Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calcitonin is present in both the hypothalamus and pituitary of the rat, and normal rat anterior pituitary cells express calcitonin receptors. Calcitonin has been reported to inhibit or to stimulate PRL release from rat anterior pituitary cells. We have investigated the effects of salmon calcitonin on basal and stimulated PRL release from rat anterior pituitary cells and have studied the effects of this peptide on the intracellular biochemical pathways involved in PRL release. Salmon calcitonin had no significant effect on basal PRL release, but inhibited (P less than 0.01) TRH-stimulated PRL release without affecting PRL release promoted by angiotensin II, neurotensin, phorbol myristate acetate (a protein kinase C activator), or maitotoxin (a calcium channel activator). Salmon calcitonin had no effect on the increase in PRL release and intracellular cAMP concentration after exposure of pituitary cells to vasoactive intestinal peptide or forskolin. Salmon calcitonin significantly decreased (P less than 0.01) the TRH-stimulated rise in inositol phosphates without affecting the angiotensin II-stimulated increase in inositol phosphates. Similarly, salmon calcitonin decreased the TRH-stimulated increase in cytosolic calcium and arachidonate liberation by pituitary cells. We conclude that salmon calcitonin selectively decreases TRH-stimulated PRL release by a mechanism that involves a decrease in inositol phosphate production, as well as a subsequent reduction in cytosolic calcium levels and in arachidonate liberation.
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PMID:Calcitonin decreases thyrotropin-releasing hormone-stimulated prolactin release through a mechanism that involves inhibition of inositol phosphate production. 216 10

Intracellular signal transduction for regulation of alkaline phosphatase (ALP) activity in renal epithelial cells treated with calcitonin is not yet completely understood, although it is known that calcitonin receptors couple to cyclic AMP-dependent protein kinase (PKA) and calcium/phospholipid-dependent protein kinase (PKC). Salmon calcitonin increased the cyclic AMP content in LLC-PK1 porcine kidney cells in a concentration-dependent manner. When the confluent cells were incubated for 47 h after a 1 h-pulse exposure or continuously exposed to calcitonin and forskolin for 48 h, ALP activity in the cells was increased by calcitonin about 2-fold compared with the basal activity at the maximum level but was not dependent on the exposure time; it was markedly increased by forskolin in parallel with the exposure time. The increase in activity produced by calcitonin was abolished by a PKA inhibitor H-89, and, in contrast, potentiated by a PKC inhibitor, NA-382 to near the forskolin-induced level. These results indicate that calcitonin exerts a dual-regulation of ALP activity in LLC-PK1 cells, positively through the PKA pathway and negatively through PKC.
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PMID:Dual regulation of alkaline phosphatase activity by calcitonin in porcine kidney cells. 944 8

Previous findings have shown that osteoblasts respond to parathyroid hormone (PTH) with an increase in extracellular acidification rate (ECAR) in addition to the known effect of PTH to increase local acidification by osteoclasts. We, therefore, investigated use of the Cytosensor to measure the ECAR response of whole intact bone to PTH employing microphysiometry. The Cytosensor measures a generic metabolic increase of cells to various agents. Using neonatal mouse calvaria, we found that the area surrounding the sagittal suture was particularly responsive to PTH. In this bone, the increase in ECAR was slower to develop (6 minutes) and more persistent than in cultured human osteoblast-like SaOS-2 cells and was preceded by a brief decrease in ECAR. Salmon calcitonin also produced an increase in ECAR in this tissue but with a different pattern than that elicited by PTH. Because PTH stimulates osteoclastic bone resorption in mouse calvaria via a cyclic adenosine monophosphate (cAMP)-mediated mechanism, we showed that the adenylyl cyclase activator forskolin also stimulated ECAR in this tissue. When the protein kinase A (PKA) pathway was activated by maintaining a high intracellular concentration of cAMP using N6-2'-0-dibutyryladenosine-cAMP (db-cAMP), there was a reduction of PTH-induced acidification, while isobutylmethylxanthine pretreatment potentiated the PTH-induced acidification, consistent with a PKA-mediated pathway. Thapsigargin and the protein kinase C (PKC) activator phorbol myristate acetate had no effect on the PTH-induced increase in ECAR in calvaria, indicating that PKC does not play a major role in the ECAR response in intact bone. These results indicate the utility of using microphysiometry to study ECAR responses in intact tissue and should enable elucidation of the relative importance of extracellular acidification by osteoblasts and osteoclasts to the anabolic and catabolic activities of PTH, respectively.
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PMID:Direct measurement of hormone-induced acidification in intact bone. 1075 May 70