Prion peptide-mediated calcium level alteration governs neuronal cell damage through AMPK-autophagy flux

Ji-Hong Moon,Sang-Youel Park

doi:10.1186/s12964-020-00590-1

Ji-Hong Moon, Sang-Youel Park

Open Access

https://doi.org/10.1186/s12964-020-00590-1

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Journal: Cell Communication and Signaling	Publication Date: Jul 11, 2020
Citations: 16	License type: open-access

Affiliation: Jeonbuk National University

Abstract

BackgroundThe distinctive molecular structure of the prion protein, PrPsc, is established only in mammals with infectious prion diseases. Prion protein characterizes either the transmissible pathogen itself or a primary constituent of the disease. Our report suggested that prion protein-mediated neuronal cell death is triggered by the autophagy flux. However, the alteration of intracellular calcium levels, AMPK activity in prion models has not been described. This study is focused on the effect of the changes in intracellular calcium levels on AMPK/autophagy flux pathway and PrP (106–126)-induced neurotoxicity.MethodsWestern blot and Immunocytochemistry was used to detect AMPK and autophagy-related protein expression. Flow cytometry and a TdT-mediated biotin-16-dUTP nick-end labeling (TUNEL) assay were used to detect the percentage of apoptotic cells. Calcium measurement was employed using fluo-4 by confocal microscope.ResultsWe examined the effect of calcium homeostasis alterations induced by human prion peptide on the autophagy flux in neuronal cells. Treatment with human prion peptide increased the intracellular calcium concentration and induced cell death in primary neurons as well as in a neuronal cell line. Using pharmacological inhibitors, we showed that the L-type calcium channel is involved in the cellular entry of calcium ions. Inhibition of calcium uptake prevented autophagic cell death and reduction in AMP-activated protein kinase (AMPK) activity induced by human prion peptide.ConclusionOur data demonstrated that prion peptide-mediated calcium inflow plays a pivotal role in prion peptide-induced autophagic cell death, and reduction in AMPK activity in neurons. Altogether, our results suggest that calcium influx might play a critical role in neurodegenerative diseases, including prion diseases.3p5PCBHnn1RWkUoaQCoeATVideo

Highlights

The distinctive molecular structure of the prion protein, Scrapie isoform of the prion protein (PrPsc), is established only in mammals with infectious prion diseases
We investigated whether prion peptide induces neuronal apoptosis using Annexin V assay
These results show that prion peptide (106–126) treatment increases intracellular calcium levels and induces neutotoxicity

Summary

Introduction

The distinctive molecular structure of the prion protein, PrPsc, is established only in mammals with infectious prion diseases. Moon and Park Cell Communication and Signaling (2020) 18:109 disease-causing protein, leading to the generation of selfreplicating particles and subsequent pathogenesis within the central nervous system (CNS) [4] It remains unclear whether scrapie pathogenesis associated neurotoxicity is through PrPc or other mechanisms [5]. Prion diseases are correlated with the deregulation of autophagy flux, as evidenced by the deposition of massive autophagic vacuoles in a hamster model of scrapie [8]. Recent studies investigating the degradation of PrPsc revealed that the lysosome performs an imperative role in prion protein degradation and autophagy flux may be the main mechanism of PrPsc transport to the lysosomes [12,13,14]. ULK1, an autophagy protein, is necessary for cell survival during nutrient deficiency and is phosphorylated by AMPK [16]

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