Emerging roles of C1Q tumor necrosis factor-related proteins in metabolic diseases

Obesity and insulin resistance are key elements of the metabolic syndrome, which includes type 2 diabetes (T2D), dyslipidemia, systemic inflammation, hypertension, elevated risk for cardiovascular diseases, non-alcoholic fatty liver disease (NAFLD) and polycystic ovary syndrome (PCOS). C1Q Tumor necrosis factor-related proteins (CTRPs) have recently emerged as important regulators of metabolism as a core component in the interrelationship between insulin resistance, adiposity and inflammation. To date 15 CTRP members have been identified and most of the CTRPs are dysregulated in obesity, T2D, coronary artery disease and NAFLD. Pharmacological intervention and lifestyle modification alter expression of CTRPs in circulation and in metabolically active tissues. CTRPs enhance metabolism mainly through activation of AMPK/AKT dependent pathways and possess insulin sensitizing properties. Thus dysregulated expression of CTRPs in metabolic disorders could contribute to the pathogenesis of the disease. For these reasons CTRPs appear to be promising targets for early detection, prevention and treatment of metabolic disorders. This review article aims at exploring the role of CTRPs in metabolic syndrome.