Modulation of Orai1 by cationic peptides triggers their direct cytosolic uptake.
At concentrations exceeding 10 μM, arginine-rich cell-penetrating peptides (CPPs) trigger a rapid cytoplasmic import that involves activation of acid sphingomyelinase (ASMase). ASMase activation occurs through a variety of stress signals and has also been related to the reorganization of membrane microdomains during entry of pathogens. However, in none of these cases has the initial trigger for ASMase activation been established on a molecular level. We here show that rapid cytosolic CPP import depends upon an increase in intracellular calcium, likely caused by modulation of the Orai1 calcium channel. At low peptide concentration, cytoplasmic import could be induced by thapsigargin, a known activator of Orai1. Compounds known to block Orai1 inhibited rapid uptake. Peptide-mediated modulation of Orai1 involved cell surface sialic acids as inhibition of sialylation as well as chemical blocking of sialic acids reduced rapid cytoplasmic uptake, which could be reconstituted by thapsigargin. These results establish a link between the known propensity of arginine-rich CPPs to interact with the glycocalyx and calcium influx as the initial step triggering direct cytosolic peptide uptake.
['Zuconelli|Cristiane R|CR|', 'Schmidt|Samuel|S|', 'Wallbrecher|Rike|R|', 'van Oostrum|Jenny|J|', 'Bartels|Yvonne L|YL|', 'Didan|Yuliia|Y|', 'Berendsen|Mike L T|MLT|', 'Brock|Roland|R|', 'Adjobo-Hermans|Merel J W|MJW|']
D002118:Calcium D015220:Calcium Channels D020013:Calcium Signaling D002412:Cations D002462:Cell Membrane D057846:Cell-Penetrating Peptides D003600:Cytosol D006367:HeLa Cells D006801:Humans D000071740:ORAI1 Protein D013108:Sphingomyelin Phosphodiesterase D019284:Thapsigargin
Cell-penetrating peptides Calcium Drug delivery Glycosylation Orai