Down regulating PHGDH affects the lactate production of sertoli cells in varicocele

Abstract

Background: Although varicocele is considered to be one of the leading causes of male infertility, the precise mechanism underlying how varicocele leads to male infertility is not completely understood. We found the lactate concentration on the varicocele side of the patients was decreased compare with peripheral venous blood. In the testicles, the lactate produced by the sertoli cells through the glycolysis pathway provides most of the energy needed for spermatogenesis, the reduction of lactate will affect spermatogenesis. The objective of this study was to investigate the mechanism of this abnormal energy metabolism phenomenon in varicocele. Methods: In this study, we collected the testicular tissue from patients with varicocele, the glycolysis related proteins PHGDH was identified by iTRAQ proteomics technology. Experimental rat varicocele model was constructed according to our new clip technique, the mRNA and protein expression levels of PHGDH were examined with qRT-PCR and Western blotting. We constructed a sertoli cell of PHGDH down-regulation model, and then detected the glucose consumption, LDH activities and lactate production in the sertoli cells. Western blot was conducted to investigate the effects of PHGDH on the expression of phosphoserine phosphatase (PSPH) and Pyruvate kinase M2 (PKM2). Flow cytometry was used to detect the cell apoptosis and cell cycle in sertoli cells. Results: The results showed that testicular protein PHGDH was down-regulated in patients with varicocele and in experimental rat varicocele model. Down-regulation of PHGDH in sertoli cells significantly decreased the glucose consumption, LDH activities and lactate production in the sertoli cells, indicating that the low expression of PHGDH ultimately led to a decrease in lactate production by affecting the glycolysis. The Western blot results showed that the down-regulation of PHGDH significantly reduced the expression of pathway protein PSPH and PKM2, leading to the reduction of lactate production. Moreover, PHGDH knockdown can promote apoptosis and inhibit cell cycle to affect cell growth. Conclusions: Overall, we conformed that varicocele lead to the decreasing of testis lactate production. Downregulation of PHGDH in sertoli cells may mediate the process of abnormal glucose metabolism. Our study provide new insight into the mechanisms underlying metabolism-associated male infertility and suggests a novel therapeutic target for male infertility.

Yangjing capsule improves oligoasthenozoospermia by promoting nitric oxide production through PLCγ1/AKT/eNOS pathway

“…The western blot analysis was performed using a previously reported protocol ( Guo et al, 2020 ). Cells or tissues were disrupted in a RIPA buffer containing protease and phosphatase inhibitors.…”

Serine Metabolic Reprogramming in Tumorigenesis, Tumor Immunity, and Clinical Treatment

“…Serine affects downstream metabolic pathways in different ways, such as the SGOCP, TCA cycle, lactic acid, and lipid synthetic pathways [ 8 , 9 , 12 , 21 , 22 ]. The changes in these metabolic pathways are closely related to energy metabolism, macromolecular biosynthesis, redox state balance, epigenetic regulation, and other processes in tumor cells and tumor-associated cells.…”

“…Lactic acid in the tumor microenvironment (TME) is associated with diverse cellular processes, such as tumor angiogenesis, invasion, metastasis, macrophage polarization, and T-cell activation [ [80] , [81] , [82] ]. Low expression of PHGDH in Sertoli cells of varicocele patients can lead to reduced lactate production by affecting glycolysis [ 22 ]. Meanwhile, lactic acid can reduce the production of glucose-derived serine in proliferating T cells by consuming NAD + [ 83 ].…”

“…[ 17 ] found that PHGDH has relatively high activity in rat liver cancer tissues with a strong cell renewal ability and increased activity in neonatal and regenerating livers [ 18 ]. The activation of the PHGDH–phosphoserine aminotransferase 1 (PSAT1)–phosphoserine phosphatase (PSPH) pathway by several factors [eg, solute carrier family 2 member 5 (GLUT5), pyruvate kinase M2 (PKM2), activating transcription factor (ATF) 3/4, P53, and liver kinase B1 (LKB1)] promotes the synthesis of serine, which can direct the downstream serine glycine 1-carbon pathway (SGOCP), tricarboxylic acid cycle (TCA) pathway, and lactic acid and lipid synthetic pathways [ 8 , 9 , 12 , [18] , [19] , [20] , [21] , [22] ]. Moreover, various substances produced by serine catabolism not only can be raw materials for the synthesis of intracellular biomacromolecules but also can maintain the redox state of cells by producing surplus nicotinamide adenine dinucleotide (NADH) and support epigenetic changes [ 8 , 10 , 23 ].…”

Varicocoele‐associated male infertility: Cellular and molecular perspectives of pathophysiology

“…Varicocoele leads to low expression of PHGDH in Sertoli cells, which affects the glycolysis pathway; hence, there is decrease in lactate production. 197 In view of better understanding the pathophysiology of male infertility and also to develop new diagnostic and prognostic tools, efforts are being made toward utilizing various "omics" techniques.…”