RCAN1 regulates mitochondrial function and increases susceptibility to oxidative stress in mammalian cells.

Heshan Peiris,Hakan Muyderman,Kimberly Mackenzie,Petra Unterweger,Melanie A Pritchard,Daphne Dubach,Damien J Keating,Ravinarayan Raghupathi,Claire F Jessup,Mark P Zanin

doi:10.1155/2014/520316

Abstract

Mitochondria are the primary site of cellular energy generation and reactive oxygen species (ROS) accumulation. Elevated ROS levels are detrimental to normal cell function and have been linked to the pathogenesis of neurodegenerative disorders such as Down's syndrome (DS) and Alzheimer's disease (AD). RCAN1 is abundantly expressed in the brain and overexpressed in brain of DS and AD patients. Data from nonmammalian species indicates that increased RCAN1 expression results in altered mitochondrial function and that RCAN1 may itself regulate neuronal ROS production. In this study, we have utilized mice overexpressing RCAN1 (RCAN1ox) and demonstrate an increased susceptibility of neurons from these mice to oxidative stress. Mitochondria from these mice are more numerous and smaller, indicative of mitochondrial dysfunction, and mitochondrial membrane potential is altered under conditions of oxidative stress. We also generated a PC12 cell line overexpressing RCAN1 (PC12RCAN1). Similar to RCAN1ox neurons, PC12RCAN1 cells have an increased susceptibility to oxidative stress and produce more mitochondrial ROS. This study demonstrates that increasing RCAN1 expression alters mitochondrial function and increases the susceptibility of neurons to oxidative stress in mammalian cells. These findings further contribute to our understanding of RCAN1 and its potential role in the pathogenesis of neurodegenerative disorders such as AD and DS.

Highlights

The RCAN1 gene is located in the 21q22.1-q22.2 region of human chromosome 21 and is expressed primarily in brain, heart, and skeletal muscle [1] and in endocrine tissues including the adrenal gland [2] and pancreas [3]
This study investigated the role of RCAN1 in regulating mitochondrial function and susceptibility to oxidative stress in a neuronal cell line and primary cells overexpressing RCAN1
Elevated RCAN1 expression in PC12 cells resulted in reactive oxygen species (ROS) accumulation, as well as decreased viability in response to H2O2

Summary

Introduction

The RCAN1 (regulator of calcineurin 1) gene is located in the 21q22.1-q22.2 region of human chromosome 21 and is expressed primarily in brain, heart, and skeletal muscle [1] and in endocrine tissues including the adrenal gland [2] and pancreas [3]. RCAN1.1, but not RCAN1.4, expression, is induced by thyroid hormone [5] These two isoforms may have independent cell functions as our own research has demonstrated that RCAN1.1 regulates exocytosis [6, Oxidative Medicine and Cellular Longevity. RCAN1 alters cellular susceptibility to oxidative stress as neurons with no RCAN1 expression display an increased resistance to damage by ROS [11]. We have utilised multiple mammalian cell types commonly used in the study of neuronal function to assess the effect of chronically increased RCAN1 expression on mitochondrial morphology and function, including ROS production, and the susceptibility of neurons to damage from oxidative stress. RCAN1 overexpression increases cellular susceptibility to oxidative stress by reducing cell viability in response to increasing ROS levels. Our findings have implications for neurodegeneration in DS and AD in which RCAN1, mitochondrial dysfunction, and oxidative stress are all thought to play a pathogenic role

Methods

Neurons Overexpressing RCAN1 Show Decreased Cell

RCAN1ox Cells Have Altered Mitochondrial Membrane

Discussion