title: The neuroprotective efficacy of cell-penetrating peptides TAT, penetratin, Arg-9, and Pep-1 in glutamic acid, kainic acid, and in vitro ischemia injury models using primary cortical neuronal cultures.
abstract: Cell-penetrating peptides (CPPs) are small peptides (typically 5-25 amino acids), which are used to facilitate the delivery of normally non-permeable cargos such as other peptides, proteins, nucleic acids, or drugs into cells. However, several recent studies have demonstrated that the TAT CPP has neuroprotective properties. Therefore, in this study, we assessed the TAT and three other CPPs (penetratin, Arg-9, Pep-1) for their neuroprotective properties in cortical neuronal cultures following exposure to glutamic acid, kainic acid, or in vitro ischemia (oxygen-glucose deprivation). Arg-9, penetratin, and TAT-D displayed consistent and high level neuroprotective activity in both the glutamic acid (IC50: 0.78, 3.4, 13.9 μM) and kainic acid (IC50: 0.81, 2.0, 6.2 μM) injury models, while Pep-1 was ineffective. The TAT-D isoform displayed similar efficacy to the TAT-L isoform in the glutamic acid model. Interestingly, Arg-9 was the only CPP that displayed efficacy when washed-out prior to glutamic acid exposure. Neuroprotection following in vitro ischemia was more variable with all peptides providing some level of neuroprotection (IC50; Arg-9: 6.0 μM, TAT-D: 7.1 μM, penetratin/Pep-1: >10 μM). The positive control peptides JNKI-1D-TAT (JNK inhibitory peptide) and/or PYC36L-TAT (AP-1 inhibitory peptide) were neuroprotective in all models. Finally, in a post-glutamic acid treatment experiment, Arg-9 was highly effective when added immediately after, and mildly effective when added 15 min post-insult, while the JNKI-1D-TAT control peptide was ineffective when added post-insult. These findings demonstrate that different CPPs have the ability to inhibit neurodamaging events/pathways associated with excitotoxic and ischemic injuries. More importantly, they highlight the need to interpret neuroprotection studies when using CPPs as delivery agents with caution. On a positive note, the cytoprotective properties of CPPs suggests they are ideal carrier molecules to deliver neuroprotective drugs to the CNS following injury and/or potential neuroprotectants in their own right.
authors.affiliation: Centre for Neuromuscular and Neurological Disorders, The University of Western Australia and Australian Neuromuscular Research Institute, A Block, 4th Floor, QEII Medical Centre, Verdun St, Nedlands, WA, 6009, Australia, bruno.meloni@anri.uwa.edu.au.
authors.forename: Bruno P
authors.initials: BP
authors.lastname: Meloni
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Craig
authors.forename: Nadia
authors.initials: N
authors.lastname: Milech
authors.forename: Richard M
authors.initials: RM
authors.lastname: Hopkins
authors.forename: Paul M
authors.initials: PM
authors.lastname: Watt
authors.forename: Neville W
authors.initials: NW
authors.lastname: Knuckey
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D057846:Cell-Penetrating Peptides / Q000737:chemistry / Q000494:pharmacology*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000473:pathology*; D003543:Cysteamine / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D015696:Gene Products, tat / Q000737:chemistry / Q000494:pharmacology; D018698:Glutamic Acid / Q000633:toxicity*; D020128:Inhibitory Concentration 50; D007511:Ischemia / Q000473:pathology*; D007608:Kainic Acid / Q000633:toxicity*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009498:Neurotoxins / Q000633:toxicity; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D015696:Gene Products, tat; D018696:Neuroprotective Agents; D009498:Neurotoxins; D009842:Oligopeptides; C503924:Pep-1 peptide; D010455:Peptides; C491427:nonaarginine; D018698:Glutamic Acid; D003543:Cysteamine; C414409:penetratin; D007608:Kainic Acid