INVESTIGADORES
OSTROWSKI Matias
congresos y reuniones científicas
Título:
Rab27a controls HIV-1 assembly by regulating plasma membrane levels of phosphatidylinositol 4,5-bisphosphate
Autor/es:
MATIAS OSTROWSKI
Lugar:
Melbourne
Reunión:
Congreso; AIDS 2014; 2014
Institución organizadora:
International AIDS Society
Resumen:
Background: During the late stages of the HIV-1 replication cycle, the viral precursor protein Pr55Gag (Gag) is recruited to plasma membrane (PM), where it directs HIV-1 assembly. Remarkably, the intracellular trafficking route followed by Gag remains poorly understood. The small GTPase Rab27a is a cellular protein involved in unconventional secretion pathways, such as exosome secretion. We hypothesized that, in order to reach the PM, Gag hijacks the endosomal trafficking pathway governed by Rab27a. Thus, in this study we investigated the role of Rab27a in Gag trafficking and HIV-1 assembly. Methods: The expression of Rab27a in purified CD4+ T lymphocytes, monocyte-derived macrophages and the lymphocytic CD4+ T cell line, Jurkat, was silenced by using an RNA interference approach. Cells were subsequently infected with HIV-1 and viral production was determined by quantitative ELISA. Intracellular Gag distribution and trafficking pathways were analyzed using a diverse array of cell biology and biochemistry techniques. The effectors recruited by Rab27a to perform its function were identified by screening the totality of Rab27a-effectors known up to date. Results: Rab27a controls membrane association of Gag, both in primary macrophages and CD4+T lymphocytes, the main targets of HIV-1 infection. In the absence of Rab27a, the levels of phosphatidylinositol-(4,5)-biphosphate [PI(4,5)P2] at the PM are decreased. Consequently, Gag remains cytosolic, impairing viral assembly and thus precluding HIV-1 replication. The establishment of virological synapses and viral transmission at points of cell-cell contacts also require functional Rab27a. To further characterize the pathway, the Rab27a effectors that participate in the arrival of Gag to the PM were identified. We show that knock-down of the effectors Slp2a, Slp3 and Slac2b, phenocopies that of Rab27a, regulating Gag association with the PM and viral assembly. Conclusions: During HIV-1 infection, Rab27a and three of its effectors control the levels of PI(4,5)P2 at the PM, thereby determining the recruitment of Gag and HIV-1 assembly. The identification of new host factors required for the last phases of the HIV-1 replication cycle opens an avenue for exploring their potential use as novel therapeutic targets.