Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
EXOSC10 is a catalytic subunit of the exosome that processes biologically active transcripts, degrades aberrant mRNAs and targets certain long non-coding RNAs (lncRNAs). The yeast orthologue Rrp6 is required for efficient growth and gametogenesis, and becomes unstable during meiosis. However, nothing is known about the localization, stability and function of EXOSC10 in the rodent male germline. We detect the protein in nucleoli and the cytoplasm of mitotic and meiotic germ cells, and find that it transiently associates with the XY body, a structure targeted by meiotic sex chromosome inactivation (MSCI). Finally, EXOSC10 becomes unstable at later stages of gamete development. To determine Exosc10's meiotic function, we inactivated the gene specifically in male germ cells using cre recombinase controlled by Stra8 or Ddx4/Vasa promoters. Mutant mice have small testes, show impaired germ cell differentiation and are subfertile. Our results demonstrate that EXOSC10 is post-translationally regulated in germ cells, associate the protein with epigenetic chromosome silencing, and reveal its essential role in germ cell growth and development.
ISSN: 2045-2322

hal-01647082
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01647082
DOI : 10.1038/s41598-017-14643-y
PUBMED : 29118343

Éditeur(s) : HAL CCSD Hindawi Publishing Corporation
Résumé : International audience
Two genes, that is, 5S ribosomal sequences and antifreeze glycoprotein (AFGP) genes, were mapped onto chromosomes of eight Antarctic notothenioid fish possessing a X1X1X2X2/X1X2Y sex chromosome system, namely, Chionodraco hamatus and Pagetopsis macropterus (family Channichthyidae), Trematomus hansoni, T. newnesi, T. nicolai, T. lepidorhinus, and Pagothenia borchgrevinki (family Nototheniidae), and Artedidraco skottsbergi (family Artedidraconidae). Through fluorescence in situ hybridization (FISH), we uncovered distinct differences in the gene content of the Y chromosomes in the eight species, with C. hamatus and P. macropterus standing out among others in bearing 5S rDNA and AFGP sequences on their Y chromosomes, respectively. Both genes were absent from the Y chromosomes of any analyzed species. The distinct patterns of Y and non-Y chromosome association of the 5S rDNA and AFGP genes in species representing different Antarctic fish families support an independent origin of the sex heterochromosomes in notothenioids with interesting implications for the evolutionary/adaptational history of these fishes living in a cold-stable environment.
ISSN: 2314-6133

hal-01544911
https://hal.archives-ouvertes.fr/hal-01544911
DOI : 10.1155/2013/243938

Éditeur(s) : HAL CCSD Wiley
Résumé : absent
ISSN: 0014-3820

hal-01032044
https://hal.archives-ouvertes.fr/hal-01032044

Éditeur(s) : HAL CCSD
Résumé : International audience
In two swordtail species of the genus Xiphophorus, the onset of puberty has been shown to be modulated at the P locus by sequence polymorphism and gene copy-number variation affecting the type 4 melanocortin hormone receptor Mc4r. The system works through the interaction of two allelic types, one encoding wild type and the other dominant-negative receptors. We have analyzed the structure and evolution of the P locus in the platyfish Xiphophorus maculatus, where as many as nine alleles of P determining the onset of sexual maturity in males and females, fecundity in females, and adult size in males are located on both the X and Y chromosomes in a region linked to the master sex-determining locus. In this species, mc4r has been amplified to up to 10 copies on both the X and Y chromosomes through recent large serial duplications. Subsequently, mc4r paralogues have diverged considerably into many different subtypes. Certain copies have acquired new untranslated regions through genomic rearrangements, and transposable element insertions and other mutations have accumulated in promoter regions, possibly explaining observed deviations from the classical mc4r transcriptional pattern. In the mc4r-coding sequence, in-frame insertions and deletions as well as nonsense and missense mutations have generated a high diversity of Mc4r-predicted proteins. Most of these variants are expressed in embryos, adults, and/or tumors. Functional receptor characterization demonstrated major divergence in pharmacological behavior for Mc4r receptors encoded by different copies of platyfish mc4r, with differences in constitutive activity as well as binding and stimulation by hormones. The high degree of allelic and copy-number variation observed between individuals can explain the high level of polymorphism for sexual maturation, fecundity, and body size in the platyfish: multiple combinations of Mc4r variants with different biochemical properties might interact to modulate the melanocortin signaling that regulates the hypothalamus-pituitary-gonadal axis.
GENETICS

hal-01544912
https://hal.archives-ouvertes.fr/hal-01544912
DOI : 10.1534/genetics.113.155952

Éditeur(s) : HAL CCSD Society for the Study of Reproduction
Résumé : International audience
Mammalian spermatogenesis is a complex and highly orchestrated combination of processes in which male germline proliferation and differentiation result in the production of mature spermatozoa. If recent genome-wide studies have contributed to the in-depth analysis of the male germline protein-encoding transcriptome, little effort has yet been devoted to the systematic identification of novel unannotated transcribed regions expressed during mammalian spermatogenesis. We report high-resolution expression profiling of male germ cells in rat, using next-generation sequencing technology and highly enriched testicular cell populations. Among 20 424 high-confidence transcripts reconstructed, we defined a stringent set of 1419 long multi-exonic unannotated transcripts expressed in the testis (testis-expressed unannotated transcripts [TUTs]). TUTs were divided into 7 groups with different expression patterns. Most TUTs share many of the characteristics of vertebrate long noncoding RNAs (lncRNAs). We also markedly reinforced the finding that TUTs and known lncRNAs accumulate during the meiotic and postmeiotic stages of spermatogenesis in mammals and that X-linked meiotic TUTs do not escape the silencing effects of meiotic sex chromosome inactivation. Importantly, we discovered that TUTs and known lncRNAs with a peak expression during meiosis define a distinct class of noncoding transcripts that exhibit exons twice as long as those of other transcripts. Our study provides new insights in transcriptional profiling of the male germline and represents a high-quality resource for novel loci expressed during spermatogenesis that significantly contributes to rat genome annotation.
ISSN: 0006-3363

hal-01063924
https://hal.archives-ouvertes.fr/hal-01063924
DOI : 10.1095/biolreprod.114.118166
PUBMED : 24740603