Intracellular delivery of a peptide nucleic acid-based hybrid of an autophagy inducing peptide with a cell-penetrating peptide

Org Biomol Chem. 2020 Mar 11;18(10):1978-1986. doi: 10.1039/c9ob02559f.

Abstract

Development of an intracellular delivery method for functional peptides via cell-penetrating peptides (CPPs) expands peptide use in basic research and therapeutic applications. Although direct conjugation of a functional peptide with a CPP is the simplest method for delivery, this method has not always been reliable. CPPs usually contain several positively charged amino acids that potentially interact non-specifically with negatively charged molecules in cells and subsequently interfere with conjugated functional peptide function. Here we demonstrate a new intracellular delivery method for peptides in which a functional peptide is released from a positively charged CPP via peptide nucleic acids (PNAs). We prepared an 8-mer PNA conjugated to octa-arginine in tandem (PNA1-CPP) and linked its complementary PNA to an autophagy inducing peptide (PNA2-AIP) by solid-phase peptide synthesis. PNA1-CPP and PNA2-AIP formed a 1 : 1 hybrid via PNA1/PNA2 interaction, thereby indirectly but stably connecting the AIP to the CPP. PNA2-AIP was successfully delivered into cells in a hybrid formation-dependent manner and at least some portion of the PNA1-CPP/PNA2-AIP hybrids dissociated into PNA2-AIP and PNA1-CPP inside the cells. Notably, PNA2-AIP delivered to cells induced more autophagy than AIP directly conjugated to CPP (CPP-AIP). Further, the PNA hybrid did not induce significant cell death. These findings indicate that the PNA1/PNA2 hybrid can function as a molecular glue enabling the delivery of functional peptides into cells.

MeSH terms

  • Autophagy / drug effects
  • Beclin-1 / metabolism
  • Beclin-1 / pharmacology*
  • Beclin-1 / toxicity
  • Cell-Penetrating Peptides / metabolism*
  • Cell-Penetrating Peptides / toxicity
  • Drug Carriers / metabolism*
  • Drug Carriers / toxicity
  • Drug Liberation
  • HeLa Cells
  • Humans
  • Leucine Zippers
  • Oligopeptides / metabolism
  • Oligopeptides / toxicity
  • Peptide Fragments / metabolism
  • Peptide Fragments / pharmacology*
  • Peptide Fragments / toxicity
  • Peptide Nucleic Acids / metabolism*
  • Peptide Nucleic Acids / toxicity
  • Protein Binding

Substances

  • Beclin-1
  • Cell-Penetrating Peptides
  • Drug Carriers
  • Oligopeptides
  • Peptide Fragments
  • Peptide Nucleic Acids
  • octaarginine