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Conditional Expression of Human PPAR? and a Dominant Negative Variant of hPPAR? In Vivo.

ABSTRACT: The nuclear receptor, NR1C2 or peroxisome proliferator-activated receptor (PPAR)-?, is ubiquitously expressed and important for placental development, fatty acid metabolism, wound healing, inflammation, and tumour development. PPAR? has been hypothesized to function as both a ligand activated transcription factor and a repressor of transcription in the absence of agonist. In this paper, treatment of mice conditionally expressing human PPAR? with GW501516 resulted in a marked loss in body weight that was not evident in nontransgenic animals or animals expressing a dominant negative derivative of PPAR?. Expression of either functional or dominant negative hPPAR? blocked bezafibrate-induced PPAR?-dependent hepatomegaly and blocked the effect of bezafibrate on the transcription of PPAR? target genes. These data demonstrate, for the first time, that PPAR? could inhibit the activation of PPAR? in vivo and provide novel models for the investigation of the role of PPAR? in pathophysiology.

SUBMITTER: Higgins LG

PROVIDER: S-EPMC3324915 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Conditional Expression of Human PPARδ and a Dominant Negative Variant of hPPARδ In Vivo.

Higgins Larry G LG Garbacz Wojciech G WG Gustafsson Mattias C U MC Nainamalai Sitheswaran S Ashby Peter R PR Wolf C Roland CR Palmer Colin N A CN

PPAR research 20120321

The nuclear receptor, NR1C2 or peroxisome proliferator-activated receptor (PPAR)-δ, is ubiquitously expressed and important for placental development, fatty acid metabolism, wound healing, inflammation, and tumour development. PPARδ has been hypothesized to function as both a ligand activated transcription factor and a repressor of transcription in the absence of agonist. In this paper, treatment of mice conditionally expressing human PPARδ with GW501516 resulted in a marked loss in body weight ...[more]

PMID: 22550474

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Project description:Loss-of-function mutations in the cardiac Na+ channel α-subunit Nav1.5, encoded by SCN5A, cause Brugada syndrome (BrS), a hereditary disease characterized by sudden cardiac death due to ventricular fibrillation. We previously evidenced in vitro the dominant-negative effect of the BrS Nav1.5-R104W variant, inducing retention of wild-type (WT) channels and leading to a drastic reduction of the resulting Na+ current (I Na ). To explore this dominant-negative effect in vivo, we created a murine model using adeno-associated viruses (AAVs).MethodsDue to the large size of SCN5A, a dual AAV vector strategy was used combining viral DNA recombination and trans-splicing. Mice were injected with two AAV serotypes capsid 9: one packaging the cardiac specific troponin-T promoter, the 5' half of hSCN5A cDNA, a splicing donor site and a recombinogenic sequence; and another packaging the complementary recombinogenic sequence, a splicing acceptor site, the 3' half of hSCN5A cDNA fused to the gfp gene sequence, and the SV40 polyA signal. Eight weeks after AAV systemic injection in wild-type (WT) mice, echocardiography and ECG were recorded and mice were sacrificed. The full-length hSCN5A-gfp expression was assessed by western blot and immunohistochemistry in transduced heart tissues and the Na+ current was recorded by the patch-clamp technique in isolated adult GFP-expressing heart cells.ResultsAlmost 75% of the cardiomyocytes were transduced in hearts of mice injected with hNav1.5 and ∼30% in hNav1.5-R104W overexpressing tissues. In ventricular mice cardiomyocytes expressing R104W mutant channels, the endogenous I Na was significantly decreased. Moreover, overexpression of R104W channels in normal hearts led to a decrease of total Nav1.5 expression. The R104W mutant also induced a slight dilatation of mice left ventricles and a prolongation of RR interval and P-wave duration in transduced mice. Altogether, our results demonstrated an in vivo dominant-negative effect of defective R104W channels on endogenous ones.ConclusionUsing a trans-splicing and viral DNA recombination strategy to overexpress the Na+ channel in mouse hearts allowed us to demonstrate in vivo the dominant-negative effect of a BrS variant identified in the N-terminus of Nav1.5.

Dataset Information

Conditional Expression of Human PPAR? and a Dominant Negative Variant of hPPAR? In Vivo.

Publications

Conditional Expression of Human PPARδ and a Dominant Negative Variant of hPPARδ In Vivo.

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