Nuclear poly(A)-binding protein 1 is an ATM target and essential for DNA double-strand break repair

Abstract

The DNA damage response (DDR) is an extensive signaling network that is robustly mobilized by DNA double-strand breaks (DSBs). The primary transducer of the DSB response is the protein kinase, ataxia-telangiectasia, mutated (ATM). Here, we establish nuclear poly(A)-binding protein 1 (PABPN1) as a novel target of ATM and a crucial player in the DSB response. PABPN1 usually functions in regulation of RNA processing and stability. We establish that PABPN1 is recruited to the DDR as a critical regulator of DSB repair. A portion of PABPN1 relocalizes to DSB sites and is phosphorylated on Ser95 in an ATM-dependent manner. PABPN1 depletion sensitizes cells to DSB-inducing agents and prolongs the DSB-induced G2/M cell-cycle arrest, and DSB repair is hampered by PABPN1 depletion or elimination of its phosphorylation site. PABPN1 is required for optimal DSB repair via both nonhomologous end-joining (NHEJ) and homologous recombination repair (HRR), and specifically is essential for efficient DNA-end resection, an initial, key step in HRR. Using mass spectrometry analysis, we capture DNA damage-induced interactions of phospho-PABPN1, including well-established DDR players as well as other RNA metabolizing proteins. Our results uncover a novel ATM-dependent axis in the rapidly growing interface between RNA metabolism and the DDR.

Integrative proteomics and phosphoproteomics in pulmonary arterial hypertension

“…PABPN1 protein levels were significantly lower in PAH than control PAEC but were more phosphorylated (Proteomics, PAH/Control, FC = 0.6922, P = 0.04; Phosphoproteomics, PAH/Control, FC = 1.5112, P = 0.02). Because phosphorylated PABPN1 is implicated in double-strand break repair, the findings suggest potentially greater ongoing DNA damage/repair in PAH PAEC 29 .…”

“…PABPN1 binds to poly A tails of nascent RNA and stimulates polyadenylation, which increases message stability and decreases alternative cleavage 29 . PABPN1 protein levels were significantly lower in PAH than control PAEC but were more phosphorylated (Proteomics, PAH/Control, FC = 0.6922, P = 0.04; Phosphoproteomics, PAH/Control, FC = 1.5112, P = 0.02).…”

Phosphoproteomics reveals novel modes of function and inter‐relationships among PIKKs in response to genotoxic stress

“…Repeated appearance in various types of screens strongly suggests the involvement of the candidate protein in central DDR pathways. Using this approach, we recently identified the DDR roles of the RNA processing factor, PABPN1 (Gavish‐Izakson et al , 2018) and the proteasome chaperone, ubiquilin 4 (Jachimowicz et al , 2019).…”

EXOSC10 is required for RPA assembly and controlled DNA end resection at DNA double-strand breaks

“…Moreover, different RNA processing factors are recruited to DSBs, which suggests that RNA plays a role in DNA repair. These include the NEXT complex 17 , the nuclear poly(A)-binding protein 18 , the C1D family proteins 19 , helicases such as DDX1 20 and senataxin 21 , the decapping protein EDC4 22 , and exoribonucleases such as XRN1 23 , XRN2 24 , and the RNA exosome 23,25,26 .…”