Tex261, a novel gene presumably related but distinct from steroidogenic acute regulatory (StAR) gene, is regulated during the development of germ cells

Comparative Transcriptome Analysis of Bombyx mori (Lepidoptera) Larval Hemolymph in Response to Autographa californica Nucleopolyhedrovirus in Differentially Resistant Strains

Bombyx mori nucleopolyhedrovirus (BmNPV) is a kind of pathogen that causes huge economic losses to silkworm production. Although Autographa californica nucleopolyhedrovirus (AcMNPV) and BmNPV are both baculoviruses, the host domains of these two viruses have almost no intersection in nature. Recently, it has been found that some silkworms could be infected by recombinant AcMNPV through a puncture, which provided valuable material for studying the infection mechanism of baculovirus to silkworm. In this study, comparative transcriptomics was used to analyse the hemolymph of two differentially resistant strains following AcMNPV inoculation. There were 678 DEGs in p50 and 515 DEGs in C108 following viral infection. Among them, the upregulation and downregulation of DEGs were similar in p50; however, the upregulated DEGs were nearly twice as numerous as the downregulated DEGs in C108. The DEGs in different resistant strains differed by GO enrichment. Based on KEGG enrichment, DEGs were mainly enriched in metabolic pathways in p50 and the apoptosis pathway in C108. Moreover, 13 genes involved in metabolic pathways and 11 genes involved in the apoptosis pathway were analysed. Among the DEGs involved in apoptosis, the function of BmTex261 in viral infection was analysed. The BmTex261 showed the highest expression in hemolymph and a significant response to viral infection in the hemolymph of C108, indicating that it is involved in anti-AcMNPV infection. This was further validated by the significantly decreased expression of viral gene lef3 after overexpression of BmTex261 in BmN cells. The results provide a theoretical reference for the molecular mechanism of resistance to BmNPV in silkworms.

Human testis-expressed (TEX) genes: a review focused on spermatogenesis and male fertility

Spermatogenesis is a complex process regulated by a multitude of genes. The identification and characterization of male-germ-cell-specific genes is crucial to understanding the mechanisms through which the cells develop. The term “TEX gene” was coined by Wang et al. (Nat Genet. 2001; 27: 422–6) after they used cDNA suppression subtractive hybridization (SSH) to identify new transcripts that were present only in purified mouse spermatogonia. TEX (Testis expressed) orthologues have been found in other vertebrates (mammals, birds, and reptiles), invertebrates, and yeasts. To date, 69 TEX genes have been described in different species and different tissues. To evaluate the expression of each TEX/tex gene, we compiled data from 7 different RNA-Seq mRNA databases in humans, and 4 in the mouse according to the expression atlas database.

Various studies have highlighted a role for many of these genes in spermatogenesis. Here, we review current knowledge on the TEX genes and their roles in spermatogenesis and fertilization in humans and, comparatively, in other species (notably the mouse). As expected, TEX genes appear to have a major role in reproduction in general and in spermatogenesis in humans but also in all mammals such as the mouse. Most of them are expressed specifically or predominantly in the testis. As most of the TEX genes are highly conserved in mammals, defects in the male (gene mutations in humans and gene-null mice) lead to infertility. In the future, cumulative data on the human TEX genes’ physiological functions and pathophysiological dysfunctions should become available and is likely to confirm the essential role of this family in the reproductive process. Thirteen TEX genes are now referenced in the OMIM database, and 3 have been linked to a specific phenotype. TEX11 (on Xq13.1) is currently the gene most frequently reported as being associated with azoospermia.

TOPAZ1, a germ cell specific factor, is essential for male meiotic progression

Topaz1 (Testis and Ovary-specific PAZ domain gene 1) is a germ cell specific gene highly conserved in vertebrates. The putative protein TOPAZ1 contains a PAZ domain, specifically found in PIWI, Argonaute and Zwille proteins. Consequently, Topaz1 is supposed to have a role during gametogenesis and may be involved in the piRNA pathway and contribute to silencing of transposable elements and maintenance of genome integrity. Here we report Topaz1 inactivation in mouse. Female fertility was not affected, but male sterility appeared exclusively in homozygous mutants in accordance with the high expression of Topaz1 in male germ cells. Pachytene Topaz1--deficient spermatocytes progress through meiosis without either derepression of retrotransposons or MSCI dysfunction, but become arrested before the post-meiotic round spermatid stage with extensive apoptosis. Consequently, an absence of spermatids and spermatozoa was observed in Topaz1(-/-) testis. Histological analysis also revealed that disturbances of spermatogenesis take place between post natal days 15 and 20, during the first wave of male meiosis and before the generation of haploid germ cells. Transcriptomic analysis at these two stages showed that TOPAZ1 influences the expression of one hundred transcripts, most of which are up-regulated in mutant testis at post natal day 20. Our results also showed that 10% of these transcripts are long non-coding RNA. This suggests that a highly regulated balance of lncRNAs seems to be essential during spermatogenesis for induction of appropriate male gamete production.

