title: Cellular uptake and intracellular fate of protein releasing bacterial amyloids in mammalian cells.
abstract: Bacterial Inclusion Bodies (IBs) are amyloidal protein deposits that functionally mimic secretory granules from the endocrine system. When formed by therapeutically relevant proteins, they complement missing intracellular activities in jeopardized cell cultures, offering an intriguing platform for protein drug delivery in substitutive therapies. Despite the therapeutic potential of IBs, their capability to interact with eukaryotic cells, cross the cell membrane and release their functional building blocks into the cytosolic space remains essentially unexplored. We have systematically dissected the process by which bacterial amyloids interact with mammalian cells. An early and tight cell membrane anchorage of IBs is followed by cellular uptake of single or grouped IBs of variable sizes by macropinocytosis. Although an important fraction of the penetrating particles is led to lysosomal degradation, biologically significant amounts of protein are released into the cytosol. In addition, our data suggest the involvement of the bacterial cell folding modulator DnaK in the release of functional proteins from these amyloidal reservoirs. The mechanisms supporting the internalization of disintegrable protein nanoparticles revealed here offer clues to implement novel approaches for protein drug delivery based on controlled protein packaging as bacterial IBs.
authors.affiliation: Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain. Joaquin.Seras@vhir.org.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Seras-Franzoso
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sánchez-Chardi
authors.forename: Elena
authors.initials: E
authors.lastname: Garcia-Fruitós
authors.forename: Esther
authors.initials: E
authors.lastname: Vázquez
authors.forename: Antonio
authors.initials: A
authors.lastname: Villaverde
mesh_terms: D000682:Amyloid / Q000378:metabolism*; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004926:Escherichia coli; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D007181:Inclusion Bodies, Viral / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D051379:Mice; D016716:PC12 Cells; D010873:Pinocytosis; D059748:Proteolysis; D051381:Rats; D014760:Viral Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000682:Amyloid; D014760:Viral Fusion Proteins; D049452:Green Fluorescent Proteins