Zmynd15 encodes a histone deacetylase-dependent transcriptional repressor essential for spermiogenesis and male fertility

Human sperm RNA in male infertility

The function and value of specific sperm RNAs in apparently idiopathic male infertility are currently poorly understood. Whether differences exist in the sperm RNA profile between patients with infertility and fertile men needs clarification. Similarly, the utility of sperm RNAs in predicting successful sperm retrieval and assisted reproductive technique (ART) outcome is unknown. Patients with infertility and fertile individuals seem to have differences in the expression of non-coding RNAs that regulate genes controlling spermatogenesis. Several RNAs seem to influence embryo quality and development. Also, RNA types seem to predict successful sperm retrieval in patients with azoospermia. These findings suggest that sperm RNAs could influence decision-making during the management of patients with infertility. This evidence might help to identify possible therapeutic approaches aimed at modulating the expression of dysregulated genes in patients with infertility. Performing prospective studies with large sample sizes is necessary to investigate cost-effective panels consisting of proven molecular targets to ensure that this evidence can be translated to clinical practice.

Epigenetics of nonobstructive azoospermia

Nonobstructive azoospermia (NOA) is a severe and heterogeneous form of male factor infertility caused by dysfunction of spermatogenesis. Although various factors are well defined in the disruption of spermatogenesis, not all aspects due to the heterogeneity of the disorder have been determined yet. In this review, we focus on the recent findings and summarize the current data on epigenetic mechanisms such as DNA methylation and different metabolites produced during methylation and demethylation and various types of small noncoding RNAs involved in the pathogenesis of different groups of NOA.

Sodium arsenite impairs sperm quality via downregulating the ZMYND15 and ZMYND10

Zinc finger MYND-type containing 15 (ZMYND15) has been documented to play important roles in spermatogenesis, and mutants contribute to recessive azoospermia, severe oligozoospermia, non-obstructive azoospermia, teratozoospermia, even male infertility. ZMYND10 is involved in sperm motility. Whether environmental pollutants impair male fertility via regulating the expression of ZMYND15 and ZMYND10 has not been studied. Arsenic exposure results in poor sperm quality and male infertility. In order to investigate whether arsenic-induced male reproductive toxicity is related to the expression of ZMYND15, ZMYND10 and their target genes, we established a male rat model of sodium arsenite exposure-induced reproductive injury, measured sperm quality, serum hormone levels, mRNA and protein expressions of intratesticular ZMYND15 and ZMYND10 as well as their target genes. The results showed that, in addition to the increased mRNA expression of Tnp1, sodium arsenite exposure reduced sperm quality, serum hormone levels, and mRNA and protein expression of intratesticular ZMYND15 and ZMYND10 and their target genes in male rats compared with the control group (p < .05). Therefore, our study first showed that the environmental pollutant arsenic impairs sperm quality in male rats by reducing the expression of ZMYND10 and ZMYND15 and their regulatory genes, which provides a possible diagnostic marker for environmental pollutants-induced male infertility.

Accurate and efficient integrative reference-informed spatial domain detection for spatial transcriptomics

Spatially resolved transcriptomics (SRT) studies are becoming increasingly common and large, offering unprecedented opportunities in mapping complex tissue structures and functions. Here we present integrative and reference-informed tissue segmentation (IRIS), a computational method designed to characterize tissue spatial organization in SRT studies through accurately and efficiently detecting spatial domains. IRIS uniquely leverages single-cell RNA sequencing data for reference-informed detection of biologically interpretable spatial domains, integrating multiple SRT slices while explicitly considering correlations both within and across slices. We demonstrate the advantages of IRIS through in-depth analysis of six SRT datasets encompassing diverse technologies, tissues, species and resolutions. In these applications, IRIS achieves substantial accuracy gains (39-1,083%) and speed improvements (4.6-666.0) in moderate-sized datasets, while representing the only method applicable for large datasets including Stereo-seq and 10x Xenium. As a result, IRIS reveals intricate brain structures, uncovers tumor microenvironment heterogeneity and detects structural changes in diabetes-affected testis, all with exceptional speed and accuracy.

Towards a Multi-Omics of Male Infertility

Infertility is a common problem affecting one in six couples and in 30% of infertile couples, the male factor is a major cause. A large number of genes are involved in spermatogenesis and a significant proportion of male infertility phenotypes are of genetic origin. Studies on infertility have so far primarily focused on chromosomal abnormalities and sequence variants in protein-coding genes and have identified a large number of disease-associated genes. However, it has been shown that a multitude of factors across various omics levels also contribute to infertility phenotypes. The complexity of male infertility has led to the understanding that an integrated, multi-omics analysis may be optimal for unravelling this disease. While there is a vast array of different factors across omics levels associated with infertility, the present review focuses on known factors from the genomics, epigenomics, transcriptomics, proteomics, metabolomics, glycomics, lipidomics, miRNomics, and integrated omics levels. These include: repeat expansions in AR, POLG, ATXN1, DMPK, and SHBG, multiple SNPs, copy number variants in the AZF region, disregulated miRNAs, altered H3K9 methylation, differential MTHFR, MEG3, PEG1, and LIT1 methylation, altered protamine ratios and protein hypo/hyperphosphorylation. This integrative review presents a step towards a multi-omics approach to understanding the complex etiology of male infertility. Currently only a few genetic factors, namely chromosomal abnormalities and Y chromosome microdeletions, are routinely tested in infertile men undergoing intracytoplasmic sperm injection. A multi-omics approach to understanding infertility phenotypes may yield a more holistic view of the disease and contribute to the development of improved screening methods and treatment options. Therefore, beside discovering as of yet unknown genetic causes of infertility, integrating multiple fields of study could yield valuable contributions to the understanding of disease development. Future multi-omics studies will enable to synthesise fragmented information and facilitate biomarker discovery and treatments in male infertility.

Sequencing of the ZMYND15 gene in a cohort of infertile Chinese men reveals novel mutations in patients with teratozoospermia

BACKGROUND

The information of ZMYND15 in human reproduction is very limited, resulting in the unclear link between ZMYND15 variants and male infertility.

METHODS

Whole exome sequencing and Sanger sequencing to identify the potential pathogenic variation of ZMYND15 in infertile men, Papanicolaou staining and electron microscopy to investigate the spermatozoa morphology, western blotting and immunofluorescence staining to confirm the pathogenicity of the identified variants, and proteomic analysis and coimmunoprecipitation to clarify the potential molecular mechanism.

