1 Instituto de Nutrición y Tecnología de los Alimentos, Armilla, Granada, España.
Introduction: Obesity is a multifactorial disease characterized by the excessive accumulation of fat in adipose tissue. Its derived metabolic complications are mediated by associated inflammation, hypoxia and oxidative stress. Catalase (CAT) is one of the most important antioxidant enzymes, located in the peroxisomes. CAT degrades any H2O2 that exceeds the physiological levels, and it has been suggested that CAT activity and expression may be involved in the defense mechanisms against obesity-derived metabolic complications. Therefore, the aim of this work was to investigate the putative role of CAT in human adipocytes. Methodology: Human adipose derived stem cells (ADSC, Lonza, Switzerland) were differentiated into adipocytes during 10 days. Adipogenic differentiation was validated by Oil Red O staining. The gene and protein expression of CAT were analyzed at the different times (d0, d5, d9 and d12) during the differentiation by RT-qPCR and Western Blot, respectively. Differentiated adipocytes were incubated with 10 mM 3-amino-1,2,4-triazole (3-AT) for 24 hours and CAT activity was determined (Arbor assays, USA). Lipolysis was determined by measuring the total glycerol content of the cells’ supernatants using Free Glycerol Reagent (Sigma Aldrich, Spain) according to the manufacturer’s instructions. All experiments were repeated three times. Results and discussion: The gene and protein expression of CAT increased during the adipogenic differentiation. Treatment with 3-AT inhibited CAT activity in adipocytes up to 85% (P=0.001). Furthermore, this phenomenon was accompanied by a decreased lipolysis as seen by lower glycerol levels in 3-AT treated adipocytes, as well as a down-regulation of the gene expression levels of PPARG (Peroxisome proliferator-activated receptor gamma) and PLIN (Perilipin) (P=0.012 and P=0.02, respectively). Conclusion: The inhibition of CAT in adipocytes leads to inhibition of lipolysis and down-regulation of lipid metabolism related genes. These results suggest that CAT may have an important function in adipocytes in the regulation of lipolysis.