Adiponectin regulates the expression of genes associated with fatty acid synthesis and oxidation in primary pig adipocytes

Abstract

Adiponectin has been implicated in the regulation of glucose uptake and fatty acid synthesis in adipocytes, and in the long-term suppression of weight gain when over-expressed in rodents by adenovirus associated virus vectors. The aim of this research was to determine whether adiponectin regulates the expression of genes associated with fatty acid oxidation in porcine adipocytes. Primary adipocytes were isolated from the dorsal subcutaneous adipose tissue of pigs (male castrates, n=5). Cells were incubated in DMEM with 3% BSA, in the presence and absence of recombinant porcine adiponectin (30 ìg/mL), and were harvested at 0, 30, 60, 120, 240 and 360 minutes. Total RNA was extracted for cDNA synthesis, and the abundance of selected transcripts determined by real time PCR analysis. Adiponectin transiently increased (2–6.5 fold, P < .05) the expression of acetyl Co-A carboxylase (ACC), AMP activated kinase (AMPK), acyl Co-A oxidase (ACO) and peroxisome proliferator activated receptor-α (PPARα). After the initial increase in mRNA abundance, there was either a return to initial levels of expression (PPARα), a significant reduction (AMPK), or a cyclic pattern of expression (ACC, ACO). The abundance of the uncoupling protein-3 (UCP3) transcript was not influenced by adiponectin until the final measure at 360 minutes, at which time it was increased 3.8-fold (P < .05). Collectively, these data indicate that adiponectin acts through autocrine/paracrine signaling pathways to coordinately regulate lipid metabolism in the adipocyte, and may thus be a determinant of adipocyte size and overall lipid accumulation. Funding is USDA