title: Store-Operated Ca2+Entry in Oocytes Modulate the Dynamics of IP3-Dependent Ca2+Release From Oscillatory to Tonic.
abstract: Ca2+signaling is ubiquitous and mediates various cellular functions encoded in its spatial, temporal, and amplitude features. Here, we investigate the role of store-operated Ca2+entry (SOCE) in regulating the temporal dynamics of Ca2+signals in Xenopus oocytes, which can be either oscillatory or tonic. Oscillatory Ca2+release from intracellular stores is typically observed at physiological agonist concentration. When Ca2+release leads to Ca2+store depletion, this triggers the activation of SOCE that translates into a low-amplitude tonic Ca2+signal. SOCE has also been implicated in fueling Ca2+oscillations when activated at low levels. Here, we show that sustained SOCE activation in the presence of IP3to gate IP3receptors (IP3R) results in a pump-leak steady state across the endoplasmic reticulum (ER) membrane that inhibits Ca2+oscillations and produces a tonic Ca2+signal. Tonic signaling downstream of SOCE activation relies on focal Ca2+entry through SOCE ER-plasma membrane (PM) junctions, Ca2+uptake into the ER, followed by release through open IP3Rs at distant sites, a process we refer to as "Ca2+teleporting." Therefore, sustained SOCE activation in the presence of an IP3-dependent "leak" pathway at the ER membrane results in a switch from oscillatory to tonic Ca2+signaling. J. Cell. Physiol. 232: 1095-1103, 2017. © 2016 Wiley Periodicals, Inc.
authors: Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Doha, Qatar.
authors: Raphaël
authors: R
authors: Courjaret
authors: Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Doha, Qatar.
authors: Maya
authors: M
authors: Dib
authors: Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Doha, Qatar.
authors: Khaled
authors: K
authors: Machaca
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D004721:Endoplasmic Reticulum / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D014982:Xenopus laevis
chemical_list: D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium