Signaling Mechanism of HIV-1 gp120 and Virion-Induced IL-1β Release in Primary Human Macrophages

Abstract

HIV-1 envelope glycoprotein gp120 induces, independently of infection, the release of proinflammatory cytokines, including IL-1β from macrophages, that are implicated in the pathogenesis of HIV-associated dementia. However, the signal transduction pathways involved have not been fully defined. Previously, our laboratory reported that soluble gp120 activates multiple protein kinases in primary human monocyte-derived macrophages, including the Src family kinase Lyn, PI3K, and the focal adhesion-related proline-rich tyrosine kinase Pyk2. In this study we showed that gp120 induces IL-1β release from macrophages in a time- and concentration-dependent manner through binding to the chemokine receptor CCR5 and coupling to Giα protein. Using pharmacological inhibitors and small interfering RNA gene knockdown, we demonstrated that concomitant activation of Lyn, Pyk2, and class IA PI3K are required for gp120-induced IL-1β production. By coimmunoprecipitation and immunofluorescence confocal microscopy, we showed that CCR5 activation by gp120 triggered the assembly of a signaling complex involving endogenous Lyn, PI3K, and Pyk2 and is associated with PI3K and Pyk2 translocation from the cytoplasm to the membrane where they colocalized with Lyn. Finally, we demonstrated that virion-associated gp120 induced similar response, as structurally intact whole virions also triggered IL-1β release and re-localization of PI3K and Pyk2. This study identifies a novel signaling mechanism for HIV-1-induced IL-1β production by primary human macrophages that may be involved in the neuropathogenesis of HIV-associated dementia.

Development of real-time RT-PCR for human metapneumovirus

“…Here, we have shown by several different techniques that there is a dramatic increase in Lyn kinase mRNA levels, suggesting that Lyn kinase is an enzyme with a potentially novel function that we observed in the THP-1 monocytes HCMV exposed to HCMV. These results are in agreement with a previous study conducted by Cheung and co-workers (Cheung et al, 2008), who have demonstrated that concomitant activation of Lyn kinase is required for HIV-1 envelope glycoprotein gp120-induced cytokine production in primary human monocyte-derived macrophages.…”

HIV-1 Proteins Preferentially Activate Anti-Inflammatory M2-Type Macrophages

“…Using the widely used method to prepare M2-MF (M-CSF derived) and M1-MF (GM-CSF derived) (13-16), we examined whether soluble Tat, gp120, or Nef differentially activated these MF by comparing the activation of MAPK, such as p38, JNK, and ERK. As reported (18)(19)(20)(21)(22)(23)(24)(25)(26)(27), all soluble HIV-1 proteins clearly activated p38 (Supplemental Fig. 1B).…”

HIV-1 gp120 Activates the STAT3/Interleukin-6 Axis in Primary Human Monocyte-Derived Dendritic Cells

“…Previous studies aimed at characterizing signal transduction pathways triggered by gp120 upon coreceptor engagement revealed that while some of them are activated by both gp120 and CCL4, others are uniquely triggered by gp120 (54)(55)(56)(57)(58)(59)(60). In this respect, it was reported that gp120, as well as CCL4, opened calcium-activated potassium-, chloride-, and calcium-permeant nonselective cation channels in macrophages.…”