کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9882385 | 1536556 | 2005 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Supernatant protein factor stimulates HMG-CoA reductase in cell culture and in vitro
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
زیست شیمی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Supernatant protein factor (SPF) is a 46-kDa cytosolic protein that stimulates squalene monooxygenase in vitro and, unexpectedly, cholesterol synthesis in cell culture. Because squalene monooxygenase is not thought to be rate-limiting with regard to cholesterol synthesis, we investigated the possibility that SPF might stimulate other enzymes in the cholesterol biosynthetic pathway. Substitution of [14C]mevalonate for [14C]acetate in McARH7777 hepatoma cells expressing SPF reduced the 1.8-fold increase in cholesterol synthesis by half, suggesting that SPF acted on or prior to mevalonate synthesis. This conclusion was supported by the finding that substitution with [14C]mevalonate completely blocked an SPF-induced increase in squalene synthesis. Evaluation of 2,3-oxidosqualene synthesis from [14C]mevalonate demonstrated that SPF also stimulated squalene monooxygenase (1.3-fold) in hepatoma cells. Immunoblot analysis showed that SPF did not increase HMG-CoA reductase or squalene monooxygenase enzyme levels, indicating a direct effect on enzyme activity. Addition of purified recombinant SPF to rat liver microsomes stimulated HMG-CoA reductase by about 1.5-fold, and the SPF-concentration/activation curve paralleled that for the SPF-mediated stimulation of squalene monooxygenase. These results reveal that SPF directly stimulates HMG-CoA reductase, the rate-limiting step of the cholesterol biosynthetic pathway, as well as squalene monooxygenase, and suggest a new means by which cholesterol synthesis can be rapidly modulated in response to hormonal and environmental signals.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Archives of Biochemistry and Biophysics - Volume 433, Issue 2, 15 January 2005, Pages 474-480
Journal: Archives of Biochemistry and Biophysics - Volume 433, Issue 2, 15 January 2005, Pages 474-480
نویسندگان
Vishwesh Mokashi, Dev K. Singh, Todd D. Porter,