Cardiovascular disease and diabetes constitute the major disease burden in the western world with growing morbidity. Exercise is known to ameliorate many of the key processes in the pathogenesis of these diseases, but the underlying mechanism is not clear. Especially little is known about how exercise affects non-muscle tissues such as the heart, fat and liver. Knowledge of such pathways could lead to new therapeutic possibilities for diabetes and cardiovascular diseases.I have recently discovered a new hormone, named Irisin. Irisin is regulated by PGC1α, secreted from muscle to plasma after exercise and promotes the formation of brown fat via an unknown receptor. Furthermore, irisin is 100% conserved between mice and humans at the amino acid level (89% identity between zebfrafish and human). Nanomolar levels of this protein increase uncoupling protein 1 (UCP1) in cultures of primary white fat cells by 50 fold or more, resulting in very large increases in uncoupled respiration. Perhaps more remarkable, in vivo delivery of irisin stimulates a robust increase in UCP1, increased energy expenditure and reversal of type II diabetes in high fat fed mice. It is thus likely that irisin is responsible for at least some of the beneficial effects of exercise on the browning of adipose tissues and increases in energy expenditure. The therapeutic potential of irisin is obvious; it is a conserved endogenous polypeptide, induced with exercise and with powerful anti-diabetic properties. Irisin could, for example, be administered exogenously, or the secretion of irisin could be enhanced. These approaches, however, require additional studies, and my aim in this project is to advance the knowledge around irisin for future therapeutic testing.Given success of the ERC grant application, I will move from Harvard/Boston 2012 and start my lab at the department of Cell- and Molecular Biology, Karolinska Institute, Sweden. As seen in my list of publication, Im well prepared for this task