Comprehensive analysis of human tissues reveals unique expression and localization patterns of HSF1 and HSF2

Heat shock factors (HSFs) are the main transcriptional regulators of the evolutionarily conserved heat shock response. Beyond cell stress, several studies have demonstrated that HSFs also contribute to a vast variety of human pathologies, ranging from metabolic diseases to cancer and neurodegeneration. Despite their evident role in mitigating cellular perturbations, the functions of HSF1 and HSF2 in physiological proteostasis have remained inconclusive. Here, we analyzed a comprehensive selection of paraffin-embedded human tissue samples with immunohistochemistry. We demonstrate that both HSF1 and HSF2 display distinct expression and subcellular localization patterns in benign tissues. HSF1 localizes to the nucleus in all epithelial cell types, whereas nuclear expression of HSF2 was limited to only a few cell types, especially the spermatogonia and the urothelial umbrella cells. We observed a consistent and robust cytoplasmic expression of HSF2 across all studied smooth muscle and endothelial cells, including the smooth muscle cells surrounding the vasculature and the high endothelial venules in lymph nodes. Outstandingly, HSF2 localized specifically at cell-cell adhesion sites in a broad selection of tissue types, such as the cardiac muscle, liver, and epididymis. To the best of our knowledge, this is the first study to systematically describe the expression and localization patterns of HSF1 and HSF2 in benign human tissues. Thus, our work expands the biological landscape of these factors and creates the foundation for the identification of specific roles of HSF1 and HSF2 in normal physiological processes.

MicroRNAs in spermatogenesis dysfunction and male infertility: clinical phenotypes, mechanisms and potential diagnostic biomarkers

Infertility affects approximately 10-15% of couples worldwide who are attempting to conceive, with male infertility accounting for 50% of infertility cases. Male infertility is related to various factors such as hormone imbalance, urogenital diseases, environmental factors, and genetic factors. Owing to its relationship with genetic factors, male infertility cannot be diagnosed through routine examination in most cases, and is clinically called 'idiopathic male infertility.' Recent studies have provided evidence that microRNAs (miRNAs) are expressed in a cell-or stage-specific manner during spermatogenesis. This review focuses on the role of miRNAs in male infertility and spermatogenesis. Data were collected from published studies that investigated the effects of miRNAs on spermatogenesis, sperm quality and quantity, fertilization, embryo development, and assisted reproductive technology (ART) outcomes. Based on the findings of these studies, we summarize the targets of miRNAs and the resulting functional effects that occur due to changes in miRNA expression at various stages of spermatogenesis, including undifferentiated and differentiating spermatogonia, spermatocytes, spermatids, and Sertoli cells (SCs). In addition, we discuss potential markers for diagnosing male infertility and predicting the varicocele grade, surgical outcomes, ART outcomes, and sperm retrieval rates in patients with non-obstructive azoospermia (NOA).

The Role of microRNA in Spermatogenesis: Is There a Place for Fertility Preservation Innovation?

Oncological treatments have dramatically improved over the last decade, and as a result, survival rates for cancer patients have also improved. Quality of life, including concerns about fertility, has become a major focus for both oncologists and patients. While oncologic treatments are often highly effective at suppressing neoplastic growth, they are frequently associated with severe gonadotoxicity, leading to infertility. For male patients, the therapeutic option to preserve fertility is semen cryopreservation. In prepubertal patients, immature testicular tissue can be sampled and stored to allow post-cure transplantation of the tissue, immature germ cells, or in vitro spermatogenesis. However, experimental techniques have not yet been proven effective for restoring sperm production for these patients. MicroRNAs (miRNAs) have emerged as promising molecular markers and therapeutic tools in various diseases. These small regulatory RNAs possess the unique characteristic of having multiple gene targets. MiRNA-based therapeutics can, therefore, be used to modulate the expression of different genes involved in signaling pathways dysregulated by changes in the physiological environment (disease, temperature, ex vivo culture, pharmacological agents). This review discusses the possible role of miRNA as an innovative treatment option in male fertility preservation-restoration strategies and describes the diverse applications where these new therapeutic tools could serve as fertility protection agents.

Unlocking the mystery associated with infertility and prostate cancer: an update

Male-specific reproductive disorders and cancers have increased intensely in recent years, making them a significant public health problem. Prostate cancer (PC) is the most often diagnosed cancer in men and is one of the leading causes of cancer-related mortality. Both genetic and epigenetic modifications contribute to the development and progression of PC, even though the exact underlying processes causing this disease have yet to be identified. Male infertility is also a complex and poorly understood phenomenon believed to afflict a significant portion of the male population. Chromosomal abnormalities, compromised DNA repair systems, and Y chromosome alterations are just a few of the proposed explanations. It is becoming widely accepted that infertility shares a link with PC. Much of the link between infertility and PC is probably attributable to common genetic defects. This article provides an overview of PC and spermatogenic abnormalities. This study also investigates the link between male infertility and PC and uncovers the underlying reasons, risk factors, and biological mechanisms contributing to this association.

HSF1 and Its Role in Huntington's Disease Pathology

PURPOSE OF REVIEW

Heat shock factor 1 (HSF1) is the master transcriptional regulator of the heat shock response (HSR) in mammalian cells and is a critical element in maintaining protein homeostasis. HSF1 functions at the center of many physiological processes like embryogenesis, metabolism, immune response, aging, cancer, and neurodegeneration. However, the mechanisms that allow HSF1 to control these different biological and pathophysiological processes are not fully understood. This review focuses on Huntington's disease (HD), a neurodegenerative disease characterized by severe protein aggregation of the huntingtin (HTT) protein. The aggregation of HTT, in turn, leads to a halt in the function of HSF1. Understanding the pathways that regulate HSF1 in different contexts like HD may hold the key to understanding the pathomechanisms underlying other proteinopathies. We provide the most current information on HSF1 structure, function, and regulation, emphasizing HD, and discussing its potential as a biological target for therapy.

DATA SOURCES

We performed PubMed search to find established and recent reports in HSF1, heat shock proteins (Hsp), HD, Hsp inhibitors, HSF1 activators, and HSF1 in aging, inflammation, cancer, brain development, mitochondria, synaptic plasticity, polyglutamine (polyQ) diseases, and HD.

STUDY SELECTIONS

Research and review articles that described the mechanisms of action of HSF1 were selected based on terms used in PubMed search.

RESULTS

HSF1 plays a crucial role in the progression of HD and other protein-misfolding related neurodegenerative diseases. Different animal models of HD, as well as postmortem brains of patients with HD, reveal a connection between the levels of HSF1 and HSF1 dysfunction to mutant HTT (mHTT)-induced toxicity and protein aggregation, dysregulation of the ubiquitin-proteasome system (UPS), oxidative stress, mitochondrial dysfunction, and disruption of the structural and functional integrity of synaptic connections, which eventually leads to neuronal loss. These features are shared with other neurodegenerative diseases (NDs). Currently, several inhibitors against negative regulators of HSF1, as well as HSF1 activators, are developed and hold promise to prevent neurodegeneration in HD and other NDs.

CONCLUSION

Understanding the role of HSF1 during protein aggregation and neurodegeneration in HD may help to develop therapeutic strategies that could be effective across different NDs.

