Role of NEDD8 in HIV-associated lipodystrophy

The pathogenetic bases of HAART-associated lipodystrophy are still poorly known, even if it is clear that adipose tissue and its metabolism are sensitive to antiretroviral therapy alone and/or in combination with HIV infection. The NEDD8 system is essential for the regulation of protein degradation pathways involved in cell cycle progression, morphogenesis and tumorigenesis. We investigated the possible involvement of NEED8 in adipogenesis and, consequently, in HIV-related lipodystrophy. One hundred HIV-1-infected patients were included in the study. Using an in vitro model of adipogenesis we evaluated the effects on adipogenesis of the forced expression of NEDD8 together with efavirenz, stavudine, saquinavir, amprenavir and indinavir, belonging to the three main classes of anti-HIV medications. We showed that NEDD8 expression level is higher in the peripheral blood of HIV patients developing lipodystrophy. Coherently, forced expression of NEDD8 in an in vitro model of adipogenesis was able to perturb expression of some key proteins involved in adipogenesis, such as C/EBPalpha and PPARgamma, possibly acting throughout the NEDD8/p27/beta-catenin pathway. Moreover, three out of five evaluated drugs were able to affect adipocyte differentiation: efavirenz, stavudine and saquinavir. Finally, we have shown that NEDD8 was expressed in the fat tissue of lipodystrophic patients, being significantly higher in the lipodystrophic patients with respect to the controls, thus further confirming the altered NEDD8 expression in the fat tissue of HIV-infected patients affected by lipodystrophy. Taken together, our data support the hypothesis of an implication of NEDD8 through p27 and beta-catenin pathways in the disruption of adipogenesis and consequent lipodystrophy in patients affected by HIV infection under HAART therapy with qualitative and quantitative differences according to diverse antiretroviral treatments. These evidences indicate the NEDD8/beta-catenin/p27 pathway as a possible molecular target for prevention of lipodystrophy development in patients under HAART therapy.