Restricted endothelial cell expression of gravin in vivo.
BACKGROUND
Gravin, a novel, high molecular weight, intracellular protein, is expressed in endothelial cells and several other adherent cell types in vitro. To gain insights into its function, we examined the distribution of gravin in tissues.


METHODS
Affinity-purified polyclonal and monoclonal antibodies were raised against a bacterial fusion protein corresponding to the carboxyl terminus of gravin and against affinity-isolated gravin. The specificity of the antibodies was characterized by immunoblotting bacterial, cell, and tissue extracts. The characterized antibodies were used to localize gravin in baboon tissue sections by immunocytochemistry and immunofluorescence microscopy.


RESULTS
The antibodies specifically immunoblotted the fusion protein and recognized either a band at 250 kDa or a doublet at 300 kDa on immunoblots of MG63 cells, HEL cells stimulated with phorbol ester, and several baboon tissues. In tissue sections, cell types that express gravin included fibroblasts, components of the peripheral and central nervous system, the adrenal medulla, the somatic layer of Bowman's capsule, cells associated with the glomerulus, and smooth muscle of certain organs. In contrast, most epithelia and all endothelia, with the exception of endothelia of the hepatic sinusoids and intestinal lacteals, lacked gravin. Levels of gravin mRNA expression in stimulated HEL cells increased dramatically when cells were stimulated in the presence of cycloheximide, suggesting that gravin expression may be partly regulated by protein-dependent mRNA catabolism.


CONCLUSIONS
These data indicate that gravin expression is regulated in endothelial cells, possibly through protein-dependent mRNA catabolism. The strong expression of gravin in fibroblasts, neurons, and cells derived from neural crest in vivo and in adherent cells in vitro further suggests that this protein may play role in the modulation of cell motility and adhesion.
Grove
B D
BD
Department of Cellular Biology and Anatomy, Louisiana State University Medical Center, Shreveport 71130.
Bowditch
R
R
Gordon
T
T
del Zoppo
G
G
Ginsberg
M H
MH
D054758:A Kinase Anchor Proteins; D000818:Animals; D000918:Antibody Specificity; D018797:Cell Cycle Proteins; D002460:Cell Line; D004730:Endothelium, Vascular / Q000737:chemistry* / Q000166:cytology; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D009132:Muscles / Q000737:chemistry*; D009420:Nervous System / Q000737:chemistry* / Q000166:cytology; D010215:Papio; D011506:Proteins / Q000032:analysis*; D011817:Rabbits
D054758:A Kinase Anchor Proteins; C491162:AKAP12 protein, human; C491161:Akap12 protein, mouse; D018797:Cell Cycle Proteins; D011506:Proteins