Differential ROS-Mediated Phosphorylation of Drp1 in Mitochondrial Fragmentation Induced by Distinct Cell Death Conditions in Cerebellar Granule Neurons.

Carolina Cid-Castro,Julio Morán,Stefano Falone

doi:10.1155/2021/8832863

Abstract

Reactive oxygen species (ROS) production has been associated with neuronal death. ROS are also involved in mitochondrial fission, which is mediated by Dynamin-related protein 1 (Drp1). The regulation of mitochondrial fragmentation mediated by Drp1 and its relationship to mitochondrial ROS (mtROS) in neuronal death have not been completely clarified. The aim of this study is to evaluate the role of mtROS in cell death and their involvement in the activation of Drp1 and mitochondrial fission in a model of cell death of cultured cerebellar granule neurons (CGN). Neuronal death of CGN induced by potassium deprivation (K5) and staurosporine (ST) triggers mitochondrial ROS production and mitochondrial fragmentation. K5 condition evoked an increase of Drp1 phosphorylation at Ser616, but ST treatment led to a decrease of Drp1 phosphorylation. Moreover, the death of CGN induced by both K5 and ST was markedly reduced in the presence of MitoTEMPO; however, mitochondrial morphology was not recovered. Here, we show that the mitochondria are the initial source of ROS involved in the neuronal death of CGN and that mitochondrial fragmentation is a common event in cell death; however, this process is not mediated by Drp1 phosphorylation at Ser616.

Highlights

Neuronal apoptotic death can be identified by multiple biochemical features [1,2,3] that involves the activation of several signaling pathways [3,4,5,6]
In order to clarify the role of potassium deprivation in the process of mitochondrial fission, we evaluated the activation of Dynamin-related protein 1 (Drp1) measured as Drp1 phosphorylation at Ser616
Since mitochondrial ROS (mtROS) mediated the phosphorylation of Drp1 (Ser616) induced by potassium deprivation, we examined whether MitoTEMPO affected the observed effect of K5 on mitochondrial morphology; we did not observe any effect of MitoTEMPO on the decrease in mitochondrial length induced by K5 at 24 h (Figure 6(a))

Summary

Introduction

Neuronal apoptotic death can be identified by multiple biochemical features [1,2,3] that involves the activation of several signaling pathways [3,4,5,6]. The high levels of ROS observed during neuronal death have been associated with morphological changes of mitochondria [18, 19]. These alterations have been linked to a process known as mitochondrial dynamics that refers to a highly coordinated event responsible for the fusion and fission of the mitochondria [20,21,22,23]. This process is orchestrated by a family of GTPases called mitofusin 1 (Mfn1), mitofusin 2 (Mfn2), and optic atrophy 1 (Opa1) that are responsible for the fusion of the inner mitochondrial membranes. An impairment in the expression or function of these proteins has been associated with pathologies of the nervous system such as Parkinson’s disease, autosomal dominant optic atrophy, Charcot-Marie-Tooth disease, Leigh syndrome, and amyotrophic lateral sclerosis, among others [29,30,31,32,33]

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