Interplay between mammalian heat shock factors 1 and 2 in physiology and pathology

The heat-shock factors (HSFs) belong to an evolutionary conserved family of transcription factors that were discovered already over 30 years ago. The HSFs have been shown to a have a broad repertoire of target genes, and they also have crucial functions during normal development. Importantly, HSFs have been linked to several disease states, such as neurodegenerative disorders and cancer, highlighting their importance in physiology and pathology. However, it is still unclear how HSFs are regulated and how they choose their specific target genes under different conditions. Posttranslational modifications and interplay among the HSF family members have been shown to be key regulatory mechanisms for these transcription factors. In this review, we focus on the mammalian HSF1 and HSF2, including their interplay, and provide an updated overview of the advances in understanding how HSFs are regulated and how they function in multiple processes of development, aging, and disease. We also discuss HSFs as therapeutic targets, especially the recently reported HSF1 inhibitors.

MicroRNA expression in male infertility

Male infertility is a multifactorial disorder that involves different physiopathological mechanisms and multiple genes. In this sense, we analyse the role of miRNAs in this pathology. Gene expression analysis can provide relevant information to detect biomarkers, signalling pathways, pathologic mechanisms, and potential therapeutic targets for the disease. In this review, we describe four miRNA microarrays related to patients who present infertility diseases, including azoospermia, asthenozoospermia, and oligoasthenozoospermic. We selected 13 miRNAs with altered expressions in testis tissue (hsa-miR-122-5p, hsa-miR-145-5p, hsa-miR-16-5p, hsa-miR-193a-3p, hsa-miR-19a-3p, hsa-miR-23a-3p, hsa-miR-30b-5p, hsa-miR-34b-5p, hsa-miR-34c-5p, hsa-miR-374b-5p, hsa-miR-449a, hsa-miR-574-3p and hsa-miR-92a-3p), and systematically examine the mechanisms of four relevant miRNAs (hsa-miR-16-5p, hsa-miR-19a-3p, hsa-miR-92a-3p and hsa-miR-30b-5p) which we found that regulated a large number of proteins. An interaction network was generated, and its connections allowed us to identify signalling pathways and interactions between proteins associated with male infertility. In this way, we confirm that the most affected and relevant pathway is the PI3K-Akt signalling.

miR-199-5p regulates spermiogenesis at the posttranscriptional level via targeting Tekt1 in allotriploid crucian carp

BACKGROUND

Sperm abnormalities are one of the primary factors leading to male sterility, but their pathogenesis is still unclear. Although miRNAs are suggested to exert important roles in the regulation of spermatogenesis at both transcriptional and posttranscriptional levels, little is currently known regarding the regulation of sperm flagella assembly by microRNAs (miRNAs). The role of miRNAs in the development of sperm abnormalities in sterile triploid fish has not been studied.

RESULTS

In this study, we found that miR-199-5p was widely expressed in all detected tissues of different-ploidy crucian carp. As one of the testis-specific candidate markers, Tekt1 was predominantly expressed in the testis. Quantitative real-time PCR (qRT-PCR) analyses showed that the expression trend of miR-199-5p was exactly opposite to that of Tekt1. Through bioinformatics analysis, we identified a putative miR-199-5p binding site in the Tekt1 mRNA. We further identified Tekt1 as a target of miR-199-5p using luciferase reporter assay. Finally, we confirmed that miR-199-5p was necessary for sperm flagellar assembly and spermatogenesis in vivo via intraperitoneal injection of miR-199-5p antagomir or agomir in diploid red crucian carp. Moreover, miR-199-5p gain-of-function could lead to spermatids apoptosis and abnormal spermatozoa structure, which is similar to that of allotriploid crucian carp.

CONCLUSIONS

Our studies suggested that abnormally elevated miR-199-5p inhibited the sperm flagella formation in spermiogenesis by negatively regulating the expression of Tekt1, thereby causing sperm abnormalities of male allotriploid crucian carp.

A functional screen with metformin identifies microRNAs that regulate metabolism in colorectal cancer cells

Metformin inhibits oxidative phosphorylation and can be used to dissect metabolic pathways in colorectal cancer (CRC) cells. CRC cell proliferation is inhibited by metformin in a dose dependent manner. MicroRNAs that regulate metabolism could be identified by their ability to alter the effect of metformin on CRC cell proliferation. An unbiased high throughput functional screen of a synthetic micoRNA (miRNA) library was used to identify miRNAs that impact the metformin response in CRC cells. Experimental validation of selected hits identified miRNAs that sensitize CRC cells to metformin through modulation of proliferation, apoptosis, cell-cycle and direct metabolic disruption. Among eight metformin sensitizing miRNAs identified by functional screening, miR-676-3p had both pro-apoptotic and cell cycle arrest activity in combination with metformin, whereas other miRNAs (miR-18b-5p, miR-145-3p miR-376b-5p, and miR-718) resulted primarily in cell cycle arrest when combined with metformin. Investigation of the combined effect of miRNAs and metformin on CRC cell metabolism showed that miR-18b-5p, miR-145-3p, miR-376b-5p, miR-676-3p and miR-718 affected glycolysis only, while miR-1181 only regulated CRC respiration. MicroRNAs can sensitize CRC cells to the anti-proliferative effects of metformin. Identifying relevant miRNA targets may enable the design of innovative therapeutic strategies.

Differential expression profiles of microRNAs in musk gland of unmated and mated forest musk deer (Moschus berezovskii)

Background

The formation of musk is a complex biophysical and biochemical process that change with the rut of male forest musk deer. We have reported that the mating status of male forest musk deer might result to the variations of chemical composition and microbiota of musk and its yields. Critical roles for microRNAs (miRNAs) of multi-tissues were profiled in our previous study; however, the role for miRNAs of the musk gland remains unclear in this species.

Methods

In this study, we used Illumina deep sequencing technology to sequence the small RNA transcriptome of unmated male (UM) and mated male (UM) of Chinese forest musk deer.

Results

We identified 1,652 known miRNAs and 45 novel miRNAs, of which there were 174 differentially expressed miRNAs between UM and MM. chi-miR-21-5p, ipu-miR-99b and bta-miR-26a were up-regulated in UM among the 10 most differentially expressed miRNAs. Functional enrichment of the target genes showed that monosaccharide biosynthetic process, protein targeting, cellular protein catabolic process enriched higher in MM. Meanwhile, structural molecule activity, secretion by cell, regulated exocytosis and circulatory system process enriched more in UM, hinting that the formation of musk in UM was mediated by target genes related to exocytosis. The miRNA-mRNA pairs such as miR-21: CHD7, miR143: HSD17B7, miR-141/200a: Noc2 might involve in musk gland development and musk secretion, which need to be verified in future study.

