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dc.contributor.advisorHamza, Iqbalen_US
dc.contributor.authorKorolnek, Tamaraen_US
dc.date.accessioned2014-10-11T05:44:45Z
dc.date.available2014-10-11T05:44:45Z
dc.date.issued2014en_US
dc.identifierhttps://doi.org/10.13016/M2K592
dc.identifier.urihttp://hdl.handle.net/1903/15744
dc.description.abstractHemes are metalloporphyrins used by nearly all organisms as cofactors for proteins involved in respiration, binding and sensing gases, and as catalysts for various reactions. Despite extensive knowledge about heme biosynthesis and catabolism, the pathways for transporting heme between cells and within cells remain poorly understood. C. elegans serves as a unique animal model for uncovering these pathways, as it is unable to synthesize its own heme and depends on the uptake of dietary heme for growth and reproduction. Functional RNAi screens implicated mrp-5 as a potential heme transporter in C. elegans. This gene encodes a membrane-bound ABC transporter that localizes to the basolateral intestinal membrane and is required for worm growth and reproduction. Depletion of mrp-5 activates heme deprivation signals within the worm, protects worms from toxicity associated with a toxic heme analog, and results in worms accumulating the fluorescent heme analog, zinc mesoporphyrin IX, in intestinal cells. Taken together, these results indicate a defect in heme export from the intestine when MRP-5 activity is lost. Functional assays in yeast support the hypothesis that MRP-5 is capable of exporting heme across cell membranes, and that this function is conserved in the human ortholog. Knockdown of mrp5 in zebrafish embryos results in developmental defects and decreased blood formation, indicating that this transporter likely regulates heme homeostasis in vertebrates. Loss of Mrp5 in mammalian cells leads to decreased heme transport into the secretory pathway as measured by activity of a Golgi-targeted heme-dependent enzyme. Furthermore, macrophages from mice lacking Mrp5 are unable to activate a number of cellular responses when undergoing erythrophagocytosis, the process whereby the heme-iron in senescent red bloods is recycled. Altogether, our results implicate MRP-5 as a key heme transporter in C. elegans, and point to an evolutionarily conserved role for MRP5 proteins in regulating heme homeostasis.en_US
dc.language.isoenen_US
dc.titleMRP5/ABCC5, A CONSERVED ABC TRANSPORTER, REGULATES METAZOAN HEME HOMEOSTASISen_US
dc.typeDissertationen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.contributor.departmentMolecular and Cell Biologyen_US
dc.subject.pqcontrolledMolecular biologyen_US
dc.subject.pqcontrolledCellular biologyen_US
dc.subject.pqcontrolledGeneticsen_US
dc.subject.pquncontrolledABC transporteren_US
dc.subject.pquncontrolledC. elegansen_US
dc.subject.pquncontrolledhematologyen_US
dc.subject.pquncontrolledhemeen_US
dc.subject.pquncontrolledironen_US
dc.subject.pquncontrolledmicronutrientsen_US


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