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Sterol‐mediated regulation of hormone‐sensitive lipase in 3T3‐L1 adipocytes
Author(s) -
Miura Shinji,
Nagura Hiromi,
Sawamura Fusae,
Tomita Isao,
Kawai Eiji,
Mochizuki Norihiro,
Ikeda Masahiko,
Kraemer Fredric B.,
Tomita Takako
Publication year - 2003
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-003-1122-9
Subject(s) - hormone sensitive lipase , sterol , lipase , cholesterol , lipidology , medicine , sterol o acyltransferase , endocrinology , sterol regulatory element binding protein , clinical chemistry , western blot , incubation , biology , messenger rna , chemistry , enzyme , biochemistry , gene , lipoprotein
We previously reported that intracellular free cholesterol at physiological concentrations regulates the activity of neutral cholesterol esterase (N‐CEase) in macrophages. The objective of the present study is to investigate whether the regulation of N‐CEase by cholesterol is generally observed in other types of cells such as adipocytes with high activity of hormone‐sensitive lipase (HSL), the same gene product as N‐CEase. 3T3‐L1 adipocytes were cultured with and without cholesterol (1–30 μg/mL) or 25‐hydroxycholesterol (0.1–10 μg/mL), and changes in the N‐CEase activity, expression of HSL mRNA, and protein were examined. Incubation (24 h) of cells with cholesterol did not change N‐CEase activity, but incubation with 25‐hydroxycholesterol decreased the activity in a concentration‐dependent manner by 24 (24 h) and 54% (36 h). Quantitative reverse transcription‐PCR indicated that 25‐hydroxycholesterol (10 μg/mL) did not influence expression of HSL mRNA. However, Western blot analysis showed that this sterol reduced HSL protein by 72 (24 h) and by 93% (36 h), respectively. It was concluded that sterol‐mediated regulation of HSL/N‐CEase occurs not only in macrophages but also in adipocytes, and regulation appears to occur not at a transcriptional level but by a post‐transcriptional process. Sterol‐mediated proteolysis may be involved in the loss of HSL protein.