Inhibition of protein phosphatase 1 decreases PTH secretion from isolated dispersed parathyroid cells. |
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Authors: | L M Matovcik S S Rhee J F Schaefer E F da Cruz e Silva B K Kinder |
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Affiliation: | VA Connecticut Healthcare System, and the Department of Surgery, Yale University School of Medicine, New Haven 06520-8062, USA. matovcik@aol.com |
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Abstract: | To investigate the regulation of parathyroid hormone secretion by phosphatases we examined the effect of okadaic acid, a selective inhibitor of protein phosphatases (PP)-1 and -2A, on isolated, dispersed parathyroid cells. Okadaic acid inhibited secretion from intact bovine, intact human and streptolysin-O permeabilized bovine cells. Approximately 10(-6) M okadaic acid resulted in a 50% decrease in parathyroid hormone (PTH) secretion from both intact and permeabilized cells, consistent with PP-1 being the target of inhibition. Upon subcellular fractionation, PP-1 overlapped but was not identical to either PTH, a marker of the secretory granule, or Na+/K+-ATPase, a plasma membrane marker. In summary, PP-1 activity is involved in Ca2+-dependent but not basal PTH secretion. |
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