Separable roles for Mec1/ATR in genome maintenance, DNA replication, and checkpoint signaling.
Separable roles for Mec1/ATR in genome maintenance, DNA replication, and checkpoint signaling.
复制标题
Mec1/ATR 在基因组维护、DNA 复制和检查点信号传导中发挥着不同的作用。
DOI：
10.1101/gad.308148.117
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发表时间：
2018
影响因子：
10.5
通讯作者：
Smolka,MarcusBustamante
中科院分区：
文献类型：
--
作者：
Lanz,MichaelCharles;Oberly,Susannah;Sanford,EthanJames;Sharma,Sushma;Chabes,Andrei;Smolka,MarcusBustamante
The Mec1/ATR kinase coordinates multiple cellular responses to replication stress. In addition to its canonical role in activating the checkpoint kinase Rad53, Mec1 also plays checkpoint-independent roles in genome maintenance that are not well understood. Here we used a combined genetic–phosphoproteomic approach to manipulate Mec1 activation and globally monitor Mec1 signaling, allowing us to delineate distinct checkpoint-independent modes of Mec1 action. Using cells in which endogenous Mec1 activators were genetically ablated, we found that expression of “free” Mec1 activation domains (MADs) can robustly activate Mec1 and rescue the severe DNA replication and growth defects of these cells back to wild-type levels. However, unlike the activation mediated by endogenous activator proteins,“free” MADs are unable to stimulate Mec1-mediated suppression of gross chromosomal rearrangements (GCRs), revealing that Mec1's role in genome maintenance is separable from a previously unappreciated proreplicative function. Both Mec1's functions in promoting replication and suppressing GCRs are independent of the downstream checkpoint kinases. Additionally, Mec1-dependent GCR suppression seems to require localized Mec1 action at DNA lesions, which correlates with the phosphorylation of activator-proximal substrates involved in homologous recombination-mediated DNA repair. These findings establish that Mec1 initiates checkpoint signaling, promotes DNA replication, and maintains genetic stability through distinct modes of action.
