Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ataxia telangiectasia-mutated and Rad3-related (ATR) kinase functions as a central node in the DNA damage response signaling network. The mechanisms by which ATR activity is amplified and/or maintained are not understood. Here we demonstrate that BRIT1/microcephalin (MCPH1), a human disease-related protein, is dispensable for the initiation but essential for the amplification of ATR signaling. BRIT1 interacts with and recruits topoisomerase-binding protein 1 (TopBP1), a key activator of ATR signaling, to the sites of DNA damage. Notably, replication stress-induced ataxia telangiectasia-mutated or ATR-dependent BRIT1 phosphorylation at Ser-322 facilitates efficient TopBP1 recruitment. These results reveal a mechanism that ensures the continuation of ATR-initiated DNA damage signaling. Our study uncovers a previously unknown regulatory axis of ATR signaling in maintaining genomic integrity, which may provide mechanistic insights into the perturbation of ATR signaling in human diseases such as neurodevelopmental defects and cancer.
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PMID:Phosphorylation of the BRCA1 C terminus (BRCT) repeat inhibitor of hTERT (BRIT1) protein coordinates TopBP1 protein recruitment and amplifies ataxia telangiectasia-mutated and Rad3-related (ATR) Signaling. 2530 47

Catalytic inhibition of topoisomerase II during G2 phase delays onset of mitosis due to the activation of the so-called decatenation checkpoint. This checkpoint is less known compared with the extensively studied G2 DNA damage checkpoint and is partially compromised in many tumor cells. We recently identified MCPH1 as a key regulator that confers cells with the capacity to adapt to the decatenation checkpoint. In the present work, we have explored the contributions of checkpoint kinase 1 (Chk1) and polo-like kinase 1 (Plk1), in order to better understand the molecular basis of decatenation checkpoint. Our results demonstrate that Chk1 function is required to sustain the G2 arrest induced by catalytic inhibition of Topo II. Interestingly, Chk1 loss of function restores adaptation in cells lacking MCPH1. Furthermore, we demonstrate that Plk1 function is required to bypass the decatenation checkpoint arrest in cells following Chk1 inhibition. Taken together, our data suggest that MCPH1 is critical to allow checkpoint adaptation by counteracting Chk1-mediated inactivation of Plk1. Importantly, we also provide evidence that MCPH1 function is not required to allow recovery from this checkpoint, which lends support to the notion that checkpoint adaptation and recovery are different mechanisms distinguished in part by specific effectors.
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PMID:Mitotic entry upon Topo II catalytic inhibition is controlled by Chk1 and Plk1. 3214 55