Sometimes the scary side of life sobers you up and wipes that stupid grin off your face. I just read that as of 2008, an estimated 1,178,350 people over the age of 13 were living with HIV in the United States. And, get this…20% were undiagnosed. So, let me stand up and clap loudly and throw flowers around the necks of the scientists trying to uncover all of HIV’s nasty secrets. Today’s image is from a paper describing how one of our own proteins binds to an HIV receptor, and negatively regulates HIV infection.
The HIV virus attaches to the membrane of a T-cell with the help of the HIV receptor proteins CD4 and CXCR4, which induce actin-mediated rearrangements that enhance entry of the virus into the cell. A recent paper identified a role for a protein called syntenin-1 in HIV entry. The adaptor protein syntenin-1 is implicated in many processes that involve polarization of the actin cytoskeleton, such as cell migration. According to Gordón-Alonso and colleagues, syntenin-1 is recruited to CD4 at the site of virus attachment to the cell, and negatively regulates virus entry by regulating actin reorganization. Overexpression of syntenin-1 inhibits HIV cell fusion and production, while depletion of syntenin-1 increases HIV entry. In the images above, T-cells were incubated with (bottom row) or without (top) HIV virus. In the presence of HIV virus, syntenin-1 (green) colocalizes with the cap of CD4 (red), which forms as a result of clustering of the receptor and enhances virus entry.
Gordón-Alonso M, Rocha-Perugini V, Alvarez S, Moreno-Gonzalo O, Ursa A, López-Martín S, Izquierdo-Useros N, Martínez-Picado J, Muñoz-Fernández MA, Yáñez-Mó M, & Sánchez-Madrid F (2012). The PDZ-adaptor protein syntenin-1 regulates HIV-1 entry. Molecular biology of the cell, 23 (12), 2253-2263 PMID: 22535526