Gene expression of sterol regulatory element-binding proteins in hamster small intestine.
Gene expression of sterol regulatory element-binding proteins 1a, 1c, and 2 (SREBP-1a, -1c, and -2) and of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) synthase, HMG-CoA reductase, and the low density lipoprotein (LDL) receptor was examined in hamster small intestine. SREBP-1c transcript predominated over SREBP-1a. mRNA levels for SREBP-1a, -1c, and -2, LDL receptor, and HMG-CoA synthase were highest in jejunum and ileum. Expression of SREBP-1a and SREBP-1c was highest in cells of the upper villus and decreased in cells of the lower villus. Gene expression of SREBP-2 was lowest in cells of the upper villus and increased in cells of the lower villus. Ileal SREBP-2 gene expression was highest in cells of the midvillus. mRNA levels for HMG-CoA synthase and the LDL receptor followed a pattern similar to that of SREBP-2. A positive correlation existed between SREBP-2 gene expression and rates of cholesterol synthesis. Fatty acid synthesis was highest in jejunum and ileum, correlating positively with the expression of SREBP-1c. Sterol influx into intestinal cells decreased mRNA levels of SREBP-2, HMG-CoA reductase, HMG-CoA synthase, and LDL receptor. In ileum, sterol influx decreased gene expression of SREBP-1a and increased expression of SREBP-1c. The results suggest that SREBP-2 regulates cholesterol synthesis in the small intestine. SREBP-1a is a minor transcript and its expression does not correlate with cholesterol-synthesizing activity. SREBP-1c is a major transcript in small intestine and its expression along the length of the gut correlates with fatty acid synthesis. Sterols regulate gene expression of sterol-responsive genes, including SREBP-2, in small intestine. - Field, F. J., E. Born, S. Murthy, and S. N. Mathur. Gene expression of sterol regulatory element-binding proteins in hamster small intestine. J. Lipid Res. 2001. 42: 1;-8.
Field
F J
FJ
Department of Internal Medicine and Veterans Administration, University of Iowa, Iowa City, IA 52242, USA.
Born
E
E
Murthy
S
S
Mathur
S N
SN
D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins / Q000187:drug effects / Q000235:genetics*; D002784:Cholesterol / Q000096:biosynthesis; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000235:genetics*; D015870:Gene Expression / Q000187:drug effects; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000378:metabolism; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008647:Mesocricetus; D012333:RNA, Messenger / Q000378:metabolism; D011973:Receptors, LDL / Q000235:genetics; D051780:Sterol Regulatory Element Binding Protein 1; D051782:Sterol Regulatory Element Binding Protein 2; D013261:Sterols / Q000378:metabolism / Q000494:pharmacology; D014018:Tissue Distribution; D014157:Transcription Factors / Q000187:drug effects / Q000235:genetics*
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D011973:Receptors, LDL; D051780:Sterol Regulatory Element Binding Protein 1; D051782:Sterol Regulatory Element Binding Protein 2; D013261:Sterols; D014157:Transcription Factors; D002784:Cholesterol; D006904:Hydroxymethylglutaryl-CoA Synthase