Inhibition of N-Methyl-D-aspartate-induced Retinal Neuronal Death by Polyarginine Peptides Is Linked to the Attenuation of Stress-induced Hyperpolarization of the Inner Mitochondrial Membrane Potential.

Abstract

It is widely accepted that overactivation of NMDA receptors, resulting in calcium overload and consequent mitochondrial dysfunction in retinal ganglion neurons, plays a significant role in promoting neurodegenerative disorders such as glaucoma. Calcium has been shown to initiate a transient hyperpolarization of the mitochondrial membrane potential triggering a burst of reactive oxygen species leading to apoptosis. Strategies that enhance cell survival signaling pathways aimed at preventing this adverse hyperpolarization of the mitochondrial membrane potential may provide a novel therapeutic intervention in retinal disease. In the retina, brain-derived neurotrophic factor has been shown to be neuroprotective, and our group previously reported a PSD-95/PDZ-binding cyclic peptide (CN2097) that augments brain-derived neurotrophic factor-induced pro-survival signaling. Here, we examined the neuroprotective properties of CN2097 using an established retinal in vivo NMDA toxicity model. CN2097 completely attenuated NMDA-induced caspase 3-dependent and -independent cell death and PARP-1 activation pathways, blocked necrosis, and fully prevented the loss of long term ganglion cell viability. Although neuroprotection was partially dependent upon CN2097 binding to the PDZ domain of PSD-95, our results show that the polyarginine-rich transport moiety C-R(7), linked to the PDZ-PSD-95-binding cyclic peptide, was sufficient to mediate short and long term protection via a mitochondrial targeting mechanism. C-R(7) localized to mitochondria and was found to reduce mitochondrial respiration, mitochondrial membrane hyperpolarization, and the generation of reactive oxygen species, promoting survival of retinal neurons.

• Authors: John