RESULTS

A total of 31 ZMYND15 variants were identified in 227 infertile patients. Three deleterious biallelic variants, including a novel compound heterozygous variant of c.1105delG (p.A369Qfs*15) and c.1853T>C (p.F618S), a new homozygous splicing mutation of c.1297+5G>A and a reported homozygous nonsense mutation of c.1209T>A (p.Y403*), were detected in three affected individuals with oligoasthenoteratozoospermia, showing a biallelic pathogenic mutation frequency of 1.3% (3/227). No biallelic pathogenic mutation was found in 692 fertile men. Morphology analysis showed abnormalities in sperm morphology in the patients harbouring ZMYND15 mutations. Western blotting and immunofluorescence staining confirmed the nearly absent ZMYND15 expression in the sperm of the patients. Mechanistically, ZMYND15 might regulate spermatogenesis by interacting with key molecules involved in sperm development, such as DPY19L2, AKAP4 and FSIP2, and might also mediate the expression of the autophagy-associated protein SPATA33 to maintain sperm individualisation and unnecessary cytoplasm removal.

CONCLUSION

Our findings broaden the variant and phenotype spectrum of ZMYND15 in male infertility, and reveal the potential signalling pathway of ZMYND15 regulating spermatogenesis, finally confirming the essential role of ZMYND15 in human fertility.

Analysis of 29 Targeted Genes for Non-Obstructive Azoospermia: The Relationship between Genetic Testing and Testicular Histology

PURPOSE

To analyze the presence of potentially pathogenic variants of 29 candidate genes known to cause spermatogenic failure (SPGF) in patients with non-obstructive azoospermia (NOA) who underwent testicular histology.

MATERIALS AND METHODS

Forty-eight patients with unexplained NOA referred to the Department of Transfusion Medicine and Transplantation Biology, University Hospital Center Zagreb, Zagreb, Croatia for testicular biopsy. They were divided into three groups: those who had cryptorchidism (n=9), those with varicocele (n=14), and those with idiopathic NOA (n=25). All included patients underwent blood withdrawal for next-generation sequencing (NGS) analysis and gene sequencing.

RESULTS

We found a possible genetic cause in 4 patients with idiopathic NOA (16%) and in 2 with cryptorchidism (22%). No pathogenic or possibly pathogenic mutations were identified in patients with varicocele. Variants of undetermined significance (VUS) were found in 11 patients with idiopathic NOA (44%), 3 with cryptorchidism (33%), and 8 patients with varicocele (57%). VUSs of the USP9Y gene were the most frequently as they were found in 14 out of 48 patients (29%). In particular, the VUS USP9Y c.7434+14del was found in 11 patients. They showed varied histological pictures, including Sertoli cell-only syndrome, mixed atrophy, and hypospermatogenesis, regardless of cryptorchidism or varicocele. No direct correlation was found between the gene mutation/variant and the testicular histological picture.

CONCLUSIONS

Different mutations of the same gene cause various testicular histological pictures. These results suggest that it is not the gene itself but the type of mutation/variation that determines the testicular histology picture. Based on the data presented above, it remains challenging to design a genetic panel with prognostic value for the outcome of testicular sperm extraction in patients with NOA.

Transcriptional control of human gametogenesis

The pathways of gametogenesis encompass elaborate cellular specialization accompanied by precise partitioning of the genome content in order to produce fully matured spermatozoa and oocytes. Transcription factors are an important class of molecules that function in gametogenesis to regulate intrinsic gene expression programs, play essential roles in specifying (or determining) germ cell fate and assist in guiding full maturation of germ cells and maintenance of their populations. Moreover, in order to reinforce or redirect cell fate in vitro, it is transcription factors that are most frequently induced, over-expressed or activated. Many reviews have focused on the molecular development and genetics of gametogenesis, in vivo and in vitro, in model organisms and in humans, including several recent comprehensive reviews: here, we focus specifically on the role of transcription factors. Recent advances in stem cell biology and multi-omic studies have enabled deeper investigation into the unique transcriptional mechanisms of human reproductive development. Moreover, as methods continually improve, in vitro differentiation of germ cells can provide the platform for robust gain- and loss-of-function genetic analyses. These analyses are delineating unique and shared human germ cell transcriptional network components that, together with somatic lineage specifiers and pluripotency transcription factors, function in transitions from pluripotent stem cells to gametes. This grand theme review offers additional insight into human infertility and reproductive disorders that are linked predominantly to defects in the transcription factor networks and thus may potentially contribute to the development of novel treatments for infertility.

Targeted next-generation sequencing panel screening of 668 Chinese patients with non-obstructive azoospermia

PURPOSE

We aimed (1) to determine the molecular diagnosis rate and the recurrent causative genes of patients with non-obstructive azoospermia (NOA) using targeted next-generation sequencing (NGS) panel screening and (2) to discuss whether these genes help in the prognosis for microsurgical testicular sperm extraction (micro-TESE).

METHODS

We used NGS panels to screen 668 Chinese men with NOA. Micro-TESE outcomes for six patients with pathogenic mutations were followed up. Functional assays were performed for two NR5A1 variants identified: p.I224V and p.R281C.

RESULTS

Targeted NGS panel sequencing could explain 4/189 (2.1% by panel 1) or 10/479 (2.1% by panel 2) of the patients with NOA after exclusion of karyotype abnormalities and Y chromosome microdeletions. Almost all mutations detected were newly described except for NR5A1 p.R281C and TEX11 p.M156V. Two missense NR5A1 mutations-p.R281C and p.I244V-were proved to be deleterious by in vitro functional assays. Mutations in TEX11, TEX14, and NR5A1 genes are recurrent causes of NOA, but each gene explains only a very small percentage (less than 4/668; 0.6%). Only the patient with NR5A1 mutations produced viable spermatozoa through micro-TESE, but other patients with TEX11 and TEX14 had poor micro-TESE prognoses.

CONCLUSIONS

A targeted NGS panel is a feasible diagnostic method for patients with NOA. Because each gene implicated explains only a small proportion of such cases, more genes should be included to further increase the diagnostic rate. Considering previous reports, we suggest that only a few genes that are directly linked to meiosis can indicate poor micro-TESE prognosis, such as TEX11, TEX14, and SYCE1.

