimulation, FAK is activated and moves into the cytoplasm, associates with other enzymes, and promotes repair/restitution of the wound under conditions of inflammation and injury. FAK activators have been shown to accelerate wound healing in the colon by enhancing IEC migration and possibly proliferation. Thus, an approach using FAK-specific pharmacological activators represents a promising therapeutic strategy for UC, addressing the critical need for therapies that not only control inflammation but also promote mucosal healing[22,24]. Taken together, understanding FAK’s molecular mechanisms and its role in diseases like IBD opens new avenues for targeted therapies, offering hope for more effective and comprehensive treatment strategies[5,6,19,22]. This review discusses the structural and functional details of FAK, the complexity of colitis-associated mucosal healing, the potential limitations of the current IBD therapies in the context of promoting mucosal healing, and the potential role of FAK as a therapeutic target in promoting colitis-associated mucosal healing.

Figure 1 Expression of activated focal adhesion kinase is upregulated in inflammatory bowel disease patients. Biopsy from inflammatory bowel disease patient’s colon were subjected to immunohistochemistry using an antibody against phosphorylated focal adhesion kinase Tyr397 and images were captured using Nikon T-20 Light microscope. Representative images showing increased focal adhesion kinase phosphorylated at tyrosine 397 in inflammatory bowel disease patients vs adjacent normal (n = 4 individual slides/group). IBD: Inflammatory bowel disease.

FAK DOMAINS

The N-terminal FERM domain contains approximately 300 amino acids and three subdomains known as F1, F2, and F3[25]. The primary role of this domain is to bind intracellular portions of transmembrane receptors, playing a role in nuclear and cytoplasmic signaling[26]. The first nuclear export signal (NES) and nuclear localization signals (NLS) are located within the F1 and F2 subdomains, respectively, while the second NES resides in the kinase domain[27]. The F1 subdomain can bind directly to p53, inhibiting its transcriptional activity and subsequent activation of target genes involved in cell cycle arrest and apoptosis, thereby reducing the tumor-suppressing functions of p53. The F2 subdomain contains a NLS imperative for nuclear-cytoplasmic shuttling of FAK[28,29]. Tyr397, located in the first of three proline-rich regions (PRR1) interspersed within the main three domains, is the subject of initial autophosphorylation that begins to activate FAK[30,31]. However, when the FERM domain intramolecularly couples with the central kinase domain, the tyrosine residue is not available for phosphorylation, preventing FAK activation[32].

The central kinase domain contains approximately 200 highly conserved amino acids[16]. The structure includes N- and C-terminal lobes, with the C-terminal lobe housing Tyr576 and Tyr577 residues that are phosphorylated by Src kinases during catalytic activation. This phosphorylated state disrupts the intramolecular binding between the FERM and kinase domains, promoting FAK activation[33]. Additionally, studies have shown a secondary NLS within the kinase domain that is solely responsible for nuclear-cytoplasmic export activities[27].

The C-terminus of FAK contains two PRRs and the approximately 300 amino acids encompassing the focal adhesion targeting (FAT) domain[34]. Both PRRs (PRR2 and PRR3) are Src homology 3 (SH3) binding domains, facilitating protein-protein interactions. The FAT domain plays a significant role in cellular adhesion and signaling through several key proteins, including paxillin, talin, and vinculin[35]. These interactions form the basis for the formation and regulation of focal adhesions. Specifically, paxillin is critical for assembling focal adhesions by providing a mechanism for FAK to localize to these sites. FAK is essential for talin recruitment, as talin stabilizes focal adhesions through linkage of integrins to the actin cytoskeleton[36,37]. Finally, FAK binds vinculin, solidifying a stable adhesion complex capable of withstanding mechanical stress.

FAK phosphorylation

FAK is crucial in regulation of the integrin-mediated signaling pathway as it intends to assist in cellular attachment to the extracellular matrix (ECM) and cell migration. Its role in focal adhesion and other adhesion complexes demonstrates its necessity in cell turnover, particularly of migratory cells[38]. Depending on the stimuli, FAK becomes linked with integrins via paxillin[39] or localizes to focal adhesions via G-protein-coupled receptors[40]. Once this initial recruitment stage occurs, FAK couples with Src and undergoes autophosphorylation of Tyr397. Src also is responsible of Tyr576 and Tyr577 phosphorylation, triggering FAK’s inherent kinase abilities towards other substrates. Finally, Tyr861 and Tyr925 phosphorylation allows for binding of growth factor receptor-bound protein 2 (Grb2)[41]. Figure 2 illustrates the various phosphorylation sites along with the various protein interactions that can occur as a result.

Figure 2 Focal adhesion kinase phosphorylation. The figure illustrates the phosphorylation of focal adhesion kinase and its interactions with various proteins, highlighting the regulatory mechanisms that govern focal adhesion kinase activation and signaling. Green “P” icons represent the various serine residues that undergo protein kinase B 1 (Akt1)-mediated phosphorylation, yellow “P” icons represent the various tyrosine residues that undergo phosphorylation by various mechanisms. NES: Nuclear export signal; NLS: Nuclear localization signals; PIAS1: Protein inhibitor of activated Stat1; Ub: Ubiquitin; SUMO: Small ubiquitin-related modifier; PR: Progesterone receptor; SH: Src homology domain; PI3K: Phosphoinositide 3-kinase; FAT: Focal adhesion targeting; Grb2: Growth factor receptor-bound protein 2.

