Dipartimento delle Scienze Biologiche, Università di Napoli Federico II, Naples, Italy. teresa.capriglione @ unina.it
Sex Dev. 2010;4(1-2):104-9. doi: 10.1159/000289579. Epub 2010 Mar 16.
DMRT genes encode a large family of transcription factors which share an unusual cysteine-rich DNA-binding motif, the DM domain. DM family members have been studied in the context of sexual development; in particular, the DMRT1 gene appeared to be the one most directly involved in sex determination, but its activity is largely unexplored and possible downstream targets of this factor have yet to be identified. DMRT1 of the lacertid lizard Podarcis sicula (PsDMRT1) was isolated as a model to study differential gene expression during the seasonal reproductive cycle of an ectothermal species. The adult testis of P. sicula exhibits full activity in spring, complete regression in summer and a slow autumnal recrudescence without spermiation. We cloned a 591-bp partial ORF of the PsDMRT1 fragment, whose putative amino acid sequence contains the conserved DM domain. Northern blot analysis of mRNA from different tissues of P. sicula individuals captured in spring demonstrated DMRT1 transcripts only in testis. Semi-quantitative RT-PCR and in situ hybridization experiments showed peak PsDMRT1 expression in spring, lower expression in autumn and no expression during the period of gonad regression. A possible correlation between androgen level variations and PsDMRT1 transcripts is hypothesized and discussed. Finally, data showed that PsDMRT1 is expressed only in spermatogenic cells, before the second meiotic division, suggesting that its role is confined to the proliferation and maintenance of spermatogonia and spermatocytes.
DMRT 基因编码一个庞大的转录因子家族，它们共享一个不寻常的富含半胱氨酸的 DNA 结合基序，即 DM 结构域。DM 家族成员在性发育方面进行了研究；特别是，DMRT1 基因似乎与性别决定最直接相关，但它的活性在很大程度上尚未被探索，其潜在的下游靶标也尚未被确定。蜥蜴 Podarcis sicula 的 DMRT1（PsDMRT1）被分离出来作为模型，以研究变温物种季节性生殖周期中差异基因表达。春季，P. sicula 的成年睾丸表现出完全的活性，夏季完全退化，秋季缓慢恢复但没有精子发生。我们克隆了 PsDMRT1 片段的 591bp 部分 ORF，其推定的氨基酸序列包含保守的 DM 结构域。对春季不同组织的 P. sicula 个体的 mRNA 进行 Northern blot 分析表明，DMRT1 转录本仅在睾丸中表达。半定量 RT-PCR 和原位杂交实验显示，PsDMRT1 在春季表达峰值最高，秋季表达较低，在性腺退化期间无表达。假设并讨论了雄激素水平变化与 PsDMRT1 转录本之间可能存在的相关性。最后，数据表明 PsDMRT1 仅在精子发生细胞中表达，即在第二次减数分裂之前，这表明其作用仅限于精原细胞和精母细胞的增殖和维持。