Genetics and molecular biology of male infertility among Iranian population: an update

Infertility is one of the main social and health problems among young couples. Although a noticeable ratio of infertilities are asymptomatic, about half of the cases are observed among males. Various environmental factors such as life style, dietary patterns, and pathogens are associated with male infertility. Mutations and chromosomal abnormalities are also the most important genetic risk factors of male infertility. Similar to other populations, there is a dramatically rising trend of male infertility among Iranian. Regarding the high ratio of asymptomatic cases, it is required to clarify the molecular biology and cellular processes involved in male infertility in this population to suggest an efficient panel of diagnostic markers. In this review, we have summarized all of the cellular and molecular processes which have been reported among Iranian infertile males to clarify the molecular biology of male infertility in this population. It was observed that the stress response, cellular detoxification, and DNA repair processes were the most common aberrant cellular mechanisms among Iranian infertile males. This review paves the way of introducing a population-based diagnostic panel of genetic markers among Iranian infertile males.

Genetics of Azoospermia

Azoospermia affects 1% of men, and it can be due to: (i) hypothalamic-pituitary dysfunction, (ii) primary quantitative spermatogenic disturbances, (iii) urogenital duct obstruction. Known genetic factors contribute to all these categories, and genetic testing is part of the routine diagnostic workup of azoospermic men. The diagnostic yield of genetic tests in azoospermia is different in the different etiological categories, with the highest in Congenital Bilateral Absence of Vas Deferens (90%) and the lowest in Non-Obstructive Azoospermia (NOA) due to primary testicular failure (~30%). Whole-Exome Sequencing allowed the discovery of an increasing number of monogenic defects of NOA with a current list of 38 candidate genes. These genes are of potential clinical relevance for future gene panel-based screening. We classified these genes according to the associated-testicular histology underlying the NOA phenotype. The validation and the discovery of novel NOA genes will radically improve patient management. Interestingly, approximately 37% of candidate genes are shared in human male and female gonadal failure, implying that genetic counselling should be extended also to female family members of NOA patients.

The possible role of sirtuins in male reproduction

Global influence of male infertility is increasing in recent decades. Proper understanding of genetics, anatomy, physiology and the intricate interrelation of male reproductive system are much needed for explaining the etiology of male infertility; and a detailed study on the epigenetics, indeed, will reveal the molecular mechanism behind its etiology. Sirtuins, the molecular sensors, are NAD⁺ dependent histone deacetylases and ADP- ribosyl transferases, participate in the chief events of epigenetics. In mammals, sirtuin family comprises seven members (SIRT1-SIRT7), and they all possess a conserved NAD⁺ binding catalytic domain, termed the sirtuin core domain which is imperative for their activity. Sirtuins exert a pivotal role in cellular homeostasis, energy metabolism, apoptosis, age-related disorders and male reproductive system. However, their exact role in male reproduction is still obscure. This article specifically reviews the role of mammalian sirtuins in male reproductive function, thereby, prompting further research to discover the restorative methods and its implementation in reproductive medicine.

Novel homozygous truncating variants in ZMYND15 causing severe oligozoospermia and their implications for male infertility

Sequence variants of ZMYND15 cause azoospermia in humans, but they have not yet been reported in infertile men with severe oligozoospermia (SO). We performed whole-exome and Sanger sequencing to identify suspected causative variants in 414 idiopathic participating infertile men with SO or azoospermia. Three novel homozygous truncating variants in ZMYND15 were identified in three of the 219 (1.37%) unrelated patients with SO, including c.1209T>A(p.Tyr403*), c.1650delC (p.Glu551Lysfs*75), and c.1622_1636delinsCCAC (p.Leu541Profs*39). In silico bioinformatic analyses as well as in vivo and in vitro experiments showed that the ZMYND15 variants carried by the affected subjects might be the underlying cause for their infertility. One patient accepted intracytoplasmic sperm injection therapy, using his ejaculated sperm, and his wife successfully became pregnant. Our findings expand the disease phenotype spectrum by indicating that ZMYND15 variants cause SO and male infertility and suggest a possible correlation between the severity of male infertility caused by ZMYND15 variants and male age.

Genes predisposing to syndromic and nonsyndromic infertility: a narrative review

Background

Advanced biological techniques have helped produce more insightful findings on the genetic etiology of infertility that may lead to better management of the condition. This review provides an update on genes predisposing to syndromic and nonsyndromic infertility.

Main body

The review identified 65 genes linked with infertility and infertility-related disorders. These genes regulate fertility. However, mutational loss of the functions of the genes predisposes to infertility. Twenty-three (23) genes representing 35% were linked with syndromic infertility, while 42 genes (65%) cause nonsyndromic infertility. Of the 42 nonsyndromic genes, 26 predispose to spermatogenic failure and sperm morphological abnormalities, 11 cause ovarian failures, and 5 cause sex reversal and puberty delay. Overall, 31 genes (48%) predispose to male infertility, 15 genes (23%) cause female infertility, and 19 genes (29%) predispose to both. The common feature of male infertility was spermatogenic failure and sperm morphology abnormalities, while ovarian failure has been the most frequently reported among infertile females. The mechanisms leading to these pathologies are gene-specific, which, if targeted in the affected, may lead to improved treatment.

Conclusions

Mutational loss of the functions of some genes involved in the development and maintenance of fertility may predispose to syndromic or nonsyndromic infertility via gene-specific mechanisms. A treatment procedure that targets the affected gene(s) in individuals expressing infertility may lead to improved treatment.

Molecular genetics of infertility: loss-of-function mutations in humans and corresponding knockout/mutated mice

BACKGROUND

Infertility is a major issue in human reproductive health, affecting an estimated 15% of couples worldwide. Infertility can result from disorders of sex development (DSD) or from reproductive endocrine disorders (REDs) with onset in infancy, early childhood or adolescence. Male infertility, accounting for roughly half of all infertility cases, generally manifests as decreased sperm count (azoospermia or oligozoospermia), attenuated sperm motility (asthenozoospermia) or a higher proportion of morphologically abnormal sperm (teratozoospermia). Female infertility can be divided into several classical types, including, but not limited to, oocyte maturation arrest, premature ovarian insufficiency (POI), fertilization failure and early embryonic arrest. An estimated one half of infertility cases have a genetic component; however, most genetic causes of human infertility are currently uncharacterized. The advent of high-throughput sequencing technologies has greatly facilitated the identification of infertility-associated gene mutations in patients over the past 20 years.

OBJECTIVE AND RATIONALE

This review aims to conduct a narrative review of the genetic causes of human infertility. Loss-of-function mutation discoveries related to human infertility are summarized and further illustrated in tables. Corresponding knockout/mutated animal models of causative genes for infertility are also introduced.

