Menadione-induced oxidative stress alters lipid metabolism of the mature adipocyte.

FUNK MELANIA; CONDE, MELISA A.; ALZA, NATALIA P.; SALVADOR GABRIELA; ROMINA URANGA

Congreso; SAIB-SAMIGE 2020, Argentina, 2-5 de noviembre de 2020.; 2020

SAIB-SAMIGE

Menadione-induced oxidative stress alters lipid metabolism of the mature adipocyteFunk, MI1; Conde, MA1,2; Alza, NP1; Salvador, GA1,2; Uranga, RM1,21INIBIBB-CONICET, 2DBByF -UNS, Bahía Blanca, Argentinae-mail: ruranga@criba.edu.arObesity is closely related to metabolic disturbances, with the latter majorly caused by adipose tissue dysfunction rather than by the amount of fat per se. Oxidative stress (OS), a major characteristic of adipose tissue in obese patients, is considered as a primary contributing factor to the etiopathogenesis of obesity adiposity states and associated comorbidities as well. However, the biochemical mechanisms by which OS alters adipocyte biology still require to be fully uncovered. We have previously demonstrated that menadione, a synthetic vitamer of vitamin K known to generate intracellular oxygen species, impairs adipogenesis by the inhibition of the PI3K/Akt pathway. Our goal in this work was to study the effect of menadione-induced OS on mature adipocytes. For this purpose, differentiated 3T3-L1 adipocytes were exposed to menadione (20 and 50 µM) for 5 h, and different biochemical parameters were assessed. The exposure to menadione resulted in increased levels of cell oxidants (65% and 122% of control, for 20 and 50 µM, respectively). However, none of the concentrations of menadione tested had any significant effect on either cell viability or morphology. The expression of adipogenic markers was evaluated by Western blot. Menadione-induced OS caused a significant decrease in the expression of PPARγ (95% and 99%, for 20 and 50 μM menadione, respectively), FAS (70% and 88%, for 20 and 50 μM menadione, respectively), C/EBPα (75% and 93%, for 20 and 50 μM menadione, respectively), and FABP4 (30% for 50 μM menadione). No changes were detected in intracellular triglyceride levels after the incubation in the presence of menadione. However, when the exposure to menadione-dependent OS was extended to 24 h, the intracellular triglyceride content augmented by 53% and 68% upon the exposure to 20 and 50 μM menadione, respectively. At the same time, ACC (the rate-limiting enzyme in fatty acid synthesis) resulted to be activated (32% and 38% decreased phosphorylation, for 20 and 50 μM menadione, respectively). On the other hand, menadione-triggered OS also activated lipolysis (40% for 50 μM menadione). Together, our results show that OS acutely modulates both the expression and the activity of different lipo/adipogenic proteins, activating the metabolic turnover of fatty acids, with an activated enhanced? lipolysis which is overcome by fatty acid synthesis, thus resulting in an increased triglyceride content. Our next goal is the unravelling of the cellular signaling responsible of these metabolic changes