Differential storage of prolactin, granins (Chromogranin B and secretogranin II), and constitutive secretory markers in rat pituitary GH4C1 cells.
The rat pituitary cell line GH4C1 secretes granins (chromogranin B and secretogranin II) and prolactin by the regulated secretory pathway. The intracellular storage of prolactin is preferentially induced by hormone treatment with estradiol, insulin, and epidermal growth factor. The goal of this study was to determine the effect of hormone treatment on storage of granins and constitutive secretory markers. The granins were efficiently stored in both hormone-treated and -untreated cells (17% of total secreted in 4 h). Secreted alkaline phosphatase (SEAP), a truncated membrane protein that would not be expected to enter secretory granules, and glycosaminoglycan, a marker for the constitutive secretory pathway, exhibited 70 80% secretion under both conditions. In comparison, the relative prolactin secretion was 31 and 68% from hormone-treated and -untreated cells, respectively. Phorbol ester and KCl stimulated prolactin secretion 2.3-fold from untreated cells and 5. 5-fold from hormone-treated cells. In contrast, SEAP secretion was stimulated 1.5-fold from both treated and untreated cells, consistent with secretion by the constitutive secretory pathway. Stimulated secretion of granins was detected from both hormone-treated and -untreated cells. These results suggest that granin and prolactin storage are differentially regulated and that the constitutive secretory pathway is not affected by hormone treatment.
Gorr
S U
SU
Endocrine Cell Biology Laboratory, Department of Biological and Biophysical Sciences, University of Louisville Health Sciences Center, Louisville, Kentucky 40292, USA.
D000469:Alkaline Phosphatase / Q000032:analysis / Q000378:metabolism; D000818:Animals; D015415:Biomarkers; D002460:Cell Line; D053378:Chromogranin B; D002864:Chromogranins / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D006025:Glycosaminoglycans / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D010902:Pituitary Gland; D011189:Potassium Chloride / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000032:analysis / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D013462:Sulfur Radioisotopes; D014162:Transfection
D015415:Biomarkers; D053378:Chromogranin B; D002864:Chromogranins; D006025:Glycosaminoglycans; D007328:Insulin; D011506:Proteins; D011994:Recombinant Proteins; D013431:Sulfates; D013462:Sulfur Radioisotopes; C506140:chromogranin B, rat; D004958:Estradiol; D004815:Epidermal Growth Factor; D011189:Potassium Chloride; D011388:Prolactin; D000469:Alkaline Phosphatase