Transgenic mice expressing lipoprotein lipase in adipose tissue. Absence of the proximal 3'-untranslated region causes translational upregulation.
Lipoprotein lipase (LPL) is a key enzyme in lipoprotein and adipocyte metabolism. Defects in LPL can lead to hypertriglyceridemia and the subsequent development of atherosclerosis. The mechanisms of regulation of this enzyme are complex and may occur at multiple levels of gene expression. Because the 3'-untranslated region (UTR) is involved in LPL translational regulation, transgenic mice were generated with adipose tissue expression of an LPL construct either with or without the proximal 3'-UTR and driven by the aP2 promoter. Both transgenic mouse colonies were viable and expressed the transgene, resulting in a 2-fold increase in LPL activity in white adipose tissue. Neither mouse colony exhibited any obvious phenotype in terms of body weight, plasma lipids, glucose, and non-esterified fatty acid levels. In the mice expressing hLPL with an intact 3'-UTR, hLPL mRNA expression approximately paralleled hLPL activity. However in the mice without the proximal 3'-UTR, hLPL mRNA was low in the setting of large amounts of hLPL protein and LPL activity. In previous studies, the 3'-UTR of LPL was critical for the inhibitory effects of constitutively expressed hormones, such as thyroid hormone and catecholamines. Therefore, these data suggest that the absence of the 3'-UTR results in a translationally unrepressed LPL, resulting in a moderate overexpression of adipose LPL activity.
Hensley
Lori L
LL
The Central Arkansas Veterans HealthCare System and Department of Medicine, Division of Endocrinology, University of Arkansas for Medicla Sciences, Little Rock, 72205, USA.
Ranganathan
Gouri
G
Wagner
Elke M
EM
Wells
Brian D
BD
Daniel
Joseph C
JC
Vu
Diane
D
Semenkovich
Clay F
CF
Zechner
Rudolf
R
Kern
Philip A
PA
D020413:3' Untranslated Regions; D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D005786:Gene Expression Regulation; D005838:Genotype; D008071:Lipoprotein Lipase / Q000378:metabolism; D008074:Lipoproteins / Q000097:blood; D051379:Mice; D008822:Mice, Transgenic; D008957:Models, Genetic; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014018:Tissue Distribution; D019076:Transgenes; D015854:Up-Regulation
D020413:3' Untranslated Regions; D008074:Lipoproteins; D012333:RNA, Messenger; D012313:RNA; D008071:Lipoprotein Lipase