March 10, 2006
Title: Lipogenesis in mice containing a targeted disruption in SREBP-1a gene
Rayshonda Williams, Linda Hammond, Tim Osborne
Department of Molecular Biology and Biochemistry
University of California, Irvine
Sterol regulatory element binding proteins (SREBPs) are a family of membrane-bound transcription factors that regulate cholesterol and fatty acid homeostasis. (1) In mammals, three SREBP isoforms: SREBP-1a, SREBP-1c, and SREBP-2 are known. (1) SREBP-1a and SREBP-1c are derived from the same gene, SREBP-1, via alternatively spiced first exons. SREBP-1a is of interest because it activates genes involved in cholesterol and triglyceride synthesis. To investigate the role of SREBP-1a, our lab is characterizing mice with a targeted insertion that disrupts SREBP-1a. To determine the genotype of the mice, DNA was isolated and amplified using Polymerase Chain Reaction (PCR). We examined insulin/glucagon levels through fasting and re-feeding the mice. From these mice, we obtained liver histology sections and stained for lipid accumulation using Oil Red-O. SREBP-1a’s role in lipogenesis was addressed through the response of knock-out mice to high fat/high sucrose diet. To confirm that the targeted insertion mutation result in a complete loss of SREBP-1a expression, we will perform quantitative real time PCR, to measure mRNA, and two dimensional gel electrophoresis, to measure protein.
1) Horton,J.D., Shimomura,I., Ikemoto,S., Bashmakov,Y., and Hammer, R.E.(2003) J.Biol. Chem. 278, 36652-36660