Pan-Cancer Integrated Analysis of HSF2 Expression, Prognostic Value and Potential Implications for Cancer Immunity

Heat shock factor 2 (HSF2), a transcription factor, plays significant roles in corticogenesis and spermatogenesis by regulating various target genes and signaling pathways. However, its expression, clinical significance and correlation with tumor-infiltrating immune cells across cancers have rarely been explored. In the present study, we comprehensively investigated the expression dysregulation and prognostic significance of HSF2, and the relationship with clinicopathological parameters and immune infiltration across cancers. The mRNA expression status of HSF2 was analyzed by TCGA, GTEx, and CCLE. Kaplan-Meier analysis and Cox regression were applied to explore the prognostic significance of HSF2 in different cancers. The relationship between HSF2 expression and DNA methylation, immune infiltration of different immune cells, immune checkpoints, tumor mutation burden (TMB), and microsatellite instability (MSI) were analyzed using data directly from the TCGA database. HSF2 expression was dysregulated in the human pan-cancer dataset. High expression of HSF2 was associated with poor overall survival (OS) in BRCA, KIRP, LIHC, and MESO but correlated with favorable OS in LAML, KIRC, and PAAD. The results of Cox regression and nomogram analyses revealed that HSF2 was an independent factor for KIRP, ACC, and LIHC prognosis. GO, KEGG, and GSEA results indicated that HSF2 was involved in various oncogenesis- and immunity-related signaling pathways. HSF2 expression was associated with TMB in 9 cancer types and associated with MSI in 5 cancer types, while there was a correlation between HSF2 expression and DNA methylation in 27 types of cancer. Additionally, HSF2 expression was correlated with immune cell infiltration, immune checkpoint genes, and the tumor immune microenvironment in various cancers, indicating that HSF2 could be a potential therapeutic target for immunotherapy. Our findings revealed the important roles of HSF2 across different cancer types.

Regulation of mammalian spermatogenesis by miRNAs

Male fertility requires the continual production of sperm by the process of spermatogenesis. This process requires the correct timing of regulatory signals to germ cells during each phase of their development. MicroRNAs (miRNAs) in germ cells and supporting Sertoli cells respond to regulatory signals and cause down- or upregulation of mRNAs and proteins required to produce proteins that act in various pathways to support spermatogenesis. The targets and functional consequences of altered miRNA expression in undifferentiated and differentiating spermatogonia, spermatocytes, spermatids and Sertoli cells are discussed. Mechanisms are reviewed by which miRNAs contribute to decisions that promote spermatogonia stem cell self-renewal versus differentiation, entry into and progression through meiosis, differentiation of spermatids, as well as the regulation of Sertoli cell proliferation and differentiation. Also discussed are miRNA actions providing the very first signals for the differentiation of spermatogonia stem cells in a non-human primate model of puberty initiation.

Integrated Bioinformatics Analysis Identifies Heat Shock Factor 2 as a Prognostic Biomarker Associated With Immune Cell Infiltration in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies and ranks as the second leading cause of cancer-related mortality worldwide. Heat shock factor 2 (HSF2) is a transcription factor that plays a critical role in development, particularly corticogenesis and spermatogenesis. However, studies examining the expression and prognostic value of HSF2 and its association with tumor-infiltrating immune cells in HCC are still rare. In the present study, we found that HSF2 expression was significantly upregulated in HCC tissues compared with normal liver tissues using the TCGA, ICGC, GEO, UALCAN, HCCDB and HPA databases. High HSF2 expression was associated with shorter survival of patients with HCC. Cox regression analyses and nomogram were used to evaluate the association of HSF2 expression with the prognosis of patients with HCC. Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and gene set enrichment analysis (GSEA) revealed that HSF2 was associated with various signaling pathways, including the immune response. Notably, HSF2 expression was significantly correlated with the infiltration levels of different immune cells using the TIMER database and CIBERSORT algorithm. HSF2 expression also displayed a significant correlation with multiple immune marker sets in HCC tissues. Knockdown of HSF2 significantly inhibited the proliferation, migration, invasion and colony formation ability of HCC cells. In summary, we explored the clinical significance of HSF2 and provided a therapeutic basis for the early diagnosis, prognostic judgment, and immunotherapy of HCC.

MiR-181a Promotes Spermatogenesis by Targeting the S6K1 Pathway

Approximately 15% of couples suffer from infertility worldwide, and male factors contribute to about 30% of total sterility cases. However, there is little progress in treatments due to the obscured understanding of underlying mechanisms. Recently microRNAs have emerged as a key player in the process of spermatogenesis. Expression profiling of miR-181a was carried out in murine testes and spermatocyte culture system. In vitro cellular and biochemical assays were used to examine the effect of miR-181a and identify its target S6K1, as well as elucidate the function with chemical inhibitor of S6K1. Human testis samples analysis was employed to validate the findings. miR-181a level was upregulated during mouse spermatogenesis and knockdown of miR-181a attenuated the cell proliferation and G1/S arrest and increased the level of S6K1, which was identified as a downstream target of miR-181a. Overexpression of S6K1 also led to growth arrest of spermatocytes while inhibitor of S6K1 rescued the miR-181a knockdown-mediated cell proliferation defect. In human testis samples of azoospermia patients, low level of miR-181a was correlated with defects in the spermatogenic process. miR-181a is identified as a new regulator and high level of miR-181a contributes to spermatogenesis via targeting S6K1.

microRNAs in the pathogenesis of non-obstructive azoospermia: the underlying mechanisms and therapeutic potentials

miRNAs are involved in different biological processes, including proliferation, differentiation, and apoptosis. Interestingly, 38% of the X chromosome-linked miRNAs are testis-specific and have crucial roles in regulating the renewal and cell cycle of spermatogonial stem cells. Previous studies demonstrated that abnormal expression of spermatogenesis-related miRNAs could lead to nonobstructive azoospermia (NOA). Moreover, differential miRNAs expression in seminal plasma of NOA patients has been reported compared to normozoospermic men. However, the role of miRNAs in NOA pathogenesis and the underlying mechanisms have not been comprehensively studied. Therefore, the aim of this review is to mechanistically describe the role of miRNAs in the pathogenesis of NOA and discuss the possibility of using the miRNAs as therapeutic targets.Abbreviations: AMO: anti-miRNA antisense oligonucleotide; AZF: azoospermia factor region; CDK: cyclin-dependent kinase; DAZ: deleted in azoospermia; ESCs: embryonic stem cells; FSH: follicle-stimulating hormone; ICSI: intracytoplasmic sperm injection; JAK/STAT: Janus kinase/signal transducers and activators of transcription; miRNA: micro-RNA; MLH1: Human mutL homolog l; NF-κB: Nuclear factor-kappa B; NOA: nonobstructive azoospermia; OA: obstructive azoospermia; PGCs: primordial germ cells; PI3K/AKT: Phosphatidylinositol 3-kinase/protein kinase B; Rb: retinoblastoma tumor suppressor; ROS: Reactive Oxygen Species; SCOS: Sertoli cell-only syndrome; SIRT: sirtuin; SNPs: single nucleotide polymorphisms; SSCs: spermatogonial stem cells; TESE: testicular sperm extraction; TGF-β: transforming growth factor-beta.

Testicular germ cell-specific lncRNA, Teshl, is required for complete expression of Y chromosome genes and a normal offspring sex ratio

Heat shock factor 2 (HSF2) regulates the transcription of the male-specific region of the mouse Y chromosome long arm (MSYq) multicopy genes only in testes, but the molecular mechanism underlying this tissue specificity remains largely unknown. Here, we report that the testicular germ cell-specific long noncoding RNA (lncRNA), NR_038002, displays a characteristic spatiotemporal expression pattern in the nuclei of round and elongating spermatids. NR_038002-knockout male mice produced sperm with abnormal head morphology and exhibited reduced fertility accompanied by a female-biased sex ratio in offspring. Molecular analyses revealed that NR_038002 interacts with HSF2 and thereby activates expression of the MSYq genes. We designate NR_038002 as testicular germ cell-specific HSF2-interacting lncRNA (Teshl). Together, our study is the first to demonstrate that the testis specificity of HSF2 activity is regulated by the lncRNA Teshl and establishes a Teshl-HSF2-MSYq molecular axis for normal Y-bearing sperm qualities and consequent balanced offspring sex ratio.

