Abstract 2050: Slc43a3 And Intracellular Fatty Acid Trafficking

Abstract

Background: Fatty acids (FAs) have important roles in many cellular functions. Dysregulation of FA flux is both a characteristic and effector of many prevalent clinical conditions, including diabetes mellitus, obesity as well as insulin resistance and/or metabolic syndrome. Adipocytes take up long chain fatty acids through diffusion and protein mediated transport, whereas fatty acid efflux is considered to occur by diffusion. Our previous study suggests the possibility of a protein facilitated/regulated process of FA efflux by demonstrating that the organic anion transport inhibitor DIDS strongly inhibits FA efflux in lipolytically-stimulated adipocytes, leading to an accumulation of intracellular FAs, while not affecting glycerol efflux. We hypothesize that there is potential regulator(s) for FA efflux. Methods and Results: In a screen of subcutaneous adipose samples from obese patients for expression levels of transporters without known function, Slc43a3 (a member of the solute carrier transporter family) shown increased expression after bariatric surgery. In addition, Slc43a3 regulates fatty acid flux in adipocytes. To study the mechanism of Slc43a3 function, clonal lines of preadipocyte OP9 cells were generated, in which green fluorescent protein has been knocked-in at the C-terminus of endogenous Slc43a3 using CRISPR/Cas9. In parallel, Slc43a3 knockout (KO) line has also been generated. Examination of the cells showed that expression of Slc43a3 induced in the cytoplasm of the adipocytes during differentiation. Slc43a3KO adipocytes accumulate bigger lipid droplets and less small lipid droplets. To study the functional significance of Slc43a3 in vivo, adipose tissue specific KO of Slc43a3 were generated with floxed Slc43a3 and tamoxifen induced adiponectin-Cre recombinase. The Slc43a3 KO mice have less body weight and less % body fat on a normal chow diet; however, no differences are noted when the mice are switched to high fat diet, indicating the lack of lipid signaling molecules in the Slc43a3 KO mice with normal chow diet. Functional analysis shows a blunted stimulated lipolysis in the Slc43a3 KO mice. Conclusions: Both in vitro and in vivo data confirmed an unique role of Slc43a3 in regulating fatty acid flux in adipose tissue.