CCR5 signal transduction in macrophages by human immunodeficiency virus and simian immunodeficiency virus envelopes - PubMed (original) (raw)

CCR5 signal transduction in macrophages by human immunodeficiency virus and simian immunodeficiency virus envelopes

J Arthos et al. J Virol. 2000 Jul.

Abstract

The capacity of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) envelopes to transduce signals through chemokine coreceptors on macrophages was examined by measuring the ability of recombinant envelope proteins to mobilize intracellular calcium stores. Both HIV and SIV envelopes mobilized calcium via interactions with CCR5. The kinetics of these responses were similar to those observed when macrophages were treated with MIP-1beta. Distinct differences in the capacity of envelopes to mediate calcium mobilization were observed. Envelopes derived from viruses capable of replicating in macrophages mobilized relatively high levels of calcium, while envelopes derived from viruses incapable of replicating in macrophages mobilized relatively low levels of calcium. The failure to efficiently mobilize calcium was not restricted to envelopes derived from CXCR4-utilizing isolates but also included envelopes derived from CCR5-utilizing isolates that fail to replicate in macrophages. We characterized one CCR5-utilizing isolate, 92MW959, which entered macrophages but failed to replicate. A recombinant envelope derived from this virus mobilized low levels of calcium. When macrophages were inoculated with 92MW959 in the presence of MIP-1alpha, viral replication was observed, indicating that a CC chemokine-mediated signal provided the necessary stimulus to allow the virus to complete its replication cycle. Although the role that envelope-CCR5 signal transduction plays in viral replication is not yet understood, it has been suggested that envelope-mediated signals facilitate early postfusion events in viral replication. The data presented here are consistent with this hypothesis and suggest that the differential capacity of viral envelopes to signal through CCR5 may influence their ability to replicate in macrophages.

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Figures

FIG. 1

FIG. 1

Flow cytometric intracellular calcium analysis of MDMs. CCR5 wild-type MDMs (A, B, E, F, and G) or CCR5-Δ32 MDMs (C and D) loaded with indo-1 were stimulated with 20 nM JR-FL gp140 (A and C), 20 nM MIP-1β (B), 20 nM SDF-1 (D), 20 nM NL4-3 gp140 (E), 20 nM PBj gp120 (F), or 20 nM Mac239 gp120 (G). Titration of JR-FL gp140 against CCR5 wild-type MDMs (H) was carried out in triplicate. Data shown are representative of at least three independent experiments using different donor MDMs.

FIG. 2

FIG. 2

Macrophage infection by HIV-1 Bal and 92MW959. (A) p24 antigen in MDM culture supernatants measured over a 12-day culture for 92MW959 and a control M-tropic isolate, HIV-1 Bal. d, day. (B) Cellular DNA PCR analysis of the entry of 92MW959 and Bal into MDMs as measured by using R/U5-specific primers (M667 and AA55).

FIG. 3

FIG. 3

Comparison of calcium mobilized in MDMs from a single donor by JR-FL gp140 and 92MW959 gp140. MDMs were treated with JR-FL gp140 or 92MW959 at a concentration of 200, 20, or 2 nM. Data shown are representative of at least three independent experiments.

FIG. 4

FIG. 4

(A) Replication of 92MW959 in the presence or absence of exogenous MIP-1α (0.1 μg/ml). A representative Ca+ mobilization of MDMs by MIP-1α is shown in the insert. (B) Replication of 2005 in the presence or absence of exogenous MIP-1β. Viral replication was assessed by measurement of p24 antigen in culture supernatants. Data shown are representative of at least three independent experiments.

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