SEARCH METHODS

A search of the PubMed database was performed to identify relevant studies published in English. The term 'mutation' was combined with a range of search terms related to the core focus of the review: infertility, DSD, REDs, azoospermia or oligozoospermia, asthenozoospermia, multiple morphological abnormalities of the sperm flagella (MMAF), primary ciliary dyskinesia (PCD), acephalic spermatozoa syndrome (ASS), globozoospermia, teratozoospermia, acrosome, oocyte maturation arrest, POI, zona pellucida, fertilization defects and early embryonic arrest.

OUTCOMES

Our search generated ∼2000 records. Overall, 350 articles were included in the final review. For genetic investigation of human infertility, the traditional candidate gene approach is proceeding slowly, whereas high-throughput sequencing technologies in larger cohorts of individuals is identifying an increasing number of causative genes linked to human infertility. This review provides a wide panel of gene mutations in several typical forms of human infertility, including DSD, REDs, male infertility (oligozoospermia, MMAF, PCD, ASS and globozoospermia) and female infertility (oocyte maturation arrest, POI, fertilization failure and early embryonic arrest). The causative genes, their identified mutations, mutation rate, studied population and their corresponding knockout/mutated mice of non-obstructive azoospermia, MMAF, ASS, globozoospermia, oocyte maturation arrest, POI, fertilization failure and early embryonic arrest are further illustrated by tables. In this review, we suggest that (i) our current knowledge of infertility is largely obtained from knockout mouse models; (ii) larger cohorts of clinical cases with distinct clinical characteristics need to be recruited in future studies; (iii) the whole picture of genetic causes of human infertility relies on both the identification of more mutations for distinct types of infertility and the integration of known mutation information; (iv) knockout/mutated animal models are needed to show whether the phenotypes of genetically altered animals are consistent with findings in human infertile patients carrying a deleterious mutation of the homologous gene; and (v) the molecular mechanisms underlying human infertility caused by pathogenic mutations are largely unclear in most current studies.

WILDER IMPLICATIONS

It is important to use our current understanding to identify avenues and priorities for future research in the field of genetic causes of infertility as well as to apply mutation knowledge to risk prediction, genetic diagnosis and potential treatment for human infertility.

Histone Post-Translational Modifications and CircRNAs in Mouse and Human Spermatozoa: Potential Epigenetic Marks to Assess Human Sperm Quality

Spermatozoa (SPZ) are motile cells, characterized by a cargo of epigenetic information including histone post-translational modifications (histone PTMs) and non-coding RNAs. Specific histone PTMs are present in developing germ cells, with a key role in spermatogenic events such as self-renewal and commitment of spermatogonia (SPG), meiotic recombination, nuclear condensation in spermatids (SPT). Nuclear condensation is related to chromatin remodeling events and requires a massive histone-to-protamine exchange. After this event a small percentage of chromatin is condensed by histones and SPZ contain nucleoprotamines and a small fraction of nucleohistone chromatin carrying a landascape of histone PTMs. Circular RNAs (circRNAs), a new class of non-coding RNAs, characterized by a nonlinear back-spliced junction, able to play as microRNA (miRNA) sponges, protein scaffolds and translation templates, have been recently characterized in both human and mouse SPZ. Since their abundance in eukaryote tissues, it is challenging to deepen their biological function, especially in the field of reproduction. Here we review the critical role of histone PTMs in male germ cells and the profile of circRNAs in mouse and human SPZ. Furthermore, we discuss their suggested role as novel epigenetic biomarkers to assess sperm quality and improve artificial insemination procedure.

A genome-wide single nucleotide polymorphism and copy number variation analysis for number of piglets born alive

Background

In this study we integrated the CNV (copy number variation) and WssGWAS (weighted single-step approach for genome-wide association) analyses to increase the knowledge about number of piglets born alive, an economically important reproductive trait with significant impact on production efficiency of pigs.

Results

A total of 3892 samples were genotyped with the Porcine SNP80 BeadChip. After quality control, a total of 57,962 high-quality SNPs from 3520 Duroc pigs were retained. The PennCNV algorithm identified 46,118 CNVs, which were aggregated by overlapping in 425 CNV regions (CNVRs) ranging from 2.5 Kb to 9718.4 Kb and covering 197 Mb (~ 7.01%) of the pig autosomal genome. The WssGWAS identified 16 genomic regions explaining more than 1% of the additive genetic variance for number of piglets born alive. The overlap between CNVR and WssGWAS analyses identified common regions on SSC2 (4.2–5.2 Mb), SSC3 (3.9–4.9 Mb), SSC12 (56.6–57.6 Mb), and SSC17 (17.3–18.3 Mb). Those regions are known for harboring important causative variants for pig reproductive traits based on their crucial functions in fertilization, development of gametes and embryos. Functional analysis by the Panther software identified 13 gene ontology biological processes significantly represented in this study such as reproduction, developmental process, cellular component organization or biogenesis, and immune system process, which plays relevant roles in swine reproductive traits.

Conclusion

Our research helps to improve the understanding of the genetic architecture of number of piglets born alive, given that the combination of GWAS and CNV analyses allows for a more efficient identification of the genomic regions and biological processes associated with this trait in Duroc pigs. Pig breeding programs could potentially benefit from a more accurate discovery of important genomic regions.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5687-0) contains supplementary material, which is available to authorized users.

Genetic defects in human azoospermia

As with many other diseases, genetic testing in human azoospermia was initially restricted to karyotype analyses (leading to diagnostic chromosome rearrangement tests for Klinefelter and other syndromes). With the advent of molecular biology in the 1980s, genetic screening was broadened to analyses of Y chromosome microdeletions and the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR). Decades later, the emergence of whole-genome techniques has led to the identification of other genetic defects associated with human azoospermia. Although TEX11 and ADGRG2 defects are frequently described in men with azoospermia, most of the causal gene defects found to date are private (i.e. identified in a small number of consanguineous families).

Here, we provide an up-to-date overview of all the types of genetic defects known to be linked to human azoospermia and try to give clinical practice guidelines according to azoospermia phenotype. Along with homozygous mutations, polymorphisms and epigenetic defects are also briefly discussed. However, as these variations predispose to azoospermia, a specific review will be needed to compile data on all the particular genetic variations reported in the literature.