Using miRNAs as diagnostic biomarkers for male infertility: opportunities and challenges

The non-coding genome has been extensively studied for its role in human development and diseases. MicroRNAs (miRNAs) are small non-coding RNAs, which can regulate the expression of hundreds of genes at the post-transcriptional level. Therefore, any defects in miRNA biogenesis or processing can affect the genes and have been linked to several diseases. Male infertility is a clinical disorder with a significant number of cases being idiopathic. Problems in spermatogenesis and epididymal maturation, testicular development, sperm maturation or migration contribute to male infertility, and many of these idiopathic cases are related to issues with the miRNAs which tightly regulate these processes. This review summarizes the recent research on various such miRNAs and puts together the candidate miRNAs that may be used as biomarkers for diagnosis. The development of strategies for male infertility treatment using anti-miRs or miRNA mimics is also discussed. Although promising, the development of miRNA diagnostics and therapeutics is challenging, and ways to overcome some of these challenges are also reviewed.

Deletion of lncRNA5512 has no effect on spermatogenesis and reproduction in mice

Long non-coding (lnc) RNAs are a series of RNAs longer than 200 nucleotides that do not code for protein products. Whole-genome expression profiles of lncRNAs suggest that they play important roles in spermatogenesis because they are particularly abundant in testes. However, most of their characteristics and functions remain unclear. The aim of this study was to define the function of lncRNA5512, which is abundant in spermatocytes and round spermatids, in mouse fertility invivo. To investigate this we generated lncRNA5512-knockout mice by clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) 9 technology. Knockout mice showed normal spermatogenesis and fertility, and had no detectable abnormalities. This indicates that lncRNA5512 does not affect mouse fertility despite its high expression in the testes. Its specific localisation in spermatocytes and round spermatids suggests that it could be a useful marker for the identification of spermatocytes and round spermatids in mouse testes.

Regulation of Human Spermatogenesis

Human spermatogenesis (HS) is an intricate network of sequential processes responsible for the production of the male gamete, the spermatozoon. These processes take place in the seminiferous tubules (ST) of the testis, which are small tubular structures considered the functional units of the testes. Each human testicle contains approximately 600-1200 STs [1], and are capable of producing up to 275 million spermatozoa per day [2].

Genome-wide association study identifies candidate markers related to lincRNAs associated with male infertility in the Greek population

BACKGROUND

Male infertility is currently one of the most common problems faced by couples worldwide. We performed a GWAS on Greek population and gathered statistically significant SNPs in order to investigate whether they lie within or near lncRNA regions.

OBJECTIVES

The aim of this study was to investigate whether polymorphisms on or near lncRNAs affect interactions with miRNAs and can cause male infertility.

MATERIALS AND METHODS

In the present study, a GWAS was conducted, using samples from 159 individuals (83 normozoospermic individuals and 76 patients of known fertility issues). Standard procedures for quality controls and association testing were followed, based on case-control testing.

RESULTS

We detected six lncRNAs (LINC02231, LINC00347, LINC02134, NCRNA00157, LINC02493, Lnc-CASK-1) that are associated with male infertility through their interaction with miRNAs. Furthermore, we identified the genes targeted by those miRNAs and highlighted their functions in spermatogenesis and the fertilization process.

DISCUSSION AND CONCLUSION

lncRNAs are involved in spermatogenesis through their interaction with miRNAs. Thus, their study is very important, and it may contribute to the understanding of the molecular mechanisms underlying male infertility.

Identification and verification of hub microRNAs in varicocele rats through high-throughput sequencing and bioinformatics analysis

Varicocele (VC) is the most common treatable cause of infertility, but it is difficult to distinguish fertile from infertile VC populations because the pathogenesis is unclear. In order to study the related mechanism of VC causing male sterility, we made VC rats model by surgery, analyzed the rat epididymal sperm, and use the transcriptome sequencing compared all the miRNA expression differences in testicular tissue between VC rats, surgical treatment rats and control rats. The differentially expressed miRNAs (DEMs) of testicular tissue were also screened by the edgeR package in R software. We found that rno-miR-210-3p, rno-miR-6316, rno-miR-190a-5p and rno-miR-135b-5p were key miRNAs for VC and they were all up-regulated in VC samples and they are enriched in regulation of immune system process (GO:0002683), innate immune system (R-RNO-168,249) and apoptotic signaling pathway (GO:0097190). We hypothesize that negative regulation of immune system and apoptosis play an important role in the occurrence and development of VC, and it is induced the abnormal expression of target genes (such as Kitlg, Cxcl12) may involve in the development of VC associated infertility. Four key miRNAs, rno-miR-210-3p, rno-miR-6316, rno-miR-190a-5p and rno-miR-135b-5p, as well as their target genes are critical in VC, which could have attractive applications to provide new biomarkers for VC.

Molecular Mechanisms of Heat Shock Factors in Cancer

Malignant transformation is accompanied by alterations in the key cellular pathways that regulate development, metabolism, proliferation and motility as well as stress resilience. The members of the transcription factor family, called heat shock factors (HSFs), have been shown to play important roles in all of these biological processes, and in the past decade it has become evident that their activities are rewired during tumorigenesis. This review focuses on the expression patterns and functions of HSF1, HSF2, and HSF4 in specific cancer types, highlighting the mechanisms by which the regulatory functions of these transcription factors are modulated. Recently developed therapeutic approaches that target HSFs are also discussed.

Functions and mechanism of noncoding RNA in the somatic cells of the testis

ncRNAs are involved in numerous biological processes by regulating gene expression and cell stability. Studies have shown that ncRNAs also contribute to spermatogenesis. Leydig cells (LCs) and Sertoli cells (SCs) are somatic cells of the testis that support spermatogenesis and are vital to male fertility. In this review, we summarized the findings from studies on ncRNAs in SCs and LCs. In SCs, ncRNAs play key roles in phagocytosis, immunoprotection and development of SCs. In LCs, ncRNAs are involved in steroidogenesis, in particular production of testosterone as well as development of LCs. Here, we discuss the possible target genes and functions of ncRNAs in both types of cells. These ncRNAs regulate the expression of target genes or mRNA coding sequence regions, resulting in a chain reaction that influences cell function. In addition, microRNAs, lncRNAs, piRNA-like RNAs (pilRNAs) and natural antisense transcripts (NATs) are discussed in this review. In summary, we suggest that these ncRNAs might act in coordination to control spermatogenesis and maintain the environmental homeostasis of the testis.

