238-LB: Erythropoietin Receptor–Mediated Erythropoietin Regulation of Energy Metabolism in Mice

Abstract

EPO receptor (EPOR) expression in white adipose tissue (WAT) mediates EPO metabolic activity and mitochondrial biogenesis. Mice that lack EPOR in adipose tissue have increase fat mass accumulation, increased susceptibility to diet induced obesity and decreased WAT mitochondrial activity. Here we assess the potential for EPO to promote a metabolic response in liver, brown adipose tissue and skeletal muscle by assessing the extent of EPOR expression using the EpoR-dtTomato-Cre mouse. We quantified EPOR in liver, brown adipose tissue and soleus muscle compared with EPOR expression in subcutaneous and epididymal WAT and found the highest level in WAT by mRNA, protein and immunohistochemical analyses. Elevated EPO by intraperitoneal injection or by transgene over expression resulted in tissue specific changes in gene expression. In liver, EPO decreased expression of genes involved in gluconeogenesis and triglyceride secretion. In brown adipose tissue, EPO increased expression of thermogenic genes. In subcutaneous WAT, EPO decreased genes involved in lipogenesis. In soleus muscle, EPO decreased expression of lipolytic genes. These findings indicate that increased EPO decreases lipogenesis gene LPI, ACC1, ACC2 and Fas expression in the BAT, skeletal muscle, ScWAT, liver and eWAT and increases lipolysis gene Atgl and Hsl expression in the BAT, ScWAT, skeletal muscle, and Atgl expression in the liver and eWAT. Measurements of energy metabolism did not detect any changes associated with EPO treatment in energy expenditure, respiratory exchange ratio, locomotor activity and total activity. However, as observed in WAT, we also find that EPO promotes mitochondria activity in liver, brown adipose tissue and skeletal muscle indicated by elevated gene expression of CytC, Idh3α, Cpt1, Pgc-1α and Cox7a1. Together, these data support the hypothesis that EPO promotes lipolysis and inhibits fat synthesis to regulate body weight and fat mass. In addition, EPO may regulate glucose metabolism via inhibition of gluconeogenesis. Disclosure W. Yin: None. H. Rogers: None. P. K. Rajvanshi: None. X. An: None. M. Gassmann: None.