scholarly journals Coordinate, equimolar secretion of smaller peptide products derived from pro-ACTH/endorphin by mouse pituitary tumor cells.

1981 ◽  
Vol 89 (1) ◽  
pp. 21-28 ◽  
Author(s):  
R E Mains ◽  
B A Eipper
Keyword(s):  
Pituitary Tumor ◽  
Culture Medium ◽  
Tumor Cell Line ◽  
Molecular Forms ◽  
Beta Endorphin ◽  
Calcium Dependent ◽  
Common Precursor ◽  
Mouse Pituitary ◽  
Secreted Peptides ◽  
Stimulation Of

The secretion of peptide products derived from pro-ACTH/endorphin was examined with several radioimmunoassays and with polyacrylamide gel analyses of immunoprecipitates of radioactively labeled peptides. In studies using a mouse pituitary tumor cell line the accumulation of each of the four molecular forms of adrenocorticotropic hormone (ACTH) in tissue culture medium was shown to be a linear function of time. No evidence for self inhibition of secretion by accumulated, secreted peptides (i.e., ultra-short feedback) was found. Furthermore, synthetic human ACTH and synthetic camel beta-endorphin did not alter secretion of peptides when added to the culture medium at levels up to 10,000 times physiological. Stimulation of the release of ACTH-, endorphin-, lipotropin-, and 16k fragment immunoreactive material by norepinephrine was fully blocked by cobalt; by this criterion, stimulated release was calcium dependent. All the smaller molecules derived from the pro-ACTH/endorphin common precursor were secreted in equimolar amounts under all circumstances tested, within the precision of these studies (+/- 11%). Norepinephrine and cobalt did not significantly alter the secretion of pro-ACTH/endorphin and ACTH biosynthetic intermediate. The stimulation of secretion by norepinephrine and inhibition of secretion by cobalt was restricted to the lower molecular weight products derived from pro-ACTH/endorphin: glycosylated and nonglycosylated ACTH(1-39); beta-lipotropin, beta-endorphin, and gamma-lipotropin; and 16k fragment.

scholarly journals A subclass of proteins and sulfated macromolecules secreted by AtT-20 (mouse pituitary tumor) cells is sorted with adrenocorticotropin into dense secretory granules.

1983 ◽  
Vol 97 (3) ◽  
pp. 810-817 ◽  
Author(s):  
H P Moore ◽  
B Gumbiner ◽  
R B Kelly
Keyword(s):  
Cell Surface ◽  
Secretory Granule ◽  
Pituitary Tumor ◽  
Common Property ◽  
Secretory Pathway ◽  
Culture Medium ◽  
Secretory Granules ◽  
Hormone Secretion ◽  
Tumor Line ◽  
Mouse Pituitary

The AtT-20 cell, a mouse pituitary tumor line that secretes adrenocorticotropin and beta-endorphin, sorts the proteins it externalizes into two exocytotic pathways. Cells that are labeled with [35S]methionine or [35S]sulfate can be shown to transport three acidic polypeptides (65,000, 60,000, and 37,000 mol wt) and at least two sulfated macromolecules into storage secretory granules. When the cells are stimulated by the secretagogue 8-bromo-cAMP, these polypeptides are coordinately secreted with mature adrenocorticotropin into the culture medium. In contrast, a completely different set of secreted polypeptides and sulfated macromolecules does not enter a storage form and is transported to the cell surface more rapidly. Their secretion from the cells is constitutive and does not require the presence of secretagogues. These molecules, like a viral membrane glycoprotein described previously (Gumbiner, B., and R. B. Kelly, 1982, Cell, 28:51-59) are not found in isolated secretory granules and therefore must reach the cell surface in a different exocytotic vesicle. The segregation of a subclass of secretory macromolecules into the secretory granules, despite the existence of another potential secretory pathway, suggests that these molecules have specific functions related to regulated hormone secretion or storage. Presumably all of the proteins secreted by the regulated secretory granule pathway share some common property that targets them to the secretory granule.

ACTH and MSH Production by a Single Cloned Mouse Pituitary Tumor Cell Line

Endocrinology ◽  
1973 ◽  
Vol 92 (2) ◽  
pp. 385-393 ◽  
Author(s):  
DAVID N. ORTH ◽  
WENDELL E. NICHOLSON ◽  
WILLIAM M. MITCHELL ◽  
DONALD P. ISLAND ◽  
MENACHEM SHAPIRO ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Cell Line ◽  
Pituitary Tumor ◽  
Tumor Cell Line ◽  
Mouse Pituitary ◽  
Pituitary Tumor Cell
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