Research during the past two decades has suggested that the retinoblastoma tumor suppressor (pRB) and two related proteins (p107 and p130;collectively referred to as pocket proteins) play a fundamental role in regulating the cell cycle, and pRB has been shown to be a prototypical tumor suppressor mutated in a large portion of human tumors. In addition, pRB has been shown to play a pivotal role in differentiation of several tissues, including muscle and bone. Our work during the previous funding period, under the auspices of our parent grant application, has highlighted unique roles for each of the pocket proteins in responding to growth arrest cues and in both promoting and maintaining differentiation of muscle. In addition, we have succeeded for the first time in purifying pRB complexes from proliferating and differentiated muscle cells. In this grant, we propose the following aims to further dissect the mechanisms underlying pocket protein involvement in cell cycle exit and differentiation. (1) We will characterize pRB complexes in proliferating and differentiated cells and examine the impact of depleting associated proteins on gene expression and differentiation;(2) we will identify targets of the pRB complexes in cultured cells and in muscle tissue and examine the role of pRB complexes in modification of target gene chromatin;and (3) we will examine whether mechanisms analogous to those discovered in Aims 1 and 2 pertain to reversible growth arrest as well and determine if there are mechanisms that distinguish reversible and irreversible cell cycle exit. In the current Revision to the original parent application, we propose broadening our investigation of chromatin modifications associated with myogenic differentiation, focusing in particular on those changes that are dependent on the pRB family of proteins. We will incorporate the new, state-of-the-art ChIP-sequencing approach to examine these modifications in an unbiased, genome-wide manner. These studies will enhance our understanding of regulatory controls that are essential for both reversible and permanent withdrawal from the cell cycle and differentiation. In addition, they will elucidate critical interactions between repressors, co-repressors, and chromatin modifications as they occur in a developmentally relevant setting.
Cancer results in some cases when cells fail to properly differentiate. Differentiation is coupled to exit from the cell cycle, and the retinoblastoma (pRB) tumor suppressor plays a pivotal role in controlling growth arrest and differentiation. This proposal seeks to understand the underlying mechanisms whereby pRB regulates gene expression and controls the decision to permanently stop dividing and to terminally differentiate.
|Lilja, Karin C; Zhang, Nan; Magli, Alessandro et al. (2017) Pax7 remodels the chromatin landscape in skeletal muscle stem cells. PLoS One 12:e0176190|
|Strikoudis, Alexandros; Lazaris, Charalampos; Trimarchi, Thomas et al. (2016) Regulation of transcriptional elongation in pluripotency and cell differentiation by the PHD-finger protein Phf5a. Nat Cell Biol 18:1127-1138|
|Yang, Yan; Li, Wencheng; Hoque, Mainul et al. (2016) PAF Complex Plays Novel Subunit-Specific Roles in Alternative Cleavage and Polyadenylation. PLoS Genet 12:e1005794|
|Blum, Roy (2015) Stepping inside the realm of epigenetic modifiers. Biomol Concepts 6:119-36|
|Blum, Roy (2014) Activation of muscle enhancers by MyoD and epigenetic modifiers. J Cell Biochem 115:1855-67|
|Bowman, Christopher John; Ayer, Donald E; Dynlacht, Brian David (2014) Foxk proteins repress the initiation of starvation-induced atrophy and autophagy programs. Nat Cell Biol 16:1202-14|
|Cheng, Jemmie; Blum, Roy; Bowman, Christopher et al. (2014) A role for H3K4 monomethylation in gene repression and partitioning of chromatin readers. Mol Cell 53:979-92|
|Blum, Roy; Dynlacht, Brian D (2013) The role of MyoD1 and histone modifications in the activation of muscle enhancers. Epigenetics 8:778-84|
|Vethantham, Vasupradha; Yang, Yan; Bowman, Christopher et al. (2012) Dynamic loss of H2B ubiquitylation without corresponding changes in H3K4 trimethylation during myogenic differentiation. Mol Cell Biol 32:1044-55|
|Blum, Roy; Vethantham, Vasupradha; Bowman, Christopher et al. (2012) Genome-wide identification of enhancers in skeletal muscle: the role of MyoD1. Genes Dev 26:2763-79|
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