| First Author | Smith KD | Year | 2009 |
| Journal | J Cell Biol | Volume | 187 |
| Issue | 1 | Pages | 15-23 |
| PubMed ID | 19805627 | Mgi Jnum | J:153811 |
| Mgi Id | MGI:4366368 | Doi | 10.1083/jcb.200905006 |
| Citation | Smith KD, et al. (2009) Tim-Tipin dysfunction creates an indispensible reliance on the ATR-Chk1 pathway for continued DNA synthesis. J Cell Biol 187(1):15-23 |
| abstractText | The Tim (Timeless)-Tipin complex has been proposed to maintain genome stability by facilitating ATR-mediated Chk1 activation. However, as a replisome component, Tim-Tipin has also been suggested to couple DNA unwinding to synthesis, an activity expected to suppress single-stranded DNA (ssDNA) accumulation and limit ATR-Chk1 pathway engagement. We now demonstrate that Tim-Tipin depletion is sufficient to increase ssDNA accumulation at replication forks and stimulate ATR activity during otherwise unperturbed DNA replication. Notably, suppression of the ATR-Chk1 pathway in Tim-Tipin-deficient cells completely abrogates nucleotide incorporation in S phase, indicating that the ATR-dependent response to Tim-Tipin depletion is indispensible for continued DNA synthesis. Replication failure in ATR/Tim-deficient cells is strongly associated with synergistic increases in H2AX phosphorylation and DNA double-strand breaks, suggesting that ATR pathway activation preserves fork stability in instances of Tim-Tipin dysfunction. Together, these experiments indicate that the Tim-Tipin complex stabilizes replication forks both by preventing the accumulation of ssDNA upstream of ATR-Chk1 function and by facilitating phosphorylation of Chk1 by ATR. |
