Comparison of proteomic profiles from the testicular tissue of males with impaired and normal spermatogenesis

Exploring the impact of lipid stress on sperm cytoskeleton: insights and prospects

The decline in male fertility correlates with the global rise in obesity and dyslipidaemia, representing significant public health challenges. High-fat diets induce metabolic alterations, including hypercholesterolaemia, hepatic steatosis and atherosclerosis, with detrimental effects on testicular function. Testicular tissue, critically dependent on lipids for steroidogenesis, is particularly vulnerable to these metabolic disruptions. Excessive lipid accumulation within the testes, including cholesterol, triglycerides and specific fatty acids, disrupts essential sperm production processes such as membrane formation, maturation, energy metabolism and cell signalling. This leads to apoptosis, impaired spermatogenesis, and abnormal sperm morphology and function, ultimately compromising male fertility. During spermiogenesis, round spermatids undergo extensive reorganization, including the formation of the acrosome, manchette and specialized filamentous structures, which are essential for defining the final sperm cell shape. In this Perspective, we examine the impact of high-fat diets on the cytoskeleton of spermatogenic cells and its consequences to identify the mechanisms underlying male infertility associated with dyslipidaemia. Understanding these processes may facilitate the development of therapeutic strategies, such as dietary interventions or natural product supplementation, that aim to address infertility in men with obesity and hypercholesterolaemia. The investigation of cytoskeleton response to lipid stress extends beyond male reproduction, offering insights with broader implications.

L(1)10Bb serves as a conservative determinant for soma-germline communications via cellular non-autonomous effects within the testicular stem cell niche

The testicular stem cell niche is the central regulator of spermatogenesis in Drosophila melanogaster. However, the underlying regulatory mechanisms are unclear. This study demonstrated the crucial role of lethal (1) 10Bb [l(1)10Bb] in regulating the testicular stem cell niche. Dysfunction of l(1)10Bb in early-stage cyst cells led to male fertility disorders and compromised cyst stem cell maintenance. Moreover, the dysfunction of l(1)10Bb in early-stage cyst cells exerted non-autonomous effects on germline stem cell differentiation, independently of hub signals. Notably, our study highlights the rescue of testicular defects through ectopic expression of L(1)10Bb and the human homologous protein BUD31 homolog (BUD31). In addition, l(1)10Bb dysfunction in early-stage cyst cells downregulated the expression of spliceosome subunits in the Sm and the precursor RNA processing complexes. Collectively, our findings established l(1)10Bb as a pivotal factor in the modulation of Drosophila soma-germline communications within the testicular stem cell niche.

Deficiency of IQCH causes male infertility in humans and mice

IQ motif-containing proteins can be recognized by calmodulin (CaM) and are essential for many biological processes. However, the role of IQ motif-containing proteins in spermatogenesis is largely unknown. In this study, we identified a loss-of-function mutation in the novel gene IQ motif-containing H (IQCH) in a Chinese family with male infertility characterized by a cracked flagellar axoneme and abnormal mitochondrial structure. To verify the function of IQCH, Iqch knockout (KO) mice were generated via CRISPR-Cas9 technology. As expected, the Iqch KO male mice exhibited impaired fertility, which was related to deficient acrosome activity and abnormal structures of the axoneme and mitochondria, mirroring the patient phenotypes. Mechanistically, IQCH can bind to CaM and subsequently regulate the expression of RNA-binding proteins (especially HNRPAB), which are indispensable for spermatogenesis. Overall, this study revealed the function of IQCH, expanded the role of IQ motif-containing proteins in reproductive processes, and provided important guidance for genetic counseling and genetic diagnosis of male infertility.

Comparative Transcriptomic Analyses for the Optimization of Thawing Regimes during Conventional Cryopreservation of Mature and Immature Human Testicular Tissue

Cryopreservation of human testicular tissue, as a key element of anticancer therapy, includes the following stages: saturation with cryoprotectants, freezing, thawing, and removal of cryoprotectants. According to the point of view existing in "classical" cryobiology, the thawing mode is the most important consideration in the entire process of cryopreservation of any type of cells, including cells of testicular tissue. The existing postulate in cryobiology states that any frozen types of cells must be thawed as quickly as possible. The technologically maximum possible thawing temperature is 100 °C, which is used in our technology for the cryopreservation of testicular tissue. However, there are other points of view on the rate of cell thawing, according to how thawing should be carried out at physiological temperatures. In fact, there are morphological and functional differences between immature (from prepubertal patients) and mature testicular tissue. Accordingly, the question of the influence of thawing temperature on both types of tissues is relevant. The purpose of this study is to explore the transcriptomic differences of cryopreserved mature and immature testicular tissue subjected to different thawing methods by RNA sequencing. Collected and frozen testicular tissue samples were divided into four groups: quickly (in boiling water at 100 °C) thawed cryopreserved mature testicular tissue (group 1), slowly (by a physiological temperature of 37 °C) thawed mature testicular tissue (group 2), quickly thawed immature testicular tissue (group 3), and slowly thawed immature testicular tissue (group 4). Transcriptomic differences were assessed using differentially expressed genes (DEG), the Kyoto Encyclopedia of Genes and Genomes (KEGG), gene ontology (GO), and protein-protein interaction (PPI) analyses. No fundamental differences in the quality of cells of mature and immature testicular tissue after cryopreservation were found. Generally, thawing of mature and immature testicular tissue was more effective at 100 °C. The greatest difference in the intensity of gene expression was observed in ribosomes of cells thawed at 100 °C in comparison with cells thawed at 37 °C. In conclusion, an elevated speed of thawing is beneficial for frozen testicular tissue.

