Unraveling mechanisms behind cross presentation during phagocytic signaling

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dc.contributor.advisorShi, Yan
dc.contributor.authorHari, Aswin
dc.date.accessioned2014-01-29T21:39:28Z
dc.date.available2014-03-15T07:00:20Z
dc.date.issued2014-01-29
dc.date.submitted2014en
dc.description.abstractMHC class I antigens come from endogenous syntheses, while class II antigens are obtained extracellularly via endocytosis. Cross presentation is the link between the two by which external antigens are targeted to the MHC class I pathway. It is generally accepted that particulate antigens are more efficient in this pathway switch. However the reason behind this phenomenon is unknown. We report that dendritic cell engagement of a phagocytic target limits endocytic maturation and inhibits the associated proteolytic activities. In this scenario, early endosomes show reduced progression towards late endosomes/lysosomes and remain spatially close to the cell membrane. In phagocytosis, the microtubular (MT) system, including tubulin filaments and microtubule organization centers (MTOCs), are heavily skewed toward the engulfed particulate matter; the remaining cytoplasmic volumes are relatively devoid of MT presence. This is accompanied by a reduced centripetal movement inward and the maturation of endosomes. The antigen processing in these arrested endosomes is under the control of Nicotinamide adenine dinucleotide phosphate-oxidase (NAPDH)-associated ROS. We also show that cathepsin S is responsible for the generation of the class I epitope for cross presentation. The rerouted antigen presentation is at least 40 fold more efficient than the same amount of antigen delivered through the phagocytic pathway, and is operational in vivo. Our results suggest that in DCs in addition to solid structure uptake, phagocytosis directs a coordinated set of enzymatic and cytoskeletal events that regulate endosomal trafficking and maturation. As a consequence, external soluble antigens are driven away from their conventional MHC class II processing, into the class I cross presentation pathway.en_US
dc.identifier.citationHari, A. (2014). Unraveling mechanisms behind cross presentation during phagocytic signaling (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/28591en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/28591
dc.identifier.urihttp://hdl.handle.net/11023/1324
dc.language.isoeng
dc.publisher.facultyGraduate Studies
dc.publisher.institutionUniversity of Calgaryen
dc.publisher.placeCalgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subjectImmunology
dc.subject.classificationcross presentationen_US
dc.titleUnraveling mechanisms behind cross presentation during phagocytic signaling
dc.typedoctoral thesis
thesis.degree.disciplineMicrobiology & Infectious Diseases
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameDoctor of Philosophy (PhD)
ucalgary.item.requestcopytrue
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