Chang-Hyon Chris Yun, PhD
Professor of Medicine
Department of Medicine
Office: Whitehead Research Bldg 201
BiographyI joined Emory University in 2002. Prior to that I received a Ph.D degree in Biophysics from the University of Illinois at Urbana-Champaign and went on to do postdoctoral training at Johns Hopkins in electrolyte transport. I was promoted to an assistant professor at Hopkins where I established an independent research career.
In mammalian intestine, NHE3 is a component of electroneutral NaCl absorption, which is a major constituent in basal Na+ and fluid absorption and this is a frequent target of inhibition in many diarrheal diseases. Another site of NHE3 is kidney where 70% of HCO3- reabsorption can be attributed to Na+/H+ exchanger NHE3. NHE3 is regulated by hormones, growth factor, and external stimuli that target protein kinases. The first goal is understand the mechanisms of NHE3 regulation by G protein-coupled receptors and protein kinases. The second goal is to delineate how the interaction of NHE3 with accessory proteins (NHERF1, NHERF2, and IRBIT) affects the signaling targeting NHE3. We are focusing on the cellular signaling elicited by glucocorticoids, angiotensin and lysophosphatidic acid (LPA).
In another project, we are investigating the role of LPA in colorectal cancer. LPA is a lipid mediator with diverse biological properties such as proliferation, apoptosis, contraction, migration, and aggregation. The effects of LPA are mediated by the G protein-coupled receptors; LPA1, LPA2 and LPA3. The first indication that LPA could contribute to tumorigenesis came from studies showing that LPA increases motility and invasiveness of cells. LPA levels are significantly increased in malignant ascites, and its receptors are aberrantly expressed in ovarian cancer. In addition, our recent study has shown that LPA2 is over-expressed in several cancers, including colon, testis, uterus, and rectum. In addition, we have recently demonstrated that cellular signaling by LPA2 is mediated through its interaction with scaffold proteins, such as NHERF2 and MAGI-3. The goals of this project is to understand the role of LPA and LPA2 receptor in colorectal cancer and the role of scaffold proteins regulation of cellular signaling by LPA2.
I am a coordinator of the basic research seminars for the Division. I am a member of BCDB and NHS programs at Emory University. I am currently one of coordinators fro BCDB 570r.
Member of the Faculty Development Committee of DOM. Chair of the Grant Review Committee. Member of the Editorial Board for Am J Physiol-GI. Member of the Research Award Review Panel of American Gastroenterology Association. Ad hoc reviewer for NIH study sections. Member of the CIMG study section at NIH. Member of the Abstract Review Committee for American Gastroenterological Association. Reviewer for more than 10 journals.
Zhang, H, Wang, D, Sun, H, Hall, R.A., and Yun, C.C. (2007) MAGI-3 regulates LPA-induced activation of ERK and RhoA, Cell. Signal. 9:261-268.
Wang, D., Zhang, H., Lang, F., and Yun, C.C. (2007) Acute activation of Na+/H+ exchanger NHE3 by glucocorticoids correlates with activation of SGK1 and is independent of glucocorticoid receptor Am. J. Physiol-Cell Physiol, 292, C396-C404.
Yun, C.C., Sun, H., Wang,, W., Rusovici, R., Castleberry, A., Hall, R, and Shim, H. (2005) The LPA2 receptor mediates mitogenic signals in human colon cancer cells Am J. Physiol-Cell. 289:C2-C11
Wang, D., Sun, H., Lang, F., and Yun, C.C. (2005) Activation of NHE3 by dexamethasone requires phosphorylation of NHE3 at S663 by SGK1. Am J. Physiol-Cell. 289: C802-810.
He, P., Zhang, H., and Yun, C.C. (2008) IRBIT, IP3 receptor binding protein released with IP3, binds Na+/H+ exchanger NHE3 and activates NHE3 activity in response to calcium. J. Biol. Chem. 283:33544-33553.
Lin, S., Wang, D., Iyer, S., Ghaleb, A.M., Shim, H., Yang, V.W., Chun, J., and Yun, C.C. (2009) LPA2 promotes tumor formation in an experimental model of colitis-associated colon cancer. Gasteroenterology, 136: 1711-1720.