Studying the effect of hyperoside on recovery from cyclophosphamide induced oligoasthenozoospermia

Oligoasthenozoospermia is becoming a serious problem, but effective prevention or treatment is lacking. Hyperoside, one of the main active ingredients in traditional Chinese medicine, may be effective in the treatment of oligoasthenozoospermia. In this study, we used cyclophosphamide (CTX: 50 mg/kg) to establish a mouse model of Oligoasthenozoospermia to investigate the therapeutic effect of hyperoside (30 mg/kg) on CTX-induced oligoasthenozoospermia. All mice were divided into four groups: blank control group (Control), treatment control group (Hyp), disease group (CTX) and treatment group (CTX + H). Mice body weight, testicular weight, sperm parameters and testicular histology were used to assess the reproductive capacity of mice and to explore the underlying mechanism of hyperoside in the treatment of oligoasthenozoospermia by assessing hormone levels, protein levels of molecules related to hormone synthesis and transcript levels of important genes related to spermatogenesis. Treatment with hyperoside significantly improved sperm density, sperm viability and testicular function compared to untreated oligoasthenozoospermia mice. In mechanism, treatment with hyperoside resulted in significant improvement in pathological changes in spermatogenic tubules, with an increase in testosterone production, and upregulations of Protein Kinase CAMP-Activated Catalytic Subunit Beta (PRKACB), Steroidogenic Acute Regulatory Protein (STAR), and Cytochrome P450 Family 17 Subfamily A Member 1 (CYP17A1) for testosterone production. Hyperoside also promoted the cell cycle of germ cells and up-regulated meiosis and spermatogenesis-related genes, including DNA Meiotic Recombinase 1 (Dmc1), Ataxia telangiectasia mutated (Atm) and RAD21 Cohesin Complex Component (Rad21). In conclusion, hyperoside exerted protective effects on oligoasthenozoospermia mice by regulating testosterone production, meiosis and sperm maturation of germ cells.

iTRAQ-based proteomic analysis provides novel insight into the postnatal testicular development of Hu sheep

Testicular development is an intricate and coordinated process in which thousands of proteins are involved in the regulation of somatic cells development and spermatogenesis. However, knowledge about the proteomic changes during postnatal testicular development in Hu sheep is still elusive. The study was conducted to characterize the protein profiles at four key stages during postnatal testicular development, including infant (0-month-old, M0), puberty (3-month-old, M3), sexual maturity (6-month-old, M6) and body maturity (12-month-old, M12), and between the large- and small-testis groups at 6 months in Hu sheep. Consequently, 5252 proteins were identified using isobaric tags for relative and absolute quantification (iTRAQ) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods, and 465, 1261, 231 and 1080 differentially abundant proteins (DAPs) were found between M0_vs_M3, M3_vs_M6L, M6L_vs_M12, and M6L_vs_M6S, respectively. GO and KEGG analysis revealed that the majority of DAPs were involved in cellular process, metabolic process and immune system-related pathways. Furthermore, a protein-protein interaction network was constructed using 86 fertility-related DAPs, and five proteins with the highest degree were represented as hub proteins, including CTNNB1, ADAM2, ACR, HSPA2 and GRB2. This study provided new insights into the regulation mechanisms of postnatal testicular development and identified several potential biomarkers for selecting the high-fertility rams. SIGNIFICANCE OF THE STUDY: Testicular development is an intricate developmental process in which thousands of proteins are involved in regulating the somatic cells development and spermatogenesis. However, knowledge about the proteome changes during postnatal testicular development in Hu sheep is still elusive. This study provides comprehensive insights into the dynamic changes in the sheep testis proteome during postnatal testicular development. Additionally, testis size is positively correlated with semen quality and ejaculation volume, also for the merits of easy measurement, high heritability and selection efficiency, is an important indicator to select candidate rams with high fertility. The functional analyses of the acquired candidate proteins may help us gain a better understanding of the molecular regulatory mechanisms of testicular development.

