Exploration of small RNA biomarkers for testicular injury in the serum exosomes of rats

Comprehensive analysis of differentially expressed mRNAs, circRNAs, and miRNAs and their ceRNA network in the testis of cattle-yak, yak, and cattle

Cattle-yak is a hybrid offspring resulting from the crossbreeding of yak and cattle, and it exhibits substantial heterosis in production performance. However, male sterility in cattle-yak remains a concern. Reports suggest that noncoding RNAs are involved in the regulation of spermatogenesis. Therefore, in this study, we comprehensively compared testicular transcription profiles among cattle, yak, and cattle-yak. Numerous differentially expressed genes (DEGs), differentially expressed circRNAs (DECs), and differentially expressed miRNAs (DEMs) were identified in the intersection of two comparison groups, namely cattle versus cattle-yak and yak versus cattle-yak, with the number of DEGs, DECs, and DEMs being 4968, 360, and 59, respectively. The DEGs in cattle-yaks, cattle, and yaks were mainly associated with spermatogenesis, male gamete generation, and sexual reproduction. Concurrently, GO and KEGG analyses indicated that DEC host genes and DEM source genes were involved in the regulation of spermatogenesis. The construction of a potential competing endogenous RNA network revealed that some differentially expressed noncoding RNAs may be involved in regulating the expression of genes related to testicular spermatogenesis, including miR-423-5p, miR-449b, miR-34b/c, and miR-15b, as well as previously unreported miR-6123 and miR-1306, along with various miRNA-circRNA interaction pairs. This study serves as a valuable reference for further investigations into the mechanisms underlying male sterility in cattle-yaks.

Potential Function of Testicular MicroRNAs in Heat-Stress-Induced Spermatogenesis Disorders

Spermatogenesis is temperature-dependent, and the increase in testicular temperature seriously affects mammalian spermatogenesis and semen quality. In this study, the testicular heat stress model of mice was made with a 43 °C water bath for 25 min, and the effects of heat stress on semen quality and spermatogenesis-related regulators were analyzed. On the 7th day after heat stress, testis weight shrank to 68.45% and sperm density dropped to 33.20%. High-throughput sequencing analysis showed that 98 microRNAs (miRNAs) and 369 mRNAs were down-regulated, while 77 miRNAs and 1424 mRNAs were up-regulated after heat stress. Through gene ontology (GO) analysis of differentially expressed genes and miRNA-mRNA co-expression networks, it was found that heat stress may be involved in the regulation of testicular atrophy and spermatogenesis disorders by affecting cell meiosis process and cell cycle. In addition, through functional enrichment analysis, co-expression regulatory network, correlation analysis and in vitro experiment, it was found that miR-143-3p may be a representative potential key regulatory factor affecting spermatogenesis under heat stress. In summary, our results enrich the understanding of miRNAs in testicular heat stress and provide a reference for the prevention and treatment of heat-stress-induced spermatogenesis disorders.

The emerging role of exosomes in the development of testicular

The mechanisms of testicular development in mammals are complex. Testis is an organ that produces sperm and secretes androgens. It is rich in exosomes and cytokines that mediate signal transduction between tubule germ cells and distal cells, promoting testicular development and spermatogenesis. Exosomes are nanoscale extracellular vesicles that transmit information between cells. By transmitting information, exosomes play an important role in male infertility diseases such as azoospermia, varicocele, and testicular torsion. However, due to the wide range of sources of exosomes, extraction methods are numerous and complex. Therefore, there are many difficulties in studying the mechanisms of exosomal effects on normal development and male infertility. Therefore, in this review, first, we introduce the formation of exosomes and methods for culturing testis and sperm. Then, we introduce the effects of exosomes on different stages of testicular development. Finally, we summarize the prospects and shortcomings of exosomes when used in clinical applications. We lay the theoretical foundation for the mechanism of the influence of exosomes on normal development and male infertility.

