UBE2B mRNA alterations are associated with severe oligozoospermia in infertile men

Microarray and in silico analysis of DNA repair genes between human testis of patients with nonobstructive azoospermia and normal cells

DNA repair processes are critical to maintaining genomic integrity. As a result, dysregulation of repair genes is likely to be linked with health implications, such as an increased prevalence of infertility and an accelerated rate of aging. We evaluated all the DNA repair genes (322 genes) by microarray. This study has provided insight into the connection between DNA repair genes, including RAD23B, OBFC2A, PMS1, UBE2V1, ERCC5, SMUG1, RFC4, PMS2L5, MMS19, SHFM1, INO80, PMS2L1, CHEK2, TRIP13, and POLD4. The microarray analysis of six human cases with different nonobstructive azoospermia revealed that RAD23B, OBFC2A, PMS1, UBE2V1, ERCC5, SMUG1, RFC4, PMS2L5, MMS19, SHFM1, and INO80 were upregulated, and expression of PMS2L1, CHEK2, TRIP13, and POLD4 was downregulated versus the normal case. For this purpose, Enrich Shiny GO, STRING, and Cytoscape online evaluation was applied to predict proteins' functional and molecular interactions and then performed to recognize the master pathways. Functional enrichment analysis revealed that the biological process (BP) terms "base-excision repair, AP site formation," "nucleotide-excision repair, DNA gap filling," and "nucleotide-excision repair, preincision complex assembly" was significantly overexpressed in upregulated differentially expressed genes (DEGs). BP analysis of downregulated DEGs highlighted "histone phosphorylation," "DNA damage response, detection DNA response," "mitotic cell cycle checkpoint signaling," and "double-strand break repair." Overrepresented molecular function (MF) terms in upregulated DEGs included "Oxidized base lesion DNA N-glycosylase activity," "uracil DNA N-glycosylase activity," "bubble DNA binding" and "DNA clamp loader activity." Interestingly, MF investigation of downregulated DEGs showed overexpression in "heterotrimeric G-protein complex," "5'-deoxyribose-5-phosphate lyase activity," "minor groove of adenine-thymine-rich DNA binding," and "histone kinase activity." Our findings suggest that these genes and their interacting hub proteins could help determine the pathophysiology of germ cell abnormalities and infertility.

RAD6 Positively Affects Tumorigenesis of Esophageal Squamous Cell Carcinoma by Regulating Histone Ubiquitination of CCNB1

Objective Esophageal carcinoma (ESCA) is deadly cancer worldwide with unknown etiology. This study aimed to investigate the impact and mechanism of RAD6 on the development of Esophageal squamous cell carcinoma (ESCC).

Expressions of RAD6A and RAD6B in ESCA were investigated from TCGA dataset and their expressions in tissue sample of ESCA patients and cells were determined. Functional experiments were conducted to explore the impact of RAD6A and RAD6B on malignant characteristics of several kinds of ESCC cells. Animal experiment was established and injected with RAD6A and RAD6B shRNA to evaluate the effect on tumor growth.

RAD6A and RAD6B were up-regulated in ESCC cells and tissues. Overexpressed RAD6A and RAD6B similarly increased ESCC cell proliferation, invasion and migration and silencing of RAD6 exerted opposite effects. Knockdown of RAD6A suppressed tumor growth and decreased the level of H2B, as data demonstrated positive correlation between RAD6A and CCNB1 in ESCC tissues.

Collectively, this study elucidates that RAD6 is up-regulated in ESCC and promotes the progression of ESCC through up-regulation of CCNB1 to enhance H2B ubiquitination. These evidence provide a novel insight into the pathogenesis of ESCC and might contribute to the development of targeted therapy.

Histone Methylation Regulates Gene Expression in the Round Spermatids to Set the RNA Payloads of Sperm

Gene expression during spermatogenesis undergoes significant changes due to a demanding sequence of mitosis, meiosis, and differentiation. We investigated the contribution of H3 histone modifications to gene regulation in the round spermatids. Round spermatids were purified from rat testes using centrifugal elutriation and Percoll density-gradient centrifugation. After enzymatic chromatin shearing, immuno-precipitation using antibodies against histone marks H3k4me3 and H3K9me3 was undertaken. The immunoprecipitated DNA fragments were subjected to massive parallel sequencing. Gene expression in round spermatids and sperm was analyzed by transcriptome sequencing using next-generation sequencing methods. ChIP-seq analysis showed significant peak enrichment in H3K4me3 marks in active chromatin regions and H3K9me3 peak enrichment in repressive regions. We found 53 genes which showed overlapping peak enrichment in both H3K4me3 and H3K9me3 marks. Some of the top H3K4me3-enriched genes were involved in sperm tail formation (Odf1, Odf3, Odf4, Oaz3, Ccdc42, Ccdc63, and Ccdc181), chromatin condensation (Dync1h1, Dynll1, and Kdm3a), and sperm functions such as acrosome reaction (Acrbp and Fabp9), energy generation (Gapdhs), and signaling for motility (Tssk1b, Tssk2, and Tssk4). Transcriptome sequencing in round spermatids found 64% transcripts of the H3K4me3-enriched genes at high levels and of about 25% of H3K9me3-enriched genes at very low levels. Transcriptome sequencing in sperm found that more than 99% of the ChIP-seq corresponding transcripts were also present in sperm. H3K4me3 enrichment in the round spermatids correlates significantly with gene expression and H3K9me3 correlates with gene silencing that contribute to sperm differentiation and setting the RNA payloads of sperm.

