Aggregation of RANTES Is Responsible for Its Inflammatory Properties: CHARACTERIZATION OF NONAGGREGATING, NONINFLAMMATORY RANTES MUTANTS

Victor Appay,Anthony Brown,Scott Cribbes,Eliot Randle,Lloyd G Czaplewski

doi:10.1074/jbc.274.39.27505

Abstract

The biology of RANTES (regulated on activation normal T cell expressed) aggregation has been investigated using RANTES and disaggregated variants, enabling comparison of aggregated, tetrameric, and dimeric RANTES forms. Disaggregated variants retain their G(i)-type G protein-coupled receptor-mediated biological activities. A correlation between RANTES aggregation and cellular activation has been demonstrated. Aggregated RANTES, but not disaggregated RANTES, activates human T cells, monocytes, and neutrophils. Dimeric RANTES has lost its cellular activating activity, rendering it noninflammatory. Macrophage inflammatory protein 1alpha, macrophage inflammatory protein-1beta, and erythrocytes are potent natural antagonists of aggregated RANTES-induced cellular activation. There is a clear difference in the signaling properties of aggregated and disaggregated RANTES forms, separating the dual signaling pathways of RANTES and the enhancing and suppressive effects of RANTES on human immunodeficiency virus infection. Disaggregated RANTES will be a valuable tool to explore the biology of RANTES action in human immunodeficiency virus infection and in inflammatory disease.

Highlights

The biology of RANTES aggregation has been investigated using RANTES and disaggregated variants, enabling comparison of aggregated, tetrameric, and dimeric RANTES forms
We show that erythrocytes inhibit cellular activation by RANTES, and we have identified MIP-1␣ and MIP-1␤ and disaggregated RANTES as potent antagonists of RANTES-induced cellular activation
Characterization of the Self-association and Gi-type G protein-coupled receptor (GPCR) Biology of RANTES and Disaggregated RANTES Mutants— The concentration-dependent self-association of RANTES, RANTES E26A, RANTES E66S, and RANTES E26A/E66S was analyzed by sedimentation equilibrium analytical ultracentrifugation at 0.1 and 0.5 mg/ml (Table I)

Summary

Introduction

The biology of RANTES (regulated on activation normal T cell expressed) aggregation has been investigated using RANTES and disaggregated variants, enabling comparison of aggregated, tetrameric, and dimeric RANTES forms. RANTES expression has been associated with transplant rejection, atherosclerosis, arthritis, atopic dermatitis, airway inflammatory disorders, delayed type hypersensitivity reactions, glomerular nephritis, asthma, endometriosis, and cancers (4 – 8) In addition, RANTES may be a key regulator of HIV-1 infection It is the most potent natural chemokine inhibitor of M-tropic HIV-1 infection (9), but at high concentration can act as a stimulator, enhancing viral. RANTES-induced stimulation of the low affinity PTK pathway leads to T cell activation, including proliferation of T cells, induction of interleukin-2 (IL-2) expression, homotypic aggregation and increases in expression of cell surface molecules such as the IL-2 receptor (CD25), CD49, CD28, CD11b, and CD11c (13–15) Both the Gi-type GPCR- and PTK-mediated responses to RANTES stimulation can be studied independently by assessing calcium mobilization in THP-1 cells, which respond only via the Gi-type GPCR signaling pathway, or in CD3ϩ Jurkat cells, which respond only via the PTK pathway (16). These studies lead us to conclude that at high concentration, RANTES is a potent immune modulator, distinct from antigen, which activates T cells, and may be an important factor in immune pathologies lacking obvious antigenic stimulation

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