Although FAK phosphorylation has traditionally been understood as a series of tyrosine phosphorylation, multiple serine (Ser)/threonine sites have also been identified through mass spectrometry and shown to be functional[38,42]. For example, Ser843 phosphorylation of FAK inhibits Tyr397 phosphorylation and cell migration[43,44]. FAK also interacts with Ser/threonine kinases, particularly protein kinase B (Akt); Akt1 and Akt2 are phosphorylated in response to extracellular pressure and implicated in cancer, including colon cancer, with Akt1 directly binding a 33-amino-acid region in the C-terminal of FAK’s F1 Lobe and phosphorylating Ser517, Ser601, and Ser695 to facilitate Tyr397 autophosphorylation, while Akt1 activation via Ser473 occurs indirectly through FAK[45,46]. Inhibiting this interaction may play a role in blocking cancer metastasis[47], but whether modulation of this Akt1-FAK interaction might play a role in the treatment of IBD awaits further exploration.

FAK CELLULAR LOCALIZATION AND IMPLICATIONS FOR FAK FUNCTION

Although FAK, as its name implies, was originally described as being localized to the focal adhesion complex, FAK, like most proteins, is synthesized and then released into the cytosol, which acts as its primary reservoir. Post-translational modifications of FAK include both the binding of protein inhibitors of activated signal transducer and activator of transcription 1 to the FERM domain and adding a small ubiquitin-related modifier specifically to Lys152 within the FERM domain. Small ubiquitin-related modifier plays a role in FAK activation by constantly connecting with the NES and NLS[48,49]. FAK’s role as a cytoplasmic protein tyrosine kinase has been discussed extensively[50,51], but its localization within a cell is dynamic, shuttling between the cytoplasm and either the focal adhesion complex or the nucleus. When in its predominant cytoplasmic state, FAK docks at specific focal adhesion sites within the cytoplasm[29]. However, relatively little is known about its potential functions within the cytosol. However, it is important to note that FAK cycles between the cytosol to the focal adhesion complex or between the cytosol and the nucleus, with different functionality in each case.

FAK within the focal adhesion complex

Regulation of FAK’s cycling between the focal adhesion complex and the cytosol is dependent on specific physiological stimuli. In a normal physiological state, FAK stays localized to the focal adhesions and the cytosol. Additionally, CRISPR associated proteins (Cas) appears to function as a switch for inducing migratory signaling through its binding to various SH2/SH3 proteins[47]. If FAK is activated at focal adhesions, it complexes with Src kinase, which can then phosphorylate Cas and create binding sites for SH2 domain proteins[52]. The ability for Cas to bind a multitude of SH2/SH3 proteins permits its versatility as an adaptor molecule significant for the “switch-like” behavior that ultimately drives cell migration[53,54]. Once FAK relocates to the focal adhesion, it has two classes of functionality: (1) Signaling through its kinase function; and (2) Scaffolding support independent of its kinase function[13,53,55].

FAK is best understood for its kinase role. FAK can interact with an array of proteins that assist in migration. Interaction with other focal adhesion related proteins, such as those within paxillin family, via the FAT domain, prompts FAK to migrate to the focal adhesions, influencing FAK’s role in downstream signaling pathways that indirectly influence transcriptional activity. FAK itself does not bind to the DNA, and proteins, such as Src and paxillin are not known to directly interact with cytosolic transcriptional factors. Rather, FAK recruits Src to form a FAK-Src signaling complex whose function acts as an intracellular protein-tyrosine kinase activated at various focal adhesions sites. When the FAK-Src phosphorylates proteins like paxillin, it can lead to cytoskeletal remodeling and focal adhesion turnover. Paxillin recruitment is critical for scaffolding protein assembly and focal adhesions disassembly during cell migration, but the precise mechanism is not fully understood[56].

FAK also acts as a structural molecule critical to focal adhesion assembly independent of its kinase function. Multiple studies have detailed FAK’s role as a central mediator of integrin signaling as it uniquely regulates focal adhesions assembly and disassembly according to the desired cellular movement direction[57,58]. Intracellular linker proteins, such as talin, can connect FAK to integrins and transmit chemical or mechanical signals into the cell, known as “outside-in signaling”. ECM ligands will bind to the integrins stimulating conformational changes that activate FAK through autophosphorylation of Tyr397 and subsequent binding with Src. This activated version of Src can then interact with p130Cas. Intracellular protein binding regulating ligand binding affinity, known as “inside-out signaling”, involves talin[59]. Talin has previously been identified as a pivotal protein involved in integrin activation and adhesion assembly. It acts as a direct linker between integrin and actin cytoskeleton and is imperative for inside-out activation of integrin. This is mediated through Ras-related protein 1 (RAP1)-GTP-interacting adapter molecule (RIAM) recruitment of talin to the membrane and the subdomains of integrin[60]. The inside-out signaling mechanism has previously been linked to adhesiogenic stimulation signals, such as extracellular pressure, and can be pertinent in cancer metastasis[61].

FAK within the nucleus

Beyond its cytoplasmic role, FAK can also translocate from the cytosol or focal adhesions to the nucleus[62-64]. While FAK’s nuclear role is less defined, evidence does suggest that nuclear FAK regulates gene expression, cell survival and proliferation, particularly within endothelial cells[29]. It should be noted that FAK’s nuclear function are not mediated through its kinase activity but rather through its scaffolding ability. FAK contains specific sequences that tightly regulates nuclear entry and exit. The NLS located in the F2 Lobe of the FERM domain directs FAK to the nucleus, whereas the NES located in the kinase domain facilitates the export back to the cytoplasm[27]. Studies have also noted neural cell adhesion molecules inducing FAK activation and nuclear localization of both the C- and N-terminals of FAK[65-67]. The migration of FAK to the nucleus involves several mechanisms and is influenced by an array of conditions.

