Review
Copyright ©The Author(s) 2022.
World J Psychiatry. Sep 19, 2022; 12(9): 1150-1168
Published online Sep 19, 2022. doi: 10.5498/wjp.v12.i9.1150
Table 1 DNA methylation studies on depressed subjects, also associated with suicidality and life adversities
Gene (region)
Alteration
Subjects and collected tissue
Ref.
NR3C1 1-F and FKBP5 intron 7 promoter↑ DNA methylation at NR3C1 1-F, without significant differences at any of the measured individual CpG site in depressed patients. Association in salivary cortisol level and DNA methylation. ↑ DNA methylation in NR3C1 1-F at CpG 38 site in depressed patients, with early life adversity. No differences in FKBP5 intron 7 promoter33 depressed patients (24 females, 9 males), 34 controls (21 females, 13 males). Whole blood and salivaFarrell et al[67], 2018
MAOA and NR3C1 exon 1-F ↓ DNA methylation at MAOA’s first exon/intron junction; significantly ↓ at CpG 8 site from the intron region. ↑ DNA methylation at NR3C1 1-F’s promoter and exon in individuals experienced early parental death; significant ↑ at CpG 35 and 10.11 (sites close to NGFI-A binding site)82 (for MAOA gene) and 93 (for NR3C1 1-F gene) depressed females, victims of early-life adversity and 92 or 83 controls. SalivaMelas et al[35], 2013
BDNF, NR3C1, and FKBP5Significant alteration in DNA methylation at 9 sites in BDNF gene body, at 6 sites in NR3C1 promoter region, and at 4 sites in FKBP5 gene body, 3’UTR and promoter94 maltreated and 96 non-traumatized children. SalivaWeder et al[68], 2014
BDNF exon I↓ DNA methylation; differences at loci 87, 88 and 92–94, located within the CpG island region on the promoter of the exon I360 depressed patients (32 females, 328 males). SalivaSong et al[69], 2014
BDNF promoter between –694 and –577 relative to the transcriptional start site (12 CpG sites). SLC6A4 promoter adjacent to exon 1a between –479 and –350 relative to the transcriptional start site (10 CpG sites)Depressed mood in 2nd trimester associated with ↓ DNA methylation at maternal SLC6A4 promoter methylation status. ↓ DNA methylation at SLC6A4 promoter in infants, from mothers with higher depressed mood during 2nd trimester. No difference in BDNF gene82 female and male infants exposed to prenatal maternal stress–33 mothers treated with SRI and 49 mothers not treated with SRI. BloodDevlin et al[70], 2010
NR3C1 exon 1-F and BDNF promoter IV↑ DNA methylation within NR3C1 1-F gene (male infants). ↓ DNA methylation within BDNF promoter IV region (female and male infants)20 female and male infants exposed to prenatal maternal stress and 37 controls. Buccal tissueBraithwaite et al[71], 2015
NR3C1 exon 1-FDepressed mood in 2nd trimester associated with ↑ DNA methylation of CpG 2 site (relative to translational start site) at NR3C1 exon 1-F in infants. Depressed mood in 3d trimester associated with ↑ DNA methylation of CpG 2 and CpG 3 site (relative to translational start site) at NR3C1 exon 1-F in infants46 depressed females (33 treated with SRI and 13 not medicated), 36 controls, and their infants. BloodOberlander et al[72], 2008
BDNF, NR3C1, CRHBP, CRHR1, FKBP5 promoterHypermethylated BDNF, NR3C1, CRHBP and FKBP5 promoter. mRNA down regulation of BDNF, NR3C1, FKBP5 and CRHBP in MDD-suicidal ideation group15 females and 9 males with MDD (14 with and 10 without suicidal ideation) and 20 controls (14 females and 6 males). PBMCRoy et al[73], 2017
BDNF exon I promoter↑ percentage of methylated reference values207 female and male MDD patients and 278 controls. PBMCCarlberg et al[58], 2014
BDNF exon I promoter↑ at CpG 1, CpG 3 and CpG 5 site, ↓ BDNF serum level49 female and male MDD patients and 57 controls. BloodSchröter et al[74], 2020
