Epidermal Growth Factor Regulates Glucose Metabolism Through Lactate Dehydrogenase A Messenger Ribonucleic Acid Expression in Cultured Porcine Sertoli Cells1

Abstract

In a previous work, we reported that lactate dehydrogenase A4 (LDH A4) activity is a key step in the stimulatory effect of epidermal growth factor (EGF) on lactate production in cultured Sertoli cells. Here, we further investigated the regulatory mechanisms involved in EGF action on LDH A mRNA expression. Steady-state levels of LDH A mRNA analyzed by Northern blot hybridization were induced to 2. 9-fold in response to a 36-h incubation with EGF (ED(50) = 4 ng/ml, 0.63 x 10(-9) M). Whether EGF-induced increases of LDH A mRNA levels are the result of increased transcription and/or altered mRNA stability was investigated. The decay curves for the 1.5-kilobase LDH A mRNA transcript in Sertoli cells were not different in the absence or presence of EGF, suggesting that EGF did not affect LDH A mRNA stability. Inhibitors of protein synthesis (cycloheximide) and RNA synthesis (actinomycin D, and 5,6-dichloro-1-beta-ribofuranosyl benzimidazole) completely abrogated the EGF-induced LDH A mRNA expression, indicating that EGF increased LDH A mRNA levels through a transcriptional mechanism, which probably involves protein synthesis. Finally, the partial inhibitory effect of a protein kinase C (PKC) inhibitor, bisindolylmaleimide, on EGF-stimulated LDH A mRNA supports a partial involvement of PKC in the action of the growth factor. Since EGF is produced in Sertoli and in germ cells, its action is probably exerted in a context of a local control. As EGF also regulates other parameters involved in glucose metabolism, its effect on LDH A might be viewed in a general context related to the control of energy metabolism by the growth factor in the testicular cells.

Regulation of lactate production and glucose transport as well as of glucose transporter 1 and lactate dehydrogenase A mRNA levels by basic fibroblast growth factor in rat Sertoli cells

“…In rat Sertoli cells, variations in LDH activity and in the distribution profile of isozymes are accompanied by an increment in ldh a gene expression after FSH and IL1 treatments (Riera et al 2001). On the other hand, similar results were obtained in porcine Sertoli cells after EGF (Boussouar & Benahmed 1999), IL1 (Nehar et al 1998) and TNF treatments (Nehar et al 1997). The present study shows that bFGF increases LDH activity and the levels of mRNA for the LDH A subunit, suggesting that the LDH isoenzyme system is another potential site of action for bFGF.…”

“…Facilitated Sertoli cell glucose transport across plasma membrane is mediated by the carrier protein termed glucose transporter 1 (GLUT1), the only glucose transporter so far demonstrated in this cell (Ulisse et al 1992). As for the LDH isoenzyme system, increments in lactate production in Sertoli cells have been correlated with an increase in the LDH5 isoenzyme -containing four subunits A. Glucose transport through the plasma membrane and LDH A mRNA levels are regulated in a distinct manner by FSH (Riera et al 2001), interleukin 1 (IL1) (Nehar et al 1998), tumor necrosis factor-(TNF ) (Nehar et al 1997) and epidermal growth factor (EGF) (Boussouar & Benahmed 1999) -factors that modify Sertoli cell lactate production. No data are available on the mechanisms involved in the recently described effect of bFGF on lactate production (Schteingart et al 1999).…”

Evaluation of LDH Activity and Its Relationship with Fructose Levels in Seminal Plasma of Normospermic and Asthenospermic Males

“…Grootegoed et al showed the conversion of glucose to lactate by Sertoli cells (27). This locally produced lactate is augmented by paracrine/autocrine factors such as transforming growth factor β, epidermal growth factor, basic fibroblast growth factor, tumor necrosis factor α and interleukin 1α (28)(29)(30)(31)(32), which are involved in cell-cell communications in the testis (33). These factors target glucose uptake and total LDH activity for stimulating lactate production.…”

Effects of Di(2-ethylhexyl) Phthalate on Regulation of Steroidogenesis or Spermatogenesis in Testes of Sprague-Dawley Rats

“…25) Indeed, it was reported that spermatids produce factors that increase the level of lactate production in Sertoli cells and stimulate lactate production and LDHA expression in Sertoli cells. 26,27) The levels of Spag4 expression were also measured to determine the factors involved in the enhanced testicular toxicity of DEHP. Taken together, it was reported that the Spag4 mRNA levels were significantly lower in the testes chronically exposed to DBP than in the controls.…”