Transcriptomic Analysis Reveals Insights on Male Infertility in Octopus maya Under Chronic Thermal Stress

Octopus maya endemic to the Yucatan Peninsula, Mexico, is an ectotherm organism particularly temperature-sensitive. Studies in O. maya females show that temperatures above 27°C reduce the number of eggs per spawn, fertilization rate and the viability of embryos. High temperatures also reduce the male reproductive performance and success. However, the molecular mechanisms are still unknown. The transcriptomic profiles of testes from thermally stressed (30°C) and not stressed (24°C) adult male octopuses were compared, before and after mating to understand the molecular bases involved in the low reproductive performance at high temperature. The testis paired-end cDNA libraries were sequenced using the Illumina MiSeq platform. Then, the transcriptome was assembled de novo using Trinity software. A total of 53,214,611 high-quality paired reads were used to reconstruct 85,249 transcripts and 77,661 unigenes with an N50 of 889 bp length. Later, 13,154 transcripts were annotated implementing Blastx searches in the UniProt database. Differential expression analysis revealed 1,881 transcripts with significant difference among treatments. Functional annotation and pathway mapping of differential expressed transcripts revealed significant enrichment for biological processes involved in spermatogenesis, gamete generation, germ cell development, spermatid development and differentiation, response to stress, inflammatory response and apoptosis. Remarkably, the transcripts encoding genes such as ZMYND15, KLHL10, TDRD1, TSSK2 and DNAJB13, which are linked to male infertility in other species, were differentially expressed among the treatments. The expression levels of these key genes, involved in sperm motility and spermatogenesis were validated by quantitative real-time PCR. The results suggest that the reduction in male fertility at high temperature can be related to alterations in spermatozoa development and motility.

New insights into the genetics of spermatogenic failure: a review of the literature

Genetic anomalies are known to affect about 15% of infertile patients with azoospermia or severe oligozoospermia. Despite a throughout diagnostic work-up, in up to the 72% of the male partners of infertile couples, no etiological factor can be found; hence, the cause of infertility remains unclear. Recently, several novel genetic causes of spermatogenic failure (SPGF) have been described. The aim of this review was to collect all the available evidence of SPGF genetics, matching data from in-vitro and animal models with those in human beings to provide a comprehensive and updated overview of the genes capable of affecting spermatogenesis. By reviewing the literature, we provided a list of 60 candidate genes for SPGF. Their investigation by Next Generation Sequencing in large cohorts of patients with apparently idiopathic infertility would provide new interesting data about their racial- and ethnic-related prevalence in infertile patients, likely raising the diagnostic yields. We propose a phenotype-based approach to identify the genes to look for.

Discovery and functional characterization of microRNAs and their potential roles for gonadal development in spotted knifejaw, Oplegnathus punctatus

The spotted knifejaw (Oplegnathus punctatus) is a newly emerging economical fishery species in China. Studies focused on the regulation of gonadal development and gametogenesis of spotted knifejaw are still insufficient. As a key post-transcriptional regulator, miRNAs have been shown to play important roles in development and reproduction systems. In this study, small RNA deep sequencing in ovary and testis of spotted knifejaw were performed to screen miRNA expression patterns. After sequencing and bioinformatics analysis, a total of 247 conserved known miRNAs and 41 novel miRNAs were identified in spotted knifejaw gonads for the first time. In addition, 36 miRNAs were differentially expressed between testis and ovary. The putative target genes of differentially expressed (DE) miRNAs were significantly enriched in several pathways related to sexual differentiation and gonadal development, such as steroid hormone biosynthesis. Sequencing data was validated through qRT-PCR analysis of selected DE miRNAs. Dual-luciferase reporter analyses of filtered miRNA-target gene pairs confirmed that opu-miR-27b-3p targeted in piwi2 and mov10l1 3' UTRs and down-regulated their expressions in spotted knifejaw. The notion that mov10l1 and piwi2 enhance germ cells proliferation and regulate gonadal development and gametogenesis suggests that opu-miR-27b-3p may attenuated this process in the gonads of spotted knifejaw. These findings provided insights into regulatory roles of gonadal miRNAs and supplied fundamental resources for further studies on miRNA-mediated post-transcriptional regulation in reproductive system of spotted knifejaw.

The histone methyltransferase SETD2 is required for expression of acrosin-binding protein 1 and protamines and essential for spermiogenesis in mice

Spermatogenesis is precisely controlled by complex gene expression programs and involves epigenetic reprogramming, including histone modification and DNA methylation. SET domain-containing 2 (SETD2) is the predominant histone methyltransferase catalyzing the trimethylation of histone H3 lysine 36 (H3K36me3) and plays key roles in embryonic stem cell differentiation and somatic cell development. However, its role in male germ cell development remains elusive. Here, we demonstrate an essential role of Setd2 for spermiogenesis, the final stage of spermatogenesis. Using RNA-seq, we found that, in postnatal mouse testes, Setd2 mRNA levels dramatically increase in 14-day-old mice. Using a germ cell-specific Setd2 knockout mouse model, we also found that targeted Setd2 knockout in germ cells causes aberrant spermiogenesis with acrosomal malformation before step 8 of the round-spermatid stage, resulting in complete infertility. Furthermore, we noted that the Setd2 deficiency results in complete loss of H3K36me3 and significantly decreases expression of thousands of genes, including those encoding acrosin-binding protein 1 (Acrbp1) and protamines, required for spermatogenesis. Our findings thus reveal a previously unappreciated role of the SETD2-dependent H3K36me3 modification in spermiogenesis and provide clues to the molecular mechanisms in epigenetic disorders underlying male infertility.

SPINK2 deficiency causes infertility by inducing sperm defects in heterozygotes and azoospermia in homozygotes

Azoospermia, characterized by the absence of spermatozoa in the ejaculate, is a common cause of male infertility with a poorly characterized etiology. Exome sequencing analysis of two azoospermic brothers allowed the identification of a homozygous splice mutation in SPINK2, encoding a serine protease inhibitor believed to target acrosin, the main sperm acrosomal protease. In accord with these findings, we observed that homozygous Spink2 KO male mice had azoospermia. Moreover, despite normal fertility, heterozygous male mice had a high rate of morphologically abnormal spermatozoa and a reduced sperm motility. Further analysis demonstrated that in the absence of Spink2, protease-induced stress initiates Golgi fragmentation and prevents acrosome biogenesis leading to spermatid differentiation arrest. We also observed a deleterious effect of acrosin overexpression in HEK cells, effect that was alleviated by SPINK2 coexpression confirming its role as acrosin inhibitor. These results demonstrate that SPINK2 is necessary to neutralize proteases during their cellular transit toward the acrosome and that its deficiency induces a pathological continuum ranging from oligoasthenoteratozoospermia in heterozygotes to azoospermia in homozygotes.