BDNF exon I and IV promoter↑ methylation at CpG site 3 of promoter IV251 female and male MDD patients aged 65 > and 773 controls. Buccal tissueJanuar et al[75], 2015
BDNF exon IXChanges in DNA methylation; ↑ at CpG site 217, ↓ at CpG site 327, and 362. ↓ BDNF level and mRNA levels51 MDD patients (35 females and 16 males) and 62 controls (39 females and 23 males). Venous bloodHsieh et al[60], 2019
BDNF upstream of exon I and IVChanges in DNA methylation within CpG exon I promoter20 MDD patients (12 females and 8 males) and 18 controls (8 females and 10 males). BloodFuchikami et al[76], 2011
MYO16 and IDE↑ 5hmc in one CpG position of MYO16 and two CpG positions of IDE in the PFC. ↑ gene expression of MYO16. ↓ gene expression of IDE19 depressed male suicide victims and 19 controls. Brain tissue (PFC; inferior frontal gyrus)Gross et al[77], 2017
GABAA receptor α1 subunit promoter↑ DNA methylation of the CpG 2 and CpG 4 site (500 bp from transcriptional start site). ↑ DNMT-3B expression in FPC. ↓ expression of DNMT1 mRNA and ↑ expression of DNMT3b mRNA in FPC. ↓ expression of DNMT3b and DNMT1 mRNA in AMG10 male suicide victims and 10 controls. Brain tissue (FPC, AMG)Poulter et al[78], 2008
SLC6A4 promoter↑ mean methylation level28 MDD patients (20 females and 8 males) and 29 controls (21 females and 8 males). BloodIga et al[79], 2016
NR3C1 exon 1 promoter↑ methylation at CpG 30 and 32 site. ↓ expression of total NR3C1 mRNA and NR3C1-1F mRNA in suicide victims without childhood abuse and control group12 suicide victims with traumatic childhood experience, 12 suicide victims without traumatic childhood experience, and 12 controls. Brain tissue (HPC)McGowan et al[80], 2009
Table 2 Histone tail modifications studies on depressed suicide victims
Gene (region)/histone tail modification
Alteration
Subjects and collected tissue
Ref.
BDNF, H3K9/14ac, H3K27me2↓ H3K9/14ac, HDAC2, HDAC3, H3K27me2, ↓ BDNF in HPC and NAc. Sin3a in HPC14 suicide victims (5 females and 9 males) without psychiatric diagnosis and 8 controls (3 females and 5 males). Brain tissue (HPC, NAc, and FCx; BA10)Misztak et al[53], 2020
H3K4me3↑ In H3K4me3 at promoter of SYN2. ↑ expression SYN2b; no changes in SYN2a expression7 females and 11 males with MDD suicide victims and 14 controls (3 females and 12 males). Brain tissue (PFC; BA10)Cruceanu et al[81], 2013
H3K14ac↑ H3K14ac. ↓ HDAC2 mRNA expression8 depressed females and males. Brain tissue (NAc)Covington et al[11], 2009
Table 3 MicroRNA expression studies on depressed suicide victims
miRNAs
Alteration
Subjects and collected tissue
Ref.
miR-218↓ miR-218 and ↑ DCC in PFC11 male suicide victims with MDD and 12 male controls. Brain tissue (PFC; BA44)Torres-Berrío et al[82], 2017
↓ miR-142-5p, miR-137, miR-489, miR-148b, miR-101, miR-324-5p, miR-301a, miR-146a, miR-335, miR-494, miR-20b, miR-376a*, miR-190, miR-155, miR-660, miR-130a, miR-27a, miR-497, miR-10a, miR-20a, miR-142-3p. ↓ by 30% or more: miR-211, miR-511, miR-424, miR-369-3p, miR-597, miR-496, miR-517c, miR-184, miR-34a, miR-34b-5p, miR-24-1*, miR-594, miR-34c-5p, miR-17*, miR-545, miR-565Globally ↓ miRNAs expression by 17% on average in depressed subjects. miR-148b targets DNMT3B, protein level was upregulated in depressed subjects. miR-34a targets BCL2, protein level was downregulated in depressed subjects18 suicide victims (2 females and 16 males) with depression and 17 male control subjects. Brain tissue (PFC; BA9)Smalheiser et al[83], 2012
miR-1202↓ miR-1202, and ↑ GRM4 mRNA expression in BA4425 suicide victims (2 females and 23 males) with MDD and 29 control subjects (4 females and 25 males). Brain tissue (PFC; BA44). 32 subjects with MDD (24 females and 10 males) and 18 control subjects (8 females and 10 males). BloodLopez et al[84], 2014
