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Coordinated regulation of p53 apoptotic targets BAX and PUMA by SMAR1 through an identical MAR element
Author(s) -
Sinha Surajit,
Malonia Sunil Kumar,
Mittal Smriti P K,
Singh Kamini,
Kadreppa Sreenath,
Kamat Rohan,
Mukhopadhyaya Robin,
Pal Jayanta K,
Chattopadhyay Samit
Publication year - 2010
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2009.395
Subject(s) - puma , biology , apoptosis , p53 protein , microbiology and biotechnology , genetics
How tumour suppressor p53 bifurcates cell cycle arrest and apoptosis and executes these distinct pathways is not clearly understood. We show that BAX and PUMA promoters harbour an identical MAR element and are transcriptional targets of SMAR1. On mild DNA damage, SMAR1 selectively represses BAX and PUMA through binding to the MAR independently of inducing p53 deacetylation through HDAC1. This generates an anti‐apoptotic response leading to cell cycle arrest. Importantly, knockdown of SMAR1 induces apoptosis, which is abrogated in the absence of p53. Conversely, apoptotic DNA damage results in increased size and number of promyelocytic leukaemia (PML) nuclear bodies with consequent sequestration of SMAR1. This facilitates p53 acetylation and restricts SMAR1 binding to BAX and PUMA MAR leading to apoptosis. Thus, our study establishes MAR as a damage responsive cis element and SMAR1–PML crosstalk as a switch that modulates the decision between cell cycle arrest and apoptosis in response to DNA damage.