1. Endocytosis of prion protein is required for ERK1/2 signaling induced by stress-inducible protein 1.
- Author
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Caetano FA, Lopes MH, Hajj GN, Machado CF, Pinto Arantes C, Magalhães AC, Vieira Mde P, Américo TA, Massensini AR, Priola SA, Vorberg I, Gomez MV, Linden R, Prado VF, Martins VR, and Prado MA
- Subjects
- Animals, Cells, Cultured, Cyclic AMP-Dependent Protein Kinases metabolism, Dynamins metabolism, Enzyme Activation physiology, Heat-Shock Proteins genetics, MAP Kinase Signaling System physiology, Mice, Mice, Inbred C57BL, Mice, Knockout, Mitogen-Activated Protein Kinase 1 metabolism, Mitogen-Activated Protein Kinase 3 metabolism, Organ Culture Techniques, PrPC Proteins genetics, Protein Transport physiology, Brain metabolism, Endocytosis physiology, Extracellular Signal-Regulated MAP Kinases metabolism, Heat-Shock Proteins metabolism, Neurons metabolism, PrPC Proteins metabolism
- Abstract
The secreted cochaperone STI1 triggers activation of protein kinase A (PKA) and ERK1/2 signaling by interacting with the cellular prion (PrP(C)) at the cell surface, resulting in neuroprotection and increased neuritogenesis. Here, we investigated whether STI1 triggers PrP(C) trafficking and tested whether this process controls PrP(C)-dependent signaling. We found that STI1, but not a STI1 mutant unable to bind PrP(C), induced PrP(C) endocytosis. STI1-induced signaling did not occur in cells devoid of endogenous PrP(C); however, heterologous expression of PrP(C) reconstituted both PKA and ERK1/2 activation. In contrast, a PrP(C) mutant lacking endocytic activity was unable to promote ERK1/2 activation induced by STI1, whereas it reconstituted PKA activity in the same condition, suggesting a key role of endocytosis in the former process. The activation of ERK1/2 by STI1 was transient and appeared to depend on the interaction of the two proteins at the cell surface or shortly after internalization. Moreover, inhibition of dynamin activity by expression of a dominant-negative mutant caused the accumulation and colocalization of these proteins at the plasma membrane, suggesting that both proteins use a dynamin-dependent internalization pathway. These results show that PrP(C) endocytosis is a necessary step to modulate STI1-dependent ERK1/2 signaling involved in neuritogenesis.
- Published
- 2008
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