Increases in cytoplasmic Ca2+ evoked by inositol(1,4,5)-trisphosphate receptors (IP3Rs) regulate many physiological events. Dysfunction of the IP3-stimulated Ca2+ release pathway is involved in neurodegenerative and neurological disease, as well as exocrine, autoimmune and kidney disorders, cardiac abnormalities and cancer. To appreciate how cellular functions are controlled by Ca2+ signals, and how pathological aberrations subvert the IP3R signaling pathway, we must understand how the distribution and properties (the `functional architecture') of IP3Rs control the spatiotemporal organization of cellular Ca2+ signals. Here, we will resolve the properties of IP3Rs at three distinct levels of organization from single molecules in vitro (Aim 1) to local, subcellular (Aim 2) and global, tissue-level IP3R architecture in live embryos (Aim 3). We will address: (1) How, for individual IP3R, does a single molecule of IP3 bind to the IP3R? (2) How is IP3R function modulated within the dynamic context of endoplasmic reticulum structures where they reside? (3) How does a changing global complement of Ca2+ channels and pumps at a regional level in a developing vertebrate embryo impacts the patterning of Ca2+ signals and cell function. To address these challenges, we have optimized: (i) a novel single molecule imaging approach competent to resolve the properties of individual IP3Rs (Aim 1), (ii) a dual confocal microscope to simultaneously resolve ER architecture and the functionality of IP3Rs (Aim 2) and (iii) designed tools and reagents to probe the distribution and role of key families of Ca2+ channels and pumps during vertebrate embryogenesis (Aim 3). The broad significance of this work is in understanding principles controlling ion channel dynamics and thereby the spatial kinetics of Ca2+ signals that control unitary, cellular and systems-level responses. Such data will aid our understanding of the role of ubiquitous Ca2+ signaling pathways in health and disease.

Public Health Relevance

The goal of this project is to understand how particular cell signaling events are organized within cells by understanding first how proteins work at the unitary level in vitro and then appreciating how these proteins work when organized within cells and within developing embryos in vivo. The goal is to provide deeper understand of how intracellular Ca2+ channels behave and how pathological events subvert their function.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Neurotransporters, Receptors, and Calcium Signaling Study Section (NTRC)
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Gindhart, Joseph G
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University of Minnesota Twin Cities
Schools of Medicine
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Gunaratne, Gihan S; Yang, Yang; Li, Fang et al. (2018) NAADP-dependent Ca2+ signaling regulates Middle East respiratory syndrome-coronavirus pseudovirus translocation through the endolysosomal system. Cell Calcium 75:30-41
Gunaratne, Gihan S; Johns, Malcolm E; Hintz, Hallie M et al. (2018) A screening campaign in sea urchin egg homogenate as a platform for discovering modulators of NAADP-dependent Ca2+ signaling in human cells. Cell Calcium 75:42-52
Subramanian, Veedamali S; Sabui, Subrata; Moradi, Hamid et al. (2018) Inhibition of intestinal ascorbic acid uptake by lipopolysaccharide is mediated via transcriptional mechanisms. Biochim Biophys Acta Biomembr 1860:556-565
Subramanian, Veedamali S; Sabui, Subrata; Subramenium, Ganapathy A et al. (2018) Tumor necrosis factor alpha reduces intestinal vitamin C uptake: a role for NF-?B-mediated signaling. Am J Physiol Gastrointest Liver Physiol 315:G241-G248
Marchant, Jonathan S (2018) Heterologous Protein Expression in the Xenopus Oocyte. Cold Spring Harb Protoc 2018:pdb.prot096990
Subramanian, Veedamali S; Srinivasan, Padmanabhan; Wildman, Alexis J et al. (2017) Molecular mechanism(s) involved in differential expression of vitamin C transporters along the intestinal tract. Am J Physiol Gastrointest Liver Physiol 312:G340-G347
Chan, John D; Cupit, Pauline M; Gunaratne, Gihan S et al. (2017) The anthelmintic praziquantel is a human serotoninergic G-protein-coupled receptor ligand. Nat Commun 8:1910
Chan, John D; McCorvy, John D; Acharya, Sreemoyee et al. (2016) A Miniaturized Screen of a Schistosoma mansoni Serotonergic G Protein-Coupled Receptor Identifies Novel Classes of Parasite-Selective Inhibitors. PLoS Pathog 12:e1005651
Hooper, Robert; Churamani, Dev; Davidson, Sean M et al. (2015) TPC1 Knockout Knocks Out TPC1. Mol Cell Biol 35:1882-3
Marchant, Jonathan S; Patel, Sandip (2015) Two-pore channels at the intersection of endolysosomal membrane traffic. Biochem Soc Trans 43:434-41

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