MicroRNAs Induced during Adipogenesis That Accelerate Fat Cell Development Are Downregulated in Obesity

Abstract

Objective: We investigated the regulation and involvement of microRNAs in fat cell development and obesity.

Research Design and Methods: Using miRNA microarrays, we profiled the expression of more than 370 miRNAs during adipogenesis of preadipocyte 3T3-L1 cells and adipocytes from leptin deficient ob/ob and diet-induced obese mice. Changes in key miRNAs were validated by RT-PCR. We further assessed the contribution of the chronic inflammatory environment in obese adipose tissue to the dysregulated miRNA expression by TNFα treatment of adipocytes. We functionally characterized two adipocyte-enriched miRNAs, miR-103 and miR-143 by a gain-of-function approach.

Results: Similar miRNAs were differentially regulated during in vitro and in vivo adipogenesis. Importantly, miRNAs that were induced during adipogenesis were downregulated in adipocytes from both types of obese mice, and vice versa. These changes are likely associated with the chronic inflammatory environment as they were mimicked by TNFα treatment of differentiated adipocytes. Ectopic expression of miR-103 or miR-143 in preadipocytes accelerated adipogenesis, as measured both by the upregulation of many adipogenesis markers and by an increase in triglyceride accumulation at an early stage of adipogenesis.

Conclusions: Our results provide the first experimental evidence for miR-103 function in adipose biology. The remarkable inverse regulatory pattern for many miRNAs during adipogenesis and obesity has important implications for the understanding adipose tissue dysfunction in obese mice and humans and the link between chronic inflammation and obesity with insulin resistance.