Single-molecule super-resolution imaging of T-cell plasma membrane CD4 redistribution upon HIV-1 binding

Abstract

The first step of cellular entry for the human immunodeficiency virus type-1 (HIV-1) occurs through the binding of its envelope protein (Env) with the plasma membrane receptor CD4 and co-receptor CCR5 or CXCR4 on susceptible cells, primarily CD4+ T cells and macrophages. Although there is considerable knowledge of the molecular interactions between Env and host cell receptors that lead to successful fusion, the precise way in which HIV-1 receptors redistribute to sites of virus binding at the nanoscale remains unknown. Here, we quantitatively examine changes in the nanoscale organisation of CD4 on the surface of CD4+ T cells following HIV-1 binding. Using single-molecule super-resolution imaging, we show that CD4 molecules are distributed mostly as either individual molecules or small clusters of up to 4 molecules. Following virus binding, we observe a local 3-to-10-fold increase in cluster diameter and molecule number for virus-associated CD4 clusters. Moreover, a similar but smaller magnitude reorganisation of CD4 was also observed with recombinant gp120. For the first time, our results quantify the nanoscale CD4 reorganisation triggered by HIV-1 on host cells. Our quantitative approach provides a robust methodology for characterising the nanoscale organisation of plasma membrane receptors in general with the potential to link spatial organisation to function.

An HIV-1 CRISPR-Cas9 membrane trafficking screen reveals a role for PICALM intersecting endolysosomes and immunity

“…Finally, our data suggest that the targeting of PICALM affects CD4 + T cell health, increasing their proliferation, preserving their activation status and possibly influencing cell differentiation while reducing PD-1 expression. Considering that the SupT1 is a CD4 + /CXCR4 + /CCR5 - cell line is derived from a T cell lymphoblastic lymphoma 112 which likely differs from primary T cells found in vivo , it will be interesting to knock-out PICALM in primary CD4 + T cells to confirm the observations made in this study. Further investigations on the precise mechanisms are warranted, as this host protein may represent an interesting target that can benefit HIV-1 and cancer patients.…”