First, external stress signals, such as oxidative stress or apoptotic inducers, can induce translocation of FAK to the nucleus[27,68]. Second, proteolytic cleavage and post-translational modifications of FAK encourage nuclear localization. For instance, the overexpression of protein inhibitors of activated signal transducer and activator of transcription 1 promotes c-terminal cleavage of FAK nuclear localization[69]. Third, autophosphorylation of Tyr397 remains to be the most critical step in activating FAK and initiating this translocation to the nucleus, but other tyrosine residues, such as Tyr861, are also phosphorylated via Src kinase. Then, as the name implies, the NLS region enhances nuclear translocation through binding with importin and subsequent movement through pores[13]. Finally, exemplified by FAK inhibitors or kinase-depleted FAK cells having increased nuclear localization, inhibition of FAK’s kinase activity promotes nuclear localization. This activity suggests that the active FAK state prefers the cytoplasm[13,70].

Once in the nucleus, FAK acts primarily as a scaffolding protein rather than a kinase, stabilizing key transcriptional regulators and ubiquitin ligases. For example, in endothelial cells, nuclear FAK promotes degradation of p53 through stabilization of murine double minute 2, an E3 ubiquitin ligase, ultimately promoting cell survival[33]. Another additional role of nuclear FAK is inhibiting autophagy, which has downstream effects on cell proliferation, ultimately impactful for GI mucosal injuries, such as UC. The specific mechanism linking nuclear FAK to autophagy and how this action indirectly feeds back to cytoplasmic FA needs further clarification.

While FAK’s nuclear role in epithelial cells has not been fully explored, there is thorough evidence of its role in endothelial cells. Nuclear FAK is critical for endothelial cell survival and migration under stress conditions which raises the possibility for a separate role of FAK within cancer[71-73]. With that being said, nuclear FAK operates in a kinase-independent manner, potential interventions that activate FAK’s kinase activity would not be expected to enhance its nuclear role, but rather, potentially drive FAK out of the nucleus to focal adhesions. Therefore, therapies that specifically target nuclear FAK scaffolding functions would be dually important in understanding FAK’s role in cancer biology (Figure 3).

Figure 3 Focal adhesion kinase cycling. Focal adhesion kinase (FAK) exhibits dynamic cycling between three cellular compartments: (1) The focal adhesion complex at the plasma membrane, where it is activated via autophosphorylation to facilitate integrin signaling and downstream Src and CRISPR associated proteins protein recruitment; (2) The primary cytosolic state, where FAK resides in an inactive or post-translationally modified (e.g., SUMOylated) reservoir, and (3) The nucleus, where stress-induced translocation via the nuclear localization signals triggers FAK nuclear functions, such as binding methyl-CpG-binding domain protein and promoting p53 degradation. FAK’s shuttling is tightly regulated, and its return to the cytosol is mediated by nuclear export signals. MBD2: Methyl-CpG-binding domain protein; FAK: Focal adhesion kinase; Cas: CRISPR associated proteins; SH: Src homology domain; SUMO: Small ubiquitin-related modifier; NES: Nuclear export signal; NLS: Nuclear localization signals.

THE DYNAMICS OF THE ROLE OF FAK IN CELL BIOLOGY

As noted, FAK plays a critical role in cell signaling and behavior, particularly related to cell adhesion, migration, proliferation, and survival. These functions are typically characterized by inside-out or outside-in signaling, both equally crucial for cellular communication with the ECM or nearby cells. Inside-out signaling has been previously depicted in detail[59,74,75]. FAK requires activation primarily from integrins, but growth factor receptors or mechanical stress have also been known to induce the same effects. The alpha and beta subunit of integrin allows for bidirectionality signals between the ECM and intracellular environment[76]. Post-activation Tyr397 phosphorylation serves as a docking site for Src kinase signaling proteins that eventually forms an active FAK-Src complex. These conformational and clustering chances enhance affinity for ECM components, modulating cell adhesion properties[77]. Conversely, Outside-in signaling occurs when integrins on a cell surface bind ECM components, forming focal adhesions that recruit FAK to these sites. From there, FAK is activated through autophosphorylation, creating docking sites for proteins, similar in premise to inside-out signaling. Downstream effects of this process might be changes in cytoskeleton, cell migration, or gene expression[76].

Regarding FAK’s inside-out signaling, previous exploration into the role of FAK in the context of immune cell adhesion to the endothelium via the FAK-RAP1-RIAM-talin pathway has been described. In finding the crystal structure of the RIAM inhibitory segment, RAS association and pleckstrin homology domains, authors demonstrated that T cell receptor activation triggers FAK-mediated phosphorylation of tyrosine residues within the RIAM inhibitory segment domain, disrupting RAP1-dependent translocation of RIAM[78]. However, inside-out signaling of FAK has also been shown to apply to epithelial cells[79]. Through FAK-Akt1 interaction, epithelial cancer cells adhere to matrix proteins and endothelial cells after exposure to mechanical stress[61,80,81]. In tumor-implanted animal models, this pathway directly affects tumor cell adhesion and metastasis, ultimately impacting survival[80,82,83].

Overall, the intricate signaling network of FAK exemplifies the complexity of cellular elasticity, stiffness and mechanotransduction, where FAK’s inside-out signaling is tightly regulated by a web of mechanical stimuli and emanating signals. For instance, repetitive deformation has opposite effects on monolayer wound closure depending on whether the substrate is fibronectin or collagen, and on whether serum fibronectin is present in the culture medium[84]. This phosphorylation is intricately dependent on the interplay with Src kinase and other factors, highlighting how mechanical stimuli integrate with biochemical signals to orchestrate cellular responses like migration and survival. An improved understanding of these interactions will not only further elucidates the complex role of FAK in normal cellular physiology but will also provide insights into its involvement in pathological conditions where homeostasis of the normal mechanotransduction is disrupted, such as cancer.

