Citation

  • Authors: Kumar A. et al.
  • Year: 2022
  • Journal: Cell Death Dis 13 520
  • Applications: in vitro / siRNA / in vivo-jetPEI

Method

In total, 6–8-week-old BALB/c mice were intravenously injected with siRNA complexed with in-vivo jetPEI for knockdown of mRnd1. Mice were randomly allocated for injection of either siCtrl or siRnd1. In all, 24 h later, mice were infected with PR8, and after 48 h, lung tissue and BAL fluids were collected. Knockdown efficiency in lung tissue was analysed by RT-PCR followed by analysis of viral load by RT-PCR in lung tissue and TCID50 assay in BAL fluid. For delivery of siRNA to liver and spleen mice were intra-peritoneally injected with siRNA complexed with in-vivo jetPEI. In all, 24 h after transfection, mice were infected intravenously with L. monocytogenes. In all, 24 h post-infection, mice were euthanized, and spleen and liver were collected, and knockdown efficiency was confirmed using RT-PCR. Tissues were homogenised, and L. monocytogenes load was analysed by colony formation assay. RT-PCR was used to analyse mIL-6 and mTNF-α RNA relative to mGAPDH RNA.

Abstract

Intracellular and cell surface pattern-recognition receptors (PRRs) are an essential part of innate immune recognition and host defense. Here, we have compared the innate immune responses between humans and bats to identify a novel membrane-associated protein, Rnd1, which defends against viral and bacterial infection in an interferon-independent manner. Rnd1 belongs to the Rho GTPase family, but unlike other small GTPase members, it is constitutively active. We show that Rnd1 is induced by pro-inflammatory cytokines during viral and bacterial infections and provides protection against these pathogens through two distinct mechanisms. Rnd1 counteracts intracellular calcium fluctuations by inhibiting RhoA activation, thereby inhibiting virus internalisation. On the other hand, Rnd1 also facilitates pro-inflammatory cytokines IL-6 and TNF-α through Plxnb1, which are highly effective against intracellular bacterial infections. These data provide a novel Rnd1-mediated innate defense against viral and bacterial infections.

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