Human and mouse ZFY genes produce a conserved testis-specific transcript encoding a zinc finger protein with a short acidic domain and modified transactivation potential

Mammalian ZFY genes are located on the Y chromosome, and code putative transcription factors with 12–13 zinc fingers preceded by a large acidic (activating) domain. In mice, there are two genes, Zfy1 and Zfy2, which are expressed mainly in the testis. Their transcription increases in germ cells as they enter meiosis, both are silenced by meiotic sex chromosome inactivation (MSCI) during pachytene, and Zfy2 is strongly reactivated later in spermatids. Recently, we have shown that mouse Zfy2, but not Zfy1, is involved in triggering the apoptotic elimination of specific types of sex chromosomally aberrant spermatocytes. In humans, there is a single widely transcribed ZFY gene, and there is no evidence for a specific role in the testis. Here, we characterize ZFY transcription during spermatogenesis in mice and humans. In mice, we define a variety of Zfy transcripts, among which is a Zfy2 transcript that predominates in spermatids, and a Zfy1 transcript, lacking an exon encoding approximately half of the acidic domain, which predominates prior to MSCI. In humans, we have identified a major testis-specific ZFY transcript that encodes a protein with the same short acidic domain. This represents the first evidence that ZFY has a conserved function during human spermatogenesis. We further show that, in contrast to the full acidic domain, the short domain does not activate transcription in yeast, and we hypothesize that this explains the functional difference observed between Zfy1 and Zfy2 during mouse meiosis

Lack of Association between Genetic Polymorphisms in Enzymes Associated with Folate Metabolism and Unexplained Reduced Sperm Counts

BACKGROUND: The metabolic pathway of folate is thought to influence DNA stability either by inducing single/double stranded breaks or by producing low levels of S-adenosyl-methionine leading to abnormal gene expression and chromosome segregation. Polymorphisms in the genes encoding enzymes in the folate metabolism pathway show distinct geographic and/or ethnic variations and in some cases have been linked to disease. Notably, the gene Methylenetetrahydrofolate reductase (MTHFR) in which the homozygous (TT) state of the polymorphism c.665C>T (p.A222V) is associated with reduced specific activity and increased thermolability of the enzyme causing mild hyperhomocysteinemia. Recently several studies have suggested that men carrying this polymorphism may be at increased risk to develop infertility. METHODOLOGY/PRINCIPAL FINDINGS: We have tested this hypothesis in a case/control study of ethnic French individuals. We examined the incidence of polymorphisms in the genes MTHFR (R68Q, A222V and E429A), Methionine synthase reductase MTRR; (I22M and S175L) and Cystathionine beta-synthase (CBS; G307S). The case population consisted of DNA samples from men with unexplained azoospermia (n = 70) or oligozoospermia (n = 182) and the control population consisted of normospermic and fertile men (n = 114). We found no evidence of an association between the incidence of any of these variants and reduced sperm counts. In addition haplotype analysis did not reveal differences between the case and control populations. CONCLUSIONS/SIGNIFICANCE: We could find no evidence for an association between reduced sperm counts and polymorphisms in enzymes involved in folate metabolism in the French population

Stratégie d'exploration moléculaire du chromosome Y dans les troubles sévères de la spermatogenèse

Les microdélétions du chromosome Y, deuxième cause génétique d'infertilité masculine, sont associées à des troubles sévères de la spermatogenèse qui relèvent de la technique d'ICSI. Après avoir évalué l'activité de recherche des microdélétions du bras long du chromosome Y en France, nous avons validé une méthode facilitant sa standardisation et comparé les performances techniques de kits commerciaux. Le génome germinal a été étudié par FISH chez dez patients avec oligozoospermie sévère d'origine non-obstructive sans anomalie chromosomiques spermatiques chez ces hommes. Enfin, nous avons montré l'inte rêt de deux techniques associées qui permettent de détecter toutes les délétions partielles de la région AZFc du chromosome Y. En conclusion, en cas de troubles sévères de la spermatogenèse, le chromosome Y doit être exploré dans le cadre du bilan avant AMPY chromosome microdeletions are the second genetic cause of male infertility. They are associated to severe spermatogenesis impairment relevant to ICSI techniques. We evaluated the research of Y chromosome long arm microdeletions in France, and then we validated a fast and easy method to facilitate standardization. We also compared technical performances of two commercial kits. The germinal genome was studied by FISH in patients with severe non obstructive oligozoospermia without karyotyping anomaly. We have identified four clinical and / or biological factors associated with higher numbers of aneuploid sperm. Finally, we showed the interest of two combined techniques to detect all the pertial deletions of the AZFc region. In conclusion, in the event of severe spermatogenesis impairment, the Y chromosome has to be screened before Assited Reproductive TechniquesLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Complete deletion of the AZFb interval from the Y chromosome in an oligozoospermic man