However, it is important to understand the context of the role of FAK even in pathological conditions. For instance, while FAK-activation promotes cancer pathogenesis, its activity is also significant in the context of mucosal injuries, such as UC. Of interest, healing under condition of colitis reduces the chances of colon cancer[85-88]. Mechanical forces, such as cyclic strain or luminal pressure, have been shown to play critical roles in mucosal healing through extracellular regulated kinase (ERK) or FAK-mediated pathways. For example, intestinal deformation or changes in luminal pressure may regulate the functionality of mucosal repair as these forces combined with the nutrient flow could impact intestinal lining healing. Conversely, cyclic strain appears to have opposing effects on epithelial processes. While it promotes epithelial proliferation, there is inhibition of epithelial migration on fibronectin, which is common in ulcerated mucosal landscapes. Additionally, decreased healing has been observed in the absence of repetitive deformation, suggesting mechanical stimuli are dually important in facilitating mucosal repair mechanisms[89]. Since FAK is a key mediator of mechanotransduction, its context-specific and regulated modulation could present a therapeutic target for enhancing mucosal healing in UC, a condition in which one would expect alterations in patterns and magnitudes of GI motility and pressure. Thus, understanding the interplay between FAK signaling and mechanical forces within the gut could lead to novel interventions aimed at improving mucosal integrity and healing in cases of UC.

PHYSIOLOGIC GI MUCOSAL HEALING AND FAK

The GI epithelial tissue exhibits a remarkable ability to renew itself, replacing damaged or dead cells in response to injury, a process that is crucial for maintaining the normal gut homeostasis. This renewal is influenced by a complex interplay of cellular and molecular mechanisms, including pre-epithelial, epithelial, and sub-epithelial defenses that protect the mucosa from constant exposure to damaging substances. Central to these processes are IECs and their tight junctions, which form a crucial barrier, and angiogenesis, which supports deeper tissue repair[90-92]. Following injury, a sequence of cellular events including redifferentiation into a proliferative and migratory phenotype (termed as fetalization), and subsequent redifferentiation into specialized cells coordinates the healing response, and is governed by the growth factors, cytokines, physical forces, and the ECM. In GI epithelial cells, damage to the apical plasma membrane is a common occurrence following mechanical or chemical stressors, necessitating prompt repair to sustain the cell viability and internal equilibrium[93-95]. Repair mechanisms such as tension reduction, budding, patch formation, and endo/exocytosis are activated by the calcium influx through membrane wounds, ensuring effective resealing[96,97]. Smaller mucosal injuries may heal through cell spreading and establishment of new cell-cell contacts, or via purse-string closure involving actin cables[98,99]. However, larger wounds cannot heal merely through the purse-string methodology detailed above. Rather, phenotypic redifferentiation, involving a combination of differentiation and proliferation, also termed as “fetalization”, and angiogenesis, are required, taking longer in duration (Figure 4)[100,101].

Figure 4 Schematic overview of colonic epithelial wound healing. Injury induces upregulated expression of extracellular matrix components, including β1 integrin and collagen, which form a supportive scaffold for epithelial cell migration and adhesion. β1 integrin engages with the extracellular matrix to activate focal adhesion kinase. Through its interaction with Src kinase, focal adhesion kinase subsequently activates Yes-associated protein. The activation of Yes-associated protein promotes epithelial cell proliferation, a crucial process for initiating mucosal repair/restitution. ECM: Extracellular matrix; FAK: Focal adhesion kinase; YAP: Yes-associated protein.

Importantly, changes in IEC morphology leading to a migratory phenotype is influenced not only by the typical activation of signaling proteins, but also by the distribution and amount of signaling proteins within the cells. Because of the decreased FAK synthesis[102], both active and total FAK protein amounts decrease even though the proportion of FAK that is activated increases when gut epithelial cells shift to the migratory phenotype[103]. In addition to changes in FAK, both paxillin protein and tyrosine-phosphorylated paxillin decrease in these migratory cells[104], which is crucial to the focal adhesion complex assembly after certain stimuli. It is then that the purse-string cables made from actin allow for the redifferentiated cells to migrate collectively to close the epithelial wound[99,105,106].

In the specific context of healing of the mucosal injury, cytoskeletal tension, initially elevated to support cell migration, diminishes as the tissue re-establishes homeostasis. FAK activation, which is responsive to cytoskeletal dynamics, also decreases with this reduction in tension, leading to lower integrin-FAK signaling and reduced downstream activity. Post-healing, FAK becomes a target for ubiquitination, tagging it for proteasomal degradation[107]. This process thus regulates FAK levels, preventing its unnecessary activation, which could otherwise drive pathological cell proliferation and/or migration. With injury resolution, the Hippo signaling pathway, known for restricting cell proliferation through Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif inhibition, resumes its activity[108]. Activation of the Hippo pathway confines YAP/transcriptional co-activator with PDZ-binding motif to the cytoplasm, counterbalancing FAK’s proliferative and migratory signals, and supporting a return to cellular quiescence[109]. In summary, FAK inhibition, post-mucosal healing, is also a multi-layered process involving decreased ECM and integrin signaling, increased expression of phosphatases, lowered cytokine and growth factor levels, cytoskeletal reorganization, and enhanced protein degradation. Together, these mechanisms help restore tissue homeostasis, prevent excess cell proliferation, and thus reduce the risk of pathological environment supportive of the oncogenic growth.