Significance and Relevance of Spermatozoal RNAs to Male Fertility in Livestock

Livestock production contributes to a significant part of the economy in developing countries. Although artificial insemination techniques brought substantial improvements in reproductive efficiency, male infertility remains a leading challenge in livestock. Current strategies for the diagnosis of male infertility largely depend on the evaluation of semen parameters and fail to diagnose idiopathic infertility in most cases. Recent evidences show that spermatozoa contains a suit of RNA population whose profile differs between fertile and infertile males. Studies have also demonstrated the crucial roles of spermatozoal RNA (spRNA) in spermatogenesis, fertilization, and early embryonic development. Thus, the spRNA profile may serve as unique molecular signatures of fertile sperm and may play pivotal roles in the diagnosis and treatment of male fertility. This manuscript provides an update on various spRNA populations, including protein-coding and non-coding RNAs, in livestock species and their potential role in semen quality, particularly sperm motility, freezability, and fertility. The contribution of seminal plasma to the spRNA population is also discussed. Furthermore, we discussed the significance of rare non-coding RNAs (ncRNAs) such as long ncRNAs (lncRNAs) and circular RNAs (circRNAs) in spermatogenic events.

Epigenetic mechanisms within the sperm epigenome and their diagnostic potential

The sperm epigenome contains a highly unique and specialized epigenetic landscape. Insightful questions need be asked about these epigenetic signatures and their predictive potential to assess the approximately 1 in 6 couples who experience infertility. Among those couples that do experience infertility, approximately half of the cases involve a male factor. Unfortunately, there is a significant lack of effective diagnostic tools in the male infertility space and thus clinicians are left with little data upon which they can formulate data driven treatment plans. Taking together this information and the striking prevalence of male infertility it's obvious that there is a need for improved diagnostic techniques for male infertility. Many studies have identified what appear to be clinically meaningful epigenetic alterations in sperm that may add utility in the diagnoses of infertility and improvement of pregnancy outcomes. Many researchers believe that continued analysis of these various epigenetic mechanisms may provide powerful predictive insight. In fact, there is promising current data suggesting that the predictive power of DNA methylation, Nuclear Proteins, and miRNA signatures in sperm likely can improve what is currently found with traditional diagnosis of male infertility. The focus of this review is to give a brief understanding to the field of epigenetics and the potential predictive power the sperm epigenome may hold in relation to improving the treatment and diagnosis of male infertility patients.

Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional Characterization

Rad6B, a principal component of the translesion synthesis pathway, and activator of canonical Wnt signaling, plays an essential role in cutaneous melanoma development and progression. As Rad6 is encoded by two genes, namely, UBE2A (RAD6A) and UBE2B (RAD6B), in humans, we compared their expressions in melanomas and normal melanocytes. While both genes are weakly expressed in normal melanocytes, Rad6B is more robustly expressed in melanoma lines and patient-derived metastatic melanomas than RAD6A. The characterization of RAD6B transcripts revealed coexpression of various splice variants representing truncated or modified functional versions of wild-type RAD6B in melanomas, but not in normal melanocytes. Notably, two RAD6B isoforms with intact catalytic domains, RAD6BΔexon4 and RAD6Bintron5ins, were identified. We confirmed that RAD6BΔexon4 and RAD6Bintron5ins variants are expressed as 14 and 15 kDa proteins, respectively, with functional in vivo ubiquitin conjugating activity. Whole exome sequence analysis of 30 patient-derived melanomas showed RAD6B variants coexpressed with wild-type RAD6B in all samples analyzed, and RAD6Bintron5ins variants were found in half the cases. These variants constitute the majority of the RAD6B transcriptome in contrast to RAD6A, which was predominantly wild-type. The expression of functional RAD6B variants only in melanomas reveals RAD6B's molecular heterogeneity and its association with melanoma pathogenesis.

