Kainic Acid-Induced Golgi Complex Fragmentation/Dispersal Shifts the Proteolysis of Reelin in Primary Rat Neuronal Cells: An In Vitro Model of Early Stage Epilepsy.

Yuji Kaneko,Naoki Tajiri,Travis Dailey,Fernando L Vale,Cesar V Borlongan,Robert Sullivan

doi:10.1007/s12035-015-9126-1

Yuji Kaneko, Naoki Tajiri + Show 4 more

Open Access

https://doi.org/10.1007/s12035-015-9126-1

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Abstract

The endoplasmic reticulum-lysosome-Golgi network plays an important role in Reelin glycosylation and its proteolytic processing. Golgi complex fragmentation is associated with the separation of Reelin from this network. Kainic acid (KA) is an excitotoxic agent commonly used to induce epilepsy in rodents. The relationship between KA-induced neuronal damage and Golgi complex fragmentation has not been investigated, leaving a major gap in our understanding of the molecular mechanism underlying the development of pathophysiology in epilepsy. We cultured primary rat cortical neurons eitherin ambient condition (control) or treated with a range of KA doses to reveal whether Golgi complex fragmentation impaired neuronal function. The half-life maximal inhibitory concentration (IC 50) value of KA was detected to be approximately 5 μM, whereby at these concentrations, KA impaired neuronal viability, which was closely associated with initial Golgi complex fragmentation and subsequent reduction in both the expression and glycosylation patterns of Reelin. These findings implicate that Golgi complex fragmentation and Reelin dysfunction are key contributors to neuronal cell death in the early stage of epilepsy pathophysiology, thereby representing as novel disease biomarkers, as well as potent therapeutic targets for epilepsy.

Highlights

The endoplasmic reticulum-lysosome-Golgi network plays an important role in Reelin glycosylation and its proteolytic processing
The cells were washed five times for 10 min in PBS containing 0.1 % Tween-20 (PBST) and soaked in 5 % normal goat serum in Primary rat neuronal cells (PRNCs) viability and mitochondrial activity were significantly decreased in a dose-dependent manner with Kainic acid (KA) administration; the estimated IC50 values for cell viability and mitochondrial activity are 5.89±0.185 μM and 2.79±0.515 μM, respectively (Fig. 1)
To confirm that reduction of both cell viability and the mitochondrial activity depends on the KA-induced activation of amino-3-hydroxy-5-methyl-4isoxazolepropionic acid (AMPA)/kainate receptors, cell viability and the mitochondrial activity were compared in the presence of both KA and TPM with that of KA alone

Summary

Introduction

The endoplasmic reticulum-lysosome-Golgi network plays an important role in Reelin glycosylation and its proteolytic processing. The half-life maximal inhibitory concentration (IC50) value of KA was detected to be approximately 5 μM, whereby at these concentrations, KA impaired neuronal viability, which was closely associated with initial Golgi complex fragmentation and subsequent reduction in both the expression and glycosylation patterns of Reelin. These findings implicate that Golgi complex fragmentation and Reelin dysfunction are key contributors to neuronal cell death in the early stage of epilepsy pathophysiology, thereby representing as novel disease biomarkers, as well as potent therapeutic targets for epilepsy. The ER-lysosome-Golgi network assumes a major function in Reelin protein modification (glycosylation), its proteolytic processing (180- and 320-kDa fragments), and the synthesis of proteoglycans, which are composed of molecules of extracellular matrix [11]

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