Effects of Protein Kinase C Down-Regulation on Secretory Events and Proopiomelanocortin Gene Expression in Anterior Pituitary Tumor (AtT-20) Cells

1990 ◽  
Vol 54 (1) ◽  
pp. 248-255 ◽  
Author(s):  
Sheela Vyas ◽  
John F. Bishop ◽  
Donald R. Gehlert ◽  
Jit Patel
2021 ◽  
Author(s):  
Mitsuhiro Kinoshita ◽  
Atsushi Yamada ◽  
Kiyohito Sasa ◽  
Kaori Ikezaki ◽  
Tatsuo Shirota ◽  
...  

Abstract Nephronectin (Npnt) is an extracellular matrix protein and ligand of integrin α8β1 known to promote differentiation of osteoblasts. A search for factors that regulate Npnt gene expression in osteoblasts revealed that phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C (PKC), had a strong effect to suppress that expression. Research was then conducted to elucidate the signaling pathway responsible for regulation of Npnt gene expression by PMA in osteoblasts. Treatment of MC3T3-E1 cells with PMA suppressed cell differentiation and Npnt gene expression. Effects were noted at a low concentration of PMA, and were time- and dose-dependent. Furthermore, treatment with the PKC signal inhibitor Gö6983 inhibited down-regulation of Npnt expression, while transfection with small interfering RNA (siRNA) of PKCα, c-Jun, and c-Fos suppressed that down-regulation. The present results suggest regulation of Npnt gene expression via the PKCα and c-Jun/c-Fos pathway.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mitsuhiro Kinoshita ◽  
Atsushi Yamada ◽  
Kiyohito Sasa ◽  
Kaori Ikezaki ◽  
Tatsuo Shirota ◽  
...  

AbstractNephronectin (Npnt) is an extracellular matrix protein and ligand of integrin α8β1 known to promote differentiation of osteoblasts. A search for factors that regulate Npnt gene expression in osteoblasts revealed that phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C (PKC), had a strong effect to suppress that expression. Research was then conducted to elucidate the signaling pathway responsible for regulation of Npnt gene expression by PMA in osteoblasts. Treatment of MC3T3-E1 cells with PMA suppressed cell differentiation and Npnt gene expression. Effects were noted at a low concentration of PMA, and were time- and dose-dependent. Furthermore, treatment with the PKC signal inhibitor Gö6983 inhibited down-regulation of Npnt expression, while transfection with small interfering RNA (siRNA) of PKCα, c-Jun, and c-Fos suppressed that down-regulation. The present results suggest regulation of Npnt gene expression via the PKCα and c-Jun/c-Fos pathway.


1987 ◽  
Vol 48 (1) ◽  
pp. 106-110 ◽  
Author(s):  
Martin Zatz ◽  
Lawrence C. Mahan ◽  
Terry Reisine

Endocrinology ◽  
1989 ◽  
Vol 124 (3) ◽  
pp. 1444-1449 ◽  
Author(s):  
TOSHIHIRO SUDA ◽  
FUMIKO TOZAWA ◽  
TSUYAKO USHIYAMA ◽  
NAOKI TOMORI ◽  
TAKASHI SUMITOMO ◽  
...  

1994 ◽  
Vol 22 (3) ◽  
pp. 291S-291S ◽  
Author(s):  
Victoria J. Wilson ◽  
Daniela Oddiah ◽  
Michael V. Sofroniew ◽  
Moeen K. Panni ◽  
Marcus Rattray

2010 ◽  
Vol 139 (6) ◽  
pp. 2061-2071.e2 ◽  
Author(s):  
Mohamad El–Zaatari ◽  
Yana Zavros ◽  
Art Tessier ◽  
Meghna Waghray ◽  
Steve Lentz ◽  
...  

2000 ◽  
Vol 78 (3) ◽  
pp. 329-343 ◽  
Author(s):  
Anderson OL Wong ◽  
Wen Sheng Li ◽  
Eric KY Lee ◽  
Mei Yee Leung ◽  
Lai Yin Tse ◽  
...  

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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