Abstract
BackgroundThe signaling pathways most critical to prion disease pathogenesis are as yet incompletely characterized. We have developed a kinomics approach to identify signaling pathways that are dysregulated during prion pathogenesis. The approach is sensitive and specific enough to detect signaling pathways dysregulated in a simple in vitro model of prion pathogenesis. Here, we used this approach to identify signaling pathways dysregulated during prion pathogenesis in vivo.MethodsMice intraperitoneally infected with scrapie (strain RML) were euthanized at 70, 90, 110, 130 days post-infection (dpi) or at terminal stages of disease (155–190 dpi). The levels of 139 protein kinases in brainstem-cerebellum homogenates were analyzed by multiplex Western blots, followed by hierarchical clustering and analyses of activation states.ResultsHierarchical and functional clustering identified CaMK4β and MST1 signaling pathways as potentially dysregulated. Targeted analyses revealed that CaMK4β and its downstream substrate CREB, which promotes neuronal survival, were activated at 70 and 90 dpi in cortical, subcortical and brainstem-cerebellum homogenates from scrapie-infected mice. The activation levels of CaMK4β/CREB signaling returned to those in mock-infected mice at 110 dpi, whereas MST1, which promotes neuronal death, became activated at 130 dpi.ConclusionPro-survival CaMK4β/CREB signaling is activated in mouse scrapie at earlier times and later inhibited, whereas pro-death MST1 signaling is activated at these later times.Electronic supplementary materialThe online version of this article (doi:10.1186/1743-422X-11-160) contains supplementary material, which is available to authorized users.
Highlights
The signaling pathways most critical to prion disease pathogenesis are as yet incompletely characterized
PrPres is first detected in scrapie-infected mice at 130 dpi Mock-infected mice or mice infected intraperitoneally with scrapie were euthanized at 70, 90, 110, 130 days post-infection, or at terminal stages of disease (155–190 dpi)
We first analyzed the levels of protease-resistant PrPSc (PrPres) and total glial fibrillary acidic protein (GFAP) by Western blot
Summary
The signaling pathways most critical to prion disease pathogenesis are as yet incompletely characterized. The approach is sensitive and specific enough to detect signaling pathways dysregulated in a simple in vitro model of prion pathogenesis. None affected survival of patients with CJD, GSS, or FFI [9,10,11,12,13,14,15,16,17,18] Another compound that prolonged survival of scrapie-infected mice after the onset of clinical disease is the calcineurin/ protein phosphatase 3 inhibitor FK506. FK506, did not affect the levels of PrPC or the accumulation of PrPSc [19], indicating that FK506 acts downstream from the accumulation of PrPSc. As FK506 is a known (calcineurin) signaling inhibitor, these results suggest that dysregulated signaling downstream of PrP conversion is an alternative therapeutic target against prion diseases
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