Siglec1 interactome after HIV-1 binding

Abstract

CD4 T lymphocytes are the main target cells of HIV-1. However, myeloid cells can also become infected by HIV-1 through interaction with CD4/CCR5 receptors. Macrophages can survive infected for long periods and present compartments containing viruses (VCCs), where HIV-1 accumulates and remains infective. For these reasons, macrophages may be potential viral reservoirs. On the other hand, dendritic cells (DCs) are rarely infected by HIV-1, but are able to uptake viruses and keep them in compartments where they are not degraded. They are also able to perform viral transfer to CD4 T cells through the trans-infection process. The capture of HIV-1 by mature DCs in trans-infection is mediated by Siglec1, a lectin from the immunoglobulin superfamily. Siglec1 binds to sialic acid from GM3 gangliosides in the viral envelope and is also expressed by macrophages, where it plays a role in the formation of VCCs. However, the molecular mechanisms of internalization and signaling by Siglec1 are not well elucidated. Therefore, the aim of this work is to identify proteins that interact with Siglec1, in DCs and macrophages, after their binding to HIV-1. Thus, we intend to perform a co-immunoprecipitation of Siglec1 on human macrophages and DCs after incubation with HIV-1. The proteins will be analyzed by mass spectrometry, and validated by microscopy and Western blotting. In addition, proteins of interest identified by mass spectrometry will be silenced in DCs and macrophages and these cells will be used in functional experiments such as trans-infection and infection. The understanding of the molecular mechanisms involved in the interaction of Siglec1 with HIV-1 may support the development of new therapeutic strategies in the future, focusing on the dispersion of the virus by DCs and in the reservoirs in macrophages. (AU)