Plasminogen activators of the pituitary gland: enzyme characterization and hormonal modulation.
Open Access
- 1 October 1983
- journal article
- research article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 97 (4), 1029-1037
- https://doi.org/10.1083/jcb.97.4.1029
Abstract
We studied plasminogen activator (PA) of the rat pituitary gland in organ and cell monolayer culture. Both anterior and intermediate lobes contain, synthesize and secrete a mixture consisting of the two known types of PA: urokinase and so-called tissue PA. Both enzymes were formed essentially by all PA secreting cells, and PA was identified specifically in mammotrophs, corticotrophs, and luteinizing hormone containing gonadotrophs. Pituitary PA production was modulated on exposure to a variety of biological effectors: anterior lobe PA secretion was stimulated by agents that raised intracellular cAMP concentration; his process depended on de novo enzyme synthesis. Enzyme production was repressed by androgens and glucocorticoids. When anterior lobe cultures were maintained in plasminogen-free media, the extracellular, secreted forms of ACTH consisted almost exclusively of the high molecular weight forms (31,000 and 23,000); the smaller forms (13,000 and 4,500) were also found in the extracellular medium of cultures supplemented with plasminogen. In contrast, the size distribution of intracellular ACTH species was unaffected by the presence of plasminogen. These results resemble those previously obtained with pancreatic islets and are consistent with the possibility that plasmin, generated by PA secretion, participates in prohormone processing. PA synthesis in intermediate lobe explants was stimulated by exposure to dibutyryl cAMP, and repressed by hydrocortisone. In accordance with the dopaminergic control of intermediate lobe function in some vertebrates, apomorphine strongly repressed PA synthesis in intermediate, but not anterior lobe cultures.This publication has 44 references indexed in Scilit:
- Characterization of proinsulin- and proglucagon-converting activities in isolated islet secretory granules.The Journal of cell biology, 1981
- Nucleotide sequence of cloned cDNA for bovine corticotropin-β-lipotropin precursorNature, 1979
- The induction of differentiation in teratocarcinoma stem cells by retinoic acidCell, 1978
- A study of proteases and protease-inhibitor complexes in biological fluidsThe Journal of Experimental Medicine, 1978
- Secretion of plasminogen activator by human polymorphonuclear leukocytes. Modulation by glucocorticoids and other effectors.The Journal of Experimental Medicine, 1977
- Macrophage plasminogen activator: induction by concanavalin A and phorbol myristate acetateCell, 1977
- Macrophage plasminogen activator: Modulation of enzyme production by anti-inflammatory steroids, mitotic inhibitors, and cyclic nucleotidesCell, 1976
- HORMONE SECRETION BY CELLS DISSOCIATED FROM RAT ANTERIOR PITUITARIESThe Journal of cell biology, 1973
- Studies on the secretion of newly synthesized proinsulin and insulin from isolated rat islets of langerhansJCI Insight, 1972
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970