MicroRNA-322 Regulates Self-renewal of Mouse Spermatogonial Stem Cells through Rassf8

Spermatogonial stem cells (SSCs) are essential for spermatogenesis and male fertility. MicroRNAs (miRs) are key regulators of gene expression involved in self-renewal, differentiation, and apoptosis. However, the function and mechanisms of individual miR in regulating self-renewal and differentiation of SSCs remain unclear. Here, we report for the first time that miR-322 regulates self-renewal of SSCs. Functional assays revealed that miR-322 was essential for SSC self-renewal. Mechanistically, miR-322 promoted SSC self-renewal by targeting RASSF8 (ras association domain family 8). Moreover, the WNT/β-catenin signaling pathway was involved in the miR-322-mediated regulation. Furthermore, miR-322 overexpression increased GFRα1, ETV5 and PLZF expression but decreased STRA8, C-KIT and BCL6 expression. Our study provides not only a novel insight into molecular mechanisms regulating SSC self-renewal but also a basis for the diagnosis, treatment, and prevention of male infertility.

MicroRNAs: Recent insights towards their role in male infertility and reproductive cancers

Spermatogenesis is a tightly controlled, multi-step process in which mature spermatozoa are produced. Disruption of regulatory mechanisms in spermatogenesis can lead to male infertility, various diseases of male reproductive system, or even cancer. The spermatogenic impairment in infertile men can be associated with different etiologies, and the exact molecular mechanisms are yet to be determined. MicroRNAs (miRNAs) are a type of non-protein coding RNAs, about 22 nucleotides long, with an essential role in post-transcriptional regulation. miRNAs have been recognized as important regulators of various biological processes, including spermatogenesis. The aim of this review is to summarize the recent literature on the role of miRNAs in spermatogenesis, male infertility and reproductive cancers, and to evaluate their potential in diagnosis, prognosis and therapy of disease. Experimental evidence shows that aberrant expression of miRNAs affects spermatogenesis at multiple stages and in different cell types, most often resulting in infertility. In more severe cases, dysregulation of miRNAs leads to cancer. miRNAs have enormous potential to be used as diagnostic and prognostic markers as well as therapeutic targets in male infertility and reproductive system diseases. However, to exploit this potential fully, we need a better understanding of miRNA-mediated regulation of spermatogenesis, including the characterization of yet unidentified miRNAs and related regulatory mechanisms.

miRNA-31-5p Mediates the Proliferation and Apoptosis of Human Spermatogonial Stem Cells via Targeting JAZF1 and Cyclin A2

Several lines of evidence highlight the important application of human spermatogonial stem cells (SSCs) in translational medicine. The fate decisions of SSCs are mainly mediated by genetic and epigenetic factors. We have recently demonstrated that PAK1 regulates the proliferation, DNA synthesis, and early apoptosis of human SSCs through the PDK1/KDR/ZNF367 and ERK1/2 and AKT pathway. However, the underlying epigenetic mechanism of PAK1 in human SSCs remains unknown. In this study, we found that the level of miRNA-31-5p was elevated by PAK1 knockdown. CCK-8, PCNA, and 5-ethynyl-2′-deoxyuridine (EDU) assays revealed that miRNA-31-5p mimics inhibited cell proliferation and DNA synthesis of human SSCs. Annexin V/propidium iodide (PI) staining and flow cytometry showed that miRNA-31-5p increased the early and late apoptosis of human SSCs. Furthermore, JAZF1 was predicted and verified as a target of miRNA-31-5p, and the three-dimensional (3D) structure model of JAZF1 protein was illustrated. JAZF1 silencing led to a reduction of cell proliferation and DNA synthesis as well as an enhancement of the early and late apoptosis of human SSCs. Finally, miRNA-31-5p mimics decreased the level of cyclin A2 rather than cyclin D1 or cyclin E1, and JAZF1 knockdown led to the reduction of cyclin A2 in human SSCs. Collectively, miRNA-31-5p regulates the proliferation, DNA synthesis, and apoptosis of human SSCs by the PAK1-JAZF1-cyclin A2 pathway. This study thus offers a novel insight into the molecular mechanisms underlying the fate determinations of human SSCs and might provide novel targets for molecular therapy of male infertility.

Roles of microRNAs in mammalian reproduction: from the commitment of germ cells to peri-implantation embryos

MicroRNAs (miRNAs) are active regulators of numerous biological and physiological processes including most of the events of mammalian reproduction. Understanding the biological functions of miRNAs in the context of mammalian reproduction will allow a better and comparative understanding of fertility and sterility in male and female mammals. Herein, we summarize recent progress in miRNA‐mediated regulation of mammalian reproduction and highlight the significance of miRNAs in different aspects of mammalian reproduction including the biogenesis of germ cells, the functionality of reproductive organs, and the development of early embryos. Furthermore, we focus on the gene expression regulatory feedback loops involving hormones and miRNA expression to increase our understanding of germ cell commitment and the functioning of reproductive organs. Finally, we discuss the influence of miRNAs on male and female reproductive failure, and provide perspectives for future studies on this topic.

Radiosensitizing effects of miR-18a-5p on lung cancer stem-like cells via downregulating both ATM and HIF-1α

Lung cancer is one of the main causes of cancer mortality globally. Most patients received radiotherapy during the course of disease. However, radioresistance generally occurs in the majority of these patients, leading to poor curative effect, and the underlying mechanism remains unclear. In the present study, miR-18a-5p expression was downregulated in irradiated lung cancer cells. Overexpression of miR-18a-5p increased the radiosensitivity of lung cancer cells and inhibited the growth of A549 xenografts after radiation exposure. Dual luciferase report system and miR-18a-5p overexpression identified ataxia telangiectasia mutated (ATM) and hypoxia inducible factor 1 alpha (HIF-1α) as the targets of miR-18a-5p. The mRNA and protein expressions of ATM and HIF-1α were dramatically downregulated by miR-18a-5p in vitro and in vivo. Clinically, plasma miR-18a-5p expression was significantly higher in radiosensitive than in radioresistant group (P < .001). The cutoff value of miR-18a-5p >2.28 was obtained from receiver operating characteristic (ROC) curve. The objective response rate (ORR) was significantly higher in miR-18a-5p-high group than in miR-18a-5p-low group (P < .001). A tendency demonstrated that the median local progression-free survival (PFS) from radiotherapy was longer in miR-18a-5p-high than in miR-18a-5p-low group (P = .082). The median overall survival (OS) from radiotherapy was numerically longer in miR-18a-5p-high than in miR-18a-5p-low group (P = .281). The sensitivity and specificity of plasma miR-18a-5p to predict radiosensitivity was 87% and 95%, respectively. Collectively, these results indicate that miR-18a-5p increases the radiosensitivity in lung cancer cells and CD133+ stem-like cells via downregulating ATM and HIF-1α expressions. Plasma miR-18a-5p would be an available indicator of radiosensitivity in lung cancer patients.

