PrP octarepeats region determined the interaction with caveolin-1 and phosphorylation of caveolin-1 and Fyn

Abstract

Caveolin-1 is one of the major constituents of caveolae. Both Cav-1 and PrP are plasma membrane proteins, which show active capacities for molecular interactions with many other proteins or agents, including themselves. Using yeast two-hybrid system and immunoprecipitation, we reconfirmed the molecular interaction between human Cav-1 and PrP. With co-immunoprecipitation tests, PrP(C)-Cav-1 and PrP(Sc)-Cav-1 complexes were identified in the brain homogenates of normal and scrapie agent 263K-infected hamsters, respectively. Transient expression of wild-type PrP (PrP-PG5) in HEK293 cells did not change the situation of Cav-1 and subsequent signal transduction pathways, while cross-linking of the expressed PrP with specific antibody induced remarkable colocalization of PrP and Cav-1 on the plasma membrane and significant increases of phosphorylated Cav-1 and phosphorylated Fyn. With deleted and inserted PrP mutants within octarepeat region, we observed obvious octarepeat-associated phenomena, including lower binding capacity with Cav-1 in vitro, unable to co-localize with Cav-1 in the cells and to induce up-regulation of p-Cav-1 and p-Fyn when removal of octarepeats in the context of full-length PrP. Moreover, we found that treatment on HEK293 cells with fibrous form of recombinant PrP protein led to up-regulating the levels of p-Cav-1 and p-Fyn. Our data here provide strong evidence that octarepeats of PrP are critical for the interaction between PrP and Cav-1. Significant alterations in the cultured cells, either the distributions of PrP and Cav-1 morphologically or the up-regulations of p-Cav-1 and p-Fyn, induced by antibody-mediated cross-linking or fibrous forms of PrP may suggest a possible internalization process of PrP(Sc).

PRNP/prion protein regulates the secretion of exosomes modulating CAV1/caveolin-1-suppressed autophagy

“…59 CAV1 is one well-described PRNP ligand that interacts with the octapeptide repeat domain to activate signal transduction events downstream of the kinases FYN and LYN (Lyn proto-oncogene Src family tyrosine kinase). 49,60 Therefore, our findings that CAV1 is localized primarily within lipid rafts instead of the cytoplasm in prnp-null cells are in accordance with these previous studies. Remarkably, CAV1 has been described as an important negative regulator of autophagosome formation, [61][62] given its ability to impair ATG12-ATG5 engagement.…”

“…48 It has been reported that the interaction between PRNP and CAV1 at the plasma membrane occurs through this region. 9,49 Interestingly, CAV1 impairs the interaction between ATG5 and ATG12 in the cytoplasm, thereby suppressing autophagy. 46 We thus investigated if CAV1 is affected by PRNP expression.…”

MicroRNA‑124 inhibits cell proliferation, invasion and migration by targeting CAV1 in bladder cancer

“…CAV1, a scaffolding protein, is the major component of caveolae within plasma membranes in most cell types (33,34). CAV1 may link integrin subunits to the tyrosine kinase FYN, which is the initiating step in the coupling of integrins to the Ras-extracellular signal-regulated kinase pathway and the promotion of cell cycle progression (35,36). It has been reported that CAV1 was significantly upregulated in high-grade BC and that CAV1 expression is correlated with tumor grade and squamous cell differentiation of BC (23,24).…”

Actin dynamics and cofilin‐actin rods in alzheimer disease

“… Schematic of abbreviated signaling pathways contributing to rod formation by some initiators of neuronal stress and factors that change during AD progression . The role of caveolin and fyn in rod formation is hypothetical but is based on their known PrP C ‐mediated phosphorylation [Shi et al, ] and that fyn inhibitors can rescue synapse loss and established memory [Kaufman et al, ]. Other steps diagrammed here are discussed in the text.…”