Gene expression alterations in brains of mice infected with three strains of scrapie

Abstract

Background: Transmissible spongiform encephalopathies (TSEs) or prion diseases are fatal neurodegenerative disorders which occur in humans and various animal species. Examples include Creutzfeldt-Jakob disease (CJD) in humans, bovine spongiform encephalopathy (BSE) in cattle, chronic wasting disease (CWD) in deer and elk, and scrapie in sheep, and experimental mice. To gain insights into TSE pathogenesis, we made and used cDNA microarrays to identify diseaseassociated alterations in gene expression. Brain gene expression in scrapie-infected mice was compared to mock-infected mice at pre-symptomatic and symptomatic time points. Three strains of mouse scrapie that show striking differences in neuropathology were studied: ME7, 22L, and Chandler/RML.

Targeting prion propagation using peptide constructs with signal sequence motifs

“…Confluent cell cultures were split at a ratio of 1:5 once a week using 1X-trypsin-EDTA (Gibco BRL). Infection of GT1-1 cells with RML/Chandler prion isolate to generate ScGT1-RML cells was performed as previously [46], and of of GT1-1 cells with 22L prion isolate to generate ScGT1-22L cells [46], by using 0.1% homogenate of mouse brains infected with the prion strain. The RML/Chandler isolate homogenate was a generous gift from Prof. Stanley B. Prusiner (Institute for Neurodegenerative Diseases and Department of Neurology, University of California, San Francisco, CA, USA).…”

Prion Infection of Mouse Brain Reveals Multiple New Upregulated Genes Involved in Neuroinflammation or Signal Transduction

“…Various high-throughput techniques, such as microarray expression profiling (11)(12)(13)(14)(15)(16)(17)(18)(19) and quantitative bead-based suspension array systems (3,20,21), have allowed elucidation of transcriptional and protein changes in brains of prion-infected mice relative to controls. These studies supported the notion that prion diseases have a neuroinflammatory component that may play a critical role in neurodegeneration (22), with increases in numerous cytokines and chemokines, such as interleukin-1␣ (IL-1␣) and IL-1␤, IL-12p40, tumor necrosis factor (TNF), CCL2 to CCL6, and CXCL10 in the brains of mice with clinical disease.…”

Microdissection and transcriptional profiling

“…As noted, some of the most prominent incipient prion-related changes from whole tissue analyses (i.e., inflammation, cell adhesion, cell proliferation, energy metabolism, pattern recognition receptors and leukocyte extravasation) [27][28][29][30][64][65][66] were largely absent from the microdissected neuronal material or relegated to the later time-points when disease coincided with the significant infiltration of immune cells into the dissection field. This means that we can start to differentiate between temporal changes in neurons and the interplay with other cells that make up the brain tissue milieu.…”

“…Therefore, although the disease course may vary within these animal models, the accumulating infectious agent that inevitably stimulates disease progression by affecting neuronal function ultimately results in evoking the same molecular responses within these animals. 27,28,30 It would be most interesting to determine which neuronal subtypes are more resilient to the advancement of the infectious agent; a molecular response best captured during preclinical disease by isolating the candidate neuronal population using a system such as the LCM. To date, only the CA1 hippocampal region has been studied in such a manner within prion disease 15 and further study of different neuronal populations within the mouse brain will help unravel neuronal specific vs. disease specific molecular responses.…”