Biology subjects

Anandachar, M. S.

Publications and source records attributed to Anandachar, M. S..

3 recordsLinked to original sources

bioRxiv2022

The crosstalk between microbial sensors ELMO1 and NOD2 shape intestinal immune responses

Microbial sensors play an essential role in maintaining cellular homeostasis. Our knowledge is limited on how microbial sensing helps in differential immune response and its link to inflammatory diseases. Recently, we have shown that cytosolic sensor ELMO1 (Engulfment and Cell Motility Protein-1) binds to effectors from pathogenic bacteria and controls intestinal inflammation. Here, we show that ELMO1 interacts with another sensor, NOD2 (Nucleotide-binding oligomerization domain-containing protein 2), that recognizes bacterial cell wall component muramyl dipeptide (MDP). The polymorphism of NOD2 is linked to Crohns disease (CD) pathogenesis. Interestingly, we found that overexpression of ELMO1 and mutant NOD2 (L1007fs) were not able to clear the CD-associated adherent invasive E. coli (AIEC-LF82). To understand the interplay of microbial sensing of ELMO1-NOD2 in epithelial cells and macrophages, we used enteroid-derived monolayers (EDMs) from ELMO1 and NOD2 KO mice and ELMO1 and NOD2-depleted murine macrophage cell lines. The infection of murine EDMs with AIEC-LF82 showed higher bacterial load in ELMO1-KO, NOD2 KO EDMs, and ELMO1 KO EDMs treated with NOD2 inhibitors. The murine macrophage cells showed that the downregulation of ELMO1 and NOD2 is associated with impaired bacterial clearance that is linked to reduced pro-inflammatory cytokines and reactive oxygen species. Our results indicated that the crosstalk between microbial sensors in enteric infection and inflammatory diseases impacts the fate of the bacterial load and disease pathogenesis.

microbiology↗

bioRxiv2022

Coupling of NOD2 to GIV is Required for Bacterial Sensing

ABSTRACT/SUMMARYSensing of pathogens by Nucleotide oligomerization domain (NOD)-like 2 receptor (NOD2) induces a protective inflammatory response that coordinates bacterial clearance. Polymorphisms in NOD2 impair bacterial clearance, leading to chronic gut inflammation in Crohns disease (CD) via mechanisms that remain incompletely understood. We identify GIV/Girdin (CCDC88A) as a NOD2-interactor that shapes bacterial sensing-and-signaling in macrophages. Myeloid-specific GIV depletion exacerbated and protracted infectious colitis and abolished the protective effect of muramyl dipeptide (MDP) in both chemical colitis and severe sepsis. In the presence of GIV, macrophages enhance anti-bacterial pathways downstream of NOD2, clear microbes rapidly and concomitantly suppress inflammation. GIVs actions are mediated via its C-terminus, which directly binds the terminal leucine-rich repeat (LRR#10) of NOD2; binding is augmented by MDP and ATP, precedes receptor oligomerization, and is abolished by the 1007fs CD-risk variant which lacks LRR#10. Findings illuminate mechanisms that underlie protective NOD2 signaling and loss of function in the major 1007fs variant. In briefThis work reveals a mechanism by which macrophages use their innate immune sensor, NOD2, to protect the host against overzealous inflammation during bacterial infections, and the consequences of its loss, as occurs in the most important Crohns disease-risk variant. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/489574v2_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@139a1feorg.highwire.dtl.DTLVardef@ba5354org.highwire.dtl.DTLVardef@b4d933org.highwire.dtl.DTLVardef@11fe12e_HPS_FORMAT_FIGEXP M_FIG GRAPHIC ABSTRACT C_FIG HIGHLIGHTSO_LIGIV is a functional and direct interactor of the terminal LRR repeat of NOD2 C_LIO_LIMice lacking M[FE] GIV develop dysbiosis, protracted ileocolitis and sepsis C_LIO_LIMDP/NOD2-dependent protective host responses require GIV C_LIO_LICD-risk NOD2 1007fs variant lacking the terminal LRR#10 cannot bind GIV C_LI

immunology↗

bioRxiv2021

The interaction of enteric bacterial effectors with the host engulfment pathway control innate immune responses

BackgroundHost engulfment protein ELMO1 generates intestinal inflammation following internalization of enteric bacteria. In Shigella, bacterial effector IpgB1 interacts with ELMO1 and promotes bacterial invasion. IpgB1 belongs to the WxxxE effector family, a motif found in several effector of enteric pathogens. Here, we have studied the role of WxxxE effectors, with emphasis on Salmonella SifA and whether it interacts with ELMO1 to regulate inflammation. MethodologyIn-silico-analysis of WxxxE effectors was performed using BLAST search and Clustal W program. The interaction of ELMO1 with SifA was assessed by GST pulldown assay and co-immunoprecipitation. ELMO1 knock-out mice, and ELMO1-depleted murine macrophage J774 cell lines were challenged with WT and SifA mutant Salmonella. Bacterial effectors containing the WxxxE motif were transfected in WT and ELMO1-depleted J774 cells to assess the inflammatory cytokines. ResultsELMO1 generates differential pro-inflammatory cytokines between pathogenic and non-pathogenic bacteria. WxxxE motif is present in pathogens and in the TIR domain of host proteins. The C-terminal part of ELMO1 interacts with SifA where WxxxE motif is important for interaction. ELMO1-SifA interaction affects the bacterial colonization, dissemination, and inflammatory cytokines in vivo. Moreover, ELMO1-SifA interaction increases TNF- and IL-6 production from the macrophage cell line and is associated with enhanced Rac1 activity. ELMO1 also interacts with WxxxE effectors IpgB1, IpgB2, and Map, and induces inflammation after challenge with microbe or microbial ligand. ConclusionELMO1 generates a differential response through interaction with the WxxxE motif which is absent in commensals. ELMO1-WxxxE interaction plays a role in bacterial pathogenesis and induction of inflammatory response. HighlightsO_LIELMO1 generates a differential immune response between enteric pathogens and commensals. C_LIO_LIEnteric bacterial effectors containing WxxxE signature motif interact with ELMO1. C_LIO_LIThe WxxxE effector of Salmonella SifA interacts with the C-terminal part of ELMO1. C_LIO_LIELMO1-SifA interaction increases the inflammatory response in vivo and in vitro. C_LI

microbiology↗