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Ramadan Ali_PhD Dissertation.pdf (3.59 MB)

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NAADP-Mediated Calcium Release in Mammalian Cells: Regulation of Naive and Effector T Cell Functions by NAADP

Ali, Ramadan
http://rave.ohiolink.edu/etdc/view?acc_num=mco1415826878

Abstract Details

2014, Doctor of Philosophy (PhD), University of Toledo, Medicinal Chemistry.
Nicotinic acid adenine dinucleotide phosphate (NAADP) is the most potent Ca2+ mobilizing second messenger identified to date. The mechanism of NAADP-mediated Ca2+ release is not completely understood. The nature of the NAADP targeted intracellular Ca2+ store as well as the molecular identity of its receptor is controversial. The structural features of NAADP required for receptor recognition is best characterized in sea urchin eggs, however, it is not known in mammalian cells. The studies described had two aims. The first aim was to investigate whether NAADP exhibits similar or different structure activity relationships (SAR) between sea urchin and mammalian cells. I synthesized novel caged 4- and 5- substituted NAADP analogs that could be activated inside the cell by flash photolysis. Their ability to mobilize Ca2+ via the NAADP receptor in the mammalian cell line SKBR3 was characterized using microinjection and single cell fluorescent imaging methods. The SAR in mammalian SKBR3 was quite different from that of sea urchin eggs. I found that the substituted NAADP analogs tested differed in activity between sea urchin and SKBR3 cells with respect to relative potencies and efficacy. This study indicated a difference in specificity for the tested analogs between the human SKBR3 and sea urchin NAADP receptor and suggests that NAADP receptors exhibit diversity across species and between tissues. The second aim was to investigate NAADP-mediated Ca2+ release in different subsets of conventional T cells. I demonstrated for the first time the importance of NAADP in the generation of Ca2+ signals in murine conventional naive T cells as well as in different effector subsets of T cells. Combining live-cell imaging methods and a pharmacological approach using the NAADP antagonist Ned-19, I addressed the involvement of NAADP in the generation of Ca2+ signals evoked by TCR stimulation and the role of this signal in downstream physiological endpoints such as proliferation, cytokine production, effector functions and other responses to stimulation of conventional T cells. Moreover, I demonstrated that acidic compartments in addition to the endoplasmic reticulum are the relevant intracellular Ca2+ stores sensitive to NAADP in conventional naive and effector T cells. Our study shows that NAADP evokes functionally relevant Ca2+ signals in naive and effector CD4 and CD8 T cells, but not in natural regulatory T cells and thus suggests immunological importance for NAADP in regulating the immune response associated with certain immune T cells.
Katherine Wall (Committee Chair)
James Slama (Committee Member)
David Giovannucci (Committee Member)
Anthony Quinn (Committee Member)
Zahoor Shah (Committee Member)
144 p.
Immunology; Pharmacy Sciences

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Citations

  • Ali, R. (2014). NAADP-Mediated Calcium Release in Mammalian Cells: Regulation of Naive and Effector T Cell Functions by NAADP [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=mco1415826878

    APA Style (7th edition)

  • Ali, Ramadan . NAADP-Mediated Calcium Release in Mammalian Cells: Regulation of Naive and Effector T Cell Functions by NAADP. 2014. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=mco1415826878.

    MLA Style (8th edition)

  • Ali, Ramadan . "NAADP-Mediated Calcium Release in Mammalian Cells: Regulation of Naive and Effector T Cell Functions by NAADP." Doctoral dissertation, University of Toledo, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=mco1415826878

    Chicago Manual of Style (17th edition)

mco1415826878
532
© 2014, all rights reserved.
This open access ETD is published by University of Toledo Health Science Campus and OhioLINK.