Evidence for the occurrence of Na-K-2Cl cotransporters in eccrine clear cells and their regulation by protein kinase a and their inhibition by protein kinase C

Pituitary adenylate cyclase activating polypeptide (PACAP) is a novel member of the secretin-glucagon peptide family. In mammals, this peptide has been located in a wide range of tissues and is involved in a variety of biological functions. In lower vertebrates, especially fish, increasing evidence suggests that PACAP may function as a hypophysiotropic factor regulating pituitary hormone secretion. PACAP has been identified in the brain-pituitary axis of representative fish species. The molecular structure of fish PACAP is highly homologous to mammalian PACAP. The prepro-PACAP in fish, however, is distinct from that of mammals as it also contains the sequence of fish GHRH. In teleosts, the anterior pituitary is under direct innervation of the hypothalamus and PACAP nerve fibers have been identified in the pars distalis. Using the goldfish as a fish model, mRNA transcripts of PACAP receptors, namely the PAC1 and VPAC1 receptors, have been identified in the pituitary as well as in various brain areas. Consistent with the pituitary expression of PACAP receptors, PACAP analogs are effective in stimulating growth hormone (GH) and gonadotropin (GTH)-II secretion in the goldfish both in vivo and in vitro. The GH-releasing action of PACAP is mediated via pituitary PAC1 receptors coupled to the adenylate cyclase-cAMP-protein kinase A and phospholipase C-IP3-protein kinase C pathways. Subsequent stimulation of Ca2+ entry through voltage-sensitive Ca2+ channels followed by activation of Ca2+-calmodulin protein kinase II is likely the downstream mechanism mediating PACAP-stimulated GH release in goldfish. Although the PACAP receptor subtype(s) and the associated post-receptor signaling events responsible for PACAP-stimulated GTH-II release have not been characterized in goldfish, these findings support the hypothesis that PACAP is produced in the hypothalamus and delivered to the anterior pituitary to regulate GH and GTH-II release in fish.Key words: PACAP, VIP, PAC1 receptor, VPAC1 receptor, VPAC2 receptor, growth hormone, gonadotropin-II, cAMP, protein kinase A, protein kinase C, calcium, pituitary cells, goldfish, and teleost.

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Phosphorylation of low molecular mass cytosolic proteins by protein kinase C and protein kinase A in the rabbit exocrine pancreas

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1989.tb15137.x ◽

1989 ◽

Vol 185 (2) ◽

pp. 461-468 ◽

Cited By ~ 3

Author(s):

Antoine G. H. EDERVEEN ◽

Jos V. M. LEEST ◽

Sjenet E. EMST-DE VRIES ◽

Jan Joep H. H. M. PONT

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Molecular Mass ◽

Protein Kinase A ◽

Exocrine Pancreas ◽

Cytosolic Proteins ◽

Kinase C ◽

Kinase A

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Activators of protein kinase A and of protein kinase C inhibit MDCK cell myo-inositol and betaine uptake.

Journal of the American Society of Nephrology ◽

10.1681/asn.v661559 ◽

1995 ◽

Vol 6 (6) ◽

pp. 1559-1564

Author(s):

A S Preston ◽

A Yamauchi ◽

H M Kwon ◽

J S Handler

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Protein Kinase A ◽

Translational Regulation ◽

Mdck Cells ◽

Relative Effect ◽

Amino Acid Sequences ◽

Prolonged Incubation ◽

Kinase C ◽

Kinase A

Amino acid sequences of the myo-inositol and betaine cotransporters that are induced in MDCK cells by hypertonicity include consensus sequences for phosphorylation by protein kinase A and by protein kinase C. To test for the effect of activation of protein kinases A and C on the activity of those cotransporters, MDCK cells were exposed to activators of each kinase and the activity of both cotransporters was assayed. Incubation with 8-bromoadenosine 3':5'-cyclic monophosphate (8Br-cAMP) or 3-isobutyl-1-methylxanthine (IBMX), activators of protein kinase A, and incubation with an active phorbol ester or with an active diacylglycerol, activators of protein kinase C, inhibited the activity of both cotransporters by about 30%. The relative effect of the activation of protein kinase A and of protein kinase C was similar in hypertonic and isotonic cells. The effects of activators of protein kinase A and of protein kinase C were not additive. The two cotransporters behaved differently when protein kinase C activity was down-regulated by prolonged incubation with a higher concentration of phorbol 12-myristate 13-acetate. There was a doubling of activity of the myo-inositol cotransporter and no change in the activity of the betaine cotransporter in hypertonic and isotonic cells. Although the mechanisms of the effects of activation of the two kinases remain to be established, it is clear that the kinases can mediate post-translational regulation of the uptake of compatible osmolytes.

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Regulation of arginine vasopressin mRNA in rat fetal hypothalamic cell culture. Role of protein kinases and glucocorticoids

Journal of Molecular Endocrinology ◽

10.1677/jme.0.0100051 ◽

1993 ◽

Vol 10 (1) ◽

pp. 51-57 ◽

Cited By ~ 8

Author(s):

S-B Hu ◽

L A Tannahill ◽

S L Lightman

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Mrna Expression ◽

Protein Kinase A ◽

Arginine Vasopressin ◽

In Situ Hybridization Histochemistry ◽

Kinase C ◽

Kinase A

ABSTRACT Studies have been performed to investigate the regulation of arginine vasopressin (AVP) mRNA expression in fetal hypothalamic cultures. AVP mRNA-positive neurones were identified by in-situ hybridization histochemistry, and changes in mRNA expression were quantitated by nuclease protection assay. Both protein kinase C and protein kinase A activators increased the expression of AVP mRNA, in contrast to dexamethasone, which inhibited the responses to both protein kinase C and protein kinase A activation.

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