Abstract

Most normal human cells undergo a limited number of cell divisions, eventually entering an irreversibly arrested state, through either senescence or differentiation. Both processes have major implications for human health; between them impacting birth defects, cancer and the degenerative effects of human aging. For example, defects in cell differentiation during embryo development result in human birth defects. Senescence and differentiation programs are both characterized by profound changes in chromatin structure, and, in both cases, this is thought to contribute to the altered cell phenotype. We are using senescence as a model system to study these changes in chromatin structure and their contribution to two hallmarks of both senescence and terminal differentiation, repression of proliferation-promoting genes and cell cycle exit. Recently, we showed that the chromatin regulatory protein, HIRA, and its physical binding partner, ASF1a, both play a key role in formation of a novel chromatin structure in senescent cells, called senescence associated heterochromatin foci (SAHF). SAHF is thought to silence genes that drive cell proliferation. HIRA and ASF1a drive SAHF formation, acting in concert with a subnuclear organelle, the PML body; and two chromatin associated proteins, HP1 and macroH2A. Preliminary data indicate that the HIRA/ASF1a pathway is activated by the key proliferation-regulating kinase, GSK3. To understand the physiological significance and molecular basis of SAHF formation and its mode of activation in presenescent cells, we will use cell and molecular biology techniques to:
Specific Aim 1. Investigate the structure of SAHF, its mechanism of assembly by HIRA/ASF1a and PML nuclear bodies and identify its key growth suppressor components.
Specific Aim 2. Investigate the function and mechanism of incorporation into SAHF of chromatin associated proteins, HP1 and macroH2A.
Specific Aim 3. Investigate the role of GSK3 activity in localization of HIRA to PML bodies, formation of SAHF and onset of senescence.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM062281-08
Application #
7367887
Study Section
Nuclear Dynamics and Transport (NDT)
Program Officer
Carter, Anthony D
Project Start
2001-03-01
Project End
2010-02-28
Budget Start
2008-03-01
Budget End
2009-02-28
Support Year
8
Fiscal Year
2008
Total Cost
$317,554
Indirect Cost

  Institution

Name
Research Institute of Fox Chase Cancer Center
Department
Type
DUNS #
064367329
City
Philadelphia
State
PA
Country
United States
Zip Code
19111

  Publications

Kennedy, Alyssa L; Morton, Jennifer P; Manoharan, Indrani et al. (2011) Activation of the PIK3CA/AKT pathway suppresses senescence induced by an activated RAS oncogene to promote tumorigenesis. Mol Cell 42:36-49
Ambagala, Aruna P; Bosma, Trent; Ali, Mir A et al. (2009) Varicella-zoster virus immediate-early 63 protein interacts with human antisilencing function 1 protein and alters its ability to bind histones h3.1 and h3.3. J Virol 83:200-9
Banumathy, Gowrishankar; Somaiah, Neeta; Zhang, Rugang et al. (2009) Human UBN1 is an ortholog of yeast Hpc2p and has an essential role in the HIRA/ASF1a chromatin-remodeling pathway in senescent cells. Mol Cell Biol 29:758-70
Adams, Peter D; Enders, Greg H (2008) Wnt-signaling and senescence: A tug of war in early neoplasia? Cancer Biol Ther 7:1706-11
Sedivy, John M; Banumathy, Gowrishankar; Adams, Peter D (2008) Aging by epigenetics--a consequence of chromatin damage? Exp Cell Res 314:1909-17
Ye, Xiaofen; Zerlanko, Brad; Kennedy, Alyssa et al. (2007) Downregulation of Wnt signaling is a trigger for formation of facultative heterochromatin and onset of cell senescence in primary human cells. Mol Cell 27:183-96
Adams, Peter D (2007) Remodeling of chromatin structure in senescent cells and its potential impact on tumor suppression and aging. Gene 397:84-93
Zhang, Rugang; Adams, Peter D; Ye, Xiaofen (2007) Design and application of a shRNA-based gene replacement retrovirus. Methods Mol Biol 408:211-21
Zhang, Rugang; Adams, Peter D (2007) Heterochromatin and its relationship to cell senescence and cancer therapy. Cell Cycle 6:784-9
Zhang, Rugang; Liu, Song-tao; Chen, Wei et al. (2007) HP1 proteins are essential for a dynamic nuclear response that rescues the function of perturbed heterochromatin in primary human cells. Mol Cell Biol 27:949-62

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