Although most current therapeutic interventions for diseases that involve GI mucosal injury have emphasized reducing the aggravating injury or treating symptoms, it would seem desirable to promote mucosal healing directly. Others have explored the use of growth factors, peptides, or cytokines to protect against mucosal damage prior to occurrence[99]. Promising agents for promoting mucosal healing include epidermal growth factor and transforming growth factor-alpha, both of which enhance cytoprotection and healing[104]. Trefoil peptides, naturally expressed on goblet and gastric mucosal cells within the GI, may also play a therapeutic role[110,111]. These peptides are upregulated post-injury to assist in wound healing by increasing rates of restitution[112,113]. Topically applied trefoil peptides showed to reduce ethanol-induced gastric damage in rats[114], further suggesting trefoil protein protective effects and potential as a therapeutic defense. Overall, these studies suggest the opportunity for a different approach that focuses on promoting healing rather than merely blocking mucosal injury, as is the case with the biologics used to manage IBD currently.

THERAPEUTIC UTILIZATION OF FAK TO PROMOTE GI MUCOSAL HEALING

GI mucosal wounds, regardless of etiology, present significant clinical challenges that have largely been addressed by anti-injury interventions[115,116]. As noted, FAK plays a pivotal role in mucosal healing by regulating the key cellular processes such as proliferation, migration, and survival, critical for restoring mucosal integrity post-injury. Thus, we aim to explore the potential of FAK as a therapeutic target, attempting to provide a holistic understanding of the interventional prospect of FAK in promoting mucosal healing. Given FAK’s ability to integrate signals from growth factors, cytokines and the ECM, it orchestrates cellular responses, including redifferentiation to a migratory phenotype essential for effective wound closure. This makes FAK activation a viable target for promoting mucosal repair and achieving ideal ulcer healing, known as “quality of ulcer healing”, while also decreasing the likelihood of ulcer recurrence[117].

Initial studies towards the goal of activating FAK to promote mucosal healing, sought small molecules that activate FAK in vitro. A potential lead compound, ZINC40099027 (Zn27), binds directly to the FAK kinase domain and accelerates its enzymatic activity, thereby enhancing its phosphorylation state. This activation was specific to FAK, as Zn27 did not significantly affect other kinases within the focal adhesion complex, such as Pyk2 or Src. The specificity of Zn27 makes it a valuable tool for studying FAK’s role in epithelial sheet migration and wound healing without the confounding effects of other kinase activations[116,118,119].

By binding to the FAK kinase domain, Zn27 potentiates FAK autophosphorylation at tyrosine Y-397, which subsequently increases phosphorylation of paxillin and activates ERK downstream. In contrast, and distinct from physiologic patterns of FAK activation at the focal adhesion complex, Zn27 activates FAK within the cytosol prior to the shuttling of active FAK to the focal adhesion complex. FAK Tyr925 phosphorylation is actually decreased, also in contrast to physiologic activation, while neither p38 nor Akt are activated, suggesting selective phosphorylation. FAK also typically interacts with Grb2. However, Zn27 enhances interactions between FAK and paxillin, but not between FAK and Grb2. Thus, Zn27 seems to be highly selective in its effects on FAK downstream signaling. Zn27 promotes the closure of epithelial monolayer wound defects by promoting autophosphorylation of cytosolic focal adhesions, leading to further downstream phosphorylation of proteins like paxillin, resulting in focal adhesion turnover and cell migration[120]. Zn27 not only activates FAK but also induces epithelial sheet migration, which is essential for mucosal repair. Zn27 stimulates wound closure in human Cancer Coli-2, AGS, and NCI-N87 cell monolayers, and promotes wound healing in ischemic and indomethacin-induced small bowel mucosal injury and aspirin-induced gastric injury[47,115,120].

Building on the success of Zn27, a library of novel FAK activators was synthesized, identifying potent FAK activators. These compounds demonstrated increased FAK phosphorylation and promoted epithelial monolayer wound closure at nanomolar concentrations. Among these, compound 3 emerged as the most potent, showing significant efficacy in both in vitro and in vivo models[115]. Structural activity relationship studies revealed that the 1-(2-morpholino-5-(trifluoromethyl)phenyl)urea moiety is critical for FAK activation. Subsequent modifications aimed at enhancing solubility and reducing lipophilicity did not yield more effective activators, underscoring the importance of the original scaffold structure for biological activity[115]. Most recently a promising water-soluble FAK-activating molecule, M64HCl, has been shown to also activated FAK through Tyr397 phosphorylation, accelerate Cancer Coli-2 monolayer wound closure, and promote intestinal mucosal healing in mouse models[121]. The ability of M64HCl to promote intestinal mucosal healing has now been validated in rats as well[122].

FAK activation through small molecules like Zn27 and its analogs represents a novel approach to treating GI mucosal injuries. Unlike traditional therapies that primarily address symptom relief, FAK activators can directly enhance the wound healing process. While carcinogenesis remains a theoretical concern for chronic use, the unusual cytoplasmic activation and distinctive downstream signaling induced by these molecules suggests that FAK activation by these molecules may not have the same consequences as endogenous physiologic FAK activation. Moreover, the nuclear FAK effects that have been implicated in some cancer biology would seem independent of FAK kinase activity and thus not relevant here. This however awaits further study.

This therapeutic strategy could significantly improve outcomes for patients with conditions such as peptic ulcers, IBDs, and non-steroidal anti-inflammatory drug-related enteropathy, which are prevalent and often challenging to manage effectively[115,116]. Future research and clinical trials are warranted to fully realize the potential of these novel therapeutic agents. This collective body of work underscores the therapeutic potential of small molecule FAK activators in the treatment of GI mucosal injuries such as IBDs, offering the promise of developing new and effective therapies for these debilitating conditions[115,116,123]. Future directions for research on FAK-activating small molecules should include optimization of drug delivery systems to enhance oral bioavailability and reduce toxicity, critical pharmacodynamic studies to evaluate dose responses, tissue distribution and mucosal healing rates in IBD models such as dextran sulfate sodium (DSS) and 2,4,6-trinitrobenzene sulfonic acid induced colitis, and eventually the development of a phased roadmap toward clinical trials.

