Molecular basis of radiation resistance in tardigrades and the medical implications

Table 1 Radiation resistance genes other than damage suppressor

Gene	Study model	Key findings	Ref.
DNA repair–related genes	Ramazzottius varieornatus exposed to γ-radiation (500 Gy) with transcriptomic analysis	Upregulation of DNA repair pathways, including those of homologous recombination and base excision repair, following γ-irradiation	Yoshida et al[28]
	Hypsibius exemplaris exposed to γ-radiation (100-2180 Gy) with transcriptomic analysis	Upregulation of multiple DNA repair pathways following γ-irradiation	Clark-Hachtel et al[29]
Antioxidative defense genes	Ramazzottius varieornatus genome analysis with desiccation-related transcriptomic analysis	Expansion of SOD genes (including as CuZn-type SODs and Mn-type SODs) and presence of bacterial-type catalases, suggesting enhanced ROS detoxification capacity	Hashimoto et al[4]
	Echiniscoides cf. sigismundi and Ramazzottius cf. coronifer with transcriptomic analysis	Antioxidative defense involving SOD, catalase, and GST, suggesting enhanced ROS detoxification capacity	Kamilari et al[30]
	Milnesium tardigradum with proteomic analysis	Presence of antioxidative enzymes, including SOD, catalase-related peroxidases, and GST, indicating ROS detoxification capacity	Schokraie et al[31]
Dihydroxyphenylalanine dioxygenase 1	Hypsibius henanensis exposed to heavy-ion radiation (200 Gy and 2000 Gy) with multi-omics analysis	Activation of a tyrosine–dihydroxyphenylalanine-betalain metabolic pathway limiting ROS	Li et al[32]
Tardigrade-specific radiation-induced disordered protein 1		Radiation-induced liquid–liquid phase separation concentrating 53BP1 and Ku70 at DNA double-strand breaks
NADH dehydrogenase (ubiquinone) 1 beta subcomplex subunit 8/ubiquinol-cytochrome C reductase synthesis		Enhanced mitochondrial oxidative phosphorylation with nicotinamide adenine dinucleotide regeneration
Tardigrade DNA damage response 1	Hypsibius exemplaris exposed to γ-radiation (500 Gy)	DNA binding and chromatin compaction with reduced phospho-H2AX levels after γ-irradiation	Anoud et al[33]

GST: Glutathione S-transferase; ROS: Reactive oxygen species; SOD: Superoxide dismutase.