Altered transcriptomic and metabolomic profiles of testicular interstitial fluid during aging in mice

The testicular interstitial fluid (TIF) that bathes seminiferous tubules and testicular interstitial cells is the main microenvironment of the testis and involved in crosstalk between testicular cells. TIF also provides a new mean to investigate dysfunctional states of testis such as spermatogenic disorder and aging. In this study, we performed integrative omics analysis on the exosomal transcriptomics and liquid chromatography-tandem mass spectrometry (LC-MS/MS) based non-targeted metabolomics in TIF by comparison between 21-month-old and 3-month-old male mice. A total of 1627 genes were identified as aging-related differently expressed genes (DEGs) in mouse TIF exosomes, with 1139 downregulated and 488 upregulated. Functional and pathway analysis revealed that the DEGs were associated with oxidative stress, carbon metabolism, and systemic lupus erythematosus. By comparing the DEGs with the Aging Atlas Database, we screened out key aging-related genes functioning as oxidative stress regulators, and their expression pattern in human testis with age was confirmed by immunohistochemistry results in the Human Protein Atlas database. In addition, the metabolomic analysis identified mild differences between young and old groups with 28 downregulated differently expressed metabolites (DEMs) and 6 upregulated DEMs, in the negative ion mode, including decreased level of several antioxidant metabolites. The KEGG analysis demonstrated that 10 pathways were upregulated, while the pyrimidine metabolism pathway was downregulated in the aged mice TIF. Taken together, this study highlighted the prominent role of oxidative stress that contributed to the aging microenvironment in the TIF, and brought comprehensive transcriptomic and metabolomic perspectives for understanding the mechanism underlying the testicular aging.

Circulating microRNAs as promising testicular translatable safety biomarkers: current state and future perspectives

Drug-induced testicular injury (DITI) is one of the often-observed and challenging safety issues seen during drug development. Semen analysis and circulating hormones currently utilized have significant gaps in their ability to detect testicular damage accurately. In addition, no biomarkers enable a mechanistic understanding of the damage to the different regions of the testis, such as seminiferous tubules, Sertoli, and Leydig cells. MicroRNAs (miRNAs) are a class of non-coding RNAs that modulate gene expression post-transcriptionally and have been indicated to regulate a wide range of biological pathways. Circulating miRNAs can be measured in the body fluids due to tissue-specific cell injury/damage or toxicant exposure. Therefore, these circulating miRNAs have become attractive and promising non-invasive biomarkers for assessing drug-induced testicular injury, with several reports on their use as safety biomarkers for monitoring testicular damage in preclinical species. Leveraging emerging tools such as 'organs-on-chips' that can emulate the human organ's physiological environment and function is starting to enable biomarker discovery, validation, and clinical translation for regulatory qualification and implementation in drug development.

The emerging role of extracellular vesicles in the testis

Extracellular vesicles (EVs) are nano-sized membrane-bounded particles, released by all cells and capable of transporting bioactive cargoes, proteins, lipids, and nucleic acids, to regulate a variety of biological functions. Seminal plasma is enriched in EVs, and extensive evidence has revealed the role of EVs (e.g. prostasomes and epididymosomes) in the male genital tract. Recently, EVs released from testicular cells have been isolated and identified, and some new insights have been generated on their role in maintaining normal spermatogenesis and steroidogenesis in the testis. In the seminiferous tubules, Sertoli cell-derived EVs can promote the differentiation of spermatogonial stem cells (SSCs), and EVs secreted from undifferentiated A spermatogonia can inhibit the proliferation of SSCs. In the testicular interstitium, EVs have been identified in endothelial cells, macrophages, telocytes, and Leydig cells, although their roles are still elusive. Testicular EVs can also pass through the blood-testis barrier and mediate inter-compartment communication between the seminiferous tubules and the interstitium. Immature Sertoli cell-derived EVs can promote survival and suppress the steroidogenesis of Leydig cells. Exosomes isolated from macrophages can protect spermatogonia from radiation-induced injury. In addition to their role in intercellular communication, testicular EVs may also participate in the removal of aberrant proteins and the delivery of antigens for immune tolerance. EVs released from testicular cells can be detected in seminal plasma, which makes them potential biomarkers reflecting testicular function and disease status. The testicular EVs in seminal plasma may also affect the female reproductive tract to facilitate conception and may even affect early embryogenesis through modulating sperm RNA. EVs represent a new type of intercellular messenger in the testis. A detailed understanding of the role of testicular EV may contribute to the discovery of new mechanisms causing male infertility and enable the development of new diagnostic and therapeutic strategies for the treatment of infertile men.

