A Cre gene directed by a human TSPY promoter is specific for germ cells and neurons

The testis-specific protein Y-encoded (TSPY) gene is a candidate for the gonadoblastoma locus on the Y chromosome and is expressed in normal testicular germ cells and gonadoblastoma cells of XY sex-reversed females. Although TSPY expression has been demonstrated in gonadoblastoma tissues, it is uncertain if such expression is involved in a causative or consequential event of the oncogenic process. We postulate that if TSPY is involved in gonadoblastoma development, its promoter should be functional in the female gonad before and/or at early stages of tumorigenesis. To test this hypothesis, we generated several lines of transgenic mice harboring a Cre-recombinase transgene directed by a 2.4-kb hTSPY promoter. These mice were crossed with the Z/EG reporter line that expresses EGFP only after a Cre-mediated recombination. Our results showed that hTSPY-Cre;Z/EG double transgenic mice expressed EGFP specifically in the germ cells of both male and female gonads. Further, neurons of the central and peripheral nervous systems also expressed EGFP as early as E12.5 embryonic stage. EGFP was particularly observed in the trigeminal nerve, trigeminal ganglion, dorsal root of the ganglia, and in postnatal and adult brains. These observations support the hypothesis that TSPY plays an active role in gonadoblastoma. The tissue-specific expression of the hTSPY-Cre transgene should also be useful in studies utilizing Cre-mediated gene activation/inactivation strategies in gamatogenesis and/or neurogenesis.     

CK2-dependent C-terminal phosphorylation at T300 directs the nuclear transport of TSPY protein

TSPY (testis-specific protein, Y-encoded) is a member of the greater SET/NAP family of molecules with various functions, e.g., in chromatin remodeling, regulation of gene expression, and has been implicated to play a role in the malignant development of gonadoblastoma, testicular and prostate cancer. Here we demonstrate that the C-terminus has a functional role for the nucleo-cytoplasmatic shuttling of the TSPY protein. Using various combinations of in vitro mutagenesis and enhanced green fluorescent protein reporter gene-expression experiments we were able to show that while the deletion of C-terminus leads to a decreased stability and enhanced degradation of the protein, the selective mutation of a C-terminal CK2 phosphorylation site (T300) prevents the TSPY protein from entering the nucleus. We conclude that phosphorylation of the (T300) residue is a necessary and functional prerequisite for TSPY's transport into the nucleus reminding of comparable data from a related Drosophila molecule, NAP1.     

Expression of a candidate gene for the gonadoblastoma locus in gonadoblastoma and testicular seminoma

The gonadoblastoma locus on the Y chromosome (GBY) predisposes the dysgenetic gonads of XY females to develop in situ tumors. It has been mapped to a critical interval on the short arm and adjacent centromeric region on the Y chromosome. Currently there are five functional genes identified on the GBY critical region, thereby providing likely candidates for this cancer predisposition locus. To evaluate the candidacy of one of these five genes, testis-specific protein Y-encoded (TSPY), as the gene for GBY, expression patterns of TSPY in four gonadoblastoma from three patients were analyzed by immunohistochemistry using a TSPY specific antibody. Results from this study showed that TSPY was preferentially expressed in tumor germ cells of all gonadoblastoma specimens. Additional study on two cases of testicular seminoma demonstrated that TSPY was also abundantly expressed in all stages of these germ cell tumors. The present observations suggest that TSPY may either be involved in the oncogenesis of or be a useful marker for both types of germ cell tumors.     

Gonadoblastoma: molecular definition of the susceptibility region on the Y chromosome.

Using sequence-tagged sites we have performed deletion mapping of the Y chromosome in sex-reversed female patients with a Y chromosome and gonadoblastoma. The GBY gene (gonadoblastoma locus on the Y chromosome) was sublocalized to a small region near the centromere of the Y chromosome. We estimate the size of the GBY critical region to be approximately 1-2 Mb. Our analysis also indicates that copies of two dispersed Y-linked gene families, TSPY (testis-specific protein, Y-encoded) and YRRM (Y-chromosome RNA recognition motif) are present in all patients and that copies of TSPY but not YRRM fall within the GBY critical region as formally defined by deletion mapping. Two tumor samples showed expression of both genes and in one patient this expression was limited to a unilateral gonadoblastoma but absent in the contralateral streak gonad. Although our results do not directly implicate TSPY or YRRM in the etiology of the tumor, they raise the issue of whether there is one GBY gene in the critical region or possibly multiple GBY loci dispersed on the Y chromosome.     

CASK point mutation regulates protein-protein interactions and NR2b promoter activity

Mutations in the CASK gene result in mental retardation and microcephaly in humans, suggesting an important role for CASK in brain. CASK gene knockout in mice causes neonatal lethality, making further elucidation in mouse models difficult. Because CASK was originally identified as a multidomain adaptor protein, identifying a point mutation interrupting a specific protein interaction would be useful in dissecting its molecular function. Here, a Thr-to-Ala mutation in the rat CASK guanylate kinase (GK) domain was shown to reduce interactions among CASK and Tbr-1 and CINAP, two critical brain proteins. The effect is specific: this mutation does not affect CASK dimerization that occurs via the GK domain. The Tbr-1-CASK-CINAP complex regulates expression of the NMDA receptor subunit 2b (NR2b), and we show that this point mutation also affects NR2b promoter activity. The identification of this mutation may make it possible to further dissect the function of CASK in brain.     

人睾丸与脑基因表达谱的相似性

人类的物种形成与进化问题一直是研究的一个焦点。近年来,对于人和灵长类以及果蝇等其他一些动物多种组织基因表达谱的研究表明,在人的进化过程中脑基因表达的改变最为显著,并且脑中许多基因的表达呈显著上调。信息学分析显示,在多种组织当中,人的脑与睾丸可能存在最为相似的基因表达谱。这些结果提示睾丸可能与脑类似,也在人的物种形成和进化历程中起着重要作用。本文对人睾丸和脑基因表达谱的研究进行了回顾,并提出了该研究方向今后的一些研究设想。     

Transcriptomic analyses support the similarity of gene expression between brain and testis in human as well as mouse

We previously revealed similarity in gene expression patterns between human brain and testis, based on digital differential display analyses of 760 human Unigenes. In the present work, we reanalyzed the gene expression data in many tissues of human and mouse for a large number of genes almost covering the respective whole genomes. The results indicated that both in human and in mouse, the gene expression profiles exhibited by brain, cerebellum and testis are most similar to each other compared with other tissues.