Explore the vast range of titles available.

The majority of histones are replaced by protamines during spermatogenesis, but small amounts are retained in mammalian spermatozoa. Since nucleosomes in spermatozoa influence epigenetic inheritance, it is important to know how histones are distributed in the sperm genome. Conflicting data, which may result from different conditions used for micrococcal nuclease (MNase) digestion, have been reported: retention of nucleosomes at either gene promoter regions or within distal gene-poor regions. Here, we find that the swim-up sperm used in many studies contain about 10% population of sperm which have not yet completed the histone-to-protamine replacement. We develop a method to purify histone replacement-completed sperm (HRCS) and to completely solubilize histones from cross-linked HRCS without MNase digestion. Our results indicate that histones are retained at specific promoter regions in HRCS. This method allows the study of epigenetic status in mature sperm. While a majority of histones are replaced by protamines during spermatogenesis, a small amount is retained in mammalian spermatozoa. Here the authors develop a method to purify histones from replacement-completed sperm (HRCS), completely solubilize histones from cross-linked HRCS without MNase digestion, and map histone-binding sites in these cells.

The small arginine-rich protein protamine condenses complete genomic DNA into the sperm head. Here, we applied its high RNA binding capacity for spontaneous electrostatic assembly of therapeutic nanoparticles decorated with tumour-cell-specific antibodies for efficiently targeting siRNA. Fluorescence microscopy and DLS measurements of these nanocarriers revealed the formation of a vesicular architecture that requires presence of antibody-protamine, defined excess of free SMCC-protamine, and anionic siRNA to form. Only these complex nanoparticles were efficient in the treatment of non-small-cell lung cancer (NSCLC) xenograft models, when the oncogene KRAS was targeted via EGFR-mediated delivery. To show general applicability, we used the modular platform for IGF1R-positive Ewing sarcomas. Anti-IGR1R-antibodies were integrated into an antibody-protamine nanoparticle with an siRNA specifically against the oncogenic translocation product EWS/FLI1. Using these nanoparticles, EWS/FLI1 knockdown blocked in vitro and in vivo growth of Ewing sarcoma cells. We conclude that these antibody-protamine-siRNA nanocarriers provide a novel platform technology to specifically target different cell types and yet undruggable targets in cancer therapy by RNAi.

CRISPR/Cas mediated genome editing has been successfully demonstrated in mammalian cells and further applications for generating mutant mice were reported by injecting humanized Cas9 ( hCas ) mRNA and single guide RNA into fertilized eggs. Here we inject the circular plasmids expressing hCas9 and sgRNA into mouse zygotes and obtained mutant mice within a month. When we targeted the Cetn1 locus, 58.8% (10/17) of the pups carried the mutations and six of them were homozygously mutated. Co-injection of the plasmids targeting different loci resulted in the successful removal of the flanked region in two out of three mutant pups. The efficient mutagenesis was also observed at the Prm1 locus. Among the 46 offspring carrying CRISPR/Cas plasmid mediated mutations, only two of them carried the hCas9 transgene. The pronuclear injection of circular plasmid expressing hCas9/sgRNA complex is a rapid, simple and reproducible method for targeted mutagenesis.

Conventional dogma presumes that protamine-mediated DNA compaction in sperm is achieved by electrostatic interactions between DNA and the arginine-rich core of protamines. Phylogenetic analysis reveals several non-arginine residues conserved within, but not across species. The significance of these residues and their post-translational modifications are poorly understood. Here, we investigated the role of K49, a rodent-specific lysine residue in protamine 1 (P1) that is acetylated early in spermiogenesis and retained in sperm. In sperm, alanine substitution (P1(K49A)) decreases sperm motility and male fertility—defects that are not rescued by arginine substitution (P1(K49R)). In zygotes, P1(K49A) leads to premature male pronuclear decompaction, altered DNA replication, and embryonic arrest. In vitro, P1(K49A) decreases protamine–DNA binding and alters DNA compaction and decompaction kinetics. Hence, a single amino acid substitution outside the P1 arginine core is sufficient to profoundly alter protein function and developmental outcomes, suggesting that protamine non-arginine residues are essential for reproductive fitness. Here, the authors show that a single substitution in mouse P1, outside of its arginine core and independently of its charge, suffices to alter sperm chromatin structure and associated developmental outcomes.