Expression of ZMYND15 in Testes of Azoospermic Men and Association With Sperm Retrieval

OBJECTIVE

To compare the expression levels of ZMYND15 and its target haploid genes (TNP1, PRM1, and SPEM1) in testicular samples of non-obstructive azoospermia (NOA) vs obstructive azoospermia (OA). The levels of these transcripts were also compared in azoospermic samples with positive and negative sperm retrieval (SR).

METHOD

This study included 63 testis biopsy samples from 16 OA and 47 NOA individuals. Expression levels of these target genes were determined by real-time reverse transcription-polymerase chain reaction using ΔΔCt method.

RESULT

The expression level of ZMYND15 and its target genes were significantly lower in testicular samples of NOA compared with OA. Similarly, the expression levels of these transcripts were lower in samples with negative vs positive SR.

CONCLUSION

Expression level of ZMYND15 may have potential for prediction of successful SR with sensitivity of 90% and specificity of 60% for total population and sensitivity of 100% and specificity of 75% for NOA, according to the receiver operating characteristics curve.

Stem cells, in vitro gametogenesis and male fertility

Reconstitution in culture of biological processes, such as differentiation and organization, is a key challenge in regenerative medicine, and one in which stem cell technology plays a central role. Pluripotent stem cells and spermatogonial stem cells are useful materials for reconstitution of germ cell development in vitro, as they are capable of differentiating into gametes. Reconstitution of germ cell development, termed in vitro gametogenesis, will provide an experimental platform for a better understanding of germ cell development, as well as an alternative source of gametes for reproduction, with the potential to cure infertility. Since germ cells are the cells for 'the next generation', both the culture system and its products must be carefully evaluated. In this issue, we summarize the progress in in vitro gametogenesis, most of which has been made using mouse models, as well as the future challenges in this field.

Mutation in TDRD9 causes non-obstructive azoospermia in infertile men

BACKGROUND

Azoospermia is diagnosed when sperm cells are completely absent in the ejaculate even after centrifugation. It is identified in approximately 1% of all men and in 10%-20% of infertile males. Non-obstructive azoospermia (NOA) is characterised by the absence of sperm due to either a Sertoli cell-only pattern, maturation arrest, hypospermatogenesis or mixed patterns. NOA is a severe form of male infertility, with limited treatment options and low fertility success rates. In the majority of patients, the cause for NOA is not known and mutations in only a few genes were shown to be causative.

AIM

We investigated the cause of maturation arrest in five azoospermic infertile men of a large consanguineous Bedouin family.

METHODS AND RESULTS

Using whole genome genotyping and exome sequencing we identified a 4 bp deletion frameshift mutation in TDRD9 as the causative mutation with a Lod Score of 3.42. We demonstrate that the mutation results in a frameshift as well as exon skipping. Immunofluorescent staining with anti-TDRD9 antibody directed towards the N terminus demonstrated the presence of the protein in testicular biopsies of patients with an intracellular distribution comparable to a control biopsy. The mutation does not cause female infertility.

CONCLUSION

This is the first report of a recessive deleterious mutation in TDRD9 in humans. The clinical phenotype recapitulates that observed in the Tdrd9 knockout mice where this gene was demonstrated to participate in long interspersed element-1 retrotransposon silencing. If this function is preserved in human, our data underscore the importance of maintaining DNA stability in the human male germ line.

Human male infertility and its genetic causes

Background

Infertility affects about 15% of couples who wish to have children and half of these cases are associated with male factors. Genetic causes of azoospermia include chromosomal abnormalities, Y chromosome microdeletions, and specific mutations/deletions of several Y chromosome genes. Many researchers have analyzed genes in the AZF region on the Y chromosome; however, in 2003 the SYCP3 gene on chromosome 12 (12q23) was identified as causing azoospermia by meiotic arrest through a point mutation.

Methods

We mainly describe the SYCP3 and PLK4 genes that we have studied in our laboratory, and add comments on other genes associated with human male infertility.

Results

Up to now, The 17 genes causing male infertility by their mutation have been reported in human.

Conclusions

Infertility caused by nonobstructive azoospermia (NOA) is very important in the field of assisted reproductive technology. Even with the aid of chromosomal analysis, ultrasonography of the testis, and detailed endocrinology, only MD‐TESE can confirm the presence of immature spermatozoa in the testes. We strongly hope that these studies help clinics avoid ineffective MD‐TESE procedures.

Single gene defects leading to sperm quantitative anomalies

Azoospermia, defined by the absence of sperm in the ejaculate, is estimated to affect up to 1% of men in the general population. Assisted reproductive technologies have revolutionized the treatment of infertility, and some azoospermic men, those with a post-meiotic defect, can conceive following the use of viable spermatoza recovered from testicular or epididymal biopsies. Although male infertility is a multifactorial disease, it is believed that genetic factors are predominant in the etiology of azoospermia and severe oligozoospermia. Despite that assumption, substantiated by the high number of infertile knockout (KO) mice and the even higher number of genes expressed essentially in the testis, little is known about the pathophysiology of reduced sperm production, its primary causes or the genetic and epigenetic consequences for the gamete and the future conceptus. The identification of genetic abnormalities is therefore paramount to understand spermatogenesis, to adopt the best course of action for the patient and to provide adequate genetic counseling. We provide here a review of the recent literature on the genetics of azoospermia and oligozoospermia, focusing on defects directly altering sperm production. New sequencing technologies are contributing to the rapid evolution of the recent field of infertility genetics.

Systematic Analysis of Protein Interaction Network Associated with Azoospermia

Non-obstructive azoospermia is a severe infertility factor. Currently, the etiology of this condition remains elusive with several possible molecular pathway disruptions identified in the post-meiotic spermatozoa. In the presented study, in order to identify all possible candidate genes associated with azoospermia and to map their relationship, we present the first protein-protein interaction network related to azoospermia and analyze the complex effects of the related genes systematically. Using Online Mendelian Inheritance in Man, the Human Protein Reference Database and Cytoscape, we created a novel network consisting of 209 protein nodes and 737 interactions. Mathematical analysis identified three proteins, ar, dazap2, and esr1, as hub nodes and a bottleneck protein within the network. We also identified new candidate genes, CREBBP and BCAR1, which may play a role in azoospermia. The gene ontology analysis suggests a genetic link between azoospermia and liver disease. The KEGG analysis also showed 45 statistically important pathways with 31 proteins associated with colorectal, pancreatic, chronic myeloid leukemia and prostate cancer. Two new genes and associated diseases are promising for further experimental validation.