An miR-200 Cluster on Chromosome 23 Regulates Sperm Motility in Zebrafish

Besides its well-documented roles in cell proliferation, apoptosis, and carcinogenesis, the function of the p53-microRNA axis has been recently revealed in the reproductive system. Recent studies indicated that miR-200 family members are dysregulated in nonobstructive azoospermia patients, whereas their functions remain poorly documented. The aim of this study was to investigate the function of the miR-200 family on zebrafish testis development and sperm activity. There was no substantial difference in testis morphology and histology between wild-type (WT) and knockout zebrafish with deletion of miR-200 cluster on chromosome 6 (chr6-miR-200-KO) or on chromosome 23 (chr23-miR-200-KO). Interestingly, compared with WT zebrafish, the chr6-miR-200-KO zebrafish had no difference on sperm motility, whereas chr23-miR-200-KO zebrafish showed significantly improved sperm motility. Consistently, ectopic expression of miR-429a, miR-200a, and miR-200b, which are located in the miR-200 cluster on chromosome 23, significantly reduced motility traits of sperm. Several sperm motility-related genes, such as amh, wt1a, and srd5a2b have been confirmed as direct targets of miR-200s on chr23. 17α-ethynylestradiol (EE2) exposure resulted in upregulated expression of p53 and miR-429a in testis and impairment of sperm motility. Strikingly, in p53 mutant zebrafish testis, the expression levels of miR-200s on chr23 were significantly reduced and accompanied by a stimulation of sperm motility. Moreover, the upregulation of miR-429a associated with EE2 treatment was abolished in testis with p53 mutation. And the impairment of sperm activity by EE2 treatment was also eliminated when p53 was mutated. Together, our results reveal that miR-200 cluster on chromosome 23 controls sperm motility in a p53-dependent manner.

Regulatory Functions of MicroRNAs in Male Reproductive Health: A New Approach to Understanding Male Infertility

MicroRNAs (miRNAs) are a novel class of small noncoding RNAs (ncRNAs) that play critical roles in regulation of gene expression, especially at posttranscriptional level. Over the past decade, the degree to which miRNAs are involved in male infertility has become clear. They are expressed in a cell- or phase-specific manner during spermatogenesis and play crucial role in male reproductive health. Therefore, dysregulation of miRNAs in testicular cells can be considered as a molecular basis for reproductive failure and male infertility. The abnormal expression pattern of miRNAs can be transmitted to the offspring via assisted reproductive techniques (ART) and results in the birth of children with a higher risk of infertility, congenital abnormalities, and morbidity. This review expounds on the miRNAs reported to play essential roles in somatic cells development, germ cells differentiation, steroidogenesis, normal spermatogenesis, sperm maturation, and male infertility, as well as emphasizes their importance as minimally invasive biomarkers of male infertility.

miR‐31 Regulates Spermatogonial Stem Cells Meiosis via Targeting Stra8

Stra8 (stimulated by retinoic acid gene 8) is a specific gene that is expressed in mammalian germ cells during transition from mitosis to meiosis and plays a key role in the initiation of meiosis in mammals and birds. So, the evaluation of the Stra8 pathway in cSSCs may provide a deeper insight into mammalian spermatogenesis. miRNA was also an important regulating factor for meiosis of SSCs. However, there is currently no data indicating that miRNA regulate the meiosis of SSCs via Stra8. Here, we predicted the prospective miRNA targeting to Stra8 using the online Bioinformatics database‐Targetscan, and performed an analysis of the dual‐luciferase recombinant vector, pGL3‐CMV‐LUC‐MCS‐Stra8‐3′UTR. miR‐31 mimics (miR‐31m), miR‐31 inhibitors (miR‐31i), Control (NC, scrambled oligonucleotides transfection) were transfected into cSSCs; Stra8 and miRNA were analyzed by RT‐qPCR, immunofluorescence, and Western blot. The detection of haploid was conducted by flow cytometry. The results showed that miR‐31 regulates meiosis of cSSCs via targeting Stra8 in vitro and in vivo. Our study identifies a new regulatory pathway that miR‐31 targets Stra8 and inhibits spermatogenesis. J. Cell. Biochem. 118: 4844–4853, 2017. © 2017 Wiley Periodicals, Inc.

Toxic metabolites, Sertoli cells and Y chromosome related genes are potentially linked to the reproductive toxicity induced by mequindox

Mequindox (MEQ) is a relatively new synthetic antibacterial agent widely applied in China since the 1980s. However, its reproductive toxicity has not been adequately performed. In the present study, four groups of male Kunming mice (10 mice/group) were fed diets containing MEQ (0, 25, 55 and 110 mg/kg in the diet) for up to 18 months. The results show that M4 could pass through the blood-testis barrier (BTB), and demonstrate that Sertoli cells (SCs) are the main toxic target for MEQ to induce spermatogenesis deficiency. Furthermore, adrenal toxicity, adverse effects on the hypothalamic-pituitary-testicular axis (HPTA) and Leydig cells, as well as the expression of genes related to steroid biosynthesis and cholesterol transport, were responsible for the alterations in sex hormones in the serum of male mice after exposure to MEQ. Additionally, the changed levels of Y chromosome microdeletion related genes, such as DDX3Y, HSF2, Sly and Ssty2 in the testis might be a mechanism for the inhibition of spermatogenesis induced by MEQ. The present study illustrates for the first time the toxic metabolites of MEQ in testis of mice, and suggests that SCs, sex hormones and Y chromosome microdeletion genes are involved in reproductive toxicity mediated by MEQ in vivo.

The roles of microRNAs and siRNAs in mammalian spermatogenesis

MicroRNAs and siRNAs, both of which are AGO-bound small RNAs, are essential for mammalian spermatogenesis. Although their precise germline roles remain largely uncharacterized, recent discoveries suggest that they function in mechanisms beyond microRNA-mediated post-transcriptional control, playing roles in DNA repair and transcriptional regulation within the nucleus. Here, we discuss the latest findings regarding roles for AGO proteins and their associated small RNAs in the male germline. We integrate genetic, clinical and genomics data, and draw upon findings from non-mammalian models, to examine potential roles for AGO-bound small RNAs during spermatogenesis. Finally, we evaluate the emerging and differing roles for AGOs and AGO-bound small RNAs in the male and female germlines, suggesting potential reasons for these sexual dimorphisms.

Summary: This Review article summarizes the latest findings regarding roles for AGO proteins and their associated small RNAs in the male germline, with a particular focus on spermatogenesis.

Genistein up-regulates miR-20a to disrupt spermatogenesis via targeting Limk1

Genistein (GEN) is one of the isoflavones that has effect on male reproduction. However, the underlying mechanism remains unknown. miRNAs are a type of small non-coding RNAs that play important roles in spermatogenesis. We measured the GEN levels and miR-17-92 cluster expression in infertile subjects and found that miR-17-92 might be involved in GEN induced abnormal spermatogenesis. To clarify, we fed adult ICR mice with different doses of GEN (0, 0.5, 5, 50 and 250 mg/kg/day) for 35 days to study the underlying mechanism. We found that sperm average path velocity, straight-line velocity and eurvilinear velocity of the mice orally with GEN at 5mg/kg/day were significantly decreased, the expression levels of miR-17 and miR-20a in mice testis were higher in corresponding group. We also found miR-20a was the only miRNA that differentially expressed both in human and mice. By applying bioinformatics methods, Limk1 was predicted to be the target gene of miR-20a that is involved in spermatogenesis. Limk1 were significantly decreased in the corresponding group. Dual-luciferase report assay also proved that miR-20a could directly target Limk1. These results implied that Limk1 might be the target gene of miR-20a that is involved in GEN induced abnormal spermatogenesis.

