Abstract

The broad, long-term objectives of this project are to gain novel knowledge about a highly specialized calcium (Ca2+) channel - the inositol (1,4,5)-trisphosphate receptor (InsP3R). InsP3R supports a major pathway for Ca2+ release from intracellular Ca2+ stores and plays a key role in the intracellular Ca2+ signaling process. Cytosolic Ca2+ influences most fundamental cellular processes and derangement of intracellular Ca2+ signaling has been implicated in a variety of pathological conditions, such as ischemia, manic and spreading depression, hypertension, atherosclerosis, immunosuppression, cancer, and Lowe's oculocerebrorenal syndrome. Thus, the proposed studies of InsP3R are fundamental to understanding Ca2+ signaling in cells and may provide novel information relevant to multiple human diseases.
The specific aims of the proposal are: 1. To identify structural determinants of InsP3R conductance. Mutations will be introduced in specific sites within the putative pore-forming region of InsP3R and properties of heterologously expressed mutant channels will be evaluated in planar lipid bilayers. 2. To elucidate the mechanism for InsP3R activation by InsP3. Mutations will be introduced in specific sites within the InsP3-binding domain region and the properties of recombinant mutant InsP3R will be evaluated by radiolabeled InsP3 binding and planar lipid bilayer assays. 3. To characterize structural determinants of InsP3R modulation. Mutations will be introduced in putative calmodulin, ATP and Ca2+ binding sites and the properties or recombinant mutant channels will be analyzed in planar lipid bilayers. 4. To evaluate a hypothesis of direct InsP3R-PIP2 (phosphatidylinositol 4,5-bisphosphate) functional coupling. Preliminary experiments presented here suggest the existence of a novel signaling InsP3R-PIP2 complex. Binding of a radiolabeled water-soluble PIP-2 analog to recombinant InsP3R fragment will be used to identify the location of a specific PIP2-binding site in the InsP3R sequence. Activity of InsP3R will be correlated with cellular PIP2 content to obtain information regarding InsP3R-PIP2 interaction in situ.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS038082-04
Application #
6477240
Study Section
Special Emphasis Panel (ZRG1-MDCN-4 (01))
Program Officer
Michel, Mary E
Project Start
1998-12-03
Project End
2003-11-30
Budget Start
2001-12-01
Budget End
2003-11-30
Support Year
4
Fiscal Year
2002
Total Cost
$268,197
Indirect Cost

  Institution

Name
University of Texas Sw Medical Center Dallas
Department
Physiology
Type
Schools of Medicine
DUNS #
City
Dallas
State
TX
Country
United States
Zip Code
75390

  Publications

Bezprozvanny, Ilya (2013) Reconstitution of endoplasmic reticulum InsP3 receptors into black lipid membranes. Cold Spring Harb Protoc 2013:
Bezprozvanny, Ilya (2013) Bilayer measurement of endoplasmic reticulum Ca2+ channels. Cold Spring Harb Protoc 2013:
Bezprozvanny, Ilya (2013) Preparation of microsomes to study Ca2+ channels. Cold Spring Harb Protoc 2013:
Kasumu, Adebimpe W; Liang, Xia; Egorova, Polina et al. (2012) Chronic suppression of inositol 1,4,5-triphosphate receptor-mediated calcium signaling in cerebellar purkinje cells alleviates pathological phenotype in spinocerebellar ataxia 2 mice. J Neurosci 32:12786-96
Kasumu, Adebimpe; Bezprozvanny, Ilya (2012) Deranged calcium signaling in Purkinje cells and pathogenesis in spinocerebellar ataxia 2 (SCA2) and other ataxias. Cerebellum 11:630-9
Kasumu, Adebimpe W; Hougaard, Charlotte; Rode, Frederik et al. (2012) Selective positive modulator of calcium-activated potassium channels exerts beneficial effects in a mouse model of spinocerebellar ataxia type 2. Chem Biol 19:1340-53
Bezprozvanny, Ilya (2011) Role of inositol 1,4,5-trisphosphate receptors in pathogenesis of Huntington's disease and spinocerebellar ataxias. Neurochem Res 36:1186-97
Bezprozvanny, Ilya (2010) Inositol 1,4,5-tripshosphate receptor, calcium signaling, and polyglutamine expansion disorders. Curr Top Membr 66:323-41
Wu, Jun; Jeong, Hye Kyoung; Bulin, Sarah Elizabeth et al. (2009) Ginsenosides protect striatal neurons in a cellular model of Huntington's disease. J Neurosci Res 87:1904-12
Tang, Tie-Shan; Guo, Caixia; Wang, Hongyu et al. (2009) Neuroprotective effects of inositol 1,4,5-trisphosphate receptor C-terminal fragment in a Huntington's disease mouse model. J Neurosci 29:1257-66

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