rAAV-Mediated Metabolic Engineering in Vivo

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DESCRIPTION (provided by applicant): The proposed project has the following objectives: (1) to test whether the novel adipocyte hormone adiponectin, when administered peripherally via recombinant adeno-associated virus (rAAV), can control body weight (BW) gain and correct the attendant metabolic disorders for extended periods of time in obese rodents with specific genetic defects and in diet-induced obese (DIO) insulin-resistant rats; (2) to determine whether constitutive expression of adiponectin increases lipogenic capacity of the liver, augments insulin sensitivity, and induces resistance to lipoatrophic injury and fibrogenesis; (3) to confirm that ectopic peripheral expression of adiponectin modulates expression of genes that enhance lipid transport, fat combustion and dissipation, thereby inducing profound changes in muscle and liver lipid metabolism. Specifically, a series of rAAV vectors carrying mouse adiponectin cDNA under the control of a strong constitutive promoter will be packaged into capsids of three different AAV serotypes: AAV1, AAV2 and AAV5. These vectors will be tested in diet-induced obese (DIO) Sprague-Dawley (SD) rats and Zucker diabetic fatty rats (fa/fa, ZDF). Earlier we have shown that a rAAV encoding either the lipostatic hormone leptin, or the pleiotropic cytokines ciliary neurotrophic factor (CNTF), or leukemia inhibitory factor (LIF) could be successfully used to curb the BW gain in lean SD rats when administered centrally. Here we propose to evaluate an anorexigenic effect of adiponectin using peripheral routes of vector delivery in several obese rodent models. The primary readouts will be assessments of BW gain and insulin resistance monitored indirectly in plasma. In order to identify genes and signaling pathways modulated in response to adiponectin ectopic expression we will use DNA microarray chip analysis of mRNA isolated from liver tissue. The results of these studies will not only determine if gene therapy is a viable long-term therapeutic strategy to control BW and insulin resistance, but may also establish that rAAV-delivered adiponectin is an effective therapeutic modality in treating obesity and diabetes caused by environmental (DIO) or genetic factors. Results of these studies should also elucidate the function of a novel white fat-derived hormone, adiponectin, as the long-sought link between obesity and insulin resistance.