Investigation of the unfolded protein response and other stress-related responses in distinct models of neurodegeneration

Abstract

There is no cure for chronic neurodegenerative diseases and disease-modifying therapies are limited. In order to develop successful disease-modifying therapies the molecules and pathways that underpin early stages of disease, such as synapse loss, need to be better defined.

Three distinct in vivo mouse models of neurodegeneration have been used to investigate molecular stress response molecules and pathways. These models are the ME7 prion model, the cysteine string protein alpha (CSP?) -/- model and a kainic acid model of excitotoxicity. In all cases hippocampal tissue from mice was used to investigate the neuropathology and associated stress-related pathways. The unfolded protein response (UPR) and other stress-related response molecules: immediate early genes (ATF3, c-Jun and c-Fos), activity-induced immediate early genes (Arc and Homer1a) and a cellular physiological and environmental damage stress sensor (GADD45?) were investigated.

Biochemical and immunohistochemistry analysis revealed no evidence for a robust and classic UPR in any of the three models despite neuropathological changes associated with these distinct insults being evident. However, other stress-related response molecules were induced in these models and the induction of some of these occurred at the same time/prior to synapse loss suggesting that these are early responses and potential therapeutic targets for modifying neurodegenerative disease.

Tissue analysis is confounded by cellular heterogeneity. To investigate discrete cell specific events laser capture microdissection (LCM) was used to isolate the cell bodies of dysfunctional CA3 pyramidal neurons across key stages of ME7 prion disease. Optimisation of LCM enabled enrichment of CA3 pyramidal neurons and targeted analysis of UPR molecules. mRNA analysis failed to show strong evidence for a robust induction of the UPR in these vulnerable CA3 pyramidal neurons. Total RNA has also been used for RNA sequencing to analyse differentially expressed genes and molecular pathways activated during prion disease progression. The aim of this targeted approach will be to resolve molecular targets and pathways which might mitigate the progression of chronic neurodegenerative diseases.

More information

Identifiers

ORCID for Vincent O'Connor: orcid.org/0000-0003-3185-5709

Catalogue record

Export record