Distribution and characterization of plasmalemma vesicle protein-1 in rat endocrine glands.
Plasmalemma vesicle protein-1 (PV-1) is an integral membrane protein associated with endothelial cell caveolae and fenestrae. Since endocrine glands are enriched with fenestrated endothelium, we examined the distribution of PV-1 mRNA and protein in endocrine glands and determined its cellular localization. A single transcript was detected by RT-PCR in all endocrine glands examined. A synthetic peptide was used to generate antibodies for Western blotting and immunohistochemistry (IHC). Western blotting of membrane fractions from lung, pituitary, adrenal, testis and PV-1-transfected Cos-1 cells revealed a major 65 kDa protein. This protein binds to heparin with high affinity. Using IHC, PV-1 was localized to both endothelial cells of the adrenal zona reticularis and chromaffin cells of the medulla. In the pancreas, PV-1 expression was restricted to a few cells in the islets of Langerhans that partially overlap with somatostatin-positive delta-cells. In both neonatal and adult pituitaries, strong PV-1 immunoreactivity was detected in neural lobe pituicytes in a pattern similar to that of glial fibrillary acidic protein (GFAP). PV-1 and GFAP expression was seen in the adult, but not neonatal, intermediate lobe. Endothelial cells throughout the neonatal anterior lobe were PV-1 positive, but PV-1 in the adult was restricted to some endothelial and endocrine cells localized near the margins of lobe. In the adult testis, strong PV-1 expression was seen in germ cells within the seminiferous tubules that varied with the stage of spermatogenesis. In contrast, PV-1 in the neonatal testis was localized to the interstitial cells but not seminiferous tubules. In the ovary, PV-1 was expressed in stromal endothelial cells as well as the thecal layer of developing follicles. Over half the corpus luteal cells were positive for PV-1. Our data have shown that PV-1 is not restricted to endothelial cells but is localized in many types of endocrine and non-endocrine cells. Furthermore, PV-1 expression in the pituitary and testis is developmentally regulated.
Hnasko
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R
Department of Cell Biology, Neurobiology and Anatomy, University of Cincinnati Medical School, 3125 Eden Ave, Cincinnati, Ohio 45267, USA.
McFarland
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Ben-Jonathan
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N
D000311:Adrenal Glands / Q000737:chemistry; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D019556:COS Cells; D002352:Carrier Proteins / Q000032:analysis* / Q000235:genetics; D004702:Endocrine Glands / Q000737:chemistry*; D005260:Female; D007150:Immunohistochemistry; D008168:Lung / Q000737:chemistry; D008297:Male; D008565:Membrane Proteins / Q000032:analysis* / Q000235:genetics; D010053:Ovary / Q000737:chemistry; D010179:Pancreas / Q000737:chemistry; D010902:Pituitary Gland / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013737:Testis / Q000737:chemistry; D014162:Transfection
D002352:Carrier Proteins; D008565:Membrane Proteins; C470505:PLVAP protein, rat