Chaudhary Jaideep, Sadler-Riggleman Ingrid, Skinner Michael K
Center for Reproductive Biology School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4231, USA.
Gene. 2004 Jan 7;324:79-88. doi: 10.1016/j.gene.2003.09.035.
Sertoli cells provide the cytoarchitectural support and microenvironment necessary for the process of spermatogenesis and have a central role in male sex determination. Characterization of Sertoli cell specific gene products provides insight into the unique functions of this testicular cell type. The current study reports the identification of a novel Sertoli cell gene product that is termed Sertoli cell specific gene (SERT). The SERT cDNA sequence shows no homology to any of the known gene sequences in the GenBank database. Some homology was found with short sequences in the expressed sequence tag (EST) database. A motif analysis demonstrates a signature to an RNA binding protein sex lethal (sx1) involved in Drosophila sex determination. The expression pattern of SERT was examined with reverse transcription polymerase chain reaction (RT-PCR) and Northern blot analysis. SERT expression was found to be specific to the testis and absent in other tissues examined. In the testis, the approximate 1.5-kb SERT transcript was localized to the Sertoli cells. A 1.1-kb spliced form of SERT was also identified by reverse transcription polymerase chain reaction analysis. The genomic structure analysis demonstrates the presence of at least three exons with 85% sequence homology between mouse and rat sequences. Treatment of cultured Sertoli cells with follicle stimulating hormone (FSH) significantly increased the expression of SERT mRNA levels. The potential role of SERT in Sertoli cell function was investigated with the use of a transferrin promoter reporter construct. Transferrin expression is a marker of Sertoli cell differentiated function. An antisense oligonucleotide to SERT significantly inhibited FSH and cAMP induced transferrin promoter activation, while control oligonucleotides had no effect. In summary, a novel gene product expressed primarily by Sertoli cells, SERT, was identified with a potential RNA binding protein motif similar to sex lethal that appears to have a role in maintaining hormone (e.g. FSH) actions in Sertoli cells.
支持细胞为精子发生过程提供细胞结构支持和必要的微环境，在雄性性别决定中起核心作用。支持细胞特异性基因产物的特征分析有助于深入了解这种睾丸细胞类型的独特功能。当前研究报告了一种新型支持细胞基因产物的鉴定，该产物被命名为支持细胞特异性基因（SERT）。SERT cDNA序列与GenBank数据库中任何已知基因序列均无同源性。在表达序列标签（EST）数据库中发现了与短序列的一些同源性。基序分析显示出与参与果蝇性别决定的RNA结合蛋白性致死（sx1）的特征。用逆转录聚合酶链反应（RT-PCR）和Northern印迹分析检测了SERT的表达模式。发现SERT表达具有睾丸特异性，在所检测的其他组织中不存在。在睾丸中，约1.5kb的SERT转录本定位于支持细胞。通过逆转录聚合酶链反应分析还鉴定出了1.1kb的SERT剪接形式。基因组结构分析表明存在至少三个外显子，小鼠和大鼠序列之间的序列同源性为85%。用促卵泡激素（FSH）处理培养的支持细胞可显著增加SERT mRNA水平的表达。使用转铁蛋白启动子报告构建体研究了SERT在支持细胞功能中的潜在作用。转铁蛋白表达是支持细胞分化功能的标志物。针对SERT的反义寡核苷酸显著抑制FSH和cAMP诱导的转铁蛋白启动子激活，而对照寡核苷酸则无作用。总之，鉴定出了一种主要由支持细胞表达的新型基因产物SERT，其具有与性致死相似的潜在RNA结合蛋白基序，似乎在维持支持细胞中的激素（如FSH）作用方面发挥作用。
