Identification, regulation and anti-proliferative role of the NPR-C receptor in gastric epithelial cells
Identification, regulation and anti-proliferative role of the NPR-C receptor in gastric epithelial cells
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DOI：
10.1007/s11010-006-9234-3
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发表时间：
2006-12-01
影响因子：
4.3
通讯作者：
Solivan, Suzanne M.
中科院分区：
文献类型：
--
作者：
Gower, William R., Jr.;Carter, Gay M.;Solivan, Suzanne M.
Evidence suggests that functional atrial natriuretic peptide (ANP) receptors occur in surface gastric mucosal epithelial cells. To evaluate functional aspects of ANP in a model of these cells we examined the expression of natriuretic peptide receptors (NPR) subtypes A and C in the non-transformed rat gastric mucosal epithelial cell line RGM1. Transcripts for NPR-A and NPR-C were detected in RGM1 cells by RT-PCR. However, only NPR-C protein was detected by Western blot and immunohistochemical analyses. Specific saturable binding of I-125-ANP to RGM1 cells revealed a single class of high affinity binding sites (K-d = 208 +/- 71 pM, B-max = 110,000 +/- 14,000 sites/cell, Hill coefficient = 0.97 +/- 0.05). ANP (IC50 130 +/- 47 pM), BNP (IC50 716 +/- 26 pM), CNP (IC50 356 +/- 85 pM) and C-ANP (IC50 134 +/- 13 pM), a specific ligand for NPR-C, effectively displaced I-125-ANP binding. Cross-linking of I-125-ANP to cells labeled predominantly a protein of 66,000 Da. These data suggest that I-125-ANP binding was primarily to NPR-C. ANP and C-ANP inhibited forskolin- and prostaglandin E-2 (PGE(2))-stimulated cAMP in a PTx-sensitive fashion. PGE(2), transforming growth factor-beta 1 (TGF-beta 1), forskolin, 8-bromo-cyclic AMP, and phorbol-12-myristate-13-acetate (PMA) caused a dose-dependent decrease in specific I-125-ANP binding, whereas epidermal growth factor (EGF), 8-bromo-cyclic GMP and 4 alpha-phorbol didecanoate had no effect. PGE(2), forskolin, TGF-beta 1 and PMA significantly decreased I-125-ANP Bmax values, NPR-C protein and steady-state NPR-C transcript levels. H89, a protein kinase A inhibitor, blocked the reduction of NPR-C mRNA produced by both forskolin and PGE(2). GF109203X,a protein kinase C inhibitor, abolished the PMA-induced decrease in NPR-C transcripts but only partially blocked that produced by TGF-beta 1. RGM1 cells exhibited a dose-dependent decrease in both DNA synthesis and cell proliferation when cultured in the presence of ANP or C-ANP. These findings indicate that RGM1 cells express functional NPR-C receptors that can influence RGM1 cell proliferation and are down-regulated by PGE(2) and TGF-beta 1.
