title: Orai1 and Orai3 in Combination with Stim1 Mediate the Majority of Store-operated Calcium Entry in Astrocytes.
abstract: Astrocytes are non-excitable cells in the brain and their activity largely depends on the intracellular calcium (Ca2+) level. Therefore, maintaining the intracellular Ca2+homeostasis is critical for proper functioning of astrocytes. One of the key regulatory mechanisms of Ca2+homeostasis in astrocytes is the store-operated Ca2+entry (SOCE). This process is mediated by a combination of the Ca2+-store-depletion-sensor, Stim, and the store-operated Ca2+-channels, Orai and TrpC families. Despite the existence of all those families in astrocytes, previous studies have provided conflicting results on the molecular identification of astrocytic SOCE. Here, using the shRNA-based gene-silencing approach and Ca2+-imaging from cultured mouse astrocytes, we report that Stim1 in combination with Orai1 and Orai3 contribute to the major portion of astrocytic SOCE. Gene-silencing of Stim1 showed a 79.2% reduction of SOCE, indicating that Stim1 is the major Ca2+-store-depletion-sensor. Further gene-silencing showed that Orai1, Orai2, Orai3, and TrpC1 contribute to SOCE by 35.7%, 20.3%, 26.8% and 12.2%, respectively. Simultaneous gene-silencing of all three Orai subtypes exhibited a 67.6% reduction of SOCE. Based on the detailed population analysis, we predict that Orai1 and Orai3 are expressed in astrocytes with a large SOCE, whereas TrpC1 is exclusively expressed in astrocytes with a small SOCE. This analytical approach allows us to identify the store operated channel (SOC) subtype in each cell by the degree of SOCE. Our results propose that Stim1 in combination with Orai1 and Orai3 are the major molecular components of astrocytic SOCE under various physiological and pathological conditions.
authors.affiliation: KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea.; Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.
authors.forename: Jea
authors.initials: J
authors.lastname: Kwon
authors.affiliation: KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea.; Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.
authors.forename: Heeyoung
authors.initials: H
authors.lastname: An
authors.affiliation: KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea.; Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.
authors.forename: Moonsun
authors.initials: M
authors.lastname: Sa
authors.affiliation: Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Department of Biological Science, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.
authors.forename: Joungha
authors.initials: J
authors.lastname: Won
authors.affiliation: Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.
authors.forename: Jeong Im
authors.initials: JI
authors.lastname: Shin
authors.affiliation: KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea.; Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.
authors.forename: C Justin
authors.initials: CJ
authors.lastname: Lee
keywords: Astrocyte; Orai1; Orai3; SOCE; Stim1; TrpC1