DNA damage activates the SAC in an ATM/ATR-dependent manner, independently of the kinetochore.
The DNA damage checkpoint and the spindle assembly checkpoint (SAC) are two important regulatory mechanisms that respond to different lesions. The DNA damage checkpoint detects DNA damage, initiates protein kinase cascades, and inhibits the cell cycle. The SAC relies on kinetochore-dependent assembly of protein complexes to inhibit mitosis when chromosomes are detached from the spindle. The two checkpoints are thought to function independently. Here we show that yeast cells lacking the DNA damage checkpoint arrest prior to anaphase in response to low doses of the DNA damaging agent methyl methane sulfonate (MMS). The arrest requires the SAC proteins Mad1, Mad2, Mad3, Bub1, and Bub3 and works through Cdc20 and Pds1 but unlike the normal SAC, does not require a functional kinetochore. Mec1 (ATR) and Tel1 (ATM) are also required, independently of Chk1 and Rad53, suggesting that Mec1 and Tel1 inhibit anaphase in response to DNA damage by utilizing SAC proteins. Our results demonstrate cross-talk between the two checkpoints and suggest that assembling inhibitory complexes of SAC proteins at unattached kinetochores is not obligatory for their inhibitory activity. Furthermore, our results suggest that there are novel, important targets of ATM and ATR for cell cycle regulation.
Kim
Eun Mi
EM
Department of Biochemistry and Molecular Genetics, University of Virginia Medical Center, Charlottesville, Virginia, United States of America.
Burke
Daniel J
DJ
D000705:Anaphase; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D018386:Kinetochores / Q000378:metabolism; D064246:Mad2 Proteins; D008741:Methyl Methanesulfonate / Q000633:toxicity; D008954:Models, Biological; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism
C070352:BUB3 protein, S cerevisiae; D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D047908:Intracellular Signaling Peptides and Proteins; C501382:MAD1 protein, S cerevisiae; C577695:MAD2 protein, S cerevisiae; C406764:MAD3 protein, S cerevisiae; D064246:Mad2 Proteins; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D008741:Methyl Methanesulfonate; C090464:Bub1 spindle checkpoint protein; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C513623:TEL1 protein, S cerevisiae