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Title: Inositol 1, 4, 5-trisphosphate receptor redistribution in RBL-2H3 cells
Author: Chalmers, M. G.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2005
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The inositol 1, 4, 5-trisphosphate receptor (IP3R) is an intracellular Ca­­2+ channel expressed in the endoplasmic reticulum (ER), and its precise localisation is important for the initiation and propagation of Ca2+ signals. The studies performed in this thesis focus on the redistribution of the IP3R following antigen stimulation in RBL-2H3 cells. In Chapter 3, the aim was to confirm the work of previous studies, which observed Ca2+-dependent IP3RII clustering, by developing a method to quantify both the number and size of IP3RII clusters. The present study observed global IP3R redistribution to the perinuclear region following antigen stimulation. IP3RII clusters colocalised with ER markers but not with markers for other membrane compartments, suggesting that IP3RII clusters were probably still in the ER and therefore may still have been functional. IP3R distribution is thought to be important for the spatio-temporal regulation of the Ca2+ signal and in turn the secretory response. In Chapter 4, the functional significance of antigen-induced IP3R redistribution in RBL-2H3 cells was investigated, by comparing the time course and dose-response of the Ca2+ signal with the time course and dose-response relationship of the secretory response. The results indicate that the redistribution of the IP3Rs takes place over the time course of the Ca2+ and secretory response suggesting that IP3R redistribution may be functionally relevant to cell physiology. Chapter 5 used YFP-IP3RI to investigate IP3R redistribution in live RBL-2H3 cells. A combination of quantitative imaging techniques was used to investigate the hypothesis that mechanisms involved in IP3R clustering might restrict YFP-IP3RI mobility. The results demonstrate that YFP-IP3RI is mobile within the ER and following antigen stimulation a significant percentage of the YFP-IP3RI becomes immobile, which may be due to the formation of clusters. Inhibition of native IP3RII clustering by overexpression of YFP-IP3RI, suggests that YFP-IP3RI is either interacting with native IP3RII to prevent clustering or is saturating the mechanism responsible for IP3R clustering.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available