Negative biomarker based male fertility evaluation: Sperm phenotypes associated with molecular-level anomalies

Abstract

Biomarker-based sperm analysis elevates the treatment of human infertility and ameliorates reproductive performance in livestock. The negative biomarker-based approach focuses on proteins and ligands unique to defective spermatozoa, regardless of their morphological phenotype, lending itself to analysis by flow cytometry (FC). A prime example is the spermatid specific thioredoxin SPTRX3/TXNDC8, retained in the nuclear vacuoles and superfluous cytoplasm of defective human spermatozoa. Infertile couples with high semen SPTRX3 are less likely to conceive by assisted reproductive therapies (ART) and more prone to recurrent miscarriage while low SPTRX3 has been associated with multiple ART births. Ubiquitin, a small, proteolysis-promoting covalent posttranslational protein modifier is found on the surface of defective posttesticular spermatozoa and in the damaged protein aggregates, the aggresomes of spermiogenic origin. Semen ubiquitin content correlates negatively with fertility and conventional semen parameters, and with sperm binding of lectins LCA (Lens culinaris agglutinin; reveals altered sperm surface) and PNA (Arachis hypogaea/peanut agglutinin; reveals acrosomal malformation or damage). The Postacrosomal Sheath WWI Domain Binding Protein (PAWP), implicated in oocyte activation during fertilization, is ectopic or absent from defective human and animal spermatozoa. Consequently, FC-parameters of PAWP correlate with ART outcomes in infertile couples and with fertility in bulls. Assays based on the above biomarkers have been combined into multiplex FC semen screening protocols, and the surface expression of lectins and ubiquitin has been utilized to develop nanoparticle-based bull semen purification method validated by field artificial insemination trials. These advances go hand-in-hand with the innovation of FC-technology and genomics/proteomics-based biomarker discovery.

Cryopreservation of fluorescence activated cell sorted boar spermatozoa based on extracellular ubiquitination

“…Muratori et al (2005) and Varum et al (2007) reported the opposite results. These discrepancies could be explained either by hypo-functionality of ubiquitin-based spermatozoa selection and degradation in epididymis (Eskandari-Shahraki et al 2013) or by detection of ubiquitinated proteins, albeit not those on the sperm surface, that are intrinsic to normal spermatozoa (Sutovsky et al 2015).…”

Flow cytometry in Spermatology: A bright future ahead

“…These factors permit the spermatozoon to penetrate extracellular matrix barriers containing hyaluronic acid (Modelski et al., ). Other proteins detected using flow cytometry that are potential sperm biomarkers include a truncated form of KIT tyrosine kinase (Muciaccia et al., ), the spermatic specific thioredoxin‐3 protein (SPTRX‐3) (Buckman et al., ) other thioredoxins, peroxiredoxins, ubiquitin and ubiquitin‐like modifier proteins (Sutovsky, Aarabi, Miranda‐Vizuete, & Oko, ). Nuclear proteins have also been investigated using flow cytometry (Zhong et al., ).…”

Zeta method: A noninvasive method based on membrane charge for selecting spermatozoa expressing high level of phospholipaseCζ

“…Following this fusion, sperm factor(s) is released into the ooplasm to hydrolyse phosphatidylinositol 4, 5‐biphosphate (PIP 2 ) into the diacylglycerol (DAG) and inositol triphosphate (IP 3 ). Then, IP 3 binds to its receptors located in the calcium intracellular store membrane to release calcium from ooplasmatic store to initiate oocyte activation which consequently leads to resumption of meiosis, progressive of metaphase to anaphase and early embryonic development (Sutovsky, Aarabi, Miranda‐Vizuete, & Oko, ; Swann & Lai, ; Yeste, Jones, Amdani, Patel, & Coward, ). So far, several sperm factors involved in oocyte activation are suggested.…”