Idiopathic fertility disorders are associated with mutations in various genes. Here, we report that coiled-coil glutamate-rich protein 1 (CCER1), a germline-specific and intrinsically disordered protein (IDP), mediates postmeiotic spermatid differentiation. In contrast, CCER1 deficiency results in defective sperm chromatin compaction and infertility in mice. CCER1 increases transition protein ( Tnp1/2 ) and protamine ( Prm1/2 ) transcription and mediates multiple histone epigenetic modifications during the histone-to-protamine (HTP) transition. Immiscible with heterochromatin in the nucleus, CCER1 self-assembles into a polymer droplet and forms a liquid-liquid phase-separated condensate in the nucleus. Notably, we identified loss-of-function (LoF) variants of human CCER1 (h CCER1 ) in five patients with nonobstructive azoospermia (NOA) that were absent in 2713 fertile controls. The mutants led to premature termination or frameshift in CCER1 translation, and disrupted condensates in vitro. In conclusion, we propose that nuclear CCER1 is a phase-separated condensate that links histone epigenetic modifications, HTP transitions, chromatin condensation, and male fertility. Here the authors reveal that phase‐separated nuclear CCER1 condensates are required for male fertility by mediating chromatin condensation and histone epigenetic modification, while loss‐of‐function variants of human CCER1 are pathogenic in patients with nonobstructive azoospermia (NOA).

Genetic studies elucidate a link between testis-specific serine/threonine kinases (TSSKs) and male infertility in mammals, but the underlying mechanisms are unclear. Here, we identify a TSSK homolog in Drosophila , CG14305 (termed dTSSK), whose mutation impairs the histone-to-protamine transition during spermiogenesis and causes multiple phenotypic defects in nuclear shaping, DNA condensation, and flagellar organization in spermatids. Genetic analysis demonstrates that kinase catalytic activity of dTSSK, which is functionally conserved with human TSSKs, is essential for male fertility. Phosphoproteomics identify 828 phosphopeptides/449 proteins as potential substrates of dTSSK enriched primarily in microtubule-based processes, flagellar organization and mobility, and spermatid differentiation and development, suggesting that dTSSK phosphorylates various proteins to orchestrate postmeiotic spermiogenesis. Among them, the two substrates, protamine-like protein Mst77F/Ser 9 and transition protein Mst33A/Ser 237 , are biochemically validated to be phosphorylated by dTSSK in vitro, and are genetically demonstrated to be involved in spermiogenesis in vivo. Collectively, our findings demonstrate that broad phosphorylation mediated by TSSKs plays an indispensable role in spermiogenesis. Testis-specific serine/threonine kinases have been associated with male infertility, but the mechanism for this connection is unclear. Here they identify a Drosophila homolog, dTSSK, which is essential for male fertility in fruit flies and has functionally conserved catalytic activity with human TSSKs.

The Valley of Sacco River (VSR) (Latium, Italy) is an area with large-scale industrial chemical production that has led over time to significant contamination of soil and groundwater with various industrial pollutants, such as organic pesticides, dioxins, organic solvents, heavy metals, and particularly, volatile organic compounds (VOCs). In the present study, we investigated the potential impact of VOCs on the spermatozoa of healthy young males living in the VSR, given the prevalent presence of several VOCs in the semen of these individuals. To accomplish this, spermiograms were conducted followed by molecular analyses to assess the content of sperm nuclear basic proteins (SNBPs) in addition to the protamine-histone ratio and DNA binding of these proteins. We found drastic alterations in the spermatozoa of these young males living in the VSR. Alterations were seen in sperm morphology, sperm motility, sperm count, and protamine/histone ratios, and included significant reductions in SNBP–DNA binding capacity. Our results provide preliminary indications of a possible correlation between the observed alterations and the presence of specific VOCs.

