The crosstalk between the endoplasmic reticulum (ER) and mitochondria facilitates the transfer of proteins, lipids and calcium between these organelles. ER-mitochondrial coupling maintains the driving force for calcium that is released from inositol-1,4,5-triphosphate receptors (IP3R) into the mitochondrial matrix where it determines mitochondrial respiration. ER-mitochondrial contact points are built by ER-bound IP3 receptors and voltage dependent anion channel 1 (VDAC1) on the outer mitochondrial membrane, that are connected by the chaperone glucose-regulated protein 75 (GRP75/mortalin). Enhanced mitochondrial calcium [Ca2+]m uptake, thus [Ca2+]m overload, and mitochondrial integrity are critical parameters during oxidative glutamate toxicity in neuronal HT22 cells. In our study, we investigated the role of ER-mitochondrial coupling in immortalized mouse hippocampal HT22 cells in response to glutamate-induced cell death. In these cells, we confirm that GRP75 determines ER-mitochondrial contact formation as shown by an in situ proximity ligation assay. Using siRNA-mediated knockdown, CRISPR/Cas9-mediated knockout and pharmacological inhibition of GRP75, we show that relieving ER-mitochondrial crosstalk protects against glutamate-induced cell death. In response to the glutamate challenge, we observe preservation of mitochondrial morphology, reduction of mitochondrial ROS formation and attenuation of both [Ca2+]c and [Ca2+]m levels. We provide for the first time evidence that disrupting ER-mitochondrial coupling, thus [Ca2+]m uptake through [Ca2+]ER release, through silencing GRP75 conferred protection against glutamate toxicity in neuronal HT22 cells.
|Publication status||Published - 2017|
|Event||EUROMIT : International meeting on mitochondrial pathology - Cologne, Germany|
Duration: 11-Jun-2017 → 15-Jun-2017
|Period||11/06/2017 → 15/06/2017|