Construction, Purification, and Biological Characterization of Plant-Made Human Recombinant Irisin

Irisin is a myokine primarily expressed in skeletal muscle, known to mediate the beneficial effects of exercise.Irisin was first reported to induce adipocyte browning by increasing the expression of uncoupling protein 1 (UCP1), and subsequent studies have also discovered anti-oxidant, anti-inflammatory, and anti-metastatic effects of irisin.Despite controversies on the circulating levels of irisin, studies that tested the therapeutic potential of irisin by injecting recombinant irisin have shown promising results.Therefore, there is a need to develop means to construct a high-yield recombinant strain with optimal human irisin coding sequence and proper glycosylation.In this study, we cloned and expressed human irisin (r-irisin) in Nicotiana benthamiana leaves and tested its biological activity in cultured adipocytes.Results showed that we have successfully constructed, expressed, and purified the glycated form of human irisin using N. benthamiana.Upon treatment with plant-made r-irisin on mature adipocytes, expression of UCP1 as well as mitochondrial biogenesis-related genes were increased, while lipid accumulation was decreased.In addition, plant made r-irisin treatment resulted in inhibition of adipogenesis evidenced by downregulated C/EBPα, PPARγ, and FABP4 expression and reduced lipid accumulation, implicating their therapeutic potential in the treatment of obesity-induced metabolic diseases.In summary, we developed a safe, efficient, cost-effective means for the production of human irisin in plants and demonstrated its biological activity in adipocytes.