Zwingman T, Fujimoto H, Lai L W, Boyer T, Ao A, Stalvey J R, Blecher S R, Erickson R P
Department of Pediatrics, University of Arizona Health Sciences Center, Tucson.
Mol Reprod Dev. 1994 Apr;37(4):370-81. doi: 10.1002/mrd.1080370403.
Although its expression in adult testis was immediately apparent, the role for Sry (sex determining region, Y) in testicular function remains elusive. We have performed transcriptional studies in an effort to elucidate potential roles of Sry by studying the time and location of its transcription in mouse testes. Northern analyses and more sensitive nuclease protection assays detected transcripts in 28-day-old testes and beyond. The highly sensitive technique of reverse transcription polymerase chain reaction (RTPCR) could not detect Sry expression in 14-day testes when primers for the most conserved portion of the gene, the high mobility group (HMG) box, were used, but primers for the circular form detected Sry transcription at all postnatal stages studied. The same HMG box primers were able to detect expression of Sry in XX, Sxra or Sxrb testes. This suggested that Sry is expressed in cells other than germ cells, which was confirmed with studies on fractionated cells--RTPCR detected transcription of Sry in the highly pure interstitial cell fraction. However, Leydig cells and a Leydig cell tumor were negative for Sry expression. We performed in situ studies in an attempt to localize the expression of Sry in the testes. Abundant expression of an Sry cross-hybridizing transcript was found in spermatogonia, in early spermatocytes, and in some interstitial cells with antisense probes to the HMG box or a more specific, 3' region, whereas the sense probe gave little or no hybridization. It is probable that the circular transcripts, which are seen in reverse transcriptase positive (RT+) and RT- reactions by PCR because of the RT activity of Taq polymerase, are responsible for the hybridization seen in spermatogonia and spermatocytes, whereas linear and circular forms are detected later. Thus Sry is expressed in pre- and postmeiotic germ cells and in somatic cells of the testes.
尽管Sry（Y染色体性别决定区）在成年睾丸中的表达立即可见，但其在睾丸功能中的作用仍不清楚。我们进行了转录研究，试图通过研究其在小鼠睾丸中转录的时间和位置来阐明Sry的潜在作用。Northern分析和更灵敏的核酸酶保护试验在28日龄及以后的睾丸中检测到了转录本。当使用针对该基因最保守部分即高迁移率族（HMG）盒的引物时，逆转录聚合酶链反应（RTPCR）这一高灵敏度技术在14日龄睾丸中检测不到Sry表达，但针对环状形式的引物在所有研究的出生后阶段都检测到了Sry转录。相同的HMG盒引物能够在XX、Sxra或Sxrb睾丸中检测到Sry表达。这表明Sry在生殖细胞以外的细胞中表达，对分离细胞的研究证实了这一点——RTPCR在高度纯化的间质细胞组分中检测到了Sry转录。然而，睾丸间质细胞和一个睾丸间质细胞瘤的Sry表达呈阴性。我们进行了原位研究，试图在睾丸中定位Sry的表达。用针对HMG盒或更特异的3'区域的反义探针发现，精原细胞、早期精母细胞和一些间质细胞中有丰富的Sry交叉杂交转录本表达，而正义探针几乎没有或没有杂交信号。很可能是由于Taq聚合酶的逆转录活性，在PCR的逆转录阳性（RT+）和RT-反应中都能看到的环状转录本，导致了在精原细胞和精母细胞中看到的杂交信号，而线性和环状形式在之后才被检测到。因此，Sry在减数分裂前和减数分裂后的生殖细胞以及睾丸的体细胞中表达。
