A novel cell adhesive basement membrane protein with a putative
role in stimulus-secretion coupling by lacrimal acinar exocrine
cells.
Laurie, Gordon W., J. Douglas Glass, Rebecca A. Ogle, Cameron M.
Stone, James R. Sluss, and Lanlin Chen.
Department of Cell Biology, University of Virginia,
Charlottesville, VA
APStracts 2:0419C, 1995.
Regulated secretion requires the developmental coupling of neuronal or
hormonal stimuli to an exocytotic response - a multistep pathway
whose appearance may be linked with cellular adhesion to the newly
formed exocrine cell basement membrane. We screened for adhesion
-associated coupling activity using lacrimal acinar cells and have
identified BM180', a novel basement membrane protein enriched in
guanidine-HCl extracts of lacrimal and parotid exocrine secretory
glands. BM180 resides primarily in a previously unexamined lower
molecular weight basement membrane peak (Pk 2') which contains cell
adhesion activity inhibitable with the anti-BM180 monoclonal antibody
3E12. Removal of Pk 2 by gel filtration or preincubation of basement
membrane with 3E12 decreased regulated peroxidase secretion by one
-half without affecting constitutive secretion nor the amount of
cellular peroxidase available for release. Adding back Pk 2 restored
regulated secretion in a dose dependent and 3E12 inhibitable manner;
and suggested a synergistic relationship between BM180 and laminin-1.
BM180 has a mobility of 180 kDa and 60 kDa in the absence or presence
of DTT, respectively; and shows no immunological identity by
competitive ELISA with laminin-1, collagen IV, entactin, fibronectin,
BM-40, perlecan or vitronectin. We propose that BM180 is an important
resident of certain glandular basement membranes where it interacts
with the cell surface thereby possibly signalling the appearance of a
transducing element in the stimulus-secretion coupling pathway.
Received 28 September 1995; accepted in final form 13 November
1995.
APS Manuscript Number C594-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95