Exploring the role of MKK7 in excitotoxicity and cerebral ischemia: a novel pharmacological strategy against brain injury

Cell Death Dis. 2015 Aug 13;6(8):e1854. doi: 10.1038/cddis.2015.226.


Excitotoxicity following cerebral ischemia elicits a molecular cascade, which leads to neuronal death. c-Jun-N-terminal kinase (JNK) has a key role in excitotoxic cell death. We have previously shown that JNK inhibition by a specific cell-permeable peptide significantly reduces infarct size and neuronal death in an in vivo model of cerebral ischemia. However, systemic inhibition of JNK may have detrimental side effects, owing to blockade of its physiological function. Here we designed a new inhibitor peptide (growth arrest and DNA damage-inducible 45β (GADD45β-I)) targeting mitogen-activated protein kinase kinase 7 (MKK7), an upstream activator of JNK, which exclusively mediates JNK's pathological activation. GADD45β-I was engineered by optimizing the domain of the GADD45β, able to bind to MKK7, and by linking it to the TAT peptide sequence, to allow penetration of biological membranes. Our data clearly indicate that GADD45β-I significantly reduces neuronal death in excitotoxicity induced by either N-methyl-D-aspartate exposure or by oxygen-glucose deprivation in vitro. Moreover, GADD45β-I exerted neuroprotection in vivo in two models of ischemia, obtained by electrocoagulation and by thromboembolic occlusion of the middle cerebral artery (MCAo). Indeed, GADD45β-I reduced the infarct size when injected 30 min before the lesion in both models. The peptide was also effective when administrated 6 h after lesion, as demonstrated in the electrocoagulation model. The neuroprotective effect of GADD45β-I is long lasting; in fact, 1 week after MCAo the infarct volume was still reduced by 49%. Targeting MKK7 could represent a new therapeutic strategy for the treatment of ischemia and other pathologies involving MKK7/JNK activation. Moreover, this new inhibitor can be useful to further dissect the physiological and pathological role of the JNK pathway in the brain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Newborn
  • Antigens, Differentiation / chemistry
  • Antigens, Differentiation / genetics
  • Antigens, Differentiation / metabolism
  • Cell Hypoxia
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / metabolism
  • Cerebral Cortex / pathology
  • Electrocoagulation
  • Gene Expression Regulation
  • Glucose / toxicity
  • Infarction, Middle Cerebral Artery / drug therapy*
  • Infarction, Middle Cerebral Artery / genetics
  • Infarction, Middle Cerebral Artery / metabolism
  • Infarction, Middle Cerebral Artery / pathology
  • JNK Mitogen-Activated Protein Kinases / genetics
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • MAP Kinase Kinase 7 / antagonists & inhibitors*
  • MAP Kinase Kinase 7 / chemistry
  • MAP Kinase Kinase 7 / genetics
  • MAP Kinase Kinase 7 / metabolism
  • Male
  • Molecular Docking Simulation
  • Molecular Sequence Data
  • N-Methylaspartate / toxicity
  • Neurons / drug effects*
  • Neurons / metabolism
  • Neurons / pathology
  • Neuroprotective Agents / chemical synthesis
  • Neuroprotective Agents / pharmacology*
  • Peptides / chemical synthesis
  • Peptides / pharmacology*
  • Primary Cell Culture
  • Protein Engineering
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • Thromboembolism
  • Tissue Culture Techniques


  • Antigens, Differentiation
  • Gadd45b protein, mouse
  • Neuroprotective Agents
  • Peptides
  • N-Methylaspartate
  • JNK Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 7
  • Map2k7 protein, mouse
  • Glucose