Wright W W, Zabludoff S D, Penttilä T L, Parvinen M
Department of Population Dynamics, Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland 21205, USA.
Dev Genet. 1995;16(2):104-13. doi: 10.1002/dvg.1020160203.
CP-2/cathepsin L mRNA is expressed primarily by rat Sertoli cells within stage VI-VIII seminiferous tubules. To test whether germ cells regulated this expression, we examined if separating Sertoli cells from specific germ cells affected expression of this transcript in Sertoli cells. First, Sertoli cells were isolated from adult (90-day-old) and immature (25-day-old) rats and levels of this transcript measured immediately or after 1, 3 and 5 days in culture. Results demonstrated that immediately upon isolation, CP-2/cathepsin L mRNA levels were significantly higher in mature cells. However, after 1 day in culture, the levels of this transcript increased in immature cells and remained high in mature cells. We therefore conclude that in vivo, a subset of germ cells inhibit the expression of CP-2/cathepsin L mRNA by immature Sertoli cells. Second, to examine the effect of specific germ cells on CP-2/cathepsin L mRNA expression, we exposed the testes of mature rats to 3 Gy of gamma-radiation and analyzed stage-specific expression of this transcript at varying times during maturation depletion and subsequent germ cell restoration. Loss of spermatogonia or spermatocytes was without effect. However, when pachytene spermatocytes through step 14 spermatids were depleted, expression at stages VI-VIII was reduced by half and expression at stages IX-I was increased 14-fold. These changes resulted in the loss of stage-specific expression of CP-2/cathepsin L mRNA by Sertoli cells. Finally, stage VI-VIII tubules, depleted primarily in step 15-19 spermatids, had levels of CP-2/cathepsin L mRNA that were 60% of control. However, stage-specific expression of this transcript was detected in these tubules. In contrast to what we noted with CP-2/cathepsin L mRNA, loss and restoration of germ cells had no effect on Sertoli cell levels of SGP-2 mRNA, indicating that testicular irradiation had no overall effect on Sertoli cell function. Taken together, these data suggest that the stage-specific expression of the CP-2/cathepsin L gene results from the sequential stimulation and inhibition of Sertoli cells by germ cells, that pachytene spermatocytes through step 14 spermatids are required for this stage-specific expression and that step 18 and 19 spermatids amplify this expression at stages VI-VIII.
CP-2/组织蛋白酶L信使核糖核酸主要由处于VI - VIII期生精小管内的大鼠支持细胞表达。为了检测生殖细胞是否调控这种表达，我们研究了将支持细胞与特定生殖细胞分离是否会影响支持细胞中该转录本的表达。首先，从成年（90日龄）和未成年（25日龄）大鼠中分离出支持细胞，并在分离后立即或培养1、3和5天后测量该转录本的水平。结果表明，分离后立即检测发现，成熟细胞中CP-2/组织蛋白酶L信使核糖核酸水平显著更高。然而，培养1天后，该转录本水平在未成熟细胞中升高，在成熟细胞中仍保持较高水平。因此我们得出结论，在体内，一部分生殖细胞抑制未成熟支持细胞中CP-2/组织蛋白酶L信使核糖核酸的表达。其次，为了研究特定生殖细胞对CP-2/组织蛋白酶L信使核糖核酸表达的影响，我们将成年大鼠的睾丸暴露于3戈瑞的γ射线辐射下，并在生殖细胞耗竭及随后恢复的不同时间分析该转录本的阶段特异性表达。精原细胞或精母细胞的缺失没有影响。然而，当粗线期精母细胞至14步精子细胞被耗尽时，VI - VIII期的表达降低一半，IX - I期的表达增加14倍。这些变化导致支持细胞中CP-2/组织蛋白酶L信使核糖核酸的阶段特异性表达丧失。最后，主要在15 - 19步精子细胞耗竭的VI - VIII期生精小管，其CP-2/组织蛋白酶L信使核糖核酸水平为对照的60%。然而，在这些生精小管中检测到了该转录本的阶段特异性表达。与我们在CP-2/组织蛋白酶L信使核糖核酸中所观察到的情况相反，生殖细胞的缺失和恢复对支持细胞中SGP-2信使核糖核酸水平没有影响，这表明睾丸辐射对支持细胞功能没有总体影响。综上所述，这些数据表明，CP-2/组织蛋白酶L基因的阶段特异性表达是由生殖细胞对支持细胞进行顺序刺激和抑制导致的，粗线期精母细胞至14步精子细胞是这种阶段特异性表达所必需的，并且18和19步精子细胞在VI - VIII期增强了这种表达。
