title: Cell-Permeable Peptide Targeting the Nrf2-Keap1 Interaction: A Potential Novel Therapy for Global Cerebral Ischemia.
abstract: The current study examined efficacy of a small Tat (trans-activator of transcription)-conjugated peptide activator of the Nrf2 (nuclear factor-E2-related factor-2) antioxidant/cell-defense pathway as a potential injury-specific, novel neuroprotectant against global cerebral ischemia (GCI). A competitive peptide, DEETGE-CAL-Tat, was designed to facilitate Nrf2 activation by disrupting interaction of Nrf2 with Keap1 (kelch-like ECH-associated protein 1), a protein that sequesters Nrf2 in the cytoplasm and thereby inactivates it. The DEETGE-CAL-Tat peptide contained the critical sequence DEETGE for the Nrf2-Keap1 interaction, the cell transduction domain of the HIV-Tat protein, and the cleavage sequence of calpain, which is sensitive to Ca(2+) increase and allows injury-specific activation of Nrf2. Using an animal model of GCI, we demonstrated that pretreatment with the DEETGE-CAL-Tat peptide markedly decreased Nrf2 interaction with Keap1 in the rat hippocampal CA1 region after GCI, and enhanced Nrf2 nuclear translocation and DNA binding. The DEETGE-CAL-Tat peptide also induced Nrf2 antioxidant/cytoprotective target genes, reduced oxidative stress, and induced strong neuroprotection and marked preservation of hippocampal-dependent cognitive function after GCI. These effects were specific as control peptides lacked neuroprotective ability. Intriguingly, the DEETGE-CAL-Tat peptide effects were also injury specific, as it had no effect upon neuronal survival or cognitive performance in sham nonischemic animals. Of significant interest, peripheral, postischemia administration of the DEETGE-CAL-Tat peptide from days 1-9 after GCI also induced robust neuroprotection and strongly preserved hippocampal-dependent cognitive function. Based on its robust neuroprotective and cognitive-preserving effects, and its unique injury-specific activation properties, the DEETGE-CAL-Tat peptide represents a novel, and potentially promising new therapeutic modality for the treatment of GCI.
  
  
  CONCLUSIONS
  The current study demonstrates that DEETGE-CAL-Tat, a novel peptide activator of a key antioxidant gene transcription pathway in the hippocampus after global cerebral ischemia, can exert robust neuroprotection and preservation of cognitive function. A unique feature of the peptide is that its beneficial effects are injury specific. This feature is attractive as it targets drug activation specifically in the site of injury, and likely would lead to a reduction of undesirable side effects if translatable to the clinic. Due to its injury-specific activation, robust neuroprotection, and cognitive-preserving effects, this novel peptide may represent a much-needed therapeutic advance that could have efficacy in the treatment of global cerebral ischemia.
authors.affiliation: Neurobiology Institute of Medical Research Center, International Science & Technology Cooperation Base of Geriatric Medicine, North China University of Science and Technology, Tangshan, Hebei 063000, China.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Tu
authors.affiliation: Neurobiology Institute of Medical Research Center, International Science & Technology Cooperation Base of Geriatric Medicine, North China University of Science and Technology, Tangshan, Hebei 063000, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Neurobiology Institute of Medical Research Center, International Science & Technology Cooperation Base of Geriatric Medicine, North China University of Science and Technology, Tangshan, Hebei 063000, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Neurobiology Institute of Medical Research Center, International Science & Technology Cooperation Base of Geriatric Medicine, North China University of Science and Technology, Tangshan, Hebei 063000, China.
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Dai
authors.affiliation: Neurobiology Institute of Medical Research Center, International Science & Technology Cooperation Base of Geriatric Medicine, North China University of Science and Technology, Tangshan, Hebei 063000, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.affiliation: Neurobiology Institute of Medical Research Center, International Science & Technology Cooperation Base of Geriatric Medicine, North China University of Science and Technology, Tangshan, Hebei 063000, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.affiliation: Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia 30912, and.
authors.forename: Quanguang
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia 30912, and Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia 30904 ruimin-wang@163.com dbrann@gru.edu.
authors.forename: Darrell W
authors.initials: DW
authors.lastname: Brann
authors.affiliation: Neurobiology Institute of Medical Research Center, International Science & Technology Cooperation Base of Geriatric Medicine, North China University of Science and Technology, Tangshan, Hebei 063000, China, ruimin-wang@163.com dbrann@gru.edu.
authors.forename: Ruimin
authors.identifier: http://orcid.org/0000-0002-1842-6291
authors.initials: R
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002545:Brain Ischemia / Q000188:drug therapy* / Q000378:metabolism*; D057846:Cell-Penetrating Peptides / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems / Q000379:methods*; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000072019:Kelch-Like ECH-Associated Protein 1; D008297:Male; D008969:Molecular Sequence Data; D051267:NF-E2-Related Factor 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010446:Peptide Fragments / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D057846:Cell-Penetrating Peptides; D047908:Intracellular Signaling Peptides and Proteins; C486610:KEAP1 protein, rat; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C495637:Nfe2l2 protein, rat; D010446:Peptide Fragments
keywords: cardiac arrest; cognitive defect; hippocampus CA1 region; neuroprotection; peptide; reactive oxidative species