Tamaru M, Nagao Y, Taira M, Tatibana M, Masamune Y, Nakanishi Y
Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
Biochim Biophys Acta. 1990 Jul 30;1049(3):331-8. doi: 10.1016/0167-4781(90)90106-c.
During mammalian spermatogenesis the isozyme pattern of a glycolytic enzyme, phosphoglycerate kinase (PGK; ATP: 3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3), changes from the somatic-type PGK-1 to the testis-specific PGK-2, and this change has been suggested to involve transcription switch. We have isolated genomic DNA fragments which code for the mouse PGK isozymes and determined the transcription start site of each gene. The results demonstrate that transcriptions of the two PGK genes are initiated at multiple sites under the control of TATA box-lacking promoters. The putative promoter regions of the two genes contain several distinct sequences known as the CCAAT box and the GC box which possibly bind CCAAT-binding proteins and Sp1, respectively. We next developed a culture system in which spermatogenic gene expression is partly reproduced. When spermatogenic cells of 20-day-old rats were cultured, transcripts from PGK-2 and another spermatogenic gene PRPS3 became detectable, while expression of other non-spermatogenic genes did not significantly change during culture. These results suggest that two spermatogenic genes PGK-2 and PRPS3 were activated in culture according to a developmental program of spermatogenesis. Thus, this culture system may be useful for studying the molecular mechanism underlying mammalian spermatogenic gene expression.
在哺乳动物精子发生过程中，一种糖酵解酶——磷酸甘油酸激酶（PGK；ATP：3-磷酸-D-甘油酸1-磷酸转移酶，EC 2.7.2.3）的同工酶模式从体细胞型PGK-1转变为睾丸特异性PGK-2，并且这种转变被认为涉及转录开关。我们分离了编码小鼠PGK同工酶的基因组DNA片段，并确定了每个基因的转录起始位点。结果表明，两个PGK基因的转录在缺乏TATA框的启动子控制下于多个位点起始。这两个基因的推定启动子区域包含几个不同的序列，分别称为CCAAT框和GC框，它们可能分别结合CCAAT结合蛋白和Sp1。接下来，我们开发了一种培养系统，其中部分再现了生精基因的表达。当培养20日龄大鼠的生精细胞时，可检测到PGK-2和另一个生精基因PRPS3的转录本，而其他非生精基因的表达在培养过程中没有显著变化。这些结果表明，两个生精基因PGK-2和PRPS3在培养中根据精子发生的发育程序被激活。因此，这种培养系统可能有助于研究哺乳动物生精基因表达的分子机制。