The control of male fertility by spermatid-specific factors: searching for contraceptive targets from spermatozoon's head to tail

Male infertility due to abnormal spermatozoa has been reported in both animals and humans, but its pathogenic causes, including genetic abnormalities, remain largely unknown. On the other hand, contraceptive options for men are limited, and a specific, reversible and safe method of male contraception has been a long-standing quest in medicine. Some progress has recently been made in exploring the effects of spermatid-specifical genetic factors in controlling male fertility. A comprehensive search of PubMed for articles and reviews published in English before July 2016 was carried out using the search terms 'spermiogenesis failure', 'globozoospermia', 'spermatid-specific', 'acrosome', 'infertile', 'manchette', 'sperm connecting piece', 'sperm annulus', 'sperm ADAMs', 'flagellar abnormalities', 'sperm motility loss', 'sperm ion exchanger' and 'contraceptive targets'. Importantly, we have opted to focus on articles regarding spermatid-specific factors. Genetic studies to define the structure and physiology of sperm have shown that spermatozoa appear to be one of the most promising contraceptive targets. Here we summarize how these spermatid-specific factors regulate spermiogenesis and categorize them according to their localization and function from spermatid head to tail (e.g., acrosome, manchette, head-tail conjunction, annulus, principal piece of tail). In addition, we emphatically introduce small-molecule contraceptives, such as BRDT and PPP3CC/PPP3R2, which are currently being developed to target spermatogenic-specific proteins. We suggest that blocking the differentiation of haploid germ cells, which rarely affects early spermatogenic cell types and the testicular microenvironment, is a better choice than spermatogenic-specific proteins. The studies described here provide valuable information regarding the genetic and molecular defects causing male mouse infertility to improve our understanding of the importance of spermatid-specific factors in controlling fertility. Although a male contraceptive 'pill' is still many years away, research into the production of new small-molecule contraceptives targeting spermatid-specific proteins is the right avenue.

Abnormal spermatogenesis and male infertility in testicular zinc finger protein Zfp318-knockout mice

Zfp318, a mouse gene with a Cys2/His2 zinc finger motif, is mainly expressed in germ cells in the testis. It encodes two alternative transcripts, which regulate androgen receptor-mediated transcriptional activation or repression by overexpression of them. However, the role of Zfp318 is still obscure in vivo, especially in spermatogenesis. To elucidate the role of Zfp318 during gamete production, we established a knockout mouse line. Zfp318-null male mice exhibited infertility, whereas Zfp318-null female mice displayed normal fertility. ZFP318 was expressed during multiple stages of spermatogenesis, from spermatocytes to round spermatids. The nuclei of secondary spermatocytes showed high levels of expression. Histological analysis and quantitative analysis of DNA content showed decreased numbers of both spermatids in the seminiferous tubules and mature spermatozoa in the epididymides of Zfp318-null mice. These results suggest that Zfp318 is expressed as a functional protein in testicular germ cells and plays an important role in meiosis during spermatogenesis.

Epigenetic regulation of the histone-to-protamine transition during spermiogenesis

In mammals, male germ cells differentiate from haploid round spermatids to flagella-containing motile sperm in a process called spermiogenesis. This process is distinct from somatic cell differentiation in that the majority of the core histones are replaced sequentially, first by transition proteins and then by protamines, facilitating chromatin hyper-compaction. This histone-to-protamine transition process represents an excellent model for the investigation of how epigenetic regulators interact with each other to remodel chromatin architecture. Although early work in the field highlighted the critical roles of testis-specific transcription factors in controlling the haploid-specific developmental program, recent studies underscore the essential functions of epigenetic players involved in the dramatic genome remodeling that takes place during wholesale histone replacement. In this review, we discuss recent advances in our understanding of how epigenetic players, such as histone variants and histone writers/readers/erasers, rewire the haploid spermatid genome to facilitate histone substitution by protamines in mammals.

Impact of metformin on reproductive tissues: an overview from gametogenesis to gestation

Metformin is an oral anti-hyperglycemic drug that acts as an insulin sensitizer in the treatment of diabetes mellitus type 2. It has also been widely used in the treatment of polycystic ovary syndrome (PCOS) and gestational diabetes. This drug has been shown to activate a protein kinase called 5' AMP-activated protein kinase or AMPK. AMPK is present in many tissues making metformin's effect multi factorial. However as metformin crosses the placenta, its use during pregnancy raises concerns regarding potential adverse effects on the mother and fetus. The majority of reports suggest no significant adverse effects or teratogenicity. However, disconcerting reports of male mouse offspring that were exposed to metformin in utero that present with a reduction in testis size, seminiferous tubule size and in Sertoli cell number suggest that we do not understand the full suite of effects of metformin. In addition, recent molecular evidence is suggesting an epigenetic effect of metformin which could explain some of the long-term effects reported. Nevertheless, the data are still insufficient to completely confirm or disprove negative effects of metformin. The aims of this review are to provide a summary of the safety of metformin in various aspects of sexual reproduction, the use of metformin by gestating mothers, and its possible side-effects on offspring from women who are administered metformin during pregnancy.

Effect of metformin on the fertilizing ability of mouse spermatozoa

Numerous antioxidants have been added to cryopreservation media with varied success. The biguanide, metformin, commonly used for the treatment of type II diabetes, possesses properties impacting metabolism control that have not been yet assessed in cryopreservation protocols. The aim of this experiment was to; (i) determine the effect of metformin on fresh spermatozoa properties; and (ii) to assess positive or negative effects of metformin in post-thaw function and fertilizing capacity of mouse spermatozoa when used in cryopreservation media. The experiments have shown that the presence of metformin in fresh semen did not induce negative effects on spermatozoa quality, except a slight reduction in sperm motility at 5000μM metformin. However, when metformin was included in a cryopreservation protocol, an improvement in the fertilization rate and a reduction in the percentage of abnormal zygotes after in vitro fertilization was observed. In conclusion, metformin did not affect sperm quality at low concentrations (50μM), but its presence in the cryopreservation media could represent a benefit to improve the quality of frozen semen.

Truncating mutations in TAF4B and ZMYND15 causing recessive azoospermia

BACKGROUND

Azoospermia is the absence of a measurable level of spermatozoa in the semen. It affects approximately 1% of all men, and the genetic basis of the majority of idiopathic cases is unknown. We investigated two unrelated consanguineous families with idiopathic azoospermia. In family 1, there were three azoospermic brothers and one oligozoospermic brother; and in family 2, there were three azoospermic brothers. Testis biopsy in the brothers in family 2 had led to the diagnosis of maturation arrest in the spermatid stage.

