Recent published work in our laboratory has shown a profound downregulation of atypical PKC in intestinal epithelial cells under TNF? stimulation, in the DSS model of murine colitis, and in Inflammatory Bowel Disease patients. In this project we will analyze mechanistically the consequences of aPKC loss on cellular functions, signaling pathways, and molecular effectors, known to be essential in the pathophysiological of IBD in these cells. Our preliminary data strongly indicate that a decrease in aPKC activity comparable to that observed in the animal model and in patients, is sufficient to trigger activation of the classic I?B pathway independently of TNFR. This observation opens the possibility that signaling downstream of aPKC may establish a negative feedback that keeps epithelial cells in an "inflamed" condition even if the original cytokine stimulaton is removed. If our hypothesis is correct, breaking this cycle may help to rapidly correct barrier defects and cytokine secretion by epithelial cells, which would be desirable in chronic intestinal inflammation. Moreover, since these pathways are specific to epithelial cells, understanding them may allow tissue-specific interventions. The mechanistic aspects and the consequences of this phenomenon will be studied in Aim 1. Our preliminary data also shows that a similar transient event occurs in epithelial wounds, suggesting the hypothesis that it may also be involved in the early stages of epithelial restitution, which will b tested in Aim 2. Finally, the molecular mechanisms studied in aims 1 and 2 will be analyzed in in the context of an animal model of colitis in Aim 3. Altogether the project is expeced to establish a totally novel signaling pathway, identify its normal function, and bring new, as ye unsuspected possible therapeutic targets to modulate the epithelial response to inflammation.
Inflammatory Bowel Disease is a multi-factorial aberrant response of the immune system that, among other effects, impacts on the layer of cells lining the intestinal lumen, the epithelium. This project studies a novel intracellular signaling pathway in the epithelium that counteracts the effects of inflammation. Importantly, if our hypothesis is correct, inhibition of this new pathway may contribute to the persistence of the effects of inflammation and may provide new unsuspected therapeutic opportunities.
|Kravtsov, Dmitri; Mashukova, Anastasia; Forteza, Radia et al. (2014) Myosin 5b loss of function leads to defects in polarized signaling: implication for microvillus inclusion disease pathogenesis and treatment. Am J Physiol Gastrointest Liver Physiol 307:G992-G1001|
|Mashukova, Anastasia; Wald, Flavia A; Salas, Pedro J (2011) Tumor necrosis factor alpha and inflammation disrupt the polarity complex in intestinal epithelial cells by a posttranslational mechanism. Mol Cell Biol 31:756-65|
|Wald, Flavia A; Forteza, Radia; Diwadkar-Watkins, Runa et al. (2011) Aberrant expression of the polarity complex atypical PKC and non-muscle myosin IIA in active and inactive inflammatory bowel disease. Virchows Arch 459:331-8|
|Pfister, Amber B; Wood, Robert C; Salas, Pedro J I et al. (2010) Early response to ErbB2 over-expression in polarized Caco-2 cells involves partial segregation from ErbB3 by relocalization to the apical surface and initiation of survival signaling. J Cell Biochem 111:643-52|
|Mashukova, Anastasia; Oriolo, Andrea S; Wald, Flavia A et al. (2009) Rescue of atypical protein kinase C in epithelia by the cytoskeleton and Hsp70 family chaperones. J Cell Sci 122:2491-503|
|Gattas, Monica Valencia; Forteza, Radia; Fragoso, Miryam A et al. (2009) Oxidative epithelial host defense is regulated by infectious and inflammatory stimuli. Free Radic Biol Med 47:1450-8|
|Wald, Flavia A; Oriolo, Andrea S; Mashukova, Anastasia et al. (2008) Atypical protein kinase C (iota) activates ezrin in the apical domain of intestinal epithelial cells. J Cell Sci 121:644-54|
|Oriolo, Andrea S; Wald, Flavia A; Ramsauer, Victoria P et al. (2007) Intermediate filaments: a role in epithelial polarity. Exp Cell Res 313:2255-64|
|Oriolo, Andrea S; Wald, Flavia A; Canessa, Gisella et al. (2007) GCP6 binds to intermediate filaments: a novel function of keratins in the organization of microtubules in epithelial cells. Mol Biol Cell 18:781-94|