miR-30e↑ miR-30e, ↓ ZDHHC21 protein16 suicide victims (7 females and 9 males) with MDD and 16 controls (6 females and 10 males). Brain tissue (PFC; BA9)Gorinski et al[85], 2019
miR-19a-3p↑ miR-19a-3p (might be involved in the modulation of TNF-α signaling)12 depressed patients with severe suicidal ideation, 12 control subjects. PBMCWang et al[86], 2018
More than 10 miRNAs↑ miR-17-5p, miR-20b-5p, miR-106a-5p, miR-330-3p, miR-541-3p, miR-582-5p, miR-890, miR-99b-3p, miR-550-5p, miR-1179. ↓ miR-409-5p, let-7g-3p, miR-11979 depressed suicide victims (3 females and 6 males) and 11 control subjects (2 females and 9 males). Brain tissue (locus coeruleus)Roy et al[37], 2017
miR-326↓ miR-326, ↑ UCN15 male suicide victims with MDD and 8 male controls. Edinger-Westphal nucleusAschrafi et al[87], 2016
10 miRNAs tested↑ miR-34c-5p, miR-139-5p, miR-195, miR-320c. ↓ SAT1 and SMOX mRNA15 male suicide victims with MDD and 16 male control subjects. Brain tissue (BA44)Lopez et al[88], 2014
miR-204-5p, miR-320b, miR-323a-3p, miR-331-3p↑ miR-204-5p, miR-320b, miR-323a-3p, miR-331-3p in ACC and lateral habenula. miR-323a-3p influences the expression of ERBB4. Decreased expression in ACC and lateral habenula39 suicide victims with MDD (13 females and 26 males) and 41 control subjects (10 females and 31 males) for ACC region. 24 suicide victims with MDD (10 females and 14 males), 13 control subjects (5 females and 8 males) for lateral habenula. Brain tissue (ACC and lateral habenula)Fiori et al[89], 2021
171 miRNA differently expressed↑ 117 miRNAs. ↓ 54 miRNAs22 (10 females and 12 males) MDD subjects (10 died by suicide, 12 died from cause other than suicide) and 25 control subjects (10 females and 15 males). Brain tissue (ACC)Yoshino et al[90], 2020
miR-128-3p↑ miR-128-3p. ↓ WNT5B, DVL1 and LEF120 MDD (10 females and 10 males) subjects and 22 control subjects (9 females and 13 males). Brain tissue (AMG)Roy et al[91], 2020
miR-16↓ miR-1636 MDD (21 females and 15 males) subjects and 30 controls (17 females and 13 males). CSFSong et al[92], 2015
Table 4 Epigenetic (DNA methylation, histone tail modifications, and microRNAs) studies on animal models of depressive disorder
Epigenetic modification
Gene (region)/histone tail modification/miRNA
Alteration
Organism and collected tissue
Ref.
DNA methylationCrf promoter of exon 1 and intronic region between exon 1 and exon 2 (relative to exon 1 start site)Overall ↑ DNA methylation, and specific ↑ in CpG –147 and CpG –101 site of the Crf gene in stressed female rats in the PVN. No changes in male rats. ↓ DNA methylation in CpG –15 (male and female rats), ↓ DNA methylation in CpG –226, CpG –55 and ↑ in CpG +485 and CpG +494 (male rats) and ↓ DNA methylation in CpG –95 site (female rats) in BNST. ↑ DNA methylation in CpG –232 and CpG –226 (male rats), ↓ CpG –226 and CpG +535 (female) in the CeAMale and female Wistar-R Amsterdam rats; sacrificed 2 h after stress. Brain tissue (PVN, BNST, CeA)Sterrenburg et al[93], 2011
DNA methylationCrf promoter (relative to exon 1 start site)Chronic social stress induced ↑ DNA methylation in Crf promoter region at CpG site –226 and ↓ DNA methylation level in intronic region of the gene Crf in the PVN. Long term effect of social defeat in mice susceptible to social defeat: ↑ in Crf mRNA levels in PVN and ↓ DNA methylation level at CpG –226, –101, –95, and –79Chronically stressed adult mice C57BL/6. Brain tissue (PVN)Elliott et al[94], 2010
DNA methylation and histone tail modificationGdnf↑ DNA methylation at CpG site 2. ↓ H3ac in NAc of BALB mice and C57BL/6 mice. C57BL/6 mice had higher H3ac and higher Gdnf expressionBALB/c mice with maladaptive response to stressful stimuli and stress resilient strain C57BL/6. Brain tissue (NAc)Uchida et al[95], 2011
