Referenced in: none

Automatically associated channels: Slo1

Title: Hormone-induced calcium oscillations depend on cross-coupling with inositol 1,4,5-trisphosphate oscillations.

Authors: Lawrence D Gaspers, Paula J Bartlett, Antonio Politi, Paul Burnett, Walson Metzger, Jane Johnston, Suresh K Joseph, Thomas Höfer, Andrew P Thomas

Journal, date & volume: Cell Rep, 2014 Nov 20 , 9, 1209-18

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25456123

Abstract
Receptor-mediated oscillations in cytosolic Ca(2+) concentration ([Ca(2+)]i) could originate either directly from an autonomous Ca(2+) feedback oscillator at the inositol 1,4,5-trisphosphate (IP3) receptor or as a secondary consequence of IP3 oscillations driven by Ca(2+) feedback on IP3 metabolism. It is challenging to discriminate these alternatives, because IP3 fluctuations could drive Ca(2+) oscillations or could just be a secondary response to the [Ca(2+)]i spikes. To investigate this problem, we constructed a recombinant IP3 buffer using type-I IP3 receptor ligand-binding domain fused to GFP (GFP-LBD), which buffers IP3 in the physiological range. This IP3 buffer slows hormone-induced [IP3] dynamics without changing steady-state [IP3]. GFP-LBD perturbed [Ca(2+)]i oscillations in a dose-dependent manner: it decreased both the rate of [Ca(2+)]i rise and the speed of Ca(2+) wave propagation and, at high levels, abolished [Ca(2+)]i oscillations completely. These data, together with computational modeling, demonstrate that IP3 dynamics play a fundamental role in generating [Ca(2+)]i oscillations and waves.