title: Amino-terminally truncated prion protein PrP90-231 induces microglial activation in vitro.
abstract: The conversion of the prion protein (PrP) into a protease-resistant isoform (PrP(Res)) is considered the pathogenic event responsible for prion encephalopathies. Microglia activation accompanies PrP(Res) deposition representing an early event in the progression of these diseases. It is now believed that microglial cells play a worsening, if not causative, role in prion-induced neuronal death, through the release of proinflammatory and neurotoxic molecules. Indeed, in vitro observations have demonstrated that PrP(Res) and the synthetic prion fragment PrP106-126 induce neuronal death by activating microglial to migrate in the lesion area and secrete cytokines. Recently, we and others have demonstrated that the recombinant peptide, corresponding to the protease-resistant portion of PrP encompassing the amino acids 90-231 (PrP90-231), when beta-structured, is toxic for neuronal cells, in vitro. Here we report that PrP90-231 induces activation of N9 microglial cells, characterized by cell proliferation arrest and increased secretion of different cytokines (RANTES, GCSF, and IL-12). Moreover, the treatment of N9 cells with PrP90-231 elicited inducible nitric oxide synthase (i-NOS) expression, nitric oxide release, and a delayed (15 min to 1 h of treatment) extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation/activation. Although ERK1/2 is known to regulate proliferative and differentiative events, we show that its blockade, using the specific MEK inhibitor PD98059, did not prevent PrP90-231-induced inhibition of N9 cell proliferation. To our knowledge, this is the first evidence that a recombinant PrP(Res)-like peptide elicits microglial activation in vitro, thus representing a potentially important tool to develop possible therapeutic strategies to target prion-induced brain inflammation.
authors.affiliation: Laboratory of Pharmacology, Department of Oncology, Biology and Genetics, University of Genova, V. le Benedetto XV, 2, 16132 Genova, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Thellung
authors.forename: Alessandro
authors.initials: A
authors.lastname: Corsaro
authors.forename: Valentina
authors.initials: V
authors.lastname: Villa
authors.forename: Valentina
authors.initials: V
authors.lastname: Venezia
authors.forename: Mario
authors.initials: M
authors.lastname: Nizzari
authors.forename: Michela
authors.initials: M
authors.lastname: Bisaglia
authors.forename: Claudio
authors.initials: C
authors.lastname: Russo
authors.forename: Gennaro
authors.initials: G
authors.lastname: Schettini
authors.forename: Antonio
authors.initials: A
authors.lastname: Aceto
authors.forename: Tullio
authors.initials: T
authors.lastname: Florio
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D016207:Cytokines / Q000378:metabolism; D007249:Inflammation; D051379:Mice; D017628:Microglia / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D011328:Prions / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D013997:Time Factors
chemical_list: D016207:Cytokines; D009573:Nitrites; D010455:Peptides; D011328:Prions; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II