title: The cell-penetrating peptide octa-arginine is a potent inhibitor of proteasome activities.
abstract: Oligo-arginines are cell-penetrating peptides and find use as carriers for transportation of various membrane-impermeable biopharmaceuticals into target cells. We have found that oligo-arginines of a length of 4-10 amino acids, but especially (Arg)(8), are able to inhibit the major intracellular proteolytic system, the proteasome, with mixed-type inhibition characteristics. The IC(50) values of (Arg)(8) for the proteasomal chymotrypsin-like and caspase-like activities are approximately 100 and 200 nM, respectively. The inhibition of the trypsin-like activity never exceeds 50% even at micromolar concentrations. (Arg)(8) also inhibits 20S proteasome/PA28 complexes as well as 26S proteasomes, although with a decreased efficiency. Due to its cell membrane-penetrating capability, incubation of HeLa cells in the presence of (Arg)(8) resulted in an impaired activity of proteasomes going along with an accumulation of high-molecular mass ubiquitin-conjugated proteins, the preferred substrates of 26S proteasomes. The in vivo susceptibility of the three proteasome activities resembles that found in vitro with chymotrypsin-like>caspase-like>trypsin-like activities. Since inhibition of the proteasome system might affect fundamental basic cellular processes but on the other side might also prevent the degradation of a proteinacous cargo, we suggest that this proteasome inhibitory activity should be taken into account when oligo-arginines are being considered for use as vectors for the intracellular delivery of pharmaceuticals.
authors.affiliation: Institut für Biochemie/CCM, Charité-Universitätsmedizin-Berlin, Berlin, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kloss
authors.forename: Peter
authors.initials: P
authors.lastname: Henklein
authors.forename: Dagmar
authors.initials: D
authors.lastname: Siele
authors.forename: Marion
authors.initials: M
authors.lastname: Schmolke
authors.forename: Sébastien
authors.initials: S
authors.lastname: Apcher
authors.forename: Lothar
authors.initials: L
authors.lastname: Kuehn
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sheppard
authors.forename: Burkhardt
authors.initials: B
authors.lastname: Dahlmann
mesh_terms: D000818:Animals; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D004337:Drug Carriers; D015195:Drug Design; D004912:Erythrocytes / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D018482:Muscle, Skeletal / Q000187:drug effects; D009842:Oligopeptides / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry; D061988:Proteasome Inhibitors; D051381:Rats; D013678:Technology, Pharmaceutical / Q000379:methods; D025801:Ubiquitin / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D009842:Oligopeptides; D010455:Peptides; D061988:Proteasome Inhibitors; D025801:Ubiquitin; C500307:octa-arginine peptide; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease