SRC family kinases in hamster spermatozoa: evidence for the presence of LCK

Cryopreservation, in addition to protein tyrosine phosphorylation, alters the distribution of phosphatidyl inositol bisphosphate and the localization of cytoskeletal and signaling proteins (gelsolin, tyrosine kinase c-SRC and phospholipase C-ζ) in the perinuclear theca of boar sperm

Cryopreservation of boar spermatozoa affects the perinuclear theca (PT) and involves several proteins and molecules that play important roles during capacitation and the acrosomal reaction. The objective of the present study was to evaluate whether the deleterious effects of cryopreservation in addition to protein tyrosine phosphorylation are accompanied by changes in the distribution of phosphatidyl inositol bisphosphate (PIP2) and the localization of cytoskeletal and signaling proteins in the perinuclear theca of cryopreserved boar spermatozoa. For this purpose, by immunocytochemistry (IC) the changes in localization of phosphorylated proteins in tyrosine residues, gelsolin, c-SRC kinase and PLC-ζ, as well as in the distribution of phosphatidyl inositol bisphosphate were analyzed in thawed spermatozoa (T) non capacitated (NC), capacitated (C) and in those with acrosomal reaction (AR) and compared with fresh spermatozoa (F) under the same physiological status. Western blotting (WB) and co-immunoprecipitation were performed to confirm the presence of these proteins in PT and to determine the interaction between these molecules. IC showed that immunostaining for phosphorylated proteins significantly increased in the acrosomal region and flagellum in TNC spermatozoa (p < 0.05). The proportion of cells displaying immunolabeling for gelsolin in the acrosomal region decreased after capacitation in cryopreserved spermatozoa; the same change was found (p < 0.05) in the proportion of spermatozoa immunoreactive to PIP2 in the sperm head. c-SRC was observed in the equatorial segment and acrosomal region, subdomains that coincide with the site where phosphorylated proteins were detected. PLC-ζ immunolocalization in fresh spermatozoa underwent changes after capacitation and acrosomal reaction, with a significant increase in the equatorial segment and post-acrosomal region in cryopreserved spermatozoa (p < 0.05). WB analysis indicated the presence of gelsolin, c-SRC and PLC-ζ in PT; besides, we confirmed that gelsolin co-immunoprecipitated with c-SRC and PLC-ζ, which changes according to the physiological state of spermatozoa. As a conclusion, cryopreservation together with increased immunodetection of tyrosine phosphorylated proteins decreases the detection of PIP2 and alters the immunolocalization patterns of gelsolin, c-SRC and PLC-ζ in the PT in boar spermatozoa.

Src family kinases-mediated negative regulation of sperm acrosome reaction in chickens (Gallus gallus domesticus)

The acrosome reaction (AR) is a strictly-regulated, synchronous exocytosis that is required for sperm to penetrate ova. This all-or-nothing process occurs only once in the sperm lifecycle through a sequence of signaling pathways. Spontaneous, premature AR therefore compromises fertilization potential. Although protein kinase A (PKA) pathways play a central role in AR across species, the signaling network used for AR induction is poorly understood in birds. Mechanistic studies of mammalian sperm AR demonstrate that PKA activity is downstreamly regulated by Src family kinases (SFKs). Using SFK inhibitors, our study shows that in chicken sperm, SFKs play a role in the regulation of PKA activity and spontaneous AR without affecting motility. Furthermore, we examined the nature of SFK phosphorylation using PKA and protein tyrosine phosphatase inhibitors, which demonstrated that unlike in mammals, SFK phosphorylation in birds does not occur downstream of PKA and is primarily regulated by calcium-dependent tyrosine phosphatase activity. Functional characterization of SFKs in chicken sperm showed that SFK activation modulates the membrane potential and plays a role in inhibiting spontaneous AR. Employing biochemical isolation, we also found that membrane rafts are involved in the regulation of SFK phosphorylation. This study demonstrates a unique mechanism for regulating AR induction inherent to avian sperm that ensure fertilization potential despite prolonged storage.

Target Identification of Active Constituents of Shen Qi Wan to Treat Kidney Yang Deficiency Using Computational Target Fishing and Network Pharmacology

Background: Kidney yang deficiency syndrome (KYDS) is one of the most common syndromes treated with traditional Chinese medicine (TCM) among elderly patients. Shen Qi Wan (SQW) has been effectively used in treating various diseases associated with KYDS for hundreds of years. However, due to the complex composition of SQW, the mechanism of action remains unknown.

Purpose: To identify the mechanism of the SQW in the treatment of KYDS and determine the molecular targets of SQW.

Methods: The potential targets of active ingredients in SQW were predicted using PharmMapper. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were carried out using the Molecule Annotation System (MAS3.0). The protein–protein interaction (PPI) network of these potential targets and “components-targets-pathways” interaction networks were constructed using Cytoscape. We also established a KYDS rat model induced by adenine to investigate the therapeutic effects of SQW. Body weight, rectal temperature, holding power, water intake, urinary output, blood urea nitrogen (BUN), serum creatinine (Scr), adrenocorticotrophic hormone (ACTH), cortisol (CORT), urine total protein (U-TP), and 17-hydroxy-corticosteroid (17-OHCS) were measured. Additionally, the mRNA expression levels of candidates were detected by qPCR.

Results: KYDS-caused changes in body weight, rectal temperature, holding power, water intake, urinary output, BUN, Scr, ACTH, CORT, U-TP, and 17-OHCS were corrected to the baseline values after SQW treatment. We selected the top 10 targets of each component and obtained 79 potential targets, which were mainly enriched in the proteolysis, protein binding, transferase activity, T cell receptor signaling pathway, and focal adhesion. SRC, MAPK14, HRAS, HSP90AA1, F2, LCK, CDK2, and MMP9 were identified as targets of SQW in the treatment of KYDS. The administration of SQW significantly suppressed the expression of SRC, HSP90AA1, LCK, and CDK2 and markedly increased the expression of MAPK14, MMP9, and F2. However, HRAS levels remained unchanged.

Conclusion: These findings demonstrated that SQW corrected hypothalamic–pituitary–target gland axis disorder in rats caused by KYDS. SRC, MAPK14, HRAS, HSP90AA1, F2, LCK, CDK2, and MMP9 were determined to the therapeutic target for the further investigation of SQW to ameliorate KYDS.

Emerging role for SRC family kinases in junction dynamics during spermatogenesis

SRC family kinases (SFKs) are known regulators of multiple cellular events, including cell movement, differentiation, proliferation, survival and apoptosis. SFKs are expressed virtually by all mammalian cells. They are non-receptor protein kinases that phosphorylate a variety of cellular proteins on tyrosine, leading to the activation of protein targets in response to environmental stimuli. Among SFKs, SRC, YES and FYN are the ubiquitously expressed and best studied members. In fact, SRC, the prototypical SFK, was the first tyrosine kinase identified in mammalian cells. Studies have shown that SFKs are regulators of cell junctions, and function in endocytosis and membrane trafficking to regulate junction restructuring events. Herein, we briefly summarize the recent findings in the field regarding the role of SFKs in the testis in regulating spermatogenesis, particularly in Sertoli-Sertoli and Sertoli-germ cell adhesion. While it is almost 50 years since the identification of the oncogene v-Src encoded by Rous sarcoma transforming virus, the understanding of SFK involvement during spermatogenesis in the testis remains far behind that in other epithelia and tissues. The goal of this review is to bridge this gap.