Nuclear GIT2 Is an ATM Substrate and Promotes DNA Repair

Abstract

Insults to nuclear DNA induce multiple response pathways to mitigate the deleterious effects of damage and mediate effective DNA repair. G-protein-coupled receptor kinase-interacting protein 2 (GIT2) regulates receptor internalization, focal adhesion dynamics, cell migration, and responses to oxidative stress. Here we demonstrate that GIT2 coordinates the levels of proteins in the DNA damage response (DDR). Cellular sensitivity to irradiation-induced DNA damage was highly associated with GIT2 expression levels. GIT2 is phosphorylated by ATM kinase and forms complexes with multiple DDR-associated factors in response to DNA damage. The targeting of GIT2 to DNA double-strand breaks was rapid and, in part, dependent upon the presence of H2AX, ATM, and MRE11 but was independent of MDC1 and RNF8. GIT2 likely promotes DNA repair through multiple mechanisms, including stabilization of BRCA1 in repair complexes; upregulation of repair proteins, including HMGN1 and RFC1; and regulation of poly(ADP-ribose) polymerase activity. Furthermore, GIT2-knockout mice demonstrated a greater susceptibility to DNA damage than their wild-type littermates. These results suggest that GIT2 plays an important role in MRE11/ATM/H2AX-mediated DNA damage responses.

GIT2 Acts as a Systems-Level Coordinator of Neurometabolic Activity and Pathophysiological Aging

“…Using a combinatorial informatics and proteomics approach, we demonstrated that GIT2 acts as a hypothalamic aging “keystone” factor ( 13 ). Subsequently, GIT2 has also been implicated in regulating DNA integrity via its interaction with ataxia telangiectasia-mutated (ATM), a DNA damage repair (DDR) kinase ( 18 ). In response to multiple forms of DNA damaging insults, GIT2 is rapidly phosphorylated by ATM and then forms a complex with multiple DDR proteins including MDC1, MRE11, and phosphorylated H2AX ( 18 ).…”

“…Subsequently, GIT2 has also been implicated in regulating DNA integrity via its interaction with ataxia telangiectasia-mutated (ATM), a DNA damage repair (DDR) kinase ( 18 ). In response to multiple forms of DNA damaging insults, GIT2 is rapidly phosphorylated by ATM and then forms a complex with multiple DDR proteins including MDC1, MRE11, and phosphorylated H2AX ( 18 ). Genomic deletion of GIT2 in mice (GIT2KO) resulted in a significant increase in the rate of DNA damage accumulation compared to wild type (WT) age-matched control mice ( 18 ).…”

“…In response to multiple forms of DNA damaging insults, GIT2 is rapidly phosphorylated by ATM and then forms a complex with multiple DDR proteins including MDC1, MRE11, and phosphorylated H2AX ( 18 ). Genomic deletion of GIT2 in mice (GIT2KO) resulted in a significant increase in the rate of DNA damage accumulation compared to wild type (WT) age-matched control mice ( 18 ). DNA instability has been associated with an advanced rate of aging for several decades ( 28 – 30 ) and this has been reinforced with the appreciation that accelerated molecular aging occurs in patients possessing mutations in multiple DDR proteins including ATM ( 31 ), WRN [Werner syndrome, RecQ helicase-like ( 32 , 33 )], and BLM [Bloom syndrome, RecQ helicase-like ( 34 )].…”

Expanding functions of GIT Arf GTPase-activating proteins, PIX Rho guanine nucleotide exchange factors and GIT–PIX complexes

“…of damage (Frank and Hansen, 2008;Lu et al, 2015). GIT-PIX complexes are dynamic within cells and exhibit high mobility among compartments, such as when cells adhere or migrate (Manabe et al, 2002) or during activation of chromaffin cells to release stored vesicles (Meyer et al, 2006).…”

Profiling of the Peripheral Blood Mononuclear Cell Proteome in Schizophrenia and Mood Disorders for the Discovery of Discriminatory Biomarkers: A Proof-of-Concept Study

“…Our proteomic analysis pipelines and methodologies have previously been demonstrated to be both rigorous and able to generate highly effective and significant data outputs that give actionable, high-dimensionality data appreciation [17][18][19][20][21][22][23][24].…”