Select Gene Expression Across Variable PrPSc Permissive Ovine Microglia

Abstract

Abstract Background: Transmissible spongiform encephalopathies (TSEs) are a group of fatal, neurodegenerative diseases that affect multiple species, including sheep, cattle, and humans. A misfolded, pathogenic isoform (PrPD) of the normal, host-encoded, cellular prion protein (PrPC) is the causative agent for TSEs. While there have been advances in understanding TSEs, antemortem diagnostic tests are limited in many species, and there are no effective treatment protocols. Filling these reagent gaps will require knowledge of the molecular pathophysiology of PrPD accumulation. Previous work has suggested that the extracellular matrix (i.e., fibronectin 1) and physiological functions (i.e., cell division) maybe key factors for cellular prion permissibility, at least in specific cell culture models. Using a natural scrapie isolate, six immortalized, ovine microglial clones, of varying permissiveness to classical scrapie were evaluated for differential gene expression in seven genes based on previous RNASeq studies (fibronectin 1 [FN1], follistatin-like 1 [FSTL1], osteonectin [SPARC], survivin [BIRC5], syndecan 4 [SDC4], AXL receptor tyrosine kinase [AXL], and prion protein [PRNP]), and to determine correlations with prion permissibility. Results: Significant differential gene expression was frequently observed for survivin, follistatin-like 1 and osteonectin between clones, and when evaluated relative to PRNP expression. However, only fibronectin 1 and survivin were significantly correlated with prion permissibility, and only when evaluated relative to PRNP expression. Inoculation had a significant effect on follistatin-like 1, syndecan 4, and osteonectin. Conclusions: Similar to previous studies in other systems, fibronectin and mitotic rate show promise as potential determinants of prion permissibility in ovine microglia. As determinants of prion permissibility, the expression of fibronectin 1 and survivin coupled with PRNP could be utilized as biomarkers for detection of prion permissibility phenotype in ovine microglia, and perhaps other cell culture models of prion disease.