CYCLIC PROTEIN-2, A SECRETORY PRODUCT OF RAT SERTOLI CELLS, IS THE PROENZYME FORM OF CATHEPSIN-L
CYCLIC PROTEIN-2, A SECRETORY PRODUCT OF RAT SERTOLI CELLS, IS THE PROENZYME FORM OF CATHEPSIN-L
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DOI：
10.1210/mend-5-12-1789
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发表时间：
1991-12-01
影响因子：
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通讯作者：
WRIGHT, WW
中科院分区：
文献类型：
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作者：
ERICKSONLAWRENCE, M;ZABLUDOFF, SD;WRIGHT, WW
先前的研究表明，成熟大鼠Sertoli细胞分泌的环状蛋白-2 （CP-2）从精原上皮周期的第II期到第VI-VII期增加了30倍，表明该蛋白集中在紧致的精细胞周围。其他器官的分析显示，CP-2也可在近端肾小管上皮和起源于下丘脑的上核和室旁核的神经元中检测到。目前，我们已经分离出CP-2 mRNA的部分1.8千碱基cDNA，序列分析表明，CP-2是半胱氨酸蛋白酶组织蛋白酶L的前酶形式；通过抗肝组织蛋白酶L免疫球蛋白G对CP-2的免疫沉淀和纯化CP-2的酶促分析证实了这一点。睾丸mRNA的Northern分析显示主要转录本（1.7 kb）和次要转录本（2.2 kb），其3'-非翻译序列的长度不同。低水平的CP-2/组织蛋白酶L转录本在许多器官中被检测到，而高水平的转录本仅在睾丸、肾脏和肝脏中被检测到。在精小管中，CP-2/cathepsin L mRNA在II期检测不到，在VI期和VIIa、b期达到最高水平，在XII期再次检测不到。在第六至七期，支持细胞中存在CP-2/cathepsin L mRNA，而生殖细胞中不存在。综上所述，这些数据表明CP-2/cathepsin L基因的表达以细胞特异性的方式受到调节，并且在支持细胞中，这种表达在特定发育阶段受到生殖细胞的影响。我们认为，在第V-VII阶段，分泌的CP-2/cathepsin L降解了将紧实的精细胞与支持细胞结合的粘附分子，从而促进了这些精细胞向小管腔的运动。
Previous studies demonstrated that secretion of Cyclic Protein-2 (CP-2) by mature rat Sertoli cells increased 30-fold from stage II to stages VI-VII of the cycle of the seminiferous epithelium and suggested that this protein was concentrated around compacted spermatids. Analysis of other organs revealed that CP-2 was also detectable in the epithelium of the proximal kidney tubule and in neurons originating from the supraotic and paraventricular nuclei of the hypothalamus. We now have isolated a partial 1.8-kilobase (kb) cDNA for CP-2 mRNA, and sequence analysis revealed that CP-2 was the proenzyme form of the cysteine protease cathepsin L; this was corroborated by immunoprecipitation of CP-2 by anticathepsin L immunoglobulin G and by enzymatic analysis of purified CP-2. Northern analysis of testis mRNA revealed major (1.7 kb) and minor (2.2 kb) transcripts which differed in the length of their 3'-untraslated sequences. Low levels of CP-2/cathepsin L transcripts were detected in many organs, while high levels were only detected in testis, kidney, and liver. In seminiferous tubules, CP-2/cathepsin L mRNA was undetectable at stage II, increased to maximal levels at stages VI and VIIa,b, and was again undetectable at stage XII. At stages VI-VII, CP-2/cathepsin L mRNA was present in Sertoli but not germ cells. Taken together, these data suggest that CP-2/cathepsin L gene expression is regulated in a cell-specific manner and that in Sertoli cells this expression is influenced by germ cells at specific steps of development. We propose that at stages V-VII, secreted CP-2/cathepsin L degrades adhesion molecules which bind compacted spermatids to Sertoli cells, thereby facilitating movement of these spermatids toward the lumen of the tubule.