Regulation of lipoprotein lipase mRNA content in 3T3-L1 cells by tumour necrosis factor.

Abstract

Tumour necrosis factor (TNF) was previously shown to suppress lipoprotein lipase (LPL) synthesis and activity in 3T3-L1 adipocytes. The present study examined the effect ofTNF on amounts ofmRNA for LPL in 3T3-Ll cells. Northern-blot analysis of polyadenylated RNA using a cDNA probe to guinea-pig LPL identified two predominant species of LPL message, 3.7 and 3.9 kilobases in size. The steady-state amounts of these mRNAs increased 10-fold upon expression of the adipocyte phenotype. A single dose of 1.5 nMTNF decreased LPL mRNA by approx. 60 % in 17 h with a corresponding decrease in LPL activity, an effect that was reversed 48 h after exposure to TNF. The results demonstrate that TNF reversibly downregulates LPL mRNA in fully differentiated 3T3-Ll adipocytes. Cells induced to differentiate in the presence of 1.5 nM-TNF exhibited a delayed time course for development of the adipocyte phenotype, as judged by attenuation of the normal increase in LPL mRNA that occurs with differentiation. Originally published Biochemical Journal, Vol. 249, No. 3, Feb 1988