Homozygous mutation of AURKC yields large-headed polyploid spermatozoa and causes male infertility.

The World Health Organization conservatively estimates that 80 million people suffer from infertility worldwide. Male factors are believed to be responsible for 20-50% of all infertility cases, but microdeletions of the Y chromosome are the only genetic defects altering human spermatogenesis that have been reported repeatedly. We focused our work on infertile men with a normal somatic karyotype but typical spermatozoa mainly characterized by large heads, a variable number of tails and an increased chromosomal content (OMIM 243060). We performed a genome-wide microsatellite scan on ten infertile men presenting this characteristic phenotype. In all of these men, we identified a common region of homozygosity harboring the aurora kinase C gene (AURKC) with a single nucleotide deletion in the AURKC coding sequence. In addition, we show that this founder mutation results in premature termination of translation, yielding a truncated protein that lacks the kinase domain. We conclude that the absence of AURKC causes male infertility owing to the production of large-headed multiflagellar polyploid spermatozoa.

Establishment of male-specific epigenetic information.

The setting of male-specific epigenetic information is a complex process, which involves a major global re-organisation, as well as localized changes of the nucleus structure during the pre-meiotic, meiotic and post-meiotic stages of the male germ cell differentiation. Although it has long been known that DNA methylation in targeted regions of the genome is associated with male-specific genomic imprinting, or that most core histones are hyperacetylated and then replaced by sperm-specific proteins during the post-meiotic condensation of the nucleus, many questions remain unanswered. How these changes interact, how they affect the epigenetic information and how the paternal epigenetic marks contribute to the future genome are indeed major issues remaining to be explored.

Clinical data and parenthood of 63 infertile and Y-microdeleted men.

OBJECTIVE: To collect follow-up data for infertile men with Y microdeletion. DESIGN: Retrospective, observational survey. SETTING: Multicenter IVF units associated with genetics laboratories. PATIENT(S): Sixty-three patients with Y microdeletion. INTERVENTION(S): Karyotype analysis, Y microdeletion screening, and assisted reproductive technology. MAIN OUTCOME MEASURES: Medical history, karyotype, nature of the AZF deletion, semen parameters, testis biopsy results, choice of assisted reproductive technology, and results of intracytoplasmic sperm injection (ICSI). RESULTS: Abnormal karyotypes were found in 8 men (12.7%), who were azoospermic except 1. Of these 8 men, 5 presented a combined AZFb+c deletion, and 3 had a deletion in AZFc only. Most men (39 of 63) were azoospermic, 3 were cryptoazoospermic, and 19 had extreme oligozoospermia (sperm concentration

Two fast methods for detection of Y-microdeletions.

OBJECTIVE: To test two recently available commercial kits: the new Promega Y Chromosome Deletion Detection System 2.0 kit and the Bird-Set kits (Y Chromosome UE and Extension). DESIGN: A comparative technical study. SETTING: Male infertility clinic. PATIENT(S): Twelve various Y chromosome microdeleted patients were included in the present study: two AZFa deleted, two AZFb deleted, four AZFb+c deleted, three AZFc deleted, and one AZF a+b+c deleted. INTERVENTION(S): DNA samples were tested with both the Promega kit and the Bird-Set kits. MAIN OUTCOME MEASURE(S): Electrophoresis and analysis comparison on a bioanalyzer. RESULT(S): Both kits (Promega 2.0 and Bird Y Chromosome UE) confirmed the 12 Y deletions. Both kits (Bird Extension and Promega 2.0) were able to determine the length of the 12 microdeletions with various differences. The new Promega 2.0 kit was considerably improved, with the addition of two sequenced tag sites (STS) in AZFa (sY86 and sY84) and the deletion of some (sY239 and sY153) but not all supernumerary inadequate STS. CONCLUSION(S): The two new commercially available kits use two different protocols to detect Y chromosome microdeletions. The Promega kit is a one-step diagnostic test. The Bird diagnostic test uses a two-step protocol. Both kits offer relevant methods such as standardization and ready-to-use mixes. However, both kits need further evaluation under routine conditions using nontested DNA samples.

HDAC6-induced premature chromatin compaction in mouse oocytes and fertilised eggs.

Chromatin remodelling in the fertilised mouse egg is intimately linked to protein synthesis and degradation, to protamine by histone replacement and to specific histone modifications. The involvement of histone deacetylases (HDACs) in the beginning of development is poorly understood. HDACs are essential for cell proliferation and in the control of gene expression in a wide variety of mammalian systems. Here we focus on mHDAC6, a recently identified class II histone deacetylase, and we analyse its expression and localisation in oocytes and pronuclear zygotes. By indirect immunofluorescence we show that mHDAC6 is detected in the cytoplasm of germinal vesicle (GV) stage oocytes and 1-cell embryos. Ectopic expression of this enzyme after injection into germinal vesicles and pronuclei alters the nuclear structure and causes premature compaction of the chromatin. Our data suggest that the effect of condensation is linked to the ubiquitin-binding activity of mHDAC6, rather than to its function as a deacetylase.