The potential of sertoli cells (SCs) derived exosomes and its therapeutic efficacy in male reproductive disorders

In the male reproductive system, seminiferous tubules in testis are lined by a complex stratified epithelium containing two distinct populations of cells, spermatogenic cells that develop into spermatozoa, and sertoli cells (SCs) that mainly support and nourish spermatogenic cell lineage as well as exerting powerful effect on men reproductive capacity. Different varieties of proteins, hormones, exosomes and growth factors are secreted by SCs. There are different kinds of junctions found between SCs called BTB. It was elucidated that complete absence of BTB or its dysfunction leads to infertility. To promote spermatogenesis, crosstalk of SCs with spermatogenic cells plays an important role. The ability of SCs to support germ cell productivity and development is related to its various products carrying out several functions. Exosomes (EXOs) are one of the main EVs with 30-100 nm size generating from endocytic pathway. They are produced in different parts of male reproductive system including epididymis, prostate and SCs. The most prominent characteristics of SC-based exosomes is considered mutual interaction of sertoli cells with spermatogonial stem cells and Leydig cells mainly through establishment of intercellular communication. Exosomes have gotten a lot of interest because of their role in pathobiological processes and as a cell free therapy which led to developing multiple exosome isolation methods based on different principles. Transmission of nucleic acids, proteins, and growth factors via SC-based exosomes and exosomal miRNAs are proved to have potential to be valuable biomarkers in male reproductive disease. Among testicular abnormalities, non-obstructive azoospermia and testicular cancer have been more contributed with SCs performance. The identification of key proteins and miRNAs involved in the signaling pathways related with spermatogenesis, can serve as diagnostic and regenerative targets in male infertility.

Exosomes as Potential Biomarkers for Erectile Dysfunction, Varicocele, and Testicular Injury

INTRODUCTION

Optimal male reproductive health is dependent upon critical mediators of cell-cell communication: exosomes or extracellular vesicles. These vesicles are nano-sized particles released into a variety of bodily fluids, such as blood and semen. Exosomes are highly stable and can carry genetic and other molecules, including DNA, RNA, and proteins, which provide information about their origin cells.

OBJECTIVE

To identify exosomes as potential biomarkers or therapeutic mediators in male sexual and reproductive disorders like erectile dysfunction (ED), varicocele, and testicular injury.

METHODS

A PubMed search was performed to highlight all articles available relating to exosomes and extracellular vesicles in the pathogenesis of different male sexual and reproductive disorders, and their importance in clinical use as both diagnostic markers and potential therapeutic mediators.

RESULTS

Various male reproductive system disorders, such as ED, varicocele, and testicular injury, are linked to increased or decreased levels of exosomes. Exosomes have a higher number of molecules such as DNA, RNA, and proteins, which can give a more precise and comprehensive result when compared to other biomarkers. Exosomes can be considered as plausible diagnostic biomarkers for male sexual and reproductive diseases, with considerable advantages over other diagnostic procedures such as invasive tissue biopsy. Exosomes can carry cargo such certain drugs and therapeutic molecules making them a promising therapeutic approach. Several studies have begun to test treating various male sexual reproductive disorders with exosomes.

CONCLUSION

Exosomes deliver many components that can regulate gene expression and target signaling pathways. Understanding how extracellular vesicles can be utilized as biomarkers in diagnosing men, particularly those with idiopathic erectile dysfunction, will not only aid in diagnosis but also help with making therapeutic targets. Khodamoradi K, Golan R, Dullea A, et al. Exosomes as Potential Biomarkers for Erectile Dysfunction, Varicocele, and Testicular Injury. Sex Med Rev 2021;XX:XXX-XXX.