METHODS

Candidate disease loci were found via linkage mapping using data from single nucleotide polymorphism genome scans. Exome sequencing was applied to find the variants at the loci.

RESULTS

We identified two candidate loci in each family and homozygous truncating mutations p.R611X in TAF4B in family 1 and p.K507Sfs*3 in ZMYND15 in family 2. We did not detect any mutations in these genes in a cohort of 45 azoospermic and 15 oligozoospermic men. Expression studies for ZMYND15 showed that the highest expression was in the testis.

CONCLUSIONS

Both genes are known to have roles in spermatogenesis in mice but neither has been studied in humans. To our knowledge, they are the first genes identified for recessive idiopathic spermatogenic failure in men. Assuming that recessive genes for isolated azoospermia are as numerous in men as in mice, each gene is possibly responsible for only a small fraction of all cases.

Sperm nuclear proteome and its epigenetic potential

The main function of the sperm cell is to transmit the paternal genetic message and epigenetic information to the embryo. Importantly, the majority of the genes in the sperm chromatin are highly condensed by protamines, whereas genes potentially needed in the initial stages of development are associated with histones, representing a form of epigenetic marking. However, so far little attention has been devoted to other sperm chromatin-associated proteins that, in addition to histones and protamines, may also have an epigenetic role. Therefore, with the goal of contributing to cover this subject we have compiled, reviewed and report a list of 581 chromatin or nuclear proteins described in the human sperm cell. Furthermore, we have analysed their Gene Ontology Biological Process enriched terms and have grouped them into different functional categories. Remarkably, we show that 56% of the sperm nuclear proteins have a potential epigenetic activity, being involved in at least one of the following functions: chromosome organization, chromatin organization, protein-DNA complex assembly, DNA packaging, gene expression, transcription, chromatin modification and histone modification. In addition, we have also included and compared the sperm cell proteomes of different model species, demonstrating the existence of common trends in the chromatin composition in the mammalian mature male gamete. Taken together, our analyses suggest that the mammalian sperm cell delivers to the offspring a rich combination of histone variants, transcription factors, chromatin-associated and chromatin-modifying proteins which have the potential to encode and transmit an extremely complex epigenetic information.

CHD5 is required for spermiogenesis and chromatin condensation

Haploid spermatids undergo extensive cellular, molecular and morphological changes to form spermatozoa during spermiogenesis. Abnormalities in these steps can lead to serious male fertility problems, from oligospermia to complete azoospermia. CHD5 is a chromatin-remodeling nuclear protein expressed almost exclusively in the brain and testis. Male Chd5 knockout (KO) mice have deregulated spermatogenesis, characterized by immature sloughing of spermatids, spermiation failure, disorganization of the spermatogenic cycle and abnormal head morphology in elongating spermatids. This results in the inappropriate placement and juxtaposition of germ cell types within the epithelium. Sperm that did enter the epididymis displayed irregular shaped sperm heads, and retained cytoplasmic components. These sperm also stained positively for acidic aniline, indicating improper removal of histones and lack of proper chromatin condensation. Electron microscopy showed that spermatids in the seminiferous tubules of Chd5 KO mice have extensive nuclear deformation, with irregular shaped heads of elongated spermatids, and lack the progression of chromatin condensation in an anterior-to-posterior direction. However, the mRNA expression levels of other important genes controlling spermatogenesis were not affected. Chd5 KO mice also showed decreased H4 hyperacetylation beginning at stage IX, step 9, which is vital for the histone-transition protein replacement in spermiogenesis. Our data indicate that CHD5 is required for normal spermiogenesis, especially for spermatid chromatin condensation.

Three testis-specific paralogous serine proteases play different roles in murine spermatogenesis and are involved in germ cell survival during meiosis

Spermatogenesis is a complex process that generates spermatozoa; its molecular mechanisms are not completely understood. Here we focused on the functions of three testis-specific serine proteases: Prss42/Tessp-2, Prss43/Tessp-3, and Prss44/Tessp-4. These protease genes, which constitute a gene cluster on chromosome 9F2-F3, were presumed to be paralogs and were expressed only in the testis. By investigating their mRNA distribution, we found that all three genes were expressed in primary and secondary spermatocytes. However, interestingly, the translated proteins were produced at different locations. Prss42/Tessp-2 was found in the membranes and cytoplasm of secondary spermatocytes and spermatids, whereas Prss43/Tessp-3 was present only in the membranes of spermatocytes and spermatids. Prss44/Tessp-4 was detected in the cytoplasm of spermatocytes and spermatids. To assess the roles of these proteases in spermatogenesis, we used organ culture of mouse testis fragments. Adding antibodies against Prss42/Tessp-2 and Prss43/Tessp-3 resulted in meiotic arrest at the stage when each protease was beginning to be translated. Furthermore, the number of apoptotic cells dramatically increased after the addition of these antibodies. These results strongly suggest that the three paralogous Prss/Tessp proteases play different roles in spermatogenesis and that Prss42/Tessp-2 and Prss43/Tessp-3 are required for germ cell survival during meiosis.

Monoubiquitination of filamin B regulates vascular endothelial growth factor-mediated trafficking of histone deacetylase 7

Nucleocytoplasmic shuttling of class IIa of histone deacetylases (HDACs) is a key mechanism that controls cell fate and animal development. We have identified the filamin B (FLNB) as a novel HDAC7-interacting protein that is required for temporal and spatial regulation of vascular endothelial growth factor (VEGF)-mediated HDAC7 cytoplasmic sequestration. This interaction occurs in the cytoplasm and requires monoubiquitination of an evolutionarily conserved lysine 1147 (K1147) in the immunoglobulin (Ig)-like repeat 10 (R10) of FLNB and the nuclear localization sequence of HDAC7. Inhibition of protein kinase C (PKC) blocks VEGF-induced ubiquitination of FLNB and its interaction with HDAC7. Small interfering RNA (siRNA) knockdown of FLNB or ubiquitin (Ub) in human primary endothelial cells blocks VEGF-mediated cytoplasmic accumulation of HDAC7, reduces VEGF-induced expression of the HDAC7 target genes Mmp-10 and Nur77, and inhibits VEGF-induced vascular permeability. Using dominant negative mutants and rescue experiments, we demonstrate the functional significance of FLNB K1147 to interfere with the ability of phorbol myristate acetate (PMA) to promote FLNB-mediated cytoplasmic accumulation of HDAC7. Taken together, our data show that VEGF and PKC promote degradation-independent protein ubiquitination of FLNB to control intracellular trafficking of HDAC7.