Prion protein complexed to N2a cellular RNAs through its N-terminal domain forms aggregates and is toxic to murine neuroblastoma cells.
Conversion of the cellular prion protein (PrP(C)) into its altered conformation, PrP(Sc), is believed to be the major cause of prion diseases. Although PrP is the only identified agent for these diseases, there is increasing evidence that other molecules can modulate the conversion. We have found that interaction of PrP with double-stranded DNA leads to a protein with higher beta-sheet content and characteristics similar to those of PrP(Sc). RNA molecules can also interact with PrP and potentially modulate PrP(C) to PrP(Sc) conversion or even bind differentially to both PrP isoforms. Here, we investigated the interaction of recombinant murine PrP with synthetic RNA sequences and with total RNA extracted from cultured neuroblastoma cells (N2aRNA). We found that PrP interacts with N2aRNA with nanomolar affinity, aggregates upon this interaction, and forms species partially resistant to proteolysis. RNA does not bind to N-terminal deletion mutants of PrP, indicating that the N-terminal region is important for this process. Cell viability assays showed that only the N2aRNA extract induces PrP-RNA aggregates that can alter the homeostasis of cultured cells. Small RNAs bound to PrP give rise to nontoxic small oligomers. Nuclear magnetic resonance measurements of the PrP-RNA complex revealed structural changes in PrP, but most of its native fold is maintained. These results indicate that there is selectivity in the species generated by interaction with different molecules of RNA. The catalytic effect of RNA on the PrP(C)-->PrP(Sc) conversion depends on the RNA sequence, and small RNA molecules may exert a protective effect.
Gomes
Mariana P B
MP
Programa de Biologia Estrutural, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, 21491-590 Rio de Janeiro, Brazil.
Millen
Thiago A
TA
Ferreira
Priscila S
PS
e Silva
Narcisa L Cunha
NL
Vieira
Tuane C R G
TC
Almeida
Marcius S
MS
Silva
Jerson L
JL
Cordeiro
Yraima
Y
D000818:Animals; D002384:Catalysis; D045744:Cell Line, Tumor; D002470:Cell Survival; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D009447:Neuroblastoma / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018621:PrPC Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018620:PrPSc Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016337:RNA, Catalytic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D004273:DNA, Neoplasm; D018621:PrPC Proteins; D018620:PrPSc Proteins; D016337:RNA, Catalytic; D012334:RNA, Neoplasm; D016601:RNA-Binding Proteins