Identification of stage-specific proteins synthesized by rat seminiferous tubules.
Identification of stage-specific proteins synthesized by rat seminiferous tubules.
复制标题
鉴定大鼠生精小管合成的阶段特异性蛋白质。
作者：
William W. Wright;M. Parvinen;N. Musto;G. Gunsalus;David M. Phillips;Jennie P. Mather;C. Bardin
进行实验以确定生精上皮的周期如何影响生精小管蛋白质的合成和分泌。用胶原酶处理管段，然后用[35S]蛋氨酸培养。这些从上皮周期不同阶段分离的肌样细胞耗尽的小管在 VI 和 XII 阶段表现出两个不同的放射性标记总蛋白分泌峰。二维凝胶电泳表明，这两个阶段的分泌蛋白模式有显着差异，而其他阶段的分泌蛋白模式介于峰值之间。至少有 15 种蛋白质被周期性分泌，其中许多是以前未被识别的生精上皮产物。一种被命名为环状蛋白-2 (CP-2) 的产品表现出明显的分泌周期，其在第 VI 阶段的峰值比第 XII-XIV 阶段的最低点高 30 倍。进一步的研究表明，CP-2 似乎并非源自肌样细胞或分散的生殖细胞，而是可以从 VI 期肾小管制备的富含支持细胞的培养物中回收。肾小管节段的蛋白质分泌也通过使用两种针对支持细胞产物的多特异性抗血清的免疫沉淀来表征。鉴定出五种分泌蛋白，它们的周期彼此不同，且与 CP-2 不同。与分泌产物相反，大多数细胞蛋白质通过管状节段的合成在整个周期中保持相对恒定。结论是：1)生精上皮片段将不同于细胞蛋白的蛋白质分泌到培养基中； 2）许多这些蛋白质的合成随着上皮周期的变化而变化； 3) 几种分泌蛋白源自支持细胞，包括新鉴定的蛋白 CP-2。这表明生精上皮的形态和蛋白质合成能力在空间和时间上是协调的。
Experiments were conducted to determine how the cycle of the seminiferous epithelium influenced synthesis and secretion of proteins by seminiferous tubules. Tubular segments were treated with collagenase and then cultured with [35S]methionine. These myoid cell-depleted tubules isolated from different stages of the epithelial cycle exhibited, at Stages VI and XII, two distinct peaks of secretion of total radiolabeled proteins. Two-dimensional gel electrophoresis indicated that the patterns of secreted proteins from these two stages were remarkably different, while those from other stages were intermediate between those at the peaks. At least 15 proteins were secreted cyclically, many of them previously unrecognized products of the seminiferous epithelium. One product, designated Cyclic Protein-2 (CP-2), exhibited a pronounced cycle of secretion, its peak at Stage VI being 30-fold greater than at its nadir at Stages XII-XIV. Further investigation indicated that CP-2 did not appear to originate from myoid cells or dispersed germ cells but could be recovered from Sertoli cell-enriched cultures prepared from Stage VI tubules. Protein secretion by tubular segments was also characterized by immunoprecipitation with two polyspecific antisera directed against Sertoli cell products. Five secretory proteins were identified which had cycles different from one another and from CP-2. In contrast to secreted products, the synthesis of most cellular proteins by tubular segments remained relatively constant throughout the cycle. It is concluded: 1) segments of the seminiferous epithelium secrete proteins into the culture medium which are distinct from cellular proteins; 2) the synthesis of many of these proteins varies with the epithelial cycle; and 3) several of the secreted proteins are of Sertoli cell origin, including a newly identified protein, CP-2. This indicates that the morphology and the protein synthetic capacity of the seminiferous epithelium are coordinated over space and time.