Sex hormone binding globulin (SHBG) modulates mitochondrial dynamics in PPARγ-depleted equine adipose derived stromal cells.

Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor that promotes adipogenesis, lipid uptake and storage, insulin sensitivity, and glucose metabolism. Hence, defects in PPARγ have been associated to the development of metabolic disorders. Sex hormone-binding globulin (SHBG) is a glycoprotein primarily produced in the liver that regulates the bioavailability of sex hormones. Alike PPARγ, low SHBG levels have been correlated with insulin resistance and associated endocrine abnormalities. Therefore, this study aimed to verify whether SHBG may restore depleted PPARγ functions and thus serve as a new candidate for the management of metabolic conditions. A model of equine adipose-derived stromal cells (EqASCs) has been used, in which a PPARγ silencing and SHBG treatment have been achieved to determine the changes in cell viability, premature senescence, oxidative stress, and mitochondrial functions. Obtained data demonstrated that loss in PPARγ triggers cell apoptosis which is not reversed by SHBG application. Moreover, PPARγ knockdown cells exhibited premature senescence, which has been substantially alleviated by SHBG concomitantly to increased BAX/BCL2 ratio, suggesting a possible effect on senescence-induced apoptosis resistance. Interestingly, PPARγ silencing induced a significant alteration in mitochondrial membrane potential as well as the expression of dynamics and metabolism-related markers. SHBG treatment enabled to ameliorate the transmembrane potential, to normalize the expression levels of key dynamics and metabolism mediators, and to restore the protein levels of PINK, which is critically involved in mitochondria recycling machinery. Presented data suggest that SHBG may provide new mechanistic insights into the regulation of PPARγ functions, and thus offers a preliminary picture on a possible SHBG-PPARγ metabolic crosstalk. KEY MESSAGES : PPARγ is a transcription factor that tightly regulates cell metabolism. Low SHBG levels correlate with insulin resistance and associated endocrine abnormalities. PPARγ silencing reduces cell viability, triggers premature senescence and profound mitochondrial failure in equine ASCs. SHBG protein reverses senescent phenotype and apoptosis resistance of PPARγ- ASCs. SHBG improves mitochondrial dynamics and metabolism following PPARγ knockdown. SHBG might serve as a PPARγ potential mimicking agent for the modulation of ASCs metabolic processes.

Characterization of Apoptosis, Autophagy and Oxidative Stress in Pancreatic Islets Cells and Intestinal Epithelial Cells Isolated from Equine Metabolic Syndrome (EMS) Horses.

Endocrine disorders are becoming an increasing problem in both human and veterinary medicine. In recent years, more and more horses worldwide have been suffering from equine metabolic syndrome (EMS). This metabolic disorder is characterized by pathological obesity, hyperinsulinaemia, hyperglycaemia and insulin resistance. Although metabolic disorders, including diabetes, have been extensively studied, there are still no data on the molecular effects of EMS in horses. Thus, the aim of this study was to evaluate apoptosis, oxidative stress, autophagy and microRNA (miR) expression in multipotent intestinal epithelial stem cells (IECs) and pancreatic islets (PIs) isolated post mortem form healthy and EMS diagnosed horses. Our group was the first to describe how EMS affects IEC and PI aging and senescence. First, we evaluated isolation and culture protocol for these cells and subsequently established their metabolic status in vitro. Both IECs and PIs isolated from EMS horses were characterized by increased apoptosis and senescence. Moreover, they accumulated elevated levels of reactive oxygen species (ROS). Here we have observed that autophagy/mitophagy may be a protective mechanism which allows those cells to maintain their physiological function, clear protein aggregates and remove damaged organelles. Furthermore, it may play a crucial role in reducing endoplasmic reticulum (ER) stress. This protective mechanism may help to overcome the harmful effects of ROS and provide building blocks for protein and ATP synthesis.

Combination of resveratrol and 5-azacytydine improves osteogenesis of metabolic syndrome mesenchymal stem cells.

Endocrine disorders have become more and more frequently diagnosed in humans and animals. In horses, equine metabolic syndrome (EMS) is characterized by insulin resistance, hyperleptinemia, hyperinsulinemia, inflammation and usually by pathological obesity. Due to an increased inflammatory response in the adipose tissue, cytophysiological properties of adipose derived stem cells (ASC) have been impaired, which strongly limits their therapeutic potential. Excessive accumulation of reactive oxygen species, mitochondria deterioration and accelerated ageing of those cells affect their multipotency and restrict the effectiveness of the differentiation process. In the present study, we have treated ASC isolated from EMS individuals with a combination of 5-azacytydine (AZA) and resveratrol (RES) in order to reverse their aged phenotype and enhance osteogenic differentiation. Using SEM and confocal microscope, cell morphology, matrix mineralization and mitochondrial dynamics were assessed. Furthermore, we investigated the expression of osteogenic-related genes with RT-PCR. We also investigated the role of autophagy during differentiation and silenced PARKIN expression with siRNA. Obtained results indicated that AZA/RES significantly enhanced early osteogenesis of ASC derived from EMS animals. Increased matrix mineralization, RUNX-2, collagen type I and osteopontin levels were noted. Furthermore, we proved that AZA/RES exerts its beneficial effects by modulating autophagy and mitochondrial dynamics through PARKIN and RUNX-2 activity.