Proliferative arrest induces neuron differentiation and innate immune responses in control and infectious CJD rat septal neurons
Rat postmitotic septal neurons (SEP) engineered to conditionally proliferate at 33oC were arrested at 37.5oC for weeks without cytotoxic effects. Nine independent cDNA libraries were interrogated to broadly evaluate elevations in b-interferon (b-IFN) and prion protein (PrP) found previously by RT/qPCR in arrested uninfected and CJD infected cells. RNA-seq revealed a variety of upregulated innate immune responses in control and CJD infected cells. Proliferating uninfected, and latently infected (CJ-) cells, showed rare RNA-seq differences. However, major quantitative changes became evident post-arrest. In uninfected cells these included anti-proliferative DNA replication/cell xxNeuregulin-1, GDF6, SFRP4 and PrP. Recruitment of many IFN innate immune pathways, complement, cytokines and clusterin were present in both sets but re-arrested cells with high infectivity (CJ+) escaped replication controls and suppressed neuronal differentiation. Moreover, IFN anti-viral stimulated networks (OAS, cytokines, IFN-?? and metalloproteinases) were also enhanced among the 342 unique CJ+ transcripts, e.g., Il17, ISG15, CXCL10 and RSAD2 (viperin). These data show 1) defensive innate immune molecules and/or pathways are produced by neurons and participate in normal neuronal differentiation; 2) CJD infectious agents that survive in an undetectable latent state can epigenetically prime cells to produce a strong anti-viral response; 3) downregulation of a plethora of proliferative pathways is also imprinted in cells exposed to infection. Several innate-immune transcripts shared with CJ+ myeloid microglia from brain may be physiologically stimulated to identify latent CJD infections that can be clinically silent for >30 years. Overall design: Rat postmitotic septal neurons (SEP) engineered to conditionally proliferate at 33oC were arrested at 37.5oC for weeks, cDNA libraries were interrogated to broadly evaluate elevations in b-interferon (b-IFN) and prion protein (PrP) in proliferating uninfected, and latently infected (CJ-), and re-arrested cells with high infectivity (CJ+)