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  • 53BP1 and USP28 mediate p53-dependent cell cycle arrest in response to centrosome loss and prolonged mitosis.

53BP1 and USP28 mediate p53-dependent cell cycle arrest in response to centrosome loss and prolonged mitosis.

eLife (2016-07-03)
Chii Shyang Fong, Gregory Mazo, Tuhin Das, Joshua Goodman, Minhee Kim, Brian P O'Rourke, Denisse Izquierdo, Meng-Fu Bryan Tsou
ABSTRACT

Mitosis occurs efficiently, but when it is disturbed or delayed, p53-dependent cell death or senescence is often triggered after mitotic exit. To characterize this process, we conducted CRISPR-mediated loss-of-function screens using a cell-based assay in which mitosis is consistently disturbed by centrosome loss. We identified 53BP1 and USP28 as essential components acting upstream of p53, evoking p21-dependent cell cycle arrest in response not only to centrosome loss, but also to other distinct defects causing prolonged mitosis. Intriguingly, 53BP1 mediates p53 activation independently of its DNA repair activity, but requiring its interacting protein USP28 that can directly deubiquitinate p53 in vitro and ectopically stabilize p53 in vivo. Moreover, 53BP1 can transduce prolonged mitosis to cell cycle arrest independently of the spindle assembly checkpoint (SAC), suggesting that while SAC protects mitotic accuracy by slowing down mitosis, 53BP1 and USP28 function in parallel to select against disturbed or delayed mitosis, promoting mitotic efficiency.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-phospho-Histone H2A.X (Ser139) Antibody, clone JBW301, clone JBW301, Upstate®, from mouse
Sigma-Aldrich
Anti-53BP1 Antibody, clone BP13, clone BP13, Chemicon®, from mouse
Sigma-Aldrich
Anti-Centrin Antibody, clone 20H5, clone 20H5, from mouse
Sigma-Aldrich
Anti-Actin antibody produced in rabbit, affinity isolated antibody, buffered aqueous solution