ERK1/2 and p38 MAP kinases control prion protein fragment 90-231-induced astrocyte proliferation and microglia activation.
Astrogliosis and microglial activation are a common feature during prion diseases, causing the release of chemoattractant and proinflammatory factors as well as reactive free radicals, involved in neuronal degeneration. The recombinant protease-resistant domain of the prion protein (PrP90-231) displays in vitro neurotoxic properties when refolded in a beta-sheet-rich conformer. Here, we report that PrP90-231 induces the secretion of several cytokines, chemokines, and nitric oxide (NO) release, in both type I astrocytes and microglial cells. PrP90-231 elicited in both cell types the activation of ERK1/2 MAP kinase that displays, in astrocytes, a rapid kinetics and a proliferative response. Conversely, in microglia, PrP90-231-dependent MAP kinase activation was delayed and long lasting, inducing functional activation and growth arrest. In microglial cells, NO release, dependent on the expression of the inducible NO synthase (iNOS), and the secretion of the chemokine CCL5 were Ca(2+) dependent and under the control of the MAP kinases ERK1/2 and p38: ERK1/2 inhibition, using PD98059, reduced iNOS expression, while p38 blockade by PD169316 inhibited CCL5 release. In summary, we demonstrate that glial cells are activated by extracellular misfolded PrP90-231 resulting in a proliferative/secretive response of astrocytes and functional activation of microglia, both dependent on MAP kinase activation. In particular, in microglia, PrP90-231 activated a complex signalling cascade involved in the regulation of NO and chemokine release. These data argue in favor of a causal role for misfolded prion protein in sustaining glial activation and, possibly, glia-mediated neuronal death.
Thellung
Stefano
S
Department of Oncology, Biology and Genetics, University of Genova, Genova, Italy.
Villa
Valentina
V
Corsaro
Alessandro
A
Pellistri
Francesca
F
Venezia
Valentina
V
Russo
Claudio
C
Aceto
Antonio
A
Robello
Mauro
M
Florio
Tullio
T
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology; D001921:Brain / Q000187:drug effects / Q000201:enzymology / Q000503:physiopathology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005911:Gliosis / Q000139:chemically induced / Q000201:enzymology* / Q000503:physiopathology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D017628:Microglia / Q000187:drug effects / Q000201:enzymology; D009457:Neuroglia / Q000201:enzymology*; D052247:Nitric Oxide Synthase Type II / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism* / Q000494:pharmacology; D017096:Prion Diseases / Q000201:enzymology / Q000503:physiopathology; D011328:Prions / Q000378:metabolism* / Q000494:pharmacology; D017510:Protein Folding; D051381:Rats; D017207:Rats, Sprague-Dawley; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D018925:Chemokines; D016207:Cytokines; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D011328:Prions; C507417:prion protein (90-231); D052247:Nitric Oxide Synthase Type II; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases