Activation of PPARalfa and PPARbeta/delta regulates Sertoli cell metabolism

REGUEIRA M ; RIERA MF ; ARTAGAVEYTIA SL ; GALARDO MN ; PELLIZZARI EH ; CIGORRAGA SB ; MERONI SB

Houston

Congreso; 94th Annual Meeting. The Endocrine Society.; 2012

The Endocrine Society

Sertoli cells (SC) provide the structural and nutritional support for germ cell development. Studies on SC glucose metabolism have shown that this cell type actively metabolizes glucose and converts it to lactate, which is the major source of energy for germ cells. On the other hand, it has been postulated that SC uses fatty acids (FA) as a source of energy. The transcription factors PPARα and PPARβ/δ ?members of the PPARs nuclear receptor family? participate in the expression of genes involved in FA metabolism in many cells types. The regulation of FA metabolism in SC has not been analyzed in detail. The aim of this work was to study the participation of PPARα and PPARβ/δ activation in the regulation of genes involved in FA metabolism and in lactate production in SC. Cultures of SC obtained from 20-day-old rats were incubated for different periods of time without (basal) or with variable doses of WY14643 (WY) or GW0742 (GW) ?pharmacological activators of PPARα and PPARβ/δ respectively. Carnitine palmitoyltransferase 1 (CPT1) mRNA levels were detected by Northern Blot and long- and medium-chain 3-hydroxyacyl-CoA dehydrogenases (LCAD, MCAD) and the fatty acid transporter CD36 (FAT/CD36) mRNA levels were analyzed by RQPCR. Results expressed as fold-increase in mRNA levels combining three independent experiments (mean±SD), obtained in 48h incubations with 10µM WY and 5µM GW are shown; CPT1 WY: 2.3±0.6*; GW: 3.3±0.2*; LCAD WY: 1.9±0.4*; GW: 2.8±0.3*; MCAD WY: 1.9±0.3*; GW: 1.8±0.4* and FAT/CD36 WY: 2.5±0.6*, GW: 2.7±0.5* (*p<0.05 vs. basal). While PPARα activation had no effect on lactate production, PPARβ/δ activation increased it (Basal: 7.9±0.5; GW: 11.4±0.6# μg/μgDNA, #p<0.001 vs. basal). Phosphorylation of the Pyruvate Dehydrogenase Complex (PDC) ?enzymatic complex that regulates pyruvate to acetylCoA flow? was also evaluated by Western Blot. PPARβ/δ activation promoted an increase in phospho-PDC, which probably resulted in the inhibition of enzymatic activity and in the increase in pyruvate availability for the conversion to lactate. Altogether these results suggest that in SC, PPARα and PPARβ/δ participate in the regulation of FA metabolism. PPARβ/δ also regulates lactate production and phosphorylation of PDC, which suggests a participation of this transcription factor in the provision of lactate for germ cell development. (PIP2008Nº806; PICT2007Nº1004)