Tex261 modulates the excitotoxic cell death induced by N-methyl-D-aspartate (NMDA) receptor activation

N-methyl-D-aspartate (NMDA) receptor is a calcium-permeable ionotropic glutamate receptor and plays a role in many neurologic disorders such as brain ischemia through its involvement in excitotoxicity. We have performed differential display PCR to identify changes in gene expression that occur in the hippocampus of the mouse brain after intraperitoneal injection of NMDA and identified a gene, Tex261 as an inducible gene by NMDA stimulation in vivo. Tex261 mRNA was gradually induced in response to NMDA and reached about 4.5-fold at 24 h. When HEK 293 cells are transfected with NMDA receptors, the cells die in a manner that mimics excitotoxicity in neurons. HEK 293 cells transfected with the combination of Tex261 and the NMDA receptors NR1/NR2A produced the greater cell death compared with the cells transfected with the NMDA receptors alone. These findings suggest that Tex261 modulates the excitotoxic cell death induced by NMDA receptor activation.

Tvp38, Tvp23, Tvp18 and Tvp15: Novel membrane proteins in the Tlg2-containing Golgi/endosome compartments of Saccharomyces cerevisiae

Four previously uncharacterized proteins (Tvp38, Tvp23, Tvp18 and Tvp15) were found in Tlg2-containing membrane by proteomic analysis of immunoisolated Golgi subcompartments of Saccharomyces cerevisiae (Inadome et al., Mol. Cell. Biol., 25 (2005) 7696-7710). Immunofluorescence double staining of HA-tagged Tvp proteins and myc-tagged tSNAREs supported that these proteins mainly localize in the Tlg2-containing compartments. Conserved sequences of Tvp38, Tvp23 and Tvp18 are found in higher eukaryotes, but these homologues have not been characterized yet. All Tvp proteins were nonessential for growth under laboratory conditions. Immunoprecipitation of Tvp proteins indicated that Tvp23, Tvp18 and Tvp15 are in an interactive network with Yip1-family proteins, Yip4 and Yip5. They may collectively assist in the effective maintenance/function of the late Golgi/endosomal compartments. Disruptions of tvp15 and tvp23 showed synthetic aggravation with ypt6 or ric1 null mutation. Processing of carboxypeptidase Y and alkaline phosphatase in tvp disruptants occurred as in the wild type.

Immunoisolaton of the yeast Golgi subcompartments and characterization of a novel membrane protein, Svp26, discovered in the Sed5-containing compartments

The Golgi apparatus consists of a set of vesicular compartments which are distinguished by their marker proteins. These compartments are physically separated in the Saccharomyces cerevisiae cell. To characterize them extensively, we immunoisolated vesicles carrying either of the SNAREs Sed5 or Tlg2, the markers of the early and late Golgi compartments, respectively, and analyzed the membrane proteins. The composition of proteins was mostly consistent with the position of each compartment in the traffic. We found six uncharacterized but evolutionarily conserved proteins and named them Svp26 (Sed5 compartment vesicle protein of 26 kDa), Tvp38, Tvp23, Tvp18, Tvp15 (Tlg2 compartment vesicle proteins of 38, 23, 18, and 15 kDa), and Gvp36 (Golgi vesicle protein of 36 kDa). The localization of Svp26 in the early Golgi compartment was confirmed by microscopic and biochemical means. Immunoprecipitation indicated that Svp26 binds to itself and a Golgi mannosyltransferase, Ktr3. In the absence of Svp26, a considerable portion of Ktr3 was mislocalized in the endoplasmic reticulum. Our data suggest that Svp26 has a novel role in retention of a subset of membrane proteins in the early Golgi compartments.

Tex27, a gene containing a zinc-finger domain, is up-regulated during the haploid stages of spermatogenesis

Tex27 is a gene encoding a protein containing a zinc-finger domain in the carboxy terminal region and a transactivation domain in the amino terminal region. The Tex27 cDNA was isolated from a subtractive library that was enriched for genes preferentially expressed during the development of the seminiferous epithelium. Northern and in situ hybridization analyses demonstrated that Tex27 is differentially expressed in the testis, showing an increased expression in the germ cells corresponding to postmeiotic stages of spermatogenesis. This expression pattern in testis has been described for other C2H2-type zinc-finger proteins in mouse and human, like CTfin51, Zpf29, Sp1, and Zpf37. RFLP-Southern assays revealed that Tex27 is conserved in mammals. The polypeptide analysis and expression pattern suggest that Tex27 is a potential transcription factor preferentially expressed in postmeiotic cells during mouse spermatogenesis.