Darlington D N, Schiller M R, Mains R E, Eipper B A
Department of Surgery, University of Maryland School of Medicine, Baltimore 21201, USA.
J Endocrinol. 1997 Nov;155(2):329-41. doi: 10.1677/joe.0.1550329.
We examined the cellular localization of regulated endocrine-specific protein of 18 kDa (RESP18) and mRNA in peripheral endocrine tissues. In situ hybridization and immunocytochemistry identified RESP18 mRNA in most cells of the anterior and intermediate pituitary, with RESP18 protein apparent in many anterior pituitary cells but very few intermediate pituitary cells. In the adrenal medulla and superior cervical ganglion, RESP18 mRNA co-localized with dopamine beta-mono-oxygenase and neuropeptide Y. In the thyroid, RESP18 mRNA was localized to C-cells. RESP18 mRNA was expressed in most of the cells of the pancreatic islets, co-localizing with insulin, glucagon, and somatostatin. No RESP18 mRNA or protein was detected in the adrenal cortex, ovary, neural lobe of the pituitary, parathyroid, exocrine pancreas, thyroid follicular cells, placenta, mammary tissue, liver, lung, or atria. As in the intermediate lobe of the pituitary, high levels of RESP18 mRNA in the pancreatic islets and adrenal medulla did not always correlate with immunodetectable RESP protein, suggesting that post-transcriptional mechanisms are important in controlling RESP18 expression. Western blot analyses identified 18 kDa RESP and higher molecular weight isoforms of RESP in most tissues and in plasma. Subcellular fractionation of the anterior pituitary identified 18 kDa RESP18 in fractions enriched in endoplasmic reticulum and secretory granules, with the higher molecular weight isoforms of RESP18 concentrated in fractions enriched in secretory granules. The broad neuroendocrine distribution of RESP18 suggests that it subserves an important function in the secretory pathway that is common to the production of many secreted peptides.
我们研究了18 kDa调节性内分泌特异性蛋白（RESP18）及其mRNA在周围内分泌组织中的细胞定位。原位杂交和免疫细胞化学检测发现，促肾上腺皮质激素释放激素（CRH）mRNA在前叶和中间叶垂体的大多数细胞中均有表达，RESP18蛋白在前叶垂体的许多细胞中可见，但在中间叶垂体细胞中很少见。在肾上腺髓质和颈上神经节中，RESP18 mRNA与多巴胺β-单加氧酶和神经肽Y共定位。在甲状腺中，RESP18 mRNA定位于C细胞。RESP18 mRNA在胰岛的大多数细胞中表达，并与胰岛素、胰高血糖素和生长抑素共定位。在肾上腺皮质、卵巢、垂体神经叶、甲状旁腺、外分泌胰腺、甲状腺滤泡细胞、胎盘、乳腺组织、肝脏、肺或心房中未检测到RESP18 mRNA或蛋白。与垂体中间叶一样，胰岛和肾上腺髓质中高水平的RESP18 mRNA并不总是与可免疫检测到的RESP蛋白相关，这表明转录后机制在控制RESP18表达中很重要。蛋白质免疫印迹分析在大多数组织和血浆中鉴定出18 kDa的RESP和更高分子量的RESP同工型。垂体前叶的亚细胞分级分离在富含内质网和分泌颗粒的级分中鉴定出18 kDa的RESP18，而RESP18的更高分子量同工型则集中在富含分泌颗粒的级分中。RESP18广泛的神经内分泌分布表明，它在许多分泌肽产生所共有的分泌途径中发挥着重要作用。
