PREFERENTIAL EXPRESSION OF CHOLESTERYL ESTER TRANSFER PROTEIN MESSENGER-RNA BY STROMAL-VASCULAR CELLS OF HUMAN ADIPOSE-TISSUE

Cholesteryl ester transfer protein (CETP) mRNA is more abundantly expr essed in small mature adipocytes as compared to large, lipid-rich adip ocytes [Radeau et al., J. Lipid Res. 36 (1995) 2552-2561]. In the pres ent study, the stromal vascular fraction (SVF) of human adipose tissue was isolated and the presence of very small fat cells in this fractio n confirmed by electron microscopy and by demonstrating the presence o f mRNA for adipsin and for CCAAT enhancer binding protein alpha (C/EBP alpha), a marker of adipocyte differentiation. sn-Glycerol 3-phosphat e dehydrogenase (GPDH) activity was present in the SVF but not in the preadipocyte fraction. Northern blot analysis of human adipose tissue demonstrated that CETP mRNA expression was significantly greater (+96% , P < 0.03) in stromal-vascular cells (SVC) as compared to mature fat cells. By comparison, lipoprotein lipase mRNA expression was lower (-7 5%, P< 0.03) in SVC while apolipoprotein E mRNA expression was not sig nificantly different in SVC as compared to isolated adipocytes. By RT- PCR analysis, we demonstrated that CETP mRNA was expressed by human pr e-adipocytes at levels less than those of SVC and adipocytes. The abse nce of monocytes/macrophages in SVC was confirmed by the absence of Fc gamma RIII (CD16) mRNA in these fractions. These data demonstrate tha t CETP mRNA is most highly expressed in the immature fat cells of huma n adipose tissue, consistent with other experiments from this laborato ry demonstrating that CETP plays an important local role in adipocyte cholesterol accumulation. (C) 1998 Elsevier Science B.V.