CLINICAL APPLICATIONS AND TRANSLATIONAL PERSPECTIVES

The clinical translation of FAK-targeted therapies especially for IBD represents a promising but complex frontier. While FAK activation has demonstrated therapeutic benefits in preclinical models, its dynamic role in cellular proliferation, migration, immune signaling, and fibrosis introduces potential risks that must be carefully managed. This section discusses the translational potential of FAK activation, experimental support for its therapeutic use, and the contextual challenges involved in clinical application, particularly as they differ between UC and CD.

FAK in epithelial repair and barrier restoration

During the initial phases of IBD, FAK plays a critical role in orchestrating epithelial repair and promoting wound healing, thereby preserving the integrity of the intestinal barrier. In this setting, epithelial integrins, such as α5β1 and αvβ6, bind to the components of the ECM[124], triggering FAK autophosphorylation at tyrosine 397, its principal activation site. This phosphorylation event recruits Src-family kinases[125,126] and initiates downstream signaling cascades, notably the phosphoinositide 3-kinase (PI3K)/AKT pathway and Rho family of small GTPases[127-129]. Collectively, these pathways enhance epithelial cell spreading, migration, and survival, thereby can accelerate mucosal restitution. Recent studies also suggest that FAK is a convergent target for multiple signaling pathways and in regulating epithelial cell adhesion, migration, survival and apoptotic processes[126,130-134]. These processes are vital for maintaining and restoring the intestinal barrier during colitis-associated injury[115,130,132-134].

Experimental evidence and preclinical therapeutics

On this line, experimental studies have provided important evidence for FAK’s therapeutic potential. An elegant study by Owen et al[14] using FAK knockout mice suggested that FAK protein is dispensable for intestinal homeostasis. However, mice subjected to experimental colitis and recovery showed severe colitis and impaired mucosal healing, respectively. They further showed that FAK activation is critical for adhesion-mediated survival and proliferation; also, FAK functions as a mechanosensor to control intestinal epithelial proliferation and help promote mucosal healing. Additionally, a benchmark experimental study supports the role of FAK activation in mechano-transduction during colitis-associated epithelium healing in a FAK/YAP-axis-dependent manner[17], which allows the injured epithelium to be temporarily reprogrammed to a primitive state (fetalization) until the normal homeostatic microenvironment is reestablished[17]. Conversely, in another study in which oxazolone was used to induce colitis, FAK was overexpressed and authors discussed FAK involvement in wound healing in an inflamed colon[135,136]. This group further suggested the importance of FAK functions in the maintenance and recovery of the barrier function in colonic epithelium[137].

Current IBD therapies tend to be centered on alleviating symptoms and reducing inflammation, and there is a notable absence of drugs that directly promote mucosal healing. However, there are some recent notable studies that highlight an urgent need for innovative therapeutic approaches for IBD and can address this deficiency. In this regard, arctigenin, a lignan derived from Arctium lappa L., a dietary product, activates FAK by binding to it, thereby increasing focal adhesion turnover, particularly assembly, and enhancing the migration of colonic epithelial cells. This promotes mucosal healing in DSS-induced colitis in mice in a YAP-dependent manner[138]. Similarly, Schisandrin B, a major bioactive compound from Schisandra chinensis, promotes intestinal epithelial barrier integrity by activating FAK, thus promoting mucosal healing[19]. Authors further showed that FAK activity is indispensable for the protective effect on DSS-induced colitis using PF-562271, a specific FAK inhibitor. Interestingly, Schisandrin B also reduces the risk of initiation and development of CAC[19]. Another study found that estrogen receptor β activation could induce FAK activation, promoting mucosal healing. Importantly, combining an estrogen receptor β agonist with 5-aminosalicylic acid significantly enhanced mucosal healing in colitis models[139-141]. Further support for FAK’s therapeutic role comes from studies showing that diallyl trisulfide, a bioactive constituent of garlic, increases FAK phosphorylation and focal adhesion assembly through the Rab21/integrin β1 axis, helping promote the migration of colonic epithelial cells and mucosal healing in DSS-induced colitis in mice[142].

Positioning FAK-targeted therapy among emerging IBD treatments

Mucosal healing has emerged as a central therapeutic goal in IBD, strongly correlated with long-term remission and improved clinical outcomes. Historically, anti-tumor necrosis factor therapies marked a breakthrough in achieving mucosal healing, yet a substantial subset of patients either fails to respond or lose responsiveness over time. This therapeutic gap has spurred the development of novel biologics, small molecules, and alternative immune-modulating strategies aimed at more consistently achieving durable mucosal and even histologic healing (HMH) in both UC and CD[143-145].

Among the most actively investigated drug classes are Janus kinase (JAK) inhibitors, which exert intracellular anti-inflammatory effects through selective or pan-JAK blockade. Tofacitinib, a non-selective oral JAK inhibitor, has shown significant clinical and endoscopic response rates in multiple large-scale randomized controlled trials, including the OCTAVE Induction and Sustain studies. These trials demonstrated mucosal healing rates as high as 45% after one year of maintenance therapy with 10 mg twice daily, even in treatment-refractory populations[146]. Other JAK inhibitors, such as peficitinib and upadacitinib, are also under investigation, with preliminary data suggesting efficacy in promoting mucosal healing and, in some cases, HMH[146,147]. Importantly, real-world data and phase 3 studies increasingly incorporate HMH as a clinical endpoint, particularly in UC, where it is emerging as a predictor of sustained remission and reduced colectomy risk[147].

