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The present data suggest involvement of the ASP/adipsin pathway in the pathogenesis of obesity.

OBJECTIVE: The purpose of the present study was to examine the effect of Acylation Stimulating Protein (ASP) on glucose transport in cultured subcutaneous adipocytes. DESIGN AND SUBJECTS: Subcutaneous adipose tissue was obtained from non-obese, healthy females (18±32 y old) undergoing mammoplasty reduction. Preadipocytes were isolated and differentiated into adipocytes. MEASUREMENTS: Following the exposure of preadipocytes and adipocytes to ASP or insulin, glucose transport was assessed as [ 3 H] 2-deoxy glucose uptake. The measurements were normalised per total cell protein. RESULTS: ASP increases speci®c membrane glucose transport in both preadipocytes and adipocytes in a time and concentration dependent manner. Stimulation in both cell types is rapid (within minutes), reaching a maximal effect between 1 and 4 h. However, after 24 h exposure to ASP, there is a downregulation in the response. The ASP response is greater following differentiation of preadipocytes to adipocytes and is compared to that of insulin. Dose response studies demonstrated a ®ve-fold greater sensitivity of adipocytes (half-maximal concentration of ASP on adipocytes 0.5 mM, preadipocytes 2.3 mM).CONCLUSION: These results demonstrate that ASP not only stimulates triglyceride synthesis, but also glucose transport in differentiated human adipocytes and is consistent with a physiologically important role for ASP in postprandial energy storage.