Mohammad Ahmad

University of Toronto, Toronto, Ontario, Canada

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Publications (1)4.78 Total impact

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    ABSTRACT: Terminally differentiated cell types are needed to live and function in a postmitotic state for a lifetime. Cellular senescence is another type of permanent arrest that blocks the proliferation of cells in response to genotoxic stress. Here we show that the retinoblastoma protein (pRB) uses a mechanism to block DNA replication in senescence that is distinct from its role in permanent cell cycle exit associated with terminal differentiation. Our work demonstrates that a subtle mutation in pRB that cripples its ability to interact with chromatin regulators impairs heterochromatinization and repression of E2F-responsive promoters during senescence. In contrast, terminally differentiated nerve and muscle cells bearing the same mutation fully exit the cell cycle and block E2F-responsive gene expression by a different mechanism. Remarkably, this reveals that pRB recruits chromatin regulators primarily to engage a stress-responsive G1 arrest program.
    Molecular and Cellular Biology 12/2009; 30(4):948-60. DOI:10.1128/MCB.01168-09 · 4.78 Impact Factor

Publication Stats

33 Citations
4.78 Total Impact Points


  • 2009
    • University of Toronto
      • Department of Laboratory Medicine and Pathobiology
      Toronto, Ontario, Canada