"BM180": a novel basement membrane protein with a role in stimulus-secretion coupling by lacrimal acinar cells

Abstract

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 inexamined lower molecular-mass basement membrane peak (peak 2) that contains cell adhesion activity inhibitable with the anti-BM180 monoclonal antibody 3E12. Removal of peak 2 by gel filtration or preincubation of basement membrane with 3E12 decreased regulated peroxidase secretion by one-half without affecting constitutive secretion or the amount of cellular peroxidase available for release. Adding back peak 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 and 60 kDa in the absence or presence of dithiothreitol, respectively, and shows no immunological identity by competitive enzyme-linked immunosorbent assay 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 signaling the appearance of a transducing element in the stimulus-secretion coupling pathway.

Effects of carbachol and catecholamines on ultrastructure and intracellular calcium-ion dynamics of acinar and myoepithelial cells of lacrimal glands

“…In contrast to the specimens having integrative conformation, fully isolated cells often showed degenerative structures as well as aberrant Ca 2+ imaging (Segawa et al 1985;Kanno et al 1991;Habara et al 1993). A recent study suggests that basement membrane can play an important role in stimu- lus-secretion coupling (Laurie et al 1996). Thus most of the current data obtained in fully isolated cultured cells may be full of unexpected artifacts.…”

Amniotic membrane as a carrier for lacrimal gland acinar cells

“…In previous studies, it was shown that lacrimal gland acinar cells cultured on plastic show disruption of cellular organisation with degranulation and loss of their ability to respond to stimulation by carbachol after approximately 3 days [4,18]. The reason for this morphologic and functional change is still unknown, but there is evidence that the integrity of cells depend on their normal paracrine, neural and endocrine environment, and that the extracellular matrix may be critical for providing this communication [12]. Matrigel, a solubilized preparation derived from the basement membranes of the EngelbrethHolm-Swarm mouse sarcoma line, is known to be rich in extracellular matrix molecules [9].…”

Quantitation of Rat Lacrimal Secretion: a Novel Sandwich ELISA with High Sensitivity

“…Released acinar cells were passed through 100 and 25 mm Nitex ®lters, centrifuged on a discontinuous 10, 30 and 60 % Percoll gradient, collected from the 30±60 % interface, washed, and plated at 1 . 9 Â 10 5 cells cm À2 on BMS-coated plates in serum-containing DMEM supplemented as detailed previously (Laurie et al, 1996). Isolation of mouse (6 week old C57BI6) lacrimal cells was similar to that used for rats, with the omission of Percoll and Nitex steps.…”

“…Once established, media (100 ml or 1/10 000 diluted) from unstimulated or stimulated rat lacrimal acinar cell cultures at different times and cellular densities were tested in parallel with known amounts of antigen, the latter providing a standard curve. Subsequent normalization to nanogram cellular DNA was made possible by DNA¯uorometric analysis of the cellular pellet (Laurie et al, 1996). Also tested were human re¯ex tears, as well as secretion media from mouse lacrimal gland fragments, and mouse and rabbit acinar cell cultures (the latter kindly provided by Dr Peter Gierow; University of Kalmar, Sweden).…”

“…Exocytosis of rat tear protein peroxidase from secretory vehicles and granules of lacrimal acinar cell cultures was monitored using a 96 well enzyme kinetic assay (Laurie et al, 1996) adapted from the Herzog et al (1976) method. Values from undiluted media were normalized to microgram cellular DNA.…”