RNAi-mediated germline knockdown of FABP4 increases body weight but does not improve the deranged nutrient metabolism of diet-induced obese mice

Objective: To investigate the impact of reduced adipocyte fatty acid-binding protein 4 (FABP4) in control of body weight, glucose and lipid homeostasis in diet-induced obese (DIO) mice. Methods: We applied RNA interference (RNAi) technology to generate FABP4 germline knockdown mice to investigate their metabolic phenotype. Results: RNAi-mediated knockdown reduced FABP4 mRNA expression and protein levels by almost 90% in adipocytes of standard chow-fed mice. In adipocytes of DIO mice, RNAi reduced FABP4 expression and protein levels by 70 and 80%, respectively. There was no increase in adipocyte FABP5 expression in FABP4 knockdown mice. The knockdown of FABP4 significantly increased body weight and fat mass in DIO mice. However, FABP4 knockdown did not affect plasma glucose and lipid homeostasis in DIO mice; nor did it improve their insulin sensitivity. Conclusion: Our data indicate that robust knockdown of FABP4 increases body weight and fat mass without improving glucose and lipid homeostasis in DIO mice. International Journal of Obesity (2011) 35, 217-225; doi: 10.1038/ijo.2010.128; published online 6 July 2010