Dataset Information

Ca²⁺ Dependence of Volume-Regulated VRAC/LRRC8 and TMEM16A Cl^- Channels.

ABSTRACT: All vertebrate cells activate Cl^- currents (I_Cl _,swell) when swollen by hypotonic bath solution. The volume-regulated anion channel VRAC has now been identified as LRRC8/SWELL1. However, apart from VRAC, the Ca²⁺-activated Cl^- channel (CaCC) TMEM16A and the phospholipid scramblase and ion channel TMEM16F were suggested to contribute to cell swelling-activated whole-cell currents. Cell swelling was shown to induce Ca²⁺ release from the endoplasmic reticulum and to cause subsequent Ca²⁺ influx. It is suggested that TMEM16A/F support intracellular Ca²⁺ signaling and thus Ca²⁺-dependent activation of VRAC. In the present study, we tried to clarify the contribution of TMEM16A to I_Cl _,swell. In HEK293 cells coexpressing LRRC8A and LRRC8C, we found that activation of I_Cl _,swell by hypotonic bath solution (Hypo; 200 mosm/l) was Ca²⁺ dependent. TMEM16A augmented the activation of LRRC8A/C by enhancing swelling-induced local intracellular Ca²⁺ concentrations. In HT₂₉ cells, knockdown of endogenous TMEM16A attenuated I_Cl _,swell and changed time-independent swelling-activated currents to VRAC-typical time-dependent currents. Activation of I_Cl _,swell by Hypo was attenuated by blocking receptors for inositol trisphosphate and ryanodine (IP₃R; RyR), as well as by inhibiting Ca²⁺ influx. The data suggest that TMEM16A contributes directly to I_Cl _,swell as it is activated through swelling-induced Ca²⁺ increase. As activation of VRAC is shown to be Ca²⁺-dependent, TMEM16A augments VRAC currents by facilitating Hypo-induced Ca²⁺ increase in submembraneous signaling compartments by means of ER tethering.

SUBMITTER: Centeio R

PROVIDER: S-EPMC7736618 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Ca2+ Dependence of Volume-Regulated VRAC/LRRC8 and TMEM16A Cl- Channels.

Centeio Raquel R Ousingsawat Jiraporn J Schreiber Rainer R Kunzelmann Karl K

Frontiers in cell and developmental biology 20201201

All vertebrate cells activate Cl- currents (ICl ,swell) when swollen by hypotonic bath solution. The volume-regulated anion channel VRAC has now been identified as LRRC8/SWELL1. However, apart from VRAC, the Ca2+-activated Cl- channel (CaCC) TMEM16A and the phospholipid scramblase and ion channel TMEM16F were suggested to contribute to cell swelling-activated whole-cell currents. Cell swelling was shown to induce Ca2+ release from ...[more]

PMID: 33335902

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Project description:BackgroundTransmembrane protein 16A (TMEM16A) Ca2+-activated Cl- channels have diverse physiological functions, such as epithelial secretion of Cl- and fluid and sensation of pain. Recent studies have demonstrated that TMEM16A contributes to the pathogenesis of infectious and non-infectious inflammatory diseases. However, the role of TMEM16A in inflammation has not been clearly elucidated.Aim of reviewIn this review, we aimed to provide comprehensive information regarding the roles of TMEM16A in inflammation by summarizing the mechanisms underlying TMEM16A expression and activation under inflammatory conditions, in addition to exploring the diverse inflammatory signaling pathways activated by TMEM16A. This review attempts to develop the idea that TMEM16A plays a diverse role in inflammatory processes and contributes to inflammatory diseases in a cellular environment-dependent manner.Key scientific concepts of reviewMultiple inflammatory mediators, including cytokines (e.g., interleukin (IL)-4, IL-13, IL-6), histamine, bradykinin, and ATP/UTP, as well as bacterial and viral infections, promote TMEM16A expression and/or activity under inflammatory conditions. In addition, TMEM16A activates diverse inflammatory signaling pathways, including the IP3R-mediated Ca2+ signaling pathway, the NF-κB signaling pathway, and the ERK signaling pathway, and contributes to the pathogenesis of many inflammatory diseases. These diseases include airway inflammatory diseases, lipopolysaccharide-induced intestinal epithelial barrier dysfunction, acute pancreatitis, and steatohepatitis. TMEM16A also plays multiple roles in inflammatory processes by increasing vascular permeability and leukocyte adhesion, promoting inflammatory cytokine release, and sensing inflammation-induced pain. Furthermore, TMEM16A plays its diverse pathological roles in different inflammatory diseases depending on the disease severity, proliferating status of the cells, and its interacting partners. We herein propose cellular environment-dependent mechanisms that explain the diverse roles of TMEM16A in inflammation.

Project description:IntroductionTransmembrane protein 16A (TMEM16A) is a Ca2+-activated chloride channel that plays a role in cancer cell proliferation, migration, invasion, and metastasis. However, whether TMEM16A contributes to breast cancer metastasis remains unknown.ObjectiveIn this study, we investigated whether TMEM16A channel activation by ROCK1/moesin promotes breast cancer metastasis.MethodsWound healing assays and transwell migration and invasion assays were performed to study the migration and invasion of MCF-7 and T47D breast cancer cells. Western blotting was performed to evaluate the protein expression, and whole-cell patch clamp recordings were used to record TMEM16A Cl- currents. A mouse model of breast cancer lung metastasis was generated by injecting MCF-7 cells via the tail vein. Metastatic nodules in the lung were assessed by hematoxylin and eosin staining. Lymph node metastasis, overall survival, and metastasis-free survival of breast cancer patients were assessed using immunohistochemistry and The Cancer Genome Atlas dataset.ResultsTMEM16A activation promoted breast cancer cell migration and invasion in vitro as well as breast cancer metastasis in mice. Patients with breast cancer who had higher TMEM16A levels showed greater lymph node metastasis and shorter survival. Mechanistically, TMEM16A promoted migration and invasion by activating EGFR/STAT3/ROCK1 signaling, and the role of the TMEM16A channel activity was important in this respect. ROCK1 activation by RhoA enhanced the TMEM16A channel activity via the phosphorylation of moesin at T558. The cooperative action of TMEM16A and ROCK1 was supported through clinical findings indicating that breast cancer patients with high levels of TMEM16A/ROCK1 expression showed greater lymph node metastasis and poor survival.ConclusionOur findings revealed a novel mechanism underlying TMEM16A-mediated breast cancer metastasis, in which ROCK1 increased TMEM16A channel activity via moesin phosphorylation and the increase in TMEM16A channel activities promoted cell migration and invasion. TMEM16A inhibition may be a novel strategy for treating breast cancer metastasis.

Dataset Information

Ca²⁺ Dependence of Volume-Regulated VRAC/LRRC8 and TMEM16A Cl^- Channels.

Publications

Ca<sup>2+</sup> Dependence of Volume-Regulated VRAC/LRRC8 and TMEM16A Cl<sup>-</sup> Channels.

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