Using microRNAs as molecular biomarkers for the evaluation of male infertility

Urinary biomarkers in diabetic nephropathy

Diabetic nephropathy (DN), a significant consequence of diabetes, is associated with adverse cardiovascular and renal disease as well as mortality. Although microalbuminuria is considered the best non-invasive marker for DN, better predictive markers are needed of sufficient sensitivity and specificity to detect disease in general and in early disease specifically. Even prior to appearance of microalbuminuria, urinary biomarkers increase in diabetics and can serve as accurate nephropathy biomarkers even in normoalbuminuria. In this review, a number of novel urine biomarkers including those reflecting kidney damage caused by glomerular/podocyte damage, tubular damage, oxidative stress, inflammation, and intrarenal renin-angiotensin system activation are discussed. Our review also includes emerging biomarkers such as urinary microRNAs. These short noncoding miRNAs regulate gene expression and could be utilized to identify potential novel biomarkers in DN development and progression. .

MicroRNAs in Male Fertility

Around 50% of all occurrences of infertility are attributable to the male factor, which is a significant global public health concern. There are numerous circumstances that might interfere with spermatogenesis and cause the body to produce abnormal sperm. While evaluating sperm, the count, the speed at which they migrate, and their appearance are the three primary characteristics that are analyzed. MicroRNAs, also known as miRNAs, are present in all physiological fluids and tissues. They participate in both physiological and pathological processes. Researches have demonstrated that the expression of microRNA genes differs in infertile men. These genes regulate spermatogenesis at various stages and in several male reproductive cells. Hence, microRNAs have the potential to act as useful indicators in the diagnosis and treatment of male infertility and other diseases affecting male reproduction. Despite this, additional research is necessary to determine the precise miRNA regulation mechanisms.

Morphological and Molecular Bases of Male Infertility: A Closer Look at Sperm Flagellum

Infertility is a major health problem worldwide without an effective therapy or cure. It is estimated to affect 8-12% of couples in the reproductive age group, equally affecting both genders. There is no single cause of infertility, and its knowledge is still far from complete, with about 30% of infertile couples having no cause identified (named idiopathic infertility). Among male causes of infertility, asthenozoospermia (i.e., reduced sperm motility) is one of the most observed, being estimated that more than 20% of infertile men have this condition. In recent years, many researchers have focused on possible factors leading to asthenozoospermia, revealing the existence of many cellular and molecular players. So far, more than 4000 genes are thought to be involved in sperm production and as regulators of different aspects of sperm development, maturation, and function, and all can potentially cause male infertility if mutated. In this review, we aim to give a brief overview of the typical sperm flagellum morphology and compile some of the most relevant information regarding the genetic factors involved in male infertility, with a focus on sperm immotility and on genes related to sperm flagellum development, structure, or function.

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.

Further Insights on RNA Expression and Sperm Motility

Asthenozoospermia is one of the main causes of male infertility and it is characterized by reduced sperm motility. Several mutations in genes that code for structural or functional constituents of the sperm have already been identified as known causes of asthenozoospermia. In contrast, the role of sperm RNA in regulating sperm motility is still not fully understood. Consequently, here we aim to contribute to the knowledge regarding the expression of sperm RNA, and ultimately, to provide further insights into its relationship with sperm motility. We investigated the expression of a group of mRNAs by using real-time PCR (CATSPER3, CFAP44, CRHR1, HIP1, IQCG KRT34, LRRC6, QRICH2, RSPH6A, SPATA33 and TEKT2) and the highest score corresponding to the target miRNA for each mRNA in asthenozoospermic and normozoospermic individuals. We observed a reduced expression of all mRNAs and miRNAs in asthenozoospermic patients compared to controls, with a more accentuated reduction in patients with progressive sperm motility lower than 15%. Our work provides further insights regarding the role of RNA in regulating sperm motility. Further studies are required to determine how these genes and their corresponding miRNA act regarding sperm motility, particularly KRT34 and CRHR1, which have not previously been seen to play a significant role in regulating sperm motility.

The gene regulatory role of non-coding RNAs in non-obstructive azoospermia

Non-coding RNAs are classified as small non-coding RNAs, long non-coding RNAs and circular RNAs, which are involved in a variety of biological processes, including cell differentiation, proliferation, apoptosis and pathological conditions of various diseases. Many studies have shown that non-coding RNAs are related to spermatogenesis, maturation, apoptosis, function, etc. In addition, the expression of non-coding RNAs in testicular tissue and semen of patients with non-obstructive azoospermia was different. However, the role of non-coding RNAs in the pathogenesis of non-obstructive azoospermia has not been fully elucidated, and the role of non-coding RNAs in non-obstructive azoospermia is rarely reviewed. Here we summarize the research progress of non-coding RNAs in the pathogenesis of non-obstructive azoospermia.