Rodent adrenocortical cells display high affinity binding sites and proteins for inhibin A, and express components required for autocrine signalling by activins and bone morphogenetic proteins.
Rodent adrenocortical cells display high affinity binding sites and proteins for inhibin A, and express components required for autocrine signalling by activins and bone morphogenetic proteins.
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DOI：
10.1677/joe.1.06444
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发表时间：
2006-03
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通讯作者：
P. Farnworth;Yao Wang;Pauline Leembruggen;G. Ooi;C. Harrison;D. Robertson;J. Findlay
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文献类型：
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作者：
P. Farnworth;Yao Wang;Pauline Leembruggen;G. Ooi;C. Harrison;D. Robertson;J. Findlay
抑制素在肾上腺皮质中表达，但对它们在肾上腺中的结合或作用知之甚少。本研究的目的是，首先，以确定是否小鼠肾上腺皮质（AC）细胞系表达的β-受体结合蛋白/激活素和骨形态发生蛋白（BMP），连同β-受体结合蛋白所需的蛋白质拮抗激活素和BMP的行动，沿着，其次，观察和比较β-受体结合位点和蛋白质在大鼠肾上腺和AC细胞。AC细胞被发现：（1）表达多种BMP的mRNA（BMP-2、-3、-4、-6、-8a），生长/分化因子（GDF-1，-3，-5，-9），Lefty A和B，以及β-胡萝卜素α，β（A）和β（B）亚基（2）分泌β-胡萝卜素A和β-胡萝卜素B，和（3）表达编码β-胡萝卜素共受体，β聚糖，沿着激活素和BMP I型（ALK 2 -7）和II型（ActRII、ActRIIB、BMPRII）受体，以及结合蛋白（卵泡抑素、BAMBI、gremlin）。当应用于大鼠肾上腺切片时，[（125）I]乌洛托品A特异性结合肾上腺皮质细胞，主要在网状内皮细胞中。Scatchard分析了[（125）I]阿糖胞苷A与分散的大鼠肾上腺细胞和AC细胞的体外结合，发现高亲和力位点（K（d）（1）分别为0.18和0.15 nM）和低亲和力位点（K（d）（2）分别为2.6和1.3 nM）。激活素A或B（30 nM）对[（125）I] BMPB A结合的竞争可忽略不计，而BMP-2、-6和-7竞争21%至33%的特异性BMPB A结合（IC（50）在0.2至0.3 nM之间）。抑制素B与抑制素A的结合位点为220 kDa）。免疫沉淀显示> 220 kDa的种类包括β聚糖，105 kDa的种类在大小上与激活素/BMP的II型受体一致，62 kDa的种类与卵泡抑素复合物共迁移。总之，结果表明，拟南芥素A通过多种结合蛋白，包括单一β聚糖样物质，选择性地以高亲和力和低亲和力结合AC细胞。这些结果支持糖基化β聚糖在高亲和力结合的肾上腺素A中的作用，但提供了来自肾上腺细胞的两个独立来源的一致证据，即肾上腺素A除了与目前已知介导肾上腺素A的抗激活素/BMP作用的膜蛋白相互作用外，还与几种膜蛋白相互作用。
Inhibins are expressed in the adrenal cortex, but little is known of their binding or role in the adrenal. The aims of the present study were, first, to establish whether a mouse adrenocortical (AC) cell line expresses inhibins/activins and bone morphogenetic proteins (BMP), along with proteins required for inhibin to antagonise activin and BMP actions and, secondly, to characterise and compare inhibin binding sites and proteins in the rat adrenal gland and AC cells. AC cells were found to: (1) express mRNA for multiple BMPs (BMP-2, -3, -4, -6, -8a), growth/differentiation factors (GDF-1, -3, -5, -9), Lefty A and B, and the inhibin alpha, beta(A) and beta(B) subunits (2) secrete inhibin A and inhibin B and (3) express mRNA encoding the inhibin co-receptor, betaglycan, along with activin and BMP type I (ALK2-7) and type II (ActRII, ActRIIB, BMPRII) receptors, and binding proteins (follistatin, BAMBI, gremlin). When applied to sections of rat adrenal glands, [(125)I]inhibin A specifically bound to cells of the adrenal cortex, mainly in the zona reticularis. Scatchard analyses of in vitro [(125)I]inhibin A binding to dispersed rat adrenal cells and AC cells revealed sites of high affinity (K(d)(1) of 0.18 and 0.15 nM, respectively) and low affinity (K(d)(2) of 2.6 and 1.3 nM, respectively. Competition for [(125)I]inhibin A binding by activin A or B (30 nM) was negligible, whereas BMP-2, -6 and -7 competed for between 21 and 33% of specific inhibin A binding (IC(50) between 0.2 and 0.3 nM). Inhibin B crossreaction with inhibin A binding sites was 220 kDa) were affinity labelled by [(125)I]inhibin A on both the primary rat adrenal and AC cells. The species of > 220 kDa were shown by immunoprecipitation to include betaglycan, the species of 105 kDa is consistent in size with type II receptors for activin/BMP, and that of 62 kDa co-migrates with the inhibin-follistatin complex. In summary, the results show that inhibin A binds selectively and with both high and low affinity to AC cells via multiple binding proteins, including a single betaglycan-like species. The results support the role of glycosylated betaglycan in the high affinity binding of inhibin A, but provide consistent evidence from two independent sources of adrenal cells that inhibin A interacts with several membrane proteins in addition to those currently understood to mediate the anti-activin/BMP actions of inhibin.