Histone tail modificationH3K14ac↓ H3K14ac 1 h after final stress. ↑ H3K14ac 24 h and 10 d after final stress. ↓ Hdac2 mRNA expression 24 h and 15 d after final stress in NAcChronically social defeated adult male mice C57BL/6J. Brain tissue (NAc).Covington et al[11], 2009
Histone tail modificationH3K14acH3K14ac ↑ after 24 h and ↓ at longer time in HPC. H3K14ac ↑ after 1 h and 24 h, no changes 10 d and longer in AMGChronically social defeated adult male mice C57/BL6J. Brain tissue (HPC and AMG)Covington et al[96], 2011
Histone tail modificationBdnf exon IV, H3ac, H4ac↓ exon IV Bdnf mRNA. ↓ H3ac and H4ac. ↑ MeCP2 levels. ↑ Hdac mRNARats (early life adversity induced by maternal separation). Brain tissue (HPC)Seo et al[97], 2016
Histone tail modificationBdnf III and IV promoter, H3K27me2↑ H3K27me2 at promoter Bdnf III and IV. ↓ total Bdnf mRNA. No change at H3K9me2Chronic social defeat stress mice. Brain tissue (HPC)Tsankova et al[62], 2006
Histone tail modificationH3K9me2↑ H3K9me2 in HPC and mPFC. ↓ Bdnf expression in HPC and mPFCWistar rats exposed to maternal separation and chronic unpredicted mild stress. Brain tissue (HPC and mPFC)Jiang et al[98], 2021
Histone tail modificationH3K4me3, H3K9me3, H3K27me3Acute restrain stress: ↑ in H3K9me3 in CA1 and DG; no changes in CA3; ↓ in H3K27me3 in DG and CA1; not significantly altered in CA3. No significant changes for H3K4me3. Subchronic 7-d restraint stress: The basal level of H3K9me3 on day 7 increased in DG, CA1 and CA3. ↓ in H3K9me3 in CA1, CA3 and DG. ↓ in H3K27me3 in DGAdult male Sprague–Dawley rats (acute stress/7 d restraint stress). Brain tissue (HPC parts: DG, CA1, CA3)Hunter et al[99], 2009
miRNAmiR Let-7a-1, miR-9, miR-25a/b↑ miR Let-7a-1, miR-9, miR-25a/b after acute stress in FCx. No changes in HPCMale CD1 mice with induced acute or repeated stress. Brain tissue (FCx and HPC)Rinaldi et al[100], 2010
miRNAmiR-218↓ miR-218 and ↑ DCC in PFCChronically social defeated adult male mice C57BL/6. Brain tissue (mPFC)Torres-Berrío et al[82], 2017
miRNAmiR-16↑ miR-16. ↓ Bdnf mRNASprague-Dawley rats exposed to maternal deprivation. Brain tissue (HPC)Bai et al[101], 2012
miRNA342 miRNAs differently expressed (response to gestational stress) and 336 miRNAs differently expressed in offspring (response to prenatal stress)↑ 147 miRNAs and ↓ 195 miRNAs in FCx of female rats. ↑ 205 miRNAs and ↓ 131 miRNAs in offspringStress induced through pregnant female Long-Evans rats. Offspring (decapitated 1 to 5 h after parturition). Brain tissue (FCx)Zucchi et al[102], 2013
miRNAAMG: 10 miRNAs under acute stress and 28 after chronic stress; HPC CA1: 16 after acute stress and 22 after chronic stressThe overlap: ↑ miR Let-7a-1 in AMG affected by acute and chronic stress. ↑ miR-376b and miR-208, ↓ miR-9 in HPC by acute and chronic stress. Other changes are unique to acute/chronic stress or brain region analyzedAdult male rats with induced acute or chronic stress. Brain tissue (AMG, HPC CA1 region)Meerson et al[103], 2010
miRNAmiR-124a, miR-18a, miR-511↑ miR-124a, miR-18a in PFC and HPC persistently. ↓ miR-511 in PFC (in adult rats experienced CUMS)Adolescent male Wistar rats were stressed with CUMS. Brain tissue (PFC and HPC)Xu et al[104], 2019
Table 5 Histone deacetylase classification and localization
HDAC category
HDAC class
HDAC type
Localization
Zinc-dependent HDACsClass IHDACs 1, 2, 3, 8Localized in nucleus
Class IIHDACs 4, 5, 7, 9, 10Pass between nucleus and cytoplasm
HDAC6Localized in the cytoplasm
Class IVHDAC11
NAD-dependent SIRTsClass IIISIRTs 1, 2, 6 and 7Localized in the nucleus
SIRTs 3, 4 and 5Localized in the mitochondria