background: Deletion of the entire AZFb interval from the Y chromosome is strictly associated with azoospermia arising from maturation arrest during meiosis. Here, we describe the exceptional case of an oligozoospermic man, 13-1217, with an AZFb + c (P5/distal-P1) deletion. Through the characterization of this patient, and two AZFb (P5/proximal-P1) patients with maturation arrest, we have explored three possible explanations for his exceptionally progressive spermatogenesis. methods and results: We have determined the precise breakpoints of the deletion in 13-1217, and shown that 13-1217 is deleted for more AZFb material than one of the AZFb-deleted men (13-5349). Immunocytochemical analysis of spermatocytes with an antibody against a synaptonemal complex component indicates synapsis to be largely unaffected in 13-1217, in contrast to 13-5349 where extended asynapsis is frequent. Using PCR-based analyses of RNA and DNA from the same testicular biopsy, we show that 13-1217 expresses post-meiotic germ cell markers in the absence of genomic DNA and transcripts from the AZFb and AZFc intervals. We have determined the Y chromosome haplogroup of 13-1217 to be HgL-M185. conclusions: Our results indicate that the post-meiotic spermatogenesis in 13-1217 is not a consequence of mosaicism or retention of a key AZFb gene. On the contrary, since the Hg-L Y chromosome carried by 13-1217 is uncommon in Western Europe, a Y-linked modifier locus remains a possible explanation for the oligozoospermia observed in patient 13-1217. Further cases must now be studied to understand how germ cells complete spermatogenesis in the absence of the AZFb interval

Predictive factors for an increased risk of sperm aneuploidies in oligo-astheno-teratozoospermic males

E-mail Address : [email protected] audiencePatients with severe spermatogenesis impairment can now successfully father a child thanks to the use of intracytoplasmic sperm injection (ICSI). In oligozoospermic patients, many studies have reported significantly higher sperm aneuploidy rates and therefore an increased risk of transmitting a chromosomal abnormality via the injection of abnormal spermatozoa. However, the frequency of aneuploidy is highly variable between patients. The aim of the present work was to identify clinical and biological factors, which, together with non-obstructive oligozoospermia, could be predictive of elevated sperm aneuploidies. The sperm aneuploidy rates for chromosomes X, Y, 13, 18 and 21 were assessed in 31 infertile men with well-characterized spermatogenesis impairment, and in a population of control men with proven fertility. The frequency of sperm aneuploidy was compared between several patient subgroups according to their clinical and biological factors. Nearly half of the oligozoospermic males (15/31) had a significantly increased disomy rate for at least one of the five chromosomes compared with that observed in the control population (mean disomy rates + 1.96 standard deviation). Factors significantly associated with higher numbers of aneuploid sperm were cigarette smoking, an elevated follicle-stimulating hormone level, a sperm concentration less than 1 M/mL, and a severe teratozoospermia. Hence, several factors predictive of an increased risk of sperm aneuploidy rates were identified in ICSI male candidates with a non-obstructive oligozoospermia

Summary of published associations between the <i>MTHFR</i> C665T variant and unexplained male infertility.

<p>Summary of published associations between the <i>MTHFR</i> C665T variant and unexplained male infertility.</p

Associations between reduced sperm counts and the most common <i>MTRR</i> haplotypes.

<p>Associations between reduced sperm counts and the most common <i>MTRR</i> haplotypes.</p

The allelic frequencies and associations between reduced sperm counts and common polymorphisms in the <i>MTHFR</i> gene.

<p>The allelic frequencies and associations between reduced sperm counts and common polymorphisms in the <i>MTHFR</i> gene.</p

The allelic frequencies and associations between reduced sperm counts and common polymorphisms in the <i>MTRR</i> gene.

<p>The allelic frequencies and associations between reduced sperm counts and common polymorphisms in the <i>MTRR</i> gene.</p