Cell and Developmental Biology University of Michigan

Current research is involved with basic mechanisms involved in regulation of exocrine and endocrine secretion, particularly with regard to vesicular transport and fusion. In collaboration with Dr. Edward Stuenkel (Molecular & integrative Physiology), my laboratory focuses on morphological aspects of regulation of insulin secretion and neurosecretion (chomaffin cells) at the plasma membrane, including interactions of small G-proteins (e.g., Rab 27A) and other modulators (e.g., tomosyn) with the t-SNARE syntaxin 1A. Methods involve confocal microscopy coupled with immunocytochemistry of expressed proteins, fluorescence recovery after photobleaching (FRAP), fluorescence resonance energy transfer (FRET), and other optical techniques.

In collaboration with Dr. John Williams (Molecular & integrative Physiology), we localize small G-proteins and other constituents thought to be involved in regulated granule secretion of digestive enzymes in pancreatic exocrine cells and purified zymogen granules, and study morphological aspects of regulation of pancreatic growth, and alterations accompanying induced pancreatitis.

Publications

Representative Publications

• *Lui, J., S.A. Ernst*, S.E. Gladycheva, Y.Y. Lee, S.I. Lentz, C.S. Ho, Q. Li, and E.L. Stuenkel. 2004. Fluorescence resonance energy transfer reports properties of syntaxin1a interaction with Munc18-1 in vivo. J. Biol. Chem. 279:55924-55936. (*Both authors contributed equally to this work)
• Chen, X., A.K. Walker, J.R. Strahler, E.S. Simon, S.L. Tomanicek-Volk, B.B. Nelson, M.C. Hurley, S.A. Ernst, J.A. Williams, and P.C. Andrews. 2006. Organellar proteomics. Analysis of pancreatic zymogen granule membranes. Mol. Cellular Proteomics 5:306-312. (includes journal cover illustration)
• D’Andrea-Merrins, M., L. Chang, A.D. Lam, S.A. Ernst, and E.L. Stuenkel. 2007. Munc18c interaction with syntaxin 4 monomers and SNARE complex intermediates in GLUT4 vesicle trafficking. J.Biol.Chem. 282:16553-16566.
• Crozier S.J., M.D. Sans, C.H. Lang, L.G. D'Alecy, S.A. Ernst, and J.A. Williams. 2008. CCK-induced pancreatic growth is not limited by mitogenic capacity in mice. Am. J. Physiol. Gastrointest. Liver Physiol. 294(5):G1148-57.
• Sabbatini, M.E., X. Chen, S.A Ernst, and J.A Williams. 2008. Rap1 activation plays a regulatory role in pancreatic amylase secretion. J. Biol. Chem., 283:23884-23894.