EVALUATION OF SIRT1, SIRT3 AND SIRT6 PROTEINS EXPRESSION IN ABDOMINAL FAT BIOPSIES

Abstract

Sirtuins, also known as silent information regulator T (SIRTs) proteins, are a family of highly conserved enzymes present across species from bacteria to humans, following their initial discovery in Saccharomyces cerevisiae. In mammals, sirtuins are implicated in a wide range of biological processes, including regulation of apoptosis, the cell cycle, DNA repair, immune function, neuroprotection, development, ageing, and cellular metabolism. Previous research has suggested that sirtuin levels may be influenced by exercise and fasting, but the mechanisms through which fasted versus fed exercise impacts sirtuin expression remain poorly understood. The present study aimed to investigate the role of three members of the sirtuin family SIRT1, SIRT3, and SIRT6 in human adipose tissue under controlled exercise conditions. A total of 24 men and women aged 18–45 years, all of whom were non-regular exercisers, were recruited and assigned to one of three groups: Group 1, individuals exercising before breakfast (fasted state); Group 2, individuals exercising after breakfast (fed state); and Group 3, non-exercising controls. Subcutaneous adipose tissue biopsies were obtained from each participant and analysed by immunohistochemistry (IHC) to assess expression levels of SIRT1, SIRT3, and SIRT6. In addition, an ELISA assay was performed to quantify serum SIRT1 protein levels in the experimental groups. The IHC results revealed no significant differences in SIRT6 expression between groups. SIRT1 was undetectable in adipose tissue samples across all groups, while SIRT3 could not be assessed because its vascular positive control lacked signal, precluding reliable evaluation. Furthermore, ELISA analysis of serum SIRT1 showed no significant differences between the fasting, fed, and control groups. In summary, this study found no measurable changes in adipose SIRT1, SIRT3, or SIRT6 expression following four weeks of exercise performed in either the fasted or fed state. These results suggest that short-term training may not induce detectable alterations in adipose sirtuin abundance, highlighting the need for longer interventions, larger cohorts, and complementary molecular approaches to clarify the role of sirtuins in exercise adaptation.