Regulation of lipoprotein lipase synthesis in 3T3-L1 adipocytes by interleukin-11/adipogenesis inhibitory factor.

Interleukin-11/adipogenesis inhibitory factor (IL-11/AGIF) inhibits adipogenesis and suppresses lipoprotein lipase (EC3.1.1.34, LPL) activity in adipocytes (1,2). We investigated the mechanism of suppression of LPL activity in 3T3-L1 adipocytes by IL-11/AGIF. Incubation of adipocytes with 50 ng/ml of IL-11/AGIF led to a 75% decrease in LPL activity within 8 hours, whereas LPL mRNA level decreased by less than 30%. The LPL synthesis, as judged by the incorporation of 35S-label into immunoprecipitable LPL, decreased at almost the same rate over the same time period as enzyme activity. The degradation rate was not significantly affected by IL-11/AGIF. These data suggest that regulation of the synthesis of the enzyme protein is at least one of the main steps in the suppression of LPL by IL-11/AGIF in 3T3-L1 adipocytes.