Actin-based confinement of calcium responses during Shigella invasion

Endogenous TRPV1 stimulation leads to the activation of the inositol phospholipid pathway necessary for sustained Ca2+ oscillations

“…The pGFP-TRPV1 plasmid resulting in a GFP-TRPV1 fusion protein, as well as the plasmid pTRPV1 encoding full-length TRPV1 were used in this study. The plasmid encoding InsP 3 5-phosphatase (pIRES-InsP3-5P-GFP) was a kind gift from Christophe Erneux, IRIBHM, Bruxelles [23]. The BFP-KDEL plasmid for ER visualization was a gift from Gia Voeltz; Addgene plasmid #49,150.…”

The Shigella type III effector IpgD recodes Ca 2+ signals during invasion of epithelial cells

“…Using computational modeling, we previously showed that restricted diffusion and increased InsP 3 synthesis at invasion sites accounted for local and long‐lasting Ca 2+ responses (RATPs) observed during invasion of WT Shigella (Tran Van Nhieu et al , ). We then used the model to investigate the respective roles of restricted diffusion and InsP 3 levels in IpgD‐mediated confinement of Ca 2+ responses during Shigella invasion ().…”

“…For the quantification of PI(4,5)P 2 enrichment fold, the average fluorescence intensity of the PH‐PLC δ1 probe of Shigella invasion foci in transfected cells corrected to background was normalized by the average fluorescence intensity of a control area in the same transfected cell. A similar method was applied to quantify the enrichment fold of InsP 3 R1 except that samples were subjected to quantitative immunofluorescence staining as described previously (Tran Van Nhieu et al , ). For focal adhesion numbers and cell adhesion surface quantification, a semi‐automated protocol was developed using Icy bioimaging software (de Chaumont et al , ).…”

The Inside Story of Shigella Invasion of Intestinal Epithelial Cells

“…These calcium responses can occur in the absence of extracellular calcium and are elicited by InsP 3 -mediated release of intracellular pools, in a process implicating PLC-b1 and PLC-d1. As for actin polymerization, Shigella-induced InsP 3 -mediated signaling does not appear to depend on injected T3S effectors, and is totally abolished in mutants for the translocon component IpaC (Tran Van Nhieu et al 2013). As described for pore-forming toxins, insertion of the Shigella translocon in the plasma membrane may lead to the destabilization of lipid bilayers leading to the activation of PLCs, that hydrolyze PIP 2 to induce InsP 3 -mediated signaling (García-Sáez et al 2011).…”

“…First, although inactivation of the above-mentioned injected T3S effectors only lead to a partial decrease of bacterial invasion, mutations in the translocon component IpaC that does not prevent effector translocation totally abolishing bacterial-induced actin polymerization and Shigella uptake (Mounier et al 2009). Interestingly, Shigella induces calcium responses localized at the site of bacterial invasion that, unlike bacterial-induced global calcium responses, are required for actin polymerization at entry sites (Tran Van Nhieu et al 2013). These calcium responses can occur in the absence of extracellular calcium and are elicited by InsP 3 -mediated release of intracellular pools, in a process implicating PLC-b1 and PLC-d1.…”