Physics and Astronomy Colloquium          THURSDAY, September 14, 2006

Biomedical and Physical Sciences Bldg.    Room 1415     4:10 p.m.

Speaker:  Bhanu P. Jena, Ph.D., D.Sc.
          George E. Palade Distinguished University Professor
          Department of Physiology
          Wayne State University School of Medicine
          Departments of Chemical Engineering & Material Science
          Director, NanoBioScience Institute



Title:    Molecular Machinery & Mechanism of Cell Secretion

Abstract:

    Secretion occurs in all living cells  and involves the delivery of
intracellular products to the cell exterior.  Defects in secretion and
membrane fusion lead to diabetes, Alzheimer's, Parkinson's, and a host
of diseases. Secretory products are packaged and stored in membraneous
sacs or vesicles within the cell.  When the cell needs to secrete, the
secretory vesicles  containing them dock and fuse  at plasma membrane-
associated supramolecular structures called porosomes or fusion pores,
to release their contents.  Porosomes were first identified  more than
a decade ago using the atomic force microscope (AFM), and subsequently
enzyme secretion, or hormone release utilize a highly regulated secre-
tory process. During secretion, swelling of secretory vesicles results
in a build-up of intravesicular pressure, allowing expulsion of vesic-
ular contents.  The extent of vesicle swelling  dictates the amount of
vesicular contents expelled. The discovery of the porosome as the uni-
versal secretory machinery,  its isolation, its structure and dynamics
and nm resolution  and in real time,  its biochemical composition  and
functional reconstitution  into artificial  lipid membrane,  have been
determined.