7. Colon Follicle-associated epithelium Small intestine Mucus Proliferative compartment (PC) Differentiating compartment (DC) Desquamating cells Cell cycle arrest Stem cells (SC) compartment Stem cells compartment Cell cycle arrest PC DC Paneth cell Crypt-Based Columnar (Lgr5+) SC +4 Radiation-resistant SC Crypt-Based Columnar (Lgr5+) SC Paneth cells ? M cells Dendritic cells Macrophages T lymphocytes B Lymphocytes IEC Paneth cell Goblet cell Enterochromaffin cell The 4 gut epithelial lineages Proliferative progenitors Absorbtive secretory cells LieberkĆ¼hnās crypt A crypt-specific core microbiota in gut homeostasis, restitutionā¦ and cancer ? Crypt stem cells (Lgr5+) Lgr5-GFP Crypt-specific core microbiota FISH
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9. VirB ipaA, ipaB, ipaC, ipaD, ipgB1, ipgD , icsB, ospC2/3/4, ospD1, ospD2 ospD3, ospE1/2, ospG , ipaH1/2, ipaH4, ipaH7, ipaH9.8 MxiE Expression / regulation / function of type III effectors before secretion after TTSS activation (target cell recognition) INVASION Modulation of INNATE RESPONSES IpaB, IpaC, IpaA, IpgB1,VirA, IpgD IpgD : phosphatidyl-inositol phosphatase, hydrolyses P in 4 in Pi(4,5)P2 (Niebuhr et al, 2002, Pendaries et al, 2006 EMBO J.). Anti-inflammatory +++ (Puhar et al., in preparation). OspG : kinase,binds/blocks ubiquitin transfer protein E2, protects I-kB from degradation. Anti-inflammatory +++ (Kim et al., 2005, PNAS). OspF : dephosphorylation of Erk1/2, epigenetic regulation of pro-inflammatory genes - i.e. IL-8. Regulates transmigration of PMNs through epithelium (Arbibe et al., 2007,Nat.Immunol.). Phosphothreonine lyase (Li et al., 2007, Science). IpaHs : (5 + 5 chromosomal copies): New family of Ubiquitin ligases (E3) (Rohde et al., 2007, Cell Host & Microbes ) IpaH9.8 targets NEMO (Ashida et al., 2010, Nat.Cell Biol.) OTHER PHENOTYPES IcsB: inhibion or autophagy (Ogawa et al., 2005, Science) VirA: inhibition of microtubules, facilitates actin-based motility (Yoshida et al., 2006, Science) ospB ospF ospC1 virA
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11. Tran Van Nhieu et al., Nat. Cell Biol. 2003 Puhar et al., in preparation ATP = danger signal Inflammasome activation Differentiation of naive T cells to Ā«Ā inflammatoryĀ Ā» Th17 cells HEMICHANNEL (Connexins) xd xd xd xd xd xd xd xd xd IpgD Pi(4,5)P2 Pi(5)P IpgD IpgD neg. phenotype wt phenotype Pi(5)P IpgD impairs danger signaling
12. IpgD impairs T cell polarization PIP 2 binding causes ERM conformation change between inactive and active / phosphorylated forms ERM proteins Ezrin, Radixin, Moesin: crucial role in cell polarization during T lymphocyte migration Lee JH et al. 2003 IpgD-mediated PIP 2 cleavage with subsequent reduction of PIP 2 pool at the plasma membrane. What about pERM ? IpgD injection/expression causes hydrolysis of Pi(4,5)P2 and dephosphorylation of Ezrin IpgD-mediated hydrolysis of PI(4,5)P2 causes activated T cell depolarization and loss of oriented movement in presence of chemokine CXCL12 Konradt et al., Cell Host Microbe, 2011
13. CD4 + T cell dynamics at 4h mm/min Velocity Uninfected T3SS - WT Uninfected T3SS- WT Salgado-Pabon et al., in preparation Straightness Confinement Uninfected T3SS - WT *** *** *** % Arrest Arrest Uninfected T3SS - WT *** ***
14. Perspectives To continue to decipher the pathways of innate and adaptive protection against pathogens by analysing how bacterial Ā«Ā anti-immunityĀ Ā» effectors subvert the molecular and cellular mechanisms of immune defenses (i.e. target identification) To identify the molecular effectors and mechanisms by which symbionts regulate host local and systemic innate and adaptive immune responses, and other key areas reflecting the duration, intimacy and depth of the host-microbe symbiosis (i.e.: metabolism, tissue repair, cancerā¦) To rationally develop novel therapeutics and vaccines based on understanding microbe-host cross talks