Positions

Assistant Professor
Molecular and Human Genetics
Baylor College of Medicine
Assistant Professor
Huffington Center On Aging
Baylor College of Medicine
Houston, TX, US
Member
Dan L Duncan Comprehensive Cancer Center
Baylor College of Medicine
Houston, Texas, United States

Education

PhD from Southern Illinois University
Post-Doctoral Fellowship at University of Pennsylvania

Professional Interests

  • Our lab uses yeast replicative aging as a model, together with human primary cell lines and adult stem cells, to study evolutionarily conserved epigenetic mechanisms during aging and development of age-related cancers

Professional Statement

Our laboratory is studying epigenetic regulation mechanisms during aging and oncogenesis. Aging is the single greatest risk factor for diseases that are principal causes of mortality, including cardiovascular diseases, diabetes, neurodegenerative diseases and infectious diseases. A breakthrough in aging research resulting in even a moderate retardation of aging and a delay in the onset of age-associated diseases, such as cancer, would have tremendous impact on the quality of life for the general public. However, aging and how it contributes to the development of age-associated diseases remain poorly understood. Epigenetic changes, including histone modifications and proteome, are critical regulatory mechanisms, involved in all developmental processes including aging and age-associated diseases. The goal of our research is to discover novel chromatin and proteomics regulation pathways that modulate longevity and regulate the development of age-associated diseases, such as cancer. This mechanistic study will form the basis in future development of therapeutic target for treating age-associated diseases and improving human health span.

Epigenetics generally includes all cellular alterations beyond genetic changes that result in observable phenotypes. In practice, epigenetics usually means persistent covalent alterations to chromatin, such as histone acetylation and DNA methylation. Recent proteomics and acetylomics studies have broadened our views of epigenetics and many more enzymes and factors can carry modifications that confer epigenetic phenomena. It is very clear now epigenetics represents a complex regulation network on top of the genetic code. In medicine, epigenetics holds a very promising future because interventions in epigenetics can alter genetic outcomes and the strength of such intervention can be fine-tuned.

Replicative aging of budding yeast has been a powerful system for aging studies, providing fundamental genetic and molecular insights into both cellular and organismal aging. Studies of chromatin biology have also immensely benefited from the yeast model, since it provides a uniquely tractable system for such studies and also because many molecular mechanisms of chromatin are highly conserved from yeast to complex eukaryotes. We use the budding yeast replicative aging as a model to study how epigenetic regulations can modulate longevity. In the past, we have shown that elevated levels of histone H4K16 acetylation near telomeres is a hallmark of old cells. It is regulated by a pair of enzymes Sir2 and Sas2 in yeast and is a causal factor in determining lifespan. Furthermore, through a series of unbiased lifespan screens and other high throughput systems biology approaches, we have identified more chromatin regulation pathways that seem to also alter lifespan. Such pathways include those involved in transcription regulation, DNA damage response, cellular stress response, chromatin compaction and heterochromatin formation, etc. Further studies are currently carried out in our lab to elucidate the molecular mechanisms and their causal relationship to aging.

Stem cell aging and cellular senescence are important processes that contribute to the aging pathology and development of cancer. As a complement to our yeast replicative aging model, we are using mammalian primary cell lines and adult stem cells to study whether and how chromatin and epigenetic regulation pathways identified in yeast are involved in stem cell aging and cellular senescence. Changes in aging and senescence phenotype are investigated by knocking down conserved enzymes. Epigenetic features are tracked during senescence and compared between young and old stem cells. Studying mechanistic conservation using mammalian cell models will provide valuable insights into mammalian aging and conditions predisposed to cancer development.

Selected Publications

Funding

CPRIT Scholar for Cancer Research
- #R1306
Grant funding from Cancer Prevention Research Institute of Texas (CPRIT)
Regulation of longevity through maintenance of transcription fidelity
- #R01AG052507
Grant funding from National Institute on Aging (NIA)