Transcriptional and phenotypic comparisons of Ppara knockout and siRNA knockdown mice

RNA interference (RNAi) has great potential as a tool for studying gene function in mammals. However, the specificity and magnitude of the in vivo response to RNAi remains to be fully characterized. A molecular and phenotypic comparison of a genetic knockout mouse and the corresponding knockdown version would help clarify the utility of the RNAi approach. Here, we used hydrodynamic delivery of small interfering RNA (siRNA) to knockdown peroxisome proliferator activated receptor alpha (Ppara), a gene that is central to the regulation of fatty acid metabolism. We found that Ppara knockdown in the liver results in a transcript profile and metabolic phenotype that is comparable to those of Ppara−/− mice. Combining the profiles from mice treated with the PPARα agonist fenofibrate, we confirmed the specificity of the RNAi response and identified candidate genes proximal to PPARα regulation. Ppara knockdown animals developed hypoglycemia and hypertriglyceridemia, phenotypes observed in Ppara−/− mice. In contrast to Ppara−/− mice, fasting was not required to uncover these phenotypes. Together, these data validate the utility of the RNAi approach and suggest that siRNA can be used as a complement to classical knockout technology in gene function studies.

[1]  B. Trump,et al.  Mouse liver cell culture , 1981, In Vitro.

[2]  J. Lieberman,et al.  The silent treatment: siRNAs as small molecule drugs , 2006, Gene Therapy.

[3]  D. Lewis,et al.  Delivery of siRNA and siRNA expression constructs to adult mammals by hydrodynamic intravascular injection. , 2005, Methods in enzymology.

[4]  Mark E. Davis,et al.  Lack of interferon response in animals to naked siRNAs , 2004, Nature Biotechnology.

[5]  B. Staels,et al.  Different ways to regulate the PPARα stability , 2004 .

[6]  B. Cha,et al.  Peroxisomal-proliferator-activated receptor alpha activates transcription of the rat hepatic malonyl-CoA decarboxylase gene: a key regulation of malonyl-CoA level. , 2004, The Biochemical journal.

[7]  B. Staels,et al.  Different ways to regulate the PPARalpha stability. , 2004, Biochemical and biophysical research communications.

[8]  D. Haro,et al.  Control of human carnitine palmitoyltransferase II gene transcription by peroxisome proliferator-activated receptor through a partially conserved peroxisome proliferator-responsive element. , 2003, The Biochemical journal.

[9]  A. Sands,et al.  Knockouts model the 100 best-selling drugs—will they model the next 100? , 2003, Nature Reviews Drug Discovery.

[10]  G. Reach,et al.  PPAR-α–Null Mice Are Protected From High-Fat Diet–Induced Insulin Resistance , 2001 .

[11]  T. Tuschl,et al.  Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells , 2001, Nature.

[12]  Yudong D. He,et al.  Expression profiling using microarrays fabricated by an ink-jet oligonucleotide synthesizer , 2001, Nature Biotechnology.

[13]  G. Reach,et al.  PPAR-alpha-null mice are protected from high-fat diet-induced insulin resistance. , 2001, Diabetes.

[14]  I. Rusyn,et al.  Peroxisome proliferator-activated receptor alpha is restricted to hepatic parenchymal cells, not Kupffer cells: implications for the mechanism of action of peroxisome proliferators in hepatocarcinogenesis. , 2000, Carcinogenesis.

[15]  T. Osumi,et al.  The peroxisome proliferator response element (PPRE) present at positions -681/-669 in the rat liver 3-ketoacyl-CoA thiolase B gene functionally interacts differently with PPARalpha and HNF-4. , 2000, Biochemical and biophysical research communications.

[16]  D. Kelly,et al.  A critical role for the peroxisome proliferator-activated receptor alpha (PPARalpha) in the cellular fasting response: the PPARalpha-null mouse as a model of fatty acid oxidation disorders. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[17]  W. Wahli,et al.  Peroxisome proliferator–activated receptor α mediates the adaptive response to fasting , 1999 .

[18]  J. Mallolas,et al.  Isolation of pig mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase gene promoter: characterization of a peroxisome proliferator-responsive element. , 1999, The Biochemical journal.

[19]  W. Wahli,et al.  Peroxisome proliferator-activated receptor alpha mediates the adaptive response to fasting. , 1999, The Journal of clinical investigation.

[20]  P. Galtier,et al.  Peroxisome Proliferator-activated Receptor α-Isoform Deficiency Leads to Progressive Dyslipidemia with Sexually Dimorphic Obesity and Steatosis* , 1998, The Journal of Biological Chemistry.

[21]  J. Saffitz,et al.  A gender-related defect in lipid metabolism and glucose homeostasis in peroxisome proliferator- activated receptor alpha- deficient mice. , 1998, The Journal of clinical investigation.

[22]  D. Kelly,et al.  Fatty Acids Activate Transcription of the Muscle Carnitine Palmitoyltransferase I Gene in Cardiac Myocytes via the Peroxisome Proliferator-activated Receptor α* , 1998, The Journal of Biological Chemistry.

[23]  J. Auwerx,et al.  Alterations in Lipoprotein Metabolism in Peroxisome Proliferator-activated Receptor α-deficient Mice* , 1997, The Journal of Biological Chemistry.

[24]  S. Eaton,et al.  Mammalian mitochondrial beta-oxidation. , 1996, The Biochemical journal.

[25]  J Auwerx,et al.  PPARalpha and PPARgamma activators direct a distinct tissue‐specific transcriptional response via a PPRE in the lipoprotein lipase gene. , 1996, The EMBO journal.

[26]  J Auwerx,et al.  Role of the peroxisome proliferator-activated receptor (PPAR) in mediating the effects of fibrates and fatty acids on gene expression. , 1996, Journal of lipid research.

[27]  T. Pineau,et al.  Targeted disruption of the alpha isoform of the peroxisome proliferator-activated receptor gene in mice results in abolishment of the pleiotropic effects of peroxisome proliferators , 1995, Molecular and cellular biology.

[28]  D. Moore,et al.  The peroxisome proliferator activated receptor regulates malic enzyme gene expression. , 1994, The Journal of biological chemistry.

[29]  S Green,et al.  PPAR-RXR heterodimer activates a peroxisome proliferator response element upstream of the bifunctional enzyme gene. , 1993, Biochemical and biophysical research communications.

[30]  F. Oesch,et al.  Induction of the peroxisome proliferator activated receptor by fenofibrate in rat liver , 1992, FEBS letters.

[31]  I. Issemann,et al.  The mouse peroxisome proliferator activated receptor recognizes a response element in the 5′ flanking sequence of the rat acyl CoA oxidase gene. , 1992, The EMBO journal.