title: Inclusion bodies as potential vehicles for recombinant protein delivery into epithelial cells.
abstract: BACKGROUND
  We present the potential of inclusion bodies (IBs) as a protein delivery method for polymeric filamentous proteins. We used as cell factory a strain of E. coli, a conventional host organism, and keratin 14 (K14) as an example of a complex protein. Keratins build the intermediate filament cytoskeleton of all epithelial cells. In order to build filaments, monomeric K14 needs first to dimerize with its binding partner (keratin 5, K5), which is then followed by heterodimer assembly into filaments.
  
  
  RESULTS
  K14 IBs were electroporated into SW13 cells grown in culture together with a "reporter" plasmid containing EYFP labeled keratin 5 (K5) cDNA. As SW13 cells do not normally express keratins, and keratin filaments are built exclusively of keratin heterodimers (i.e. K5/K14), the short filamentous structures we obtained in this study can only be the result of: a) if both IBs and plasmid DNA are transfected simultaneously into the cell(s); b) once inside the cells, K14 protein is being released from IBs; c) released K14 is functional, able to form heterodimers with EYFP-K5.
  
  
  CONCLUSIONS
  Soluble IBs may be also developed for complex cytoskeletal proteins and used as nanoparticles for their delivery into epithelial cells.
authors.affiliation: Medical Center for Molecular Biology, University of Ljubljana, Ljubljana, Slovenia. mirjana.liovic@mf.uni-lj.si
authors.forename: Mirjana
authors.initials: M
authors.lastname: Liovic
authors.forename: Mateja
authors.initials: M
authors.lastname: Ozir
authors.forename: Apolonija Bedina
authors.initials: AB
authors.lastname: Zavec
authors.forename: Spela
authors.initials: S
authors.lastname: Peternel
authors.forename: Radovan
authors.initials: R
authors.lastname: Komel
authors.forename: Tina
authors.initials: T
authors.lastname: Zupancic
mesh_terms: D016503:Drug Delivery Systems / Q000379:methods*; D018274:Electroporation; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006801:Humans; D002479:Inclusion Bodies / Q000235:genetics / Q000378:metabolism*; D007382:Intermediate Filaments / Q000235:genetics / Q000378:metabolism; D053547:Keratin-14 / Q000235:genetics / Q000378:metabolism / Q000627:therapeutic use; D053555:Keratin-5 / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism* / Q000627:therapeutic use
chemical_list: D053547:Keratin-14; D053555:Keratin-5; D011994:Recombinant Proteins