Integrated analysis miRNA and mRNA profiling in patients with severe oligozoospermia reveals miR-34c-3p downregulates PLCXD3 expression

Our previous research suggested that an integrated analysis of microRNA (miRNA) and messenger RNA (mRNA) expression is helpful to explore miRNA-mRNA interactions and to uncover the molecular mechanisms of male infertility. In this study, microarrays were used to compare the differences in the miRNA and mRNA expression profiles in the testicular tissues of severe oligozoospermia (SO) patients with obstructive azoospermia (OA) controls with normal spermatogenesis. Four miRNAs (miR-1246, miR-375, miR-410, and miR-758) and six mRNAs (SLC1A3, PRKAR2B, HYDIN, WDR65, PRDX1, and ADATMS5) were selected to validate the microarray data using quantitative real-time PCR. Using statistical calculations and bioinformatics predictions, we identified 33 differentially expressed miRNAs and 1,239 differentially expressed mRNAs, among which one potential miRNA-target gene pair, miR-34c-3p and PLCXD3 (Phosphatidylinositol-Specific Phospholipase C, X Domain Containing 3), was identified. Immunohistochemical analysis indicated that PLCXD3 was located within the germ cells of the mouse and human testis. Moreover, we found that miR-34c-3p was able to decrease PLCXD3 expression in mouse (GC-1 and TM4) and human (NCM460) cell lines, presumably indicating the possibility that miR-34c-3p acts as an intracellular mediator in germinal lineage differentiation. Notably, we reported the expression of the PLCXD3 protein in a man with normal spermatogenesis and the lack of the PLCXD3 protein in a man with SO. Therefore, the identified miRNA and mRNA may represent a potentially novel molecular regulatory network and therapeutic targets for the study or treatment of SO, which might provide a better understanding of the molecular basis of spermatogenesis dysfunction.

A functional variant in the UBE2B gene promoter is associated with idiopathic azoospermia

BACKGROUND

A variety of genetic variants lead to abnormal human spermatogenesis. The ubiquitin-conjugating enzyme E2B (UBE2B) plays a significant role in spermatogenesis as Ube2b-knockout male mice are infertile.

METHODS

In this study, we sequenced the exon and promoter region of UBE2B in 776 patients diagnosed with idiopathic azoospermia (IA) and 709 proven fertile men to examine whether UBE2B is involved in the pathogenesis of IA.

RESULTS

In the exon region, two novel synonymous variants were detected in the patient group. In the promoter region, four known variants and four novel variants were identified in the patient group. Of the novel variants in the promoter region, three were located at the binding site of specificity protein 1 (SP1) transcription factor analyzed by TRANSFAC software. Luciferase assays demonstrated that one heterozygous variant (Chr5.133706925 A > G) inhibited the transcriptional regulation activity of SP1.

CONCLUSIONS

A novel variant (Chr5.133706925 A > G) residing in the UBE2B gene promoter region confers a high risk for IA in a Chinese population. These results support a role for UBE2B in the pathogenesis of IA.

MicroRNA and Male Infertility: A Potential for Diagnosis

MicroRNAs (miRNAs) are small non-coding single stranded RNA molecules that are physiologically produced in eukaryotic cells to regulate or mostly down-regulate genes by pairing with their complementary base-sequence in related mRNA molecules in the cytoplasm. It has been reported that other than its function in many physiological cell processes, dysregulation of miRNAs plays a role in the development of many diseases. In this short review, the association between miRNAs and some male reproductive disorders is surveyed. Male factor Infertility is a devastating problem from which a notable percentage of couples suffer. However, the molecular mechanism of many infertility disorders has not been clearly elucidated. Since miRNAs have an important role in numerous biological cell processes and cellular dysfunctions, it is of interest to review the related literature on the role of miRNAs in the male reproductive organs. Aberrant expression of specific miRNAs is associated with certain male reproductive dysfunctions. For this reason, assessment of expression of such miRNAs may serve as a suitable molecular biomarker for diagnosis of those male infertility disorders. The presence of a single nucleotide polymorphism (SNP) at the miRNAs' binding site in its targeted mRNA has been reported to have an association with idiopathic male infertility. Also, a relation with male infertility has been shown with SNP in the genes of the factors necessary for miRNA biogenesis. Therefore, focusing on the role of miRNAs in male reproductive disorders can further elucidate the molecular mechanisms of male infertility and generate the potential for locating efficient biomarkers and therapeutic agents for these disorders.

The Genetics of Infertility: Current Status of the Field

Infertility is a relatively common health condition, affecting nearly 7% of all couples. Clinically, it is a highly heterogeneous pathology with a complex etiology that includes environmental and genetic factors. It has been estimated that nearly 50% of infertility cases are due to genetic defects. Hundreds of studies with animal knockout models convincingly showed infertility to be caused by gene defects, single or multiple. However, despite enormous efforts, progress in translating basic research findings into clinical studies has been challenging. The genetic causes remain unexplained for the vast majority of male or female infertility patients. A particular difficulty is the huge number of candidate genes to be studied; there are more than 2,300 genes expressed in the testis alone, and hundreds of those genes influence reproductive function in humans and could contribute to male infertility. At present, there are only a handful of genes or genetic defects that have been shown to cause, or to be strongly associated with, primary infertility. Yet, with completion of the human genome and progress in personalized medicine, the situation is rapidly changing. Indeed, there are 10-15 new gene tests, on average, being added to the clinical genetic testing list annually.