Protamines are proteins responsible for condensing sperm chromatin. There are two protamines whose ratio remains constant in each species and which is related to fertility. To quantify their expression, it is necessary to have a good protocol of sample collection ( i . e ., RNA stabilizing buffers and temperature conditions). The aim of this work was to compare gene expression of protamines, with analysis of RNA quality and ratios, in testis samples from wild-derived mice, Mus musculus , preserved in different buffers (RNAlater ® or Nucleic Acid Preservation–NAP–buffer) and different temperatures (room temperature -RT-, 4°C, -20°C, -80°C or liquid nitrogen) for different times (one week, one month, 3 months and one year). The relative abundance of protamine expression was assessed by qPCR using 18S rRNA as housekeeping. The results showed that the preservation of testes in RNAlater ® or NAP buffer at -80°C afforded equivalent good preservation as in somatic tissues. Testis samples stored at RT in both buffers for 1 week resulted in a similar RNA quality and protamine expression over time. Moreover, samples in RNAlater ® stored at RT, 4°C, -20°C and -80°C, were analyzed after 24 h, 7 days, 30 days, 90 days or 365 days; samples stored at RT resulted in a loss of RNA quality but protamine ratio was maintained up to 90 days. Samples stored at 4°C and -20°C showed similar values of RNA integrity and protamine expression than those stored at -80°C. Finally, we stored testis samples at -80°C or -196°C, after initial snap-freezing in liquid nitrogen. Both methods afforded very good preservation of RNA integrity and protamine expression. These results open new possibilities for the collection, transport and storage of testes samples under field conditions.

B chromosomes are non-essential, extra chromosomes that can exhibit transmission-enhancing behaviors, including meiotic drive, mitotic drive, and induction of genome elimination, in plants and animals. A fundamental but poorly understood question is what characteristics allow B chromosomes to exhibit these extraordinary behaviors. The jewel wasp, Nasonia vitripennis, harbors a heterochromatic, paternally transmitted B chromosome known as paternal sex ratio (PSR), which causes complete elimination of the sperm-contributed half of the genome during the first mitotic division of fertilized embryos. This genome elimination event may result from specific, previously observed alterations of the paternal chromatin. Due to the haplo-diploid reproduction of the wasp, genome elimination by PSR causes female-destined embryos to develop as haploid males that transmit PSR. PSR does not undergo self-elimination despite its presence with the paternal chromatin until the elimination event. Here we performed fluorescence microscopic analyses aimed at understanding this unexplained property. Our results show that PSR, like the rest of the genome, participates in the histone-to-protamine transition, arguing that PSR does not avoid this transition to escape self-elimination. In addition, PSR partially escapes the chromatin-altering activity of the intracellular bacterium, Wolbachia, demonstrating that this ability to evade chromatin alteration is not limited to PSR’s own activity. Finally, we observed that the rDNA locus and other unidentified heterochromatic regions of the wasp’s genome also seem to evade chromatin disruption by PSR, suggesting that PSR’s genome-eliminating activity does not affect heterochromatin. Thus, PSR may target an aspect of euchromatin to cause genome elimination.

Spermatogenesis starts with the onset of puberty within the seminiferous epithelium of the testes. It is a complex process under intricate control of the endocrine system. Physiological regulations by steroid hormones in general and by estrogens in particular are due to their chemical nature prone to be disrupted by exogenous factors acting as endocrine disruptors (EDs). 17α-Ethynylestradiol (EE2) is an environmental pollutant with a confirmed ED activity and a well-known effect on spermatogenesis and chromatin remodeling in haploid germ cells. The aim of our study was to assess possible effects of two doses (2.5ng/ml; 2.5 μg/ml) of EE2 on both histone-to-protamine exchange and epigenetic profiles during spermatogenesis performing a multi/transgenerational study in mice. Our results demonstrated an impaired histone-to-protamine exchange with a significantly higher histone retention in sperm nuclei of exposed animals, when this process was accompanied by the changes of histone post-translational modifications (PTMs) abundancies with a prominent effect on H3K9Ac and partial changes in protamine 1 promoter methylation status. Furthermore, individual changes in molecular phenotypes were partially transmitted to subsequent generations, when no direct trans-generational effect was observed. Finally, the uncovered specific localization of the histone retention in sperm nuclei and their specific PTMs profile after EE2 exposure may indicate an estrogenic effect on sperm motility and early embryonic development via epigenetic mechanisms.