Nascent RHOH acts as a molecular brake on actomyosin-mediated effector functions of inflammatory neutrophils

PLoS Biol. 2022 Sep 15;20(9):e3001794. doi: 10.1371/journal.pbio.3001794. eCollection 2022 Sep.

Abstract

In contrast to molecular changes associated with increased inflammatory responses, little is known about intracellular counter-regulatory mechanisms that control signaling cascades associated with functional responses of neutrophils. Active RHO GTPases are typically considered as effector proteins that elicit cellular responses. Strikingly, we show here that RHOH, although being constitutively GTP-bound, limits neutrophil degranulation and the formation of neutrophil extracellular traps (NETs). Mechanistically, RHOH is induced under inflammatory conditions and binds to non-muscle myosin heavy chain IIA (NMHC IIA) in activated neutrophils in order to inhibit the transport of mitochondria and granules along actin filaments, which is partially reverted upon disruption of the interaction with NMHC IIA by introducing a mutation in RhoH at lysine 34 (RhoHK34A). In parallel, RHOH inhibits actin polymerization presumably by modulating RAC1 activity. In vivo studies using Rhoh-/- mice, demonstrate an increased antibacterial defense capability against Escherichia coli (E. coli). Collectively, our data reveal a previously undefined role of RHOH as a molecular brake for actomyosin-mediated neutrophil effector functions, which represents an intracellular regulatory axis involved in controlling the strength of an antibacterial inflammatory response.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actins / metabolism
  • Actomyosin* / metabolism
  • Animals
  • Anti-Bacterial Agents
  • Cytoskeletal Proteins / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Guanosine Triphosphate
  • Lysine
  • Mice
  • Myosin Heavy Chains / metabolism
  • Neutrophils* / metabolism
  • Transcription Factors* / metabolism
  • rho GTP-Binding Proteins* / genetics
  • rho GTP-Binding Proteins* / metabolism

Substances

  • Actins
  • Anti-Bacterial Agents
  • Cytoskeletal Proteins
  • RhoH protein, mouse
  • Transcription Factors
  • Guanosine Triphosphate
  • Actomyosin
  • Myosin Heavy Chains
  • rho GTP-Binding Proteins
  • Lysine

Grants and funding

This work was supported by the Swiss National Science Foundation (grant No. 310030_184816 to HUS and 31003A_173215 to SY) and the Russian Government Program “Recruitment of the Leading Scientists into the Russian Institutions of Higher Education” (grant No. 075-15-2021-600 to HUS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.