Dual role for RhoA in suppression and induction of cytokines in the human neutrophil

Michael B. Fessler, Patrick G. Arndt, Ingo Just, Jerry A. Nick, Kenneth C. Malcolm, G. Scott Worthen

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Production of tumor necrosis factor-α (TNFα) by the neutrophil (PMN) is a pivotal event in innate immunity, but the signals regulating TNFα induction in this primary cell are poorly understood. Herein, we use protein transduction to identify novel, opposing anti- and pro-cytokine-inducing roles for RhoA in the resting and lipopolysaccharide (LPS)-stimulated human PMN, respectively. In the resting cell, RhoA suppresses Cdc42 activation, IκBα degradation, nuclear factor-κB (NF-κB) activation, and induction of TNFα and NF-κB-dependent chemokines. Suppression of TNFα induction by RhoA is Rho kinase α (ROCKα) independent, but Cdc42 dependent, because TNFα induction by C3 transferase is attenuated by inhibition of Cdc42, and constitutively active Cdc42 suffices to activate NF-κB and induce TNFα. By contrast, we also place RhoA downstream of p38 mitogen-activated protein kinase and Cdc42 in a novel LPS-activated pathway in which p38, Cdc42, and ROCKα all promote TNFα protein expression. The p65 subunit of NF-κB coprecipitates with RhoA in a manner sensitive to the RhoA activation state. Our findings suggest a new, 2-faced role for RhoA as a checkpoint in innate immunity.

Original languageEnglish (US)
Pages (from-to)1248-1256
Number of pages9
JournalBlood
Volume109
Issue number3
DOIs
StatePublished - Feb 1 2007

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