MicroRNA-202 maintains spermatogonial stem cells by inhibiting cell cycle regulators and RNA binding proteins

miRNAs play important roles during mammalian spermatogenesis. However, the function of most miRNAs in spermatogenesis and the underlying mechanisms remain unknown. Here, we report that miR-202 is highly expressed in mouse spermatogonial stem cells (SSCs), and is oppositely regulated by Glial cell-Derived Neurotrophic Factor (GDNF) and retinoic acid (RA), two key factors for SSC self-renewal and differentiation. We used inducible CRISPR-Cas9 to knockout miR-202 in cultured SSCs, and found that the knockout SSCs initiated premature differentiation accompanied by reduced stem cell activity and increased mitosis and apoptosis. Target genes were identified with iTRAQ-based proteomic analysis and RNA sequencing, and are enriched with cell cycle regulators and RNA-binding proteins. Rbfox2 and Cpeb1 were found to be direct targets of miR-202 and Rbfox2 but not Cpeb1, is essential for the differentiation of SSCs into meiotic cells. Accordingly, an SSC fate-regulatory network composed of signaling molecules of GDNF and RA, miR-202 and diverse downstream effectors has been identified.

Expression of microRNA in male reproductive tissues and their role in male fertility

MicroRNA (miRNA) are small non-coding RNA, approximately 22 nucleotides in length, that regulate gene expression through their ability to bind to mRNA. The role of miRNA in cellular and tissue development is well documented and their importance in male reproductive tissue development is actively being evaluated. They are present in spermatogonia, Sertoli and Leydig cells within the testis and are present in mature spermatozoa, indicating roles in normal testicular development, function and spermatogenesis. Their presence in spermatozoa has led to postulations about the roles of male miRNA during early embryonic development after fertilisation, including chromatin restructuring and possible epigenetic effects on embryo development. MiRNAs are also present in body fluids, such as blood serum, milk, ovarian follicular fluid and seminal fluid. Circulating miRNAs are stable, and aberrant expression of cellular or extracellular miRNA has been associated with multiple pathophysiological conditions, the most studied being numerous forms of cancer. Considering that miRNAs are present in spermatozoa and in seminal fluid, their stability and the relatively non-invasive procedures required to obtain these samples make miRNAs excellent candidates for use as biomarkers of male reproduction and fertility. Biomarkers, such as miRNAs, identifying fertile males would be of financial interest to the animal production industry.

p53-mediated miR-18 repression activates HSF2 for IGF-IIR-dependent myocyte hypertrophy in hypertension-induced heart failure

Hypertension-induced cardiac hypertrophy and attenuated cardiac function are the major characteristics of early stage heart failure. Cardiomyocyte death in pathological cardiac conditions is the primary cause of heart failure and mortality. Our previous studies found that heat shock factor 1 (HSF1) protected cardiomyocytes from death by suppressing the IGF-IIR signaling pathway, which is critical for hypertensive angiotensin II-induced cardiomyocyte apoptosis. However, the role of heat shock factor 2 (HSF2) in hypertension-induced cardiac hypertrophy is unknown. We identified HSF2 as a miR-18 target for cardiac hypertrophy. p53 activation in angiotensin II (ANG II)-stimulated NRVMs is responsible for miR-18 downregulation both in vitro and in vivo, which triggers HSF2 expression and the activation of IGF-IIR-induced cardiomyocyte hypertrophy. Finally, we provide genetic evidence that miR-18 is required for cardiomyocyte functions in the heart based on the gene transfer of cardiac-specific miR-18 via adenovirus-associated virus 2 (AAV2). Transgenic overexpression of miR-18 in cardiomyocytes is sufficient to protect against dilated cardiomyopathy during hypertension-induced heart failure. Our results demonstrated that the p53-miR-18-HSF2-IGF-IIR axis was a critical regulatory pathway of cardiomyocyte hypertrophy in vitro and in vivo, suggesting that miR-18 could be a therapeutic target for the control of cardiac functions and the alleviation of cardiomyopathy during hypertension-induced heart failure.

Chronic low-dose exposure to a mixture of environmental endocrine disruptors induces microRNAs/isomiRs deregulation in mouse concomitant with intratesticular estradiol reduction

Humans are environmentally exposed not only to single endocrine-disrupting chemicals (EDCs) but to mixtures that affect their reproductive health. In reproductive tissues, microRNAs (miRNAs) are emerging as key targets of EDCs. Here, we analysed changes in the testis "miRNome" (and their biogenesis mechanism) in chronically exposed adult mice to a cocktail of five EDCs containing 0.3 mg/kg-body weight (BW)/day of each phthalate (DEHP, DBP, BBP) and 0.05 mg/kg-BW/day of each alkylphenol (NP, OP), from conception to adulthood. The testis "miRNome" was characterised using next-generation sequencing (NGS). Expression levels of genes involved in miRNA biogenesis were measured by RT-qPCR, as well as several physiological and cytological parameters. We found two up-regulated, and eight down-regulated miRNAs and thirty-six differentially expressed isomiRs along with an over-expression of Drosha, Adar and Zcchc11. A significant decrease of intratesticular estradiol but not testosterone was detected. Functional analysis showed altered spermatogenesis, germ cell apoptosis and negative correlation of miR-18a-5p with Nr1h2 involved in the deregulation of the steroidogenesis pathway. Here, we present the first association between miRNA/isomiRs deregulation, their mechanisms of biogenesis and histopathological and hormonal alterations in testes of adult mice exposed to a mixture of low-dose EDCs, which can play a role in male infertility.

MicroRNA-150 regulates steroidogenesis of mouse testicular Leydig cells by targeting STAR

Leydig cells are essential for male reproductive development throughout life. Production of androgens as well as intermediate steroids is tightly regulated. Although microRNAs (miRNAs) are suggested to play important roles in spermatogenesis, little is currently known regarding the regulation of steroidogenesis by miRNAs in Leydig cells. Here, we found that miR-150 was predominantly expressed in Leydig cells within mouse testis. Therefore, we determined steroidogenesis of the Leydig cells in which miR-150 was knocked down or overexpressed using miR-150 antagomir and agomir, respectively. Compared with negative control group, a significant increase of STAR expression was observed in miR-150 antagomir-treated Leydig cells. Conversely, STAR expression was significantly reduced in miR-150 agomir-transfected Leydig cells. Production of sex-steroid precursors and testosterone of Leydig cells was also negatively controlled by miR-150. We further identified Star as a target of miR-150 using luciferase reporter assay. Finally, we confirmed that miR-150 was necessary for steroidogenesis and spermatogenesis in vivo via intratesticular injection of miR-150 antagomir or agomir. Taken together, our studies suggest that miR-150 negatively regulates the expression of STAR and steroidogenesis of Leydig cells in mice.

The roles of microRNAs in regulation of mammalian spermatogenesis

Mammalian spermatogenesis contains three continuous and organized processes, by which spermatogonia undergo mitosis and differentiate to spermatocytes, follow on meiosis to form haploid spermatids and ultimately transform into spermatozoa. These processes require an accurately, spatially and temporally regulated gene expression patterns. The microRNAs are a novel class of post-transcriptional regulators. Cumulating evidences have demonstrated that microRNAs are expressed in a cell-specific or stage-specific manner during spermatogenesis. In this review, we focus on the roles of microRNAs in spermatogenesis. We highlight that N6-methyladenosine (m6A) is involved in the biogenesis of microRNAs and miRNA regulates the m6A modification on mRNA, and that specific miRNAs have been exploited as potential biomarkers for the male factor infertility, which will provide insightful understanding of microRNA roles in spermatogenesis.

