Trol the biogenesis, folding, trafficking, and degradation of proteins) inside the approach; whereas the internalization of little acidic aggregates is HSF1-independent, the uptake of larger standard aggregates was HSF1-dependent, requiring Hsp70. Our outcomes show that the biophysical properties of aggregates IFN-alpha 16 Proteins site decide each their mechanism of internalization and proteostatic response. It remains to be observed whether or not these differences in cellular response contribute to the specific part of precise aggregated proteins in illness. This perform was supported in portion by VIB, University of Leuven, Grant GOA/11/009 (to W. A.), the Funds for Scientific Investigation Flanders (FWO), the Flanders Institute for Science and Technology (IWT), Federal Office for Scientific Affairs of Belgium (Belspo) Grant IUAP P7/16, and Hercules Foundation Grants AKUL/09/037 and AKUL/11/30. S This article contains supplemental Videos 1. 1 To whom correspondence must be addressed: Switch Laboratory, Dept. of Cellular and Molecular Medicine, Gasthuisberg Campus O N1, Herestraat 49 bus 802, B-3000 Leuven, Belgium. Tel.: 32-16-3-72572; Fax: 32-16-372571; E-mail: [email protected] too long ago, it has been demonstrated that various disease-associated aggregates, such as human (1) and yeast prions (4), A (5), Tau (6), –IL-18RAP Proteins Biological Activity synuclein (7), SOD1 (8), and PolyQ (9), can cross cellular membranes and spread aggregation from cell to cell (10). This has led towards the notion that all of these proteins potentially possess a specific degree of prionoid behavior (8, 11, 12). In spite of these reports, the mechanism by which this approach takes location remains obscure since the transmission of a protein or aggregate from the cytosol of a single cell to the cytosol of a neighboring cell needs the crossing of each cellular membranes. The existence of cell membrane translocation mechanisms has been proposed for some amyloids, including nanotubules for prions (three) or membrane diffusion by an unknown mechanism for a 40 (13, 14) and -synuclein (15), although it really is now widely accepted that aggregate transmission may also occur via a mixture of exocytosis, endocytosis, and endosomal escape (16). In accordance with this hypothesis, numerous mechanisms of endocytosis and exocytosis have already been postulated for the most typical amyloids. Exocytosis by standard exosomes, consequently with the fusion of multivesicular bodies with the plasma membrane, has been reported for monomeric A (17), -synuclein (18 0), PrpSc (2, 21), and Tau (22) in neuroblastoma cell lines. Other unconventional exocytosis mechanisms happen to be described for PrP (23) and -synuclein (19). Endocytosis of monomeric A (13, 14, 24 six) and -synuclein (15, 279) and endocytosis from the fibrillar and oligomeric states of some amyloids have also been reported. For example, fibrilar A is often cleared in the medium by microglia and astroglia (30 32), whereas oligomeric A is often taken up by neuroblastoma SH-SY5Y cells (33). The internalization of PrpSc aggregates has been reported in murine and human neuroblastoma cell linesVOLUME 290 Number 1 JANUARY 2,242 JOURNAL OF BIOLOGICAL CHEMISTRYSize-dependent Uptake of Peptide Aggregatesand mouse fibroblasts, whereby heparan sulfates and lipid rafts turned out to be involved (1, 34 7). SOD1 aggregates are internalized by macropinocytosis by N2a cells, a neuroblastoma cell line (8), whereas Tau aggregates were taken up by HEK-293 cells and neuroblastoma cell lines (6, 38, 39). Currently, it’s not know.