Recent organoid-based studies have further nuanced our understanding of JAK inhibitors’ effects on epithelial repair. Tofacitinib not only suppressed pro-inflammatory chemokines in stimulated colonoids but also promoted epithelial stemness, growth, and proliferation under both normoxic and physioxic conditions. This proliferative and regenerative effect stands in contrast to budesonide, which reduced colonoid size and had variable or negative effects on stemness and proliferation markers such as leucine-rich-repeat-containing G-protein-coupled receptor 5 and ephrin type-B receptor 2. These findings underscore the capacity of certain small-molecule therapies to directly influence epithelial biology and regeneration in addition to immune modulation, positioning them as multi-functional agents in IBD treatment[148].

Beyond JAK inhibitors, several other emerging therapies aim to improve mucosal healing by alternative mechanisms. Sphingosine 1-phosphate modulators, such as ozanimod, influence lymphocyte trafficking and have shown promise in achieving both mucosal healing and HMH[146]. Similarly, α4 integrin antagonists like AJM300 target gut-specific immune cell recruitment and have demonstrated mucosal healing rates nearing 60% in phase II trials, with relatively favorable safety profiles[146]. Phosphatidylcholine replacement therapy (e.g., LT-02) offers a non-immunosuppressive approach aimed at restoring mucus barrier integrity and has shown modest yet promising results in achieving endoscopic and histologic improvement in UC patients[146].

In this evolving therapeutic landscape, FAK-targeted therapy presents a novel, mechanistically distinct strategy focused primarily on promoting epithelial repair and mucosal regeneration. Unlike traditional immunosuppressants or biologics, FAK activators such as Zn27, M64HCl, arctigenin, and Schisandrin B directly enhance epithelial cell proliferation, migration, and adhesion remodeling. Importantly, some FAK activators have demonstrated selective intracellular activation and signaling profiles that differentiate them from endogenous FAK signaling, potentially mitigating risks associated with chronic activation.

Nevertheless, unlike JAK inhibitors and other emerging agents, FAK-targeted therapies currently lack clinical trial data and remain in preclinical stages. Although FAK activation seems able to broadly stimulate intestinal epithelial migration and mucosal repair, regardless of the mechanism of injury[120,121], further study must address extension to various mouse IBD models, including other chemically-induced injuries (e.g. dextran sodium sulfate or 246-trinitrobenzene sulfonic acid)[8,149] as well as adoptive T-cell-transfer leading to IBD-like inflammation[8] and genetic models that spontaneously develop an IBD-like phenotype such as SAMP1/YitFc mice[150]. Such further studies will be important in validating this concept. Moreover, questions of dosing, long-term safety, and integration with standard IBD care remain unresolved. For instance, current trials are exploring the potential role of FAK inhibitors to modulate the immune response in IBD[25,151,152]. If these are successful, future work will need to investigate proper patient selection to determine in which patients the benefits of FAK activation to heal the mucosa may outweigh foregoing FAK inhibition to downregulate the immune response or vice versa. Conversely, FAK is so enmeshed within a web of critical intracellular signaling that it would be a mistake to assume that all FAK activation or all FAK inhibition has similar consequences. In addition to the different roles of FAK as a scaffolding protein or within the nucleus alluded to above, the same FAK signal in the same place may have different and indeed opposing consequences depending upon the other inputs interacting with the FAK signal[84]. However, the potential for FAK-activating agents to directly restore mucosal architecture while avoiding systemic immune suppression may position FAK activators as ideal adjuncts or alternatives in future combinatorial IBD treatment paradigms, especially for patients where epithelial repair is the primary therapeutic objective.

Safety concerns and oncogenic risk

Despite encouraging preclinical data, translating FAK-targeted therapies into clinical use warrants caution. FAK’s role in cell proliferation and survival raises concerns about potential long-term risks, including dysplasia or colon cancer in chronically inflamed tissues under acquired genetic mutation[15,19]. However, outcome from recent studies demonstrating mechanotransduction as the stimulus to activate FAK under colitis conditions suggest that the FAK-activation should return to the homeostatic levels after the wound healing. To regulate FAK activation in IBD in a precise manner is important. Specific tyrosine phosphatases, including protein tyrosine phosphatase, non-receptor type 12 and Src homology 2 domain-containing protein tyrosine phosphatase 2, dephosphorylate Tyr397 and other key sites on FAK, thereby dismantling active signaling complexes and promoting functional inactivation[153,154]. Concurrently, a reduction in integrin-ECM engagement diminishes mechanical tension at focal adhesions, leading to their disassembly and the detachment of FAK from the membrane. Moreover, E3 ubiquitin ligases such as c-Cbl ubiquitinate FAK, marking it for degradation via the proteasome system[155]. In parallel, fully activated PI3K/AKT and ERK pathways exert feedback inhibition, suppressing upstream kinases like Src and further silencing FAK signaling[156,157]. However, to date, no data are available for clinical trials for FAK activators in IBD. Overall, while preclinical data using mouse models are encouraging, a cautious and evidence-driven approach is essential before FAK activation can be widely adopted as a therapeutic strategy in IBD management.

Differential FAK activity in UC vs CD

During chronic inflammation, FAK becomes aberrantly activated. Pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-6, and interleukin-1β regulate ECM production[158,159], leading to persistent integrin–ECM interactions. Dysregulated deposition of fibronectin and collagen further amplifies β1 integrin-mediated FAK activation, and thus can maintain its phosphorylation state even in the absence of acute injury. Sustained FAK activity drives the PI3K/AKT[160], Rho/Rho-associated coiled-coil containing protein kinase[161], and transforming growth factor-β/small mother against decapentaplegic[162] pathways, and thus can promote fibroblast proliferation, myofibroblast differentiation, and excessive ECM accumulation, ultimately resulting in intestinal fibrosis.

