The Ataxia telangiectasia-mutated and Rad3-related protein kinase regulates cellular hydrogen sulfide concentrations

Abstract

The ataxia telangiectasia-mutated and Rad3-related (ATR) serine/threonine kinase plays a central role in the repair of replication-associated DNA damage, the maintenance of S and G2/M-phase genomic stability, and the promotion of faithful mitotic chromosomal segregation. A number of stimuli activate ATR, including persistent single-stranded DNA at stalled replication folks, R loop formation, hypoxia, ultraviolet light, and oxidative stress, leading to ATR-mediated protein phosphorylation. Recently, hydrogen sulfide (H2S), an endogenous gasotransmitter, has been found to regulate multiple cellular processes through complex redox reactions under similar cell stress environments. Three enzymes synthesize H2S: cystathionine-β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase. Since H2S can under some conditions cause DNA damage, we hypothesized that ATR activity may regulate cellular H2S concentrations and H2S-syntheszing enzymes. Here we show that human colorectal cancer cells carrying biallelic knock-in hypomorphic ATR mutations have lower cellular H2S concentrations than do syngeneic ATR wild-type cells, and all three H2S-synthesizing enzymes show lower protein expression in the ATR hypomorphic mutant cells. Additionally, ATR serine 428 phosphorylation is altered by H2S donor and H2S synthesis enzyme inhibition, while the oxidative-stress induced phosphorylation of the ATR-regulated protein CHK1 on serine 345 is increased by H2S synthesis enzyme inhibition. Lastly, inhibition of H2S production potentiated oxidative stress-induced double-stranded DNA breaks in the ATR hypomorphic mutant compared to ATR wild-type cells. Our findings demonstrate that the ATR kinase regulates and is regulated by H2S.

Sodium sulfide selectively induces oxidative stress, DNA damage, and mitochondrial dysfunction and radiosensitizes glioblastoma (GBM) cells.

“…An increase in DNA damage can be due to induction of damage or inhibition of repair. H 2 S has been shown to alter DNA damage and repair signaling via ATR [53] and can also modulate DNA repair protein activity via post-translational sulfhydration [54,55]. However, we did not observe any differences in NHEJ or OGG1-mediated BER suggesting Na 2 S is inducing DNA damage.…”

The Role of DNA Damage Response in Dysbiosis-Induced Colorectal Cancer

“…The presented data show how ATR orchestrates the DDR induced by H 2 S. Indeed, cells carrying ATR mutations showed DNA damage after low H 2 S exposure, and were hypersensitive to higher concentrations [28]. However, a complex regulatory mechanism between ATR and H 2 S was postulated [28]. First, ATR inversely regulates enzymes involved in H 2 S synthesis and hence H 2 S concentration.…”

“…The resulting ATR-CHK1 complex mediates various cell responses that include S and G2/M checkpoints that facilitate DNA repair [27]. Additionally, ATR promotes Homologous Recombination (HR), regulates proper replication initiation and faithful chromosomal segregation [27,28].…”

“…In 2019, Chen and coworkers showed how H 2 S regulates ATR levels and its phosphorylation [28]. The presented data show how ATR orchestrates the DDR induced by H 2 S. Indeed, cells carrying ATR mutations showed DNA damage after low H 2 S exposure, and were hypersensitive to higher concentrations [28]. However, a complex regulatory mechanism between ATR and H 2 S was postulated [28].…”

“…First, ATR inversely regulates enzymes involved in H 2 S synthesis and hence H 2 S concentration. Second, high H 2 S concentrations suppress ATR phosphorylation at serine 435 (ATR-pS435) while low levels increase it [28]. Of interest, PKA-mediated ATR phosphorylation at serine 435 is required to promote NER and reduces mutagenesis via ATR-XPA complex formation [105].…”