The Role of Heat Shock Factors in Mammalian Spermatogenesis

Heat shock transcription factors (HSFs), as regulators of heat shock proteins (HSPs) expression, are well known for their cytoprotective functions during cellular stress. They also play important yet less recognized roles in gametogenesis. All HSF family members are expressed during mammalian spermatogenesis, mainly in spermatocytes and round spermatids which are characterized by extensive chromatin remodeling. Different HSFs could cooperate to maintain proper spermatogenesis. Cooperation of HSF1 and HSF2 is especially well established since their double knockout results in meiosis arrest, spermatocyte apoptosis, and male infertility. Both factors are also involved in the repackaging of the DNA during spermatid differentiation. They can form heterotrimers regulating the basal level of transcription of target genes. Moreover, HSF1/HSF2 interactions are lost in elevated temperatures which can impair the transcription of genes essential for spermatogenesis. In most mammals, spermatogenesis occurs a few degrees below the body temperature and spermatogenic cells are extremely heat-sensitive. Pro-survival pathways are not induced by heat stress (e.g., cryptorchidism) in meiotic and postmeiotic cells. Instead, male germ cells are actively eliminated by apoptosis, which prevents transition of the potentially damaged genetic material to the next generation. Such a response depends on the transcriptional activity of HSF1 which in contrary to most somatic cells, acts as a proapoptotic factor in spermatogenic cells. HSF1 activation could be the main trigger of impaired spermatogenesis related not only to elevated temperature but also to other stress conditions; therefore, HSF1 has been proposed to be the quality control factor in male germ cells.

Fluoride exposure changed the structure and the expressions of Y chromosome related genes in testes of mice

It is known that during spermatogenesis, pluripotent germ cells differentiate to become efficient delivery vehicles to the oocyte of paternal DNA, and the process is easily damaged by external poison. In this study, the effects of fluoride on the body weight, fluoride content in femur, testosterone levels in serum and testis, sperm quality, and the expressions of Y chromosome microdeletion genes and protein levels were examined in testes of Kunming male mice treated with different concentrations of 0, 25, 50, 100 mg/L of NaF in drinking water for 11 weeks, respectively. The results showed that compared with the control group, fluoride contents in three treatment groups were significantly increased and the structure of testes was seriously injured. The testosterone contents and the sperm count were decreased. Sperm malformation ratio was distinctly elevated. The expressions of Sly and HSF2 mRNA were markedly reduced in 100 mg/L NaF group and Ssty2 mRNA expression was dramatically decreased in 50 and 100 mg/L NaF groups. Meanwhile, the protein levels of Ssty2 and Sly were significantly reduced in 50 and 100 mg/L NaF groups and HSF2 protein levels were significantly decreased in 100 mg/L NaF group. These studies indicated that fluoride had toxic effects on male reproductive system by reducing the testosterone and sperm count, and increasing the sperm malformation ratio, supported by the damage of testicular structure, as a consequence of depressed HSF2 level, which resulted in the down-regulation of Ssty2 and Sly mRNA and protein.

The Role of the Membrane-Initiated Heat Shock Response in Cancer

The heat shock response (HSR) is a cellular response to diverse environmental and physiological stressors resulting in the induction of genes encoding molecular chaperones, proteases, and other proteins that are essential for protection and recovery from cellular damage. Since different perturbations cause accumulation of misfolded proteins, cells frequently encounter fluctuations in the environment which alter proteostasis. Since tumor cells use their natural adaptive mechanism of coping with stress and misfolded proteins, in recent years, the proteostasis network became a promising target for anti-tumor therapy. The membrane is the first to be affected by heat shock and therefore may be the first one to sense heat shock. The membrane also connects between the extracellular and the intracellular signals. Hence, there is a “cross talk” between the HSR and the membranes since heat shock can induce changes in the fluidity of membranes, leading to membrane lipid remodeling that occurs in several diseases such as cancer. During the last decade, a new possible therapy has emerged in which an external molecule is used that could induce membrane lipid re-organization. Since at the moment there are very few substances that regulate the HSR effectively, an alternative way has been searched to modulate chaperone activities through the plasma membrane. Recently, we suggested that the use of the membrane Transient Receptor Potential Vanilloid-1 (TRPV1) modulators regulated the HSR in cancer cells. However, the primary targets of the signal transduction pathway are yet un-known. This review provides an overview of the current literature regarding the role of HSR in membrane remodeling in cancer since a deep understanding of the membrane biology in cancer and the membrane heat sensing pathway is essential to design novel efficient therapies.

MicroRNA-224 regulates self-renewal of mouse spermatogonial stem cells via targeting DMRT1

MicroRNAs (miRs) play a key role in the control of gene expression in a wide array of tissue systems, where their functions include the regulation of self-renewal, cellular differentiation, proliferation and apoptosis. However, the function and mechanisms of individual miRs in regulating spermatogonial stem cell (SSC) homeostasis remain unclear. In the present study, we report for the first time that miR-224 is highly expressed in mouse SSCs. Functional assays using miRNA mimics and inhibitors reveal that miR-224 is essential for differentiation of SSCs. Mechanistically, miR-224 promotes differentiation of SSCs via targeting doublesex and Mab-3-related transcription factor 1 (DMRT1). Moreover, WNT/β-catenin signalling pathway is involved in miR-224-mediated regulation of SSCs self-renewal. We further demonstrate that miR-224 overexpression increases the expression of GFRα1 and PLZF, accompanied by the down-regulation of DMRT1 in mouse testes. Our findings provide novel insights into molecular mechanisms regulating differentiation of SSCs and may have important implications for regulating male reproduction.

MicroRNA expression in hepatocellular carcinoma after the eradication of chronic hepatitis virus C infection using interferon therapy

AIM

Hepatocellular carcinoma (HCC) develops in up to 5% of patients after the successful treatment of chronic hepatitis C virus (HCV) infection using interferon therapy. The aim of this study was to characterize miRNA expression in liver tissues from patients who achieved a sustained viral response (SVR).

METHODS

Seventy-one patients with resected HCC were enrolled into the present study: 61 HCC from patients with continuously infected HCV (HCV-HCC) and 10 from patients who had achieved SVR (SVR-HCC). We also included non-tumor tissues (SVR-NT) from four patients with SVR-HCC, and liver tissue (SVR-CH) from four SVR patients without HCC. Total RNA was extracted from liver samples. The miRNA expression patterns were analyzed using microarrays. In addition, target gene expression was quantified after miRNA overexpression in HEK293 cells.

RESULTS

We could discriminate between SVR-HCC and HCV-HCC with 75.36% accuracy using the expression pattern of six specific miRNA. The expression levels of 37 miRNA were significantly lower in HCV-HCC than in SVR-HCC, whereas the expression of 25 miRNA was significantly higher in HCV-HCC than SVR-HCC (P < 1.0E-05). The expression of thrombospondin 1 was regulated in an opposing manner by miR-30a-3p in SVR-HCC and HCV-HCC. In non-tumor tissues, the expression pattern of seven miRNA could distinguish between SVR-CH and SVR-NT with 87.50% accuracy.

CONCLUSION

Comprehensive miRNA expression analyses could not only differentiate between SVR-HCC and HCV-HCC but also forecast hepatocarcinogenesis after achieving SVR.