Caffeine can override the S-M checkpoint in fission yeast.

نویسندگان

  • S W Wang
  • C Norbury
  • A L Harris
  • T Toda
چکیده

The replication checkpoint (or 'S-M checkpoint') control prevents progression into mitosis when DNA replication is incomplete. Caffeine has been known for some time to have the capacity to override the S-M checkpoint in animal cells. We show here that caffeine also disrupts the S-M checkpoint in the fission yeast Schizosaccharomyces pombe. By contrast, no comparable effects of caffeine on the S. pombe DNA damage checkpoint were seen. S. pombe cells arrested in early S phase and then exposed to caffeine lost viability rapidly as they attempted to enter mitosis, which was accompanied by tyrosine dephosphorylation of Cdc2. Despite this, the caffeine-induced loss of viability was not blocked in a temperature-sensitive cdc2 mutant incubated at the restrictive temperature, although catastrophic mitosis was prevented under these conditions. This suggests that, in addition to S-M checkpoint control, a caffeine-sensitive function may be important for maintenance of cell viability during S phase arrest. The lethality of a combination of caffeine with the DNA replication inhibitor hydroxyurea was suppressed by overexpression of Cds1 or Chk1, protein kinases previously implicated in S-M checkpoint control and recovery from S phase arrest. In addition, the same combination of drugs was specifically tolerated in cells overexpressing either of two novel S. pombe genes isolated in a cDNA library screen. These findings should allow further molecular investigation of the regulation of S phase arrest, and may provide a useful system with which to identify novel drugs that specifically abrogate the checkpoint control.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Caffeine-mediated override of checkpoint controls. A requirement for rhp6 (Schizosaccharomyces pombe).

Cells exposed to inhibitors of DNA synthesis or suffering DNA damage are arrested or delayed in interphase through the action of checkpoint controls. If the arrested cell is exposed to caffeine, relatively normal cell cycle progression is resumed and, as observed in checkpoint control mutants, loss of checkpoint control activity is associated with a reduction in cell viability. To address the m...

متن کامل

Nuclear exclusion of Cdc25 is not required for the DNA damage checkpoint in fission yeast

Maintenance of genome integrity requires a checkpoint that restrains mitosis in response to DNA damage [1]. This checkpoint is enforced by Chk1, a protein kinase that targets Cdc25 [2--7]. Phosphorylated Cdc25 associates with 14-3-3 proteins, which appear to occlude a nuclear localization signal (NLS) and thereby inhibit Cdc25 nuclear import [6, 8--14]. Proficient checkpoint arrest is thought t...

متن کامل

Caffeine inhibits the checkpoint kinase ATM

The basis of many anti-cancer therapies is the use of genotoxic agents that damage DNA and thus kill dividing cells. Agents that cause cells to override the DNA-damage checkpoint are predicted to sensitize cells to killing by genotoxic agents. They have therefore been sought as adjuncts in radiation therapy and chemotherapy. One such compound, caffeine, uncouples cell-cycle progression from the...

متن کامل

Caffeine stabilizes Cdc25 independently of Rad3 in S chizosaccharomyces pombe contributing to checkpoint override

Cdc25 is required for Cdc2 dephosphorylation and is thus essential for cell cycle progression. Checkpoint activation requires dual inhibition of Cdc25 and Cdc2 in a Rad3-dependent manner. Caffeine is believed to override activation of the replication and DNA damage checkpoints by inhibiting Rad3-related proteins in both Schizosaccharomyces pombe and mammalian cells. In this study, we have inves...

متن کامل

The fission yeast Rad32 (Mre11)-Rad50-Nbs1 complex is required for the S-phase DNA damage checkpoint.

Mre11, Rad50, and Nbs1 form a conserved heterotrimeric complex that is involved in recombination and DNA damage checkpoints. Mutations in this complex disrupt the S-phase DNA damage checkpoint, the checkpoint which slows replication in response to DNA damage, and cause chromosome instability and cancer in humans. However, how these proteins function and specifically where they act in the checkp...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:
  • Journal of cell science

دوره 112 ( Pt 6)  شماره 

صفحات  -

تاریخ انتشار 1999