Liver-specific disruption of PPARγ in leptin-deficient mice improves fatty liver but aggravates diabetic phenotypes
Kimihiko Matsusue, … , Marc L. Reitman, Frank J. Gonzalez
Kimihiko Matsusue, … , Marc L. Reitman, Frank J. Gonzalez
Published March 1, 2003
Citation Information: J Clin Invest. 2003;111(5):737-747. https://doi.org/10.1172/JCI17223.
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Article Metabolism

Liver-specific disruption of PPARγ in leptin-deficient mice improves fatty liver but aggravates diabetic phenotypes

Abstract

To elucidate the function of PPARγ in leptin-deficient mouse (ob/ob) liver, a PPARγ liver-null mouse on an ob/ob background, ob/ob-PPARγ(fl/fl)AlbCre+, was produced using a floxed PPARγ allele, PPARγ(fl/fl), and Cre recombinase under control of the albumin promoter (AlbCre). The liver of ob/ob-PPARγ(fl/fl)AlbCre+ mice had a deletion of exon 2 and a corresponding loss of full-length PPARγ mRNA and protein. The PPARγ-deficient liver in ob/ob mice was smaller and had a dramatically decreased triglyceride (TG) content compared with equivalent mice lacking the AlbCre transgene (ob/ob-PPARγ(fl/fl)AlbCre–). Messenger RNA levels of the hepatic lipogenic genes, fatty acid synthase, acetyl-CoA carboxylase, and stearoyl-CoA desaturase-1, were reduced in ob/ob-PPARγ(fl/fl)AlbCre+ mice, and the levels of serum TG and FFA in ob/ob-PPARγ(fl/fl)AlbCre+ mice were significantly higher than in the control ob/ob-PPARγ(fl/fl)AlbCre– mice. Rosiglitazone treatment exacerbated the fatty liver in ob/ob-PPARγ(fl/fl)AlbCre– mice compared with livers from nonobese Cre– mice; there was no effect of rosiglitazone in ob/ob-PPARγ(fl/fl)AlbCre+ mice. The deficiency of hepatic PPARγ further aggravated the severity of diabetes in ob/ob mice due to decreased insulin sensitivity in muscle and fat. These data indicate that hepatic PPARγ plays a critical role in the regulation of TG content and in the homeostasis of blood glucose and insulin resistance in steatotic diabetic mice.

Authors

Kimihiko Matsusue, Martin Haluzik, Gilles Lambert, Sun-Hee Yim, Oksana Gavrilova, Jerrold M. Ward, Bryan Brewer Jr., Marc L. Reitman, Frank J. Gonzalez

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Figure 1

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Gene targeting and conditional deletion of exon 2 of the PPARγ gene. (a)...
Gene targeting and conditional deletion of exon 2 of the PPARγ gene. (a) Restriction maps of the wild-type allele, targeting vector, targeted allele, floxed allele, and null allele. The indicated 3′ probe was used to assess recombination events by Southern blot analysis. Open boxes represent exons and are numbered as indicated. PGK neomycin (PGK Neo) and thymidine kinase (TK) are positive and negative selection cassettes, respectively. Restriction sites: B, BamHI; E, EcoRI; S, SacI. (b) Southern blot analysis of BamHI-digested genomic DNA isolated from brain (B), liver (L), colon (C), spleen (S), kidney (K), white adipose (W), and tail (T) in ob/ob-PPARγ(fl/fl)AlbCre+ or ob/ob-PPARγ(fl/fl)AlbCre– mice. Fragments hybridizing with 3′ probe from the wild-type, floxed, and deleted alleles migrate at approximately 14, 10, and 8 kb, respectively. (c) RNase protection analysis of PPARγ mRNA in OB/OB- or ob/ob-PPARγ(fl/fl)AlbCre mouse livers. Total RNA from three separate mouse livers in each genotype were hybridized with riboprobes for β-actin and PPARγ. The products were then separated on a 5.0% polyacrylamide gel. The size of the protected mRNA fragments for PPARγ and β-actin is as follows; wild-type PPARγ, 195 nt; null PPARγ, 165 nt; and β-actin; 250 nt.