Meinhardt A, Parvinen M, Bacher M, Aumüller G, Hakovirta H, Yagi A, Seitz J
Department of Anatomy and Cell Biology, Philipps University of Marburg, Germany.
Biol Reprod. 1995 Apr;52(4):798-807. doi: 10.1095/biolreprod52.4.798.
Changes in the level of the gene transcript of heat shock protein (hsp)60, a mitochondrial chaperonin, during the cycle of rat seminiferous epithelium and its cellular localization were studied. The seminiferous epithelium showed a cell type-specific expression of hsp60. Immunostaining of adult rat testis revealed localization in Sertoli and Leydig cells. In germ cells, mitochondria of spermatogonia and early primary spermatocytes were immunoreactive for hsp60. Mitochondria of all other germ cell types were completely negative for hsp60. Stage-specific expression of hsp60 was determined from pooled segments of stage-specific microdissected tubules by a combination of Western blotting and polymerase chain reaction (PCR). High concentrations of hsp60 were found in stages I-V and IX-XIV, and low levels were detected in the other stages, i.e., VI-VIII. In stages with high hsp60 expression, spermatogonia divide mitotically, whereas in stages lacking mitosis, the hsp60 level was much weaker. In seminiferous epithelium, two different types of mitochondria are present. Therefore, immunoelectron microscopy was used to differentiate these two morphologically distinct types of mitochondria. The crista type of mitochondria (e.g., in Sertoli cells and spermatogonia) reacted with the antibody against hsp60, whereas hsp60 was negative in so-called "condensed"-type mitochondria found in midpachytene spermatocytes and more advanced germ cells. It could be shown for the first time that expression of the hsp60 gene is regulated during the cycle of the seminiferous epithelium. The results indicate that the gene product is primarily needed during the initial steps of spermatogenesis in which most of the cell divisions occur, while its expression during the differentiation of spermatids and sperm is obviously not necessary. The presence of hsp60 in stages with mitotic activity suggests a very active mitochondrial protein import and protein assembly machinery that generates further mitochondria for the dividing cells.
研究了线粒体伴侣蛋白热休克蛋白（hsp）60基因转录水平在大鼠生精上皮周期中的变化及其细胞定位。生精上皮呈现hsp60的细胞类型特异性表达。成年大鼠睾丸的免疫染色显示其定位于支持细胞和间质细胞。在生殖细胞中，精原细胞和早期初级精母细胞的线粒体对hsp60呈免疫反应性。所有其他生殖细胞类型的线粒体对hsp60完全呈阴性。通过蛋白质印迹法和聚合酶链反应（PCR）相结合的方法，从特定阶段显微切割小管的汇集片段中确定hsp60的阶段特异性表达。在第I-V期和第IX-XIV期发现hsp浓度高，而在其他阶段，即第VI-VIII期检测到低水平。在hsp60高表达的阶段，精原细胞进行有丝分裂，而在缺乏有丝分裂的阶段，hsp60水平则弱得多。在生精上皮中，存在两种不同类型的线粒体。因此，使用免疫电子显微镜来区分这两种形态上不同的线粒体类型。嵴型线粒体（如在支持细胞和精原细胞中）与抗hsp60抗体发生反应，而在粗线期中期精母细胞和更晚期生殖细胞中发现的所谓“浓缩”型线粒体中hsp60呈阴性。首次表明hsp60基因的表达在生精上皮周期中受到调节。结果表明，该基因产物主要在精子发生的初始步骤中需要，其中大多数细胞分裂发生，而其在精子细胞和精子分化过程中的表达显然不是必需的。hsp60在有丝分裂活性阶段的存在表明存在非常活跃的线粒体蛋白质导入和蛋白质组装机制，为分裂细胞产生更多的线粒体。
