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23 Congress of the International Union for Biochemistry and Molecular Biology
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44 Annual Meeting of the Brazilian Society for Biochemistry and Molecular Biology
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Foz do Iguaçu, PR, Brazil, August 24 to 28 , 2015
PRION PROPAGATION, NUCLEIC ACIDS & INNATE IMMUNITY: PRION PROTEIN
AGGREGATION TRIGGERED BY NEUTROPHIL EXTRACELLULAR TRAPS (NETs)
Dos Anjos, D.M.1,2; Medeiros, S.3; Azevedo, E.P.1; Vieira T.C.2,3; Foguel, D.1; Saraiva,
E.M. 4; Silva, J.L.1
1
Instituto de Bioquímica Médica Leopoldo de Meis, IBqM de Meis-UFRJ, RJ, Brazil;
Instituto Nacional de Biologia Estrutural e Bioimagem, UFRJ, Brazil; 3Instituto Federal
de Educação, Ciência e Tecnologia do Rio de Janeiro, RJ, Brazil; 4Dep. de
Microbiologia, IMPPG-UFRJ, RJ, Brazil
2
INTRODUCTION: Prion diseases are fatal neurodegenerative protein-misfolding
diseases related to a protein known as prion protein (PrP). The constitutive cellular
isoform of PrP (PrPC) present in cell surface, can be converted into its abnormal, βsheet-rich isoform (PrPSc) that undergoes aggregation. PrPSc can be transmissible and
infectious. Evidences suggest that cofactors may play a role in the conversion process.
Our group previously reported that DNA can convert PrPC into the β-sheet conformation
leading to aggregation[1]. Innate immune system cells have been proven to play critical
roles in the early events of prion diseases and may be involved in its progression[2].
Following peripheral exposure, the replication of prions within lymphoid tissue has been
shown to be important for the efficient spread of the disease to the brain. Neutrophil
extracellular traps (NETs) are large DNA networks decorated with histones and granule
proteins that trap and kill pathogens, being extruded by activated neutrophils in
response to several stimuli. Furthermore NETs were recently found in association with
amyloid fibrils in tissues of patients with other protein-misfolding diseases and these
fibrils triggered the release of NETs[3]. Regarding these observations and considering
the large quantity of DNA provided by NETs we asked if NETs could induce PrPC
aggregation in vitro. MATERIALS AND METHODS: Murine recombinant PrP(23-231)
was added into the supernatant from activated human neutrophils containing NETs. We
used light scattering and electron microscopy to measure and characterize aggregation.
RESULTS AND DISCUSSION: NETs dose-dependently triggered an instantaneous
PrPC aggregation wich decreased over time due to protease activity in NETs. The
aggregates showed amorphous morphology and absence of fibrils. NETs previous
treatment with DNase I inhibited PrPC aggregation, pointing out the importance of the
DNA integrity for its effect. CONCLUSION: Our data suggest that NETs are an intriguing
factor that must be appraised in studies concerning prion propagation mechanisms.
[1] Cordeiro Y, Machado F, Juliano L, Juliano MA, Brentani RR, Foguel D, Silva JL.
(2001) J. Biol. Chem. 276(52), 49400-49409
[2] Michael, B. et al. (2012) Sci Rep. 2, 440
[3] Azevedo EP, Guimarães-Costa AB, Torezani GS, Braga CA, Palhano FL, Kelly JW,
Saraiva EM, Foguel D. (2012) J. Biol. Chem. 287, 37206-37218
Palavras chave: prion, neutrophil extracelular traps, protein aggregation, neutrophil
Patrocínio: FAPERJ, CNPq, CAPES, IMBEBB
Brazilian Society for Biochemistry and
Molecular Biology (SBBq)