Chronic inflammation also exacerbates epithelial barrier dysfunction[163]. Infiltrating immune cells, such as macrophages, neutrophils, and T cells, release chemokines that indirectly activate FAK in both epithelial and stromal compartments[164,165]. FAK activation in macrophages enhances their migration and retention within the mucosa and perpetuates the inflammatory cycle through FAK-nuclear factor-κB crosstalk. FAK activation also enables dendritic cells and macrophages to sense matrix stiffness and chemotactic gradients, modulating their inflammatory responses and contributing to the pathogenesis of chronic intestinal inflammation.

In both CD and UC, FAK plays a pivotal role in preserving epithelial integrity and coordinating cell adhesion, migration, and survival. However, its functional dynamics differ markedly between these conditions, reflecting their distinct pathological features. In UC, FAK activity is closely associated with epithelial barrier regulation and decreases transepithelial electrical resistance, a sensitive measure of epithelial barrier permeability[163]. This decline in transepithelial electrical resistance indicates compromised epithelial cohesion and increased paracellular permeability, facilitating the translocation of luminal antigens and exacerbating mucosal inflammation. FAK, through its interaction with integrins and cytoskeletal elements, modulates the assembly of tight junction proteins, and its dysregulation can perpetuate epithelial injury and impaired restitution.

Conversely, in CD, the role of FAK extends beyond the epithelium and involves stromal components, particularly colonic lamina propria fibroblasts[166,167]. In these fibroblasts, FAK phosphorylation is notably diminished, impairing their migratory ability, a critical function for proper tissue remodeling and repair. This attenuation of FAK signaling may hinder wound healing responses and promote pathological matrix deposition. As a result, defective fibroblast function in the context of reduced FAK activity contributes to chronic tissue injury and fibrotic remodeling, which are hallmark features of Crohn’s-associated strictures and penetrating disease[168]. Together, these distinct alterations in FAK activity in UC and CD underscore its multifaceted role in IBD pathogenesis, ranging from regulation of epithelial barrier dynamics in UC to modulation of mesenchymal cell function and fibrogenesis in CD, which should be taken in account in testing of the potential of FAK-activation in IBD associated mucosal healing.

Importantly though, the role and impact of FAK activation in IBD are likely influenced by several subtype-dependent factors that remain incompletely understood and warrant further investigation. Both the levels of FAK activation and effects from FAK activation in the epithelium could differ based on immune cytokine response, differences in ECM composition, and specific cellular context. Similarly, the motogenic effects of FAK signaling are known to be fibronectin-dependent, suggesting that ECM alterations in fibrotic vs healthy mucosa could significantly influence FAK-mediated repair processes[84]. Furthermore, FAK signaling could elicit divergent responses in different cell types. For example, increased extracellular pressure activates FAK in epithelial cells but inhibits it in macrophages[169,170]. These complex and variable dynamics highlight the necessity of future studies to dissect the cell-specific and disease-subtype specific functions of FAK in IBD pathogenesis and repair.

CONCLUSION

Mucosal healing under the settings of inflammation and colitis is highly complex and not a well understood process. Nevertheless, a delicate interplay between the immune cells[171-173], signaling pathways[174-176], and epithelial repair mechanisms[177] orchestrates inflammation-associated mucosal healing. Findings from related investigations suggest that this complex process unfolds in three distinct yet interconnected phases: Epithelial restitution, cellular proliferation, differentiation, and maturation. Multiple signaling pathways including growth factor signaling, known to promote IEC survival, proliferation, and migration, can promote mucosal healing under the conditions of colitis. However, caution is required in manipulating these pathways because the same signals that can stimulate proliferation and migration in the setting of inflammation and injury can be carcinogenic in some contexts. Growth factors can activate their receptors in autocrine, paracrine and/or juxtacrine manners.

While FAK overactivation is also associated with oncogenic potential, its role in promoting colitis-associated mucosal healing suggest it may have a unique and paradigm-shifting role as mucosal healing in IBD patients has been associated with significantly reduced risk of CAC. This distinctiveness for FAK in the context of colitis seems to stem from the fact that its activation during colitis is highly regulated through a complex interconnected biological process where FAK is activated in response to the biological processes taking place precisely at the mucosal injury site. The repair of the mucosal injury, in turn, reverts the signals that activate FAK, returning FAK to its normal homeostatic levels and thus lessening the risk for sustained FAK activation, and oncogenic potential. Localized FAK activation may support normal tissue remodeling, potentially reducing fibrosis, a known comorbidity of IBD, and may pose less oncogenic or systemic risk. Additionally, by stabilizing tissue structure and function, FAK activators could help reduce the inflammation, cellular stress, and mutations that contribute to cancer risk.

While FAK activators prove to have potential to reduce CAC, it is critical to recognize that FAK-targeted therapies are still in the early stages of development. To date, no clinical trials have been conducted evaluating FAK activators in human IBD patients, and their pharmacokinetics, long-term safety, and integration into current therapeutic regimens remain largely uncharacterized. While several preclinical models have demonstrated efficacy in promoting mucosal healing through FAK activation, these findings must be validated in translational and clinical studies.

This review has synthesized a broad scope of emerging evidence regarding FAK’s structure, mechanistic signaling in colitis, epithelial and stromal roles in UC and CD, and its integration into the broader therapeutic landscape alongside agents such as JAK inhibitors, sphingosine 1-phosphate modulators, and α4 integrin antagonists. By contextualizing FAK among current and emerging therapies and highlighting both its therapeutic promise and associated risks, this review provides a comprehensive foundation for future investigation. Continued research should focus on refining FAK-targeted interventions and rigorously evaluating their efficacy and safety through clinical studies, with the ultimate goal of advancing a regenerative, precision-based approach to IBD treatment.