Russell D L, Kim K H
Department of Genetics and Cell Biology, Washington State University, Pullman 99164, USA.
Biol Reprod. 1996 Jul;55(1):11-8. doi: 10.1095/biolreprod55.1.11.
Vitamin A is essential for mammalian spermatogenesis. To isolate retinol-induced cDNAs from rat testis, vitamin A-deficient (VAD) rats were treated with retinol for 4 h and mRNA isolated from their testes was used to construct a subtractive cDNA library. One cDNA isolated from this library contained a sequence for triosephosphate isomerase (TPI). Northern blot analysis showed that the TPI cDNA hybridized with two transcripts in testis. A 1.4-kb transcript, which is the sole transcript found in most tissues, was expressed in the somatic cells of testis, whereas a novel 1.5-kb transcript was detected only in haploid spermatids. However, only the level of the shorter transcript increased with retinol treatment of the testis or of cultured Sertoli cells. Furthermore, screening of an adult rat testis cDNA library with the TPI cDNA yielded a cDNA putatively corresponding to the 1.5-kb transcript. Sequence analyses of the two TPI cDNAs revealed a 100-bp deletion in one cDNA that may be due to use of an alternative polyadenylation signal. These results suggest independent processing mechanisms for TPI expression in the somatic cells and the haploid germ cells of testis.
维生素A对哺乳动物精子发生至关重要。为了从大鼠睾丸中分离视黄醇诱导的cDNA，给维生素A缺乏（VAD）大鼠用视黄醇处理4小时，从其睾丸中分离的mRNA用于构建消减cDNA文库。从该文库中分离出的一个cDNA包含磷酸丙糖异构酶（TPI）的序列。Northern印迹分析表明，TPI cDNA与睾丸中的两种转录本杂交。一种1.4kb的转录本是大多数组织中唯一发现的转录本，在睾丸的体细胞中表达，而一种新的1.5kb转录本仅在单倍体精子细胞中检测到。然而，只有较短转录本的水平在视黄醇处理睾丸或培养的支持细胞后升高。此外，用TPI cDNA筛选成年大鼠睾丸cDNA文库得到一个推测对应于1.5kb转录本的cDNA。对两个TPI cDNA的序列分析揭示了一个cDNA中有100bp的缺失，这可能是由于使用了替代的聚腺苷酸化信号。这些结果表明睾丸体细胞和单倍体生殖细胞中TPI表达存在独立的加工机制。
