From Sperm Motility to Sperm-Borne microRNA Signatures: New Approaches to Predict Male Fertility Potential

Abstract

In addition to the paternal genome, spermatozoa carry several intrinsic factors, including organelles (e.g., centrioles and mitochondria) and molecules (e.g., proteins and RNAs), which are involved in important steps of reproductive biology such as spermatogenesis, sperm maturation, oocyte fertilization and embryo development. These factors constitute potential biomarkers of "viable sperm" and male fertility status and may become major assets for diagnosing instances of idiopathic male infertility in both humans and livestock animals. A better understanding of the mechanism of action of these sperm intrinsic factors in the regulation of reproductive and developmental processes still presents a major challenge that must be addressed. This review assembles the main data regarding morpho-functional and intrinsic sperm features that are associated with male infertility, with a particular focus on microRNA (miRNA) molecules.

A Combined Flow Cytometric Semen Analysis and miRNA Profiling as a Tool to Discriminate Between High- and Low-Fertility Bulls

“…Among the numerous variables evaluated, they found that only sperm motility traits and parameters related to chromatin structure are associated with field fertility, in agreement with our results, confirming that this model could be easily implemented in bull AI centers, which routinely evaluate sperm motility and may instruct external laboratories to assess DNA integrity. Recently, Alves et al ( 31 ) reviewed the important role of miRNAs in physiological processes related to spermatozoa biogenesis, maturation, oocyte fecundation, and embryo development.…”

Mitochondrial Reactive Oxygen Species (ROS) Production Alters Sperm Quality

“…In this regard, microRNAs (miRNAs), encoded by the nuclear or mitochondrial genome, have a dual role through the regulation of the nuclear genome, encoding mitochondria-related proteins, or translocating into the mitochondria in order to regulate mitochondrial genome expression [ 30 ]. MiRNAs might modulate sperm functions through mitochondria-dependent pathways; their aberrant expression in sperm of aging males has been correlated with poor semen quality caused by the suppression of the mitochondrial function and the reduction of ATP production [ 31 ]. Other small RNAs encoded by the mtDNA, overall known as mitosRNAs, have been recently discovered [ 32 ].…”

Cellular and Molecular Insights Into the Etiology of Subfertility/Infertility in Crossbred Bulls (Bos taurus × Bos indicus): A Review

“…paternal DNA (Alves et al, 2020). Although differences in opinion exist about the transcription and translation activities in spermatozoa, it was observed that paternal RNAs reside in the perinuclear theca of spermatozoa and are transferred during fertilization (Ostermeier et al, 2005).…”