Involvement of sperm acetylated histones and the nuclear isoform of Glutathione peroxidase 4 in fertilization.

We previously demonstrated that the nuclear form of Glutathione peroxidase 4 (nGPx4) has a peculiar distribution in sperm head, being localized to nuclear matrix and acrosome and that sperm lacking nGPx4 are more prone to decondensation in vitro. In this study we have hypothesized that sperm retained acetylated histones and nGPx4 are implicated in paternal chromatin decondensation and male pronucleus formation at fertilization. Indeed, significant higher amounts of acetylated histone H4 and acetylated histone H3 were observed by both immunofluorescence and western blotting in nGPx4-KO sperm vs WT ones. In vitro fertilization of zona pellucida-deprived oocytes by WT sperm in the presence of trichostatin (TSA) also demonstrated that paternal histone acetylation was inversely related to the timing of sperm nucleus decondensation at fertilization. In contrast, TSA had no effect on nGPx4-KO sperm, indicating they had a maximal level of histone acetylation. Moreover the paternally imprinted gene Igf2/H19 was hypomethylated in KO sperm compared to WT ones. The lack of nGPx4 negatively affected male fertility, causing a marked decrease in total pups and pregnancies with delivery, a significant reduction in pronuclei (PN) embryos in in vitro fertilization assays and an approximately 2 h delay in egg fertilization in vivo. Because the zona pellucida binding and fusion to oolemma of nGPx4-KO and WT sperm were similar, the subfertility of nGPx4 sperm reflected a decreased sperm progression through egg cumulus/zona pellucida, pinpointing a defective acrosome in line with acrosomal nGPx4 localization. We conclude that paternal acetylated histones and acrosomal nGPx4 are directly involved in fertilization.

Mutations Impairing GSK3-Mediated MAF Phosphorylation Cause Cataract, Deafness, Intellectual Disability, Seizures, and a Down Syndrome-like Facies.

Transcription factors operate in developmental processes to mediate inductive events and cell competence, and perturbation of their function or regulation can dramatically affect morphogenesis, organogenesis, and growth. We report that a narrow spectrum of amino-acid substitutions within the transactivation domain of the v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog (MAF), a leucine zipper-containing transcription factor of the AP1 superfamily, profoundly affect development. Seven different de novo missense mutations involving conserved residues of the four GSK3 phosphorylation motifs were identified in eight unrelated individuals. The distinctive clinical phenotype, for which we propose the eponym Aymé-Gripp syndrome, is not limited to lens and eye defects as previously reported for MAF/Maf loss of function but includes sensorineural deafness, intellectual disability, seizures, brachycephaly, distinctive flat facial appearance, skeletal anomalies, mammary gland hypoplasia, and reduced growth. Disease-causing mutations were demonstrated to impair proper MAF phosphorylation, ubiquitination and proteasomal degradation, perturbed gene expression in primary skin fibroblasts, and induced neurodevelopmental defects in an in vivo model. Our findings nosologically and clinically delineate a previously poorly understood recognizable multisystem disorder, provide evidence for MAF governing a wider range of developmental programs than previously appreciated, and describe a novel instance of protein dosage effect severely perturbing development.

Molecular cloning and expression analysis of MPP alpha-2, a novel mouse transcript detected in a differential screen of pituitary libraries.

We identified a novel isoform transcript, MPP alpha-2, of the mouse Mg(2+)-dependent protein phosphatase (MPP) alpha gene. The amino acid sequence encoded by MPP alpha-2 differs from the previously known MPP alpha-1 sequence only at the carboxyl terminal region. Northern and in situ hybridization analysis revealed differential expression patterns of these two transcripts in the embryo and in the adult organism, suggesting an elaborate regulation of the MPP alpha gene.