A multimolecular signaling complex including PrPC and LRP1 is strictly dependent on lipid rafts and is essential for the function of tissue plasminogen activator. Issue 4 (25th October 2019)

• Record Type: Journal Article
• Authors: Mattei, Vincenzo; Manganelli, Valeria; Martellucci, Stefano; Capozzi, Antonella; Mantuano, Elisabetta; Longo, Agostina; Ferri, Alberto; Garofalo, Tina; Sorice, Maurizio; Misasi, Roberta
• Is Part Of: Journal of neurochemistry. Volume 152:Issue 4(2020)
• Page Start: 468
• Page End: 481
• Publication Date: 2019-10-25
• Subjects: GM1 -- lipid rafts -- LRP1 -- methyl‐β‐cyclodextrin -- prion protein -- tPA; Neurochemistry -- Periodicals; 616.8042
• DOI: 10.1111/jnc.14891
• Languages: English
• ISSNs: 0022-3042

Abstract

Abstract: Prion protein (PrP C ) localizes stably in lipid rafts microdomains and is able to recruit downstream signal transduction pathways by the interaction with promiscuous partners. Other proteins have the ability to occasionally be recruited to these specialized membrane areas, within multimolecular complexes. Among these, we highlight the presence of the low‐density lipoprotein receptor‐related protein 1 (LRP1), which was found localized transiently in lipid rafts, suggesting a different function of this receptor that through lipid raft becomes able to activate a signal transduction pathway triggered by specific ligands, including Tissue plasminogen activator (tPA). Since it has been reported that PrP C participates in the tPA‐mediated plasminogen activation, in this study, we describe the role of lipid rafts in the recruitment and activation of downstream signal transduction pathways mediated by the interaction among tPA, PrP C and LRP1 in human neuroblastoma SK‐N‐BE2 cell line. Co‐immunoprecipitation analysis reveals a consistent association between PrP C and GM1, as well as between LRP1 and GM1, indicating the existence of a glycosphingolipid‐enriched multimolecular complex. In our cell model, knocking‐down PrP C by siRNA impairs ERK phosphorylation induced by tPA. Moreover the alteration of the lipidic milieu of lipid rafts, perturbing the physical/functional interaction between PrP C and LRP1, inhibits this response. We show that LRP1 and PrP C, following tPA stimulation, may function as a system associated with lipid rafts, involved in receptor‐mediated neuritogenic pathway. We suggest this as a multimolecular signaling complex, whose activity depends strictly on the integrity of lipid raft and is involved in the neuritogenic signaling. Abstract : Prion protein (PrPC) localizes stably in lipid rafts microdomains and is able to recruit downstream signal transduction pathways by the interaction with promiscuous partners. It is known that tissue plasminogen activator (tPA) functions by binding a prion–plasminogen complex and forming activated plasmin and that tPA acts as a ligand for LRP1 (lipoprotein receptor‐related protein 1), leading to receptor recruitment in lipid rafts and inducing neurodifferentiation signaling.In this research we show that: Knocking‐down PrP or LRP1 by siRNA impairs ERK phosphorylation induced by tPA. Perturbation of lipid raft inhibits the binding of tPA to LRP1/PrP complex . Inhibition of the interaction among PrP and LRP1 alters signaling mediated by tPA. Thus we can say that PrP, LRP1 and tPA work in a single complex whose activity depends on lipid raft.