ALC1/CHD1L, a chromatin-remodeling enzyme, is required for efficient base excision repair.

Abstract

ALC1/CHD1L is a member of the SNF2 superfamily of ATPases carrying a macrodomain that binds poly(ADP-ribose). Poly(ADP-ribose) polymerase (PARP) 1 and 2 synthesize poly(ADP-ribose) at DNA-strand cleavage sites, promoting base excision repair (BER). Although depletion of ALC1 causes increased sensitivity to various DNA-damaging agents (H2O2, UV, and phleomycin), the role played by ALC1 in BER has not yet been established. To explore this role, as well as the role of ALC1's ATPase activity in BER, we disrupted the ALC1 gene and inserted the ATPase-dead (E165Q) mutation into the ALC1 gene in chicken DT40 cells, which do not express PARP2. The resulting ALC1-/- and ALC1-/E165Q cells displayed an indistinguishable hypersensitivity to methylmethane sulfonate (MMS), an alkylating agent, and to H2O2, indicating that ATPase plays an essential role in the DNA-damage response. PARP1-/- and ALC1-/-/PARP1-/- cells exhibited a very similar sensitivity to MMS, suggesting that ALC1 and PARP1 collaborate in BER. Following pulse-exposure to H2O2, PARP1-/- and ALC1-/-/PARP1-/- cells showed similarly delayed kinetics in the repair of single-strand breaks, which arise as BER intermediates. To ascertain ALC1's role in BER in mammalian cells, we disrupted the ALC1 gene in human TK6 cells. Following exposure to MMS and to H2O2, the ALC1-/- TK6 cell line showed a delay in single-strand-break repair. We therefore conclude that ALC1 plays a role in BER. Following exposure to H2O2, ALC1-/- cells showed compromised chromatin relaxation. We thus propose that ALC1 is a unique BER factor that functions in a chromatin context, most likely as a chromatin-remodeling enzyme.

• Authors: Masataka Tsuda, Kosai Cho, Masato Ooka, Naoto Shimizu, Reiko Watanabe, Akira Yasui, Yuka Nakazawa, Tomoo Ogi, Hiroshi Harada, Keli Agama, Jun Nakamura, Ryuta Asada, Haruna Fujiike, Tetsushi Sakuma, Takashi Yamamoto, Junko Murai, Masahiro Hiraoka, Kaoru Koike, Yves Pommier, Shunichi Takeda, Kouji Hirota
• Journal: PloS one (PLoS One) Vol. 12 Issue 11 Pg. e0188320 ( 2017) ISSN: 1932-6203 [Electronic] United States
• PMID: 29149203 (Publication Type: Journal Article)

Chemical References

• Chromatin
• DNA-Binding Proteins
• Methyl Methanesulfonate
• Hydrogen Peroxide
• PARP1 protein, human
• PARP2 protein, human
• Poly (ADP-Ribose) Polymerase-1
• Poly(ADP-ribose) Polymerases
• DNA Helicases
• CHD1L protein, human

Topics

• Animals
• B-Lymphocytes (cytology, drug effects, metabolism)
• Cell Line, Transformed
• Cell Line, Tumor
• Chickens
• Chromatin (chemistry, metabolism)
• Chromatin Assembly and Disassembly
• DNA Helicases (deficiency, genetics)
• DNA Repair
• DNA-Binding Proteins (deficiency, genetics)
• Gene Expression Regulation
• HeLa Cells
• Humans
• Hydrogen Peroxide (pharmacology)
• Methyl Methanesulfonate (pharmacology)
• Osteoblasts (cytology, drug effects, metabolism)
• Poly (ADP-Ribose) Polymerase-1 (genetics, metabolism)
• Poly(ADP-ribose) Polymerases (genetics, metabolism)
• Signal Transduction