Identification and validation of CCL2 as a potential biomarker relevant to mast cell infiltration in the testicular immune microenvironment of spermatogenic dysfunction

BACKGROUND

Spermatogenic dysfunction is an important cause of azoospermia. Numerous studies have focused on germ-cell-related genes that lead to spermatogenic impairment. However, based on the immune-privileged characteristics of the testis, the relationship of immune genes, immune cells or immune microenvironment with spermatogenic dysfunction has rarely been reported.

RESULTS

Using integrated methods including single-cell RNA-seq, microarray data, clinical data analyses and histological/pathological staining, we found that testicular mast cell infiltration levels were significantly negatively related to spermatogenic function. We next identified a functional testicular immune biomarker, CCL2, and externally validated that testicular CCL2 was significantly upregulated in spermatogenic dysfunctional testes and was negatively correlated with Johnsen scores (JS) and testicular volumes. We also demonstrated that CCL2 levels showed a significant positive correlation with testicular mast cell infiltration levels. Moreover, we showed myoid cells and Leydig cells were two of the important sources of testicular CCL2 in spermatogenic dysfunction. Mechanistically, we drew a potential "myoid/Leydig cells-CCL2-ACKR1-endothelial cells-SELE-CD44-mast cells" network of somatic cell-cell communications in the testicular microenvironment, which might play roles in spermatogenic dysfunction.

CONCLUSIONS

The present study revealed CCL2-relevant changes in the testicular immune microenvironment in spermatogenic dysfunction, providing new evidence for the role of immunological factors in azoospermia.

iTRAQ-based comparative proteomics reveal an enhancing role of PRDX6 in the freezability of Mediterranean buffalo sperm

BACKGROUND

Semen cryopreservation is a critical tool for breed improvement and preservation of biodiversity. However, instability of sperm freezability affects its application. The Mediterranean buffalo is one of the river-type buffaloes with the capacity for high milk production. Until now, there is no specific cryopreservation system for Mediterranean buffalo, which influences the promotion of excellent cultivars. To improve the semen freezing extender used in cryopreservation of Mediterranean buffalo, different protein datasets relating to freezability sperm were analyzed by iTRAQ-based proteomics. This study will be beneficial for further understanding the sperm freezability mechanism and developing new cryopreservation strategy for buffalo semen.

RESULTS

2652 quantified proteins were identified, including 248 significantly differentially expressed proteins (DEP). Gene Ontology (GO) analysis indicated that many these were mitochondrial proteins, enriched in the molecular function of phospholipase A2 activity and enzyme binding, and biological processes of regulation of protein kinase A signaling and motile cilium assembly. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis identified 17 significant pathways, including oxidative phosphorylation (OXPHOS). Furthermore, 7 DEPs were verified using parallel reaction monitoring or western blot, which confirmed the accuracy of the iTRAQ data. Peroxiredoxin 6 (PRDX6), which expressed 1.72-fold higher in good freezability ejaculate (GFE) compared to poor freezability ejaculate (PFE) sperms, was selected to explore the function in sperm freezability by adding recombinant PRDX6 protein into the semen freezing extender. The results showed that the motility, mitochondrial function and in vitro fertilization capacity of frozen-thawed sperm were significantly increased, while the oxidation level was significantly decreased when 0.1 mg/L PRDX6 was added compared with blank control.

CONCLUSIONS

Above results revealed the metabolic pattern of freezability of Mediterranean buffalo sperms was negatively associated with OXPHOS, and PRDX6 had protective effect on cryo-damage of frozen-thawed sperms.

Two-Dye Versus Three-Dye DIGE for Comparative Testis Tissue Proteomic Analysis

The global analysis of the proteome is an important tool in cell biology. Comparative proteomic evaluations can identify and compare the composition, dynamics, and modifications between different samples. Comparing tissue proteomes under different conditions is crucial for advancing the biomedical field. Fluorescence two-dimensional difference gel electrophoresis (2D-DIGE) is a sensitive and robust biochemical method that can compare multiple protein samples over a broad dynamic range on the same analytical gel and can be used to establish differentially expressed protein profiles between different sample groups. 2D-DIGE involves fluorescently labeling protein samples with CyDye flours, via a two-dye or a three-dye system, pre-separation by isoelectric point, and molecular weight. DIGE circumvents gel-to-gel variability by multiplexing samples to a single gel and through the use of a pooled internal standard for normalization, thus enabling accurate high-resolution analysis of differences in protein abundance between samples. This chapter discusses 2D-DIGE as a comparative tissue proteomic technique and describes in detail the experimental steps required for comparative proteomic analysis employing both options of two-dye and three-dye DIGE minimal labeling.