TNF-α/ENO1 signaling facilitates testicular phagocytosis by directly activating Elmo1 gene expression in mouse Sertoli cells

STUB1 directs FOXQ1-mediated transactivation of Ldha gene and facilitates lactate production in mouse Sertoli cells

Sertoli cells (SCs) preferentially use glucose to convert to lactate. As an energy source, lactate is essential for survival of developed germ cells (GCs) due to its anti-apoptotic effect. Failure to maintain lactate metabolism homeostasis leads to infertility or germ cell apoptosis. Several Sertoli cell-expressed genes, such as Foxq1 and Gata4, have been identified as critical regulators for lactate synthesis, but the pathways that potentially modulate their expression remain ill defined. Although recent work from our collaborators pointed to an involvement of STIP1 homology and U-box-containing protein 1 (STUB1) in the modulation of Sertoli cell response to GCs-derived IL-1α, a true physiological function of STUB1 signaling in SCs has not been demonstrated. We therefore conditionally ablated Stub1 in SCs using Amh-Cre. Stub1 knockout males exhibited impaired fertility due to oligozoospermia and asthenospermia, possibly caused by lactate deficiency. Furthermore, by means of chromatin immunoprecipitation, in vivo ubiquitination, and luciferase reporter assays, we showed that STUB1 directed forkhead box Q1 (FOXQ1)-mediated transactivation of the lactate dehydrogenase A (Ldha) gene via K63-linked non-proteolytic polyubiquitination, thus facilitating lactate production in follicle-stimulating hormone (FSH)-stimulated SCs. In agreement, overexpression of LDHA by lentivirus infection effectively rescued the lactate production in TM4Stub1-/- cells. Our results collectively identify STUB1-mediated transactivation of FOXQ1 signaling as a post-translationally modified transcriptional regulatory network underlying nursery function in SCs, which may nutritionally contribute to Sertoli cell dysfunction of male infertility.

A comparative proteomic study of high and low semen quality seminal plasma in drakes

Semen quality is the most important indicator in evaluating drake fecundity. At present, the low semen quality has become a major factor restricting the development of artificial insemination (AI) technology in ducks. Numerous studies have indicated that seminal plasma proteins play a crucial role in semen quality, but the mechanism of seminal plasma proteins regulating semen quality of drakes remains unclear. Thus, the objective of this study was to identify seminal plasma proteins associated with semen quality by comparing the seminal plasma proteomic profile of drakes with high-quality semen (HQS) and low-quality semen (LQS). Using a label-free MS-based method, a total of 745 seminal plasma proteins were identified. Of these, 55 differentially expressed proteins (DEPs) were identified (40 up-regulated and 15 down-regulated). Gene Ontology (GO) analysis showed that the DEPs were mainly enriched in transmembrane transport, extracellular matrix structural constituent, transferase activity, transferring acyl groups other than amino-acyl groups, transmembrane transporter activity, and integral component of membrane (P < 0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis indicated that the DEPs were significantly enriched in apoptosis, tyrosine metabolism, glycerophospholipid metabolism, and sulfur metabolism pathways (P < 0.05). Moreover, through protein-protein interaction (PPI) network analysis, eight potential candidate proteins were identified, including P19140 (Alpha-enolase), R0KUV7 (Calreticulin), R0K3X3 (Solute carrier family 2, facilitated glucose transporter member 5), R0L6V0 (Proteasome subunit beta), R0JKW0 (Cytochrome c), R0JMC5 (Tubulin alpha chain), R0LCK1 (Cathepsin C), and R0JUP6 (Cathepsin D), which could play crucial roles in semen quality. Notably, further analysis demonstrated that key protein P19140 (Alpha-enolase) might can control the semen quality of drakes by regulating the expression of proteins related to apoptosis pathway. This study is the first systematically comparing the seminal plasma proteome of drakes exhibiting high and low semen quality. These results provide novel insights into the mechanisms regulating semen quality of drakes.