Adipocytes are highly specialized cells that play a major role in energy homeostasis in vertebrate organisms. Adipocytes are insulin-sensitive cells that have endocrine properties. Obesity is the primary disease of fat cells and a major risk factor for the development of type 2 diabetes (T2DM), cardiovascular disease, and hypertension. Obesity and its related disorders results in dysregulation of the mechanisms that control lipid storage, insulin action, and hormone secretion from adipocytes. The Stephens lab at LSU is largely focused on adipocyte biology.
Project: The regulation and activation of STATs in adipocytes. Significant advances towards an understanding how adipocytes contribute to disease has been made by the identification of transcription factors that regulate the differentiation of fat cells and are involved in the induction and maintenance of adipocyte gene expression. Our research has focused on the STAT family of transcription factors. STATs comprise a family of latent transcription factors that upon activation by a variety of hormones and growth factors will translocate to the nucleus. STATs can be rapidly activated to regulate gene expression and represent a relatively unexplored paradigm in the transcriptional regulation of fat cells.
Our recent studies demonstrate that STAT 5A can promote adipogenesis. We have also identified some STAT5 target genes in adipocytes, including fatty acid synthase, acyl CoA oxidase, and PDK4. Our studies will hopefully lead to insights into the molecular mechanisms regulating energy homeostasis and may contribute to understanding the defects underlying obesity and T2DM. This project is currently funded by the NIH.
Project: The modulation of adipocyte function by botanicals. In the last few years, we have obtained funds from the Pennington Biomedical Research Center to screen for botanicals that modulate fat cell function. We have several interesting projects examining the effects of botanicals and hope to identify botanical components that could be helpful for disease treatment.
White, U.A., Stewart, W. C. and Stephens, J. M. (2010) Neuropoietin and Oncostatin M have distinct crosstalk capabilities compared to other gp130 cytokines. Submitted.
Stewart, W.C., Pearcy, L.L., Floyd, Z.E., and Stephens, J.M. (2010) STAT5A expression confers adipogenesis in vivo. In revision.
White, U.A., and Stephens, J. M. Neuropoietin activates STAT3 independent of LIFR LIFR activation in adipocytes. (2010) Biochem. Biophys. Res. Commun. 395:48-50.
White, U.A and Stephens, J.M. (2010) Transcriptional factors that promote formation of white adipose tissue Molecular and Cellular Endocrinology 318:10-14
Amini, Z. J., Boyd, B., Doucet, J.A., Ribnicky, D.M. and Stephens, J. M. (2009) St. John's Wort inhibits adipocyte differentiation and induces insulin resistance in adipocytes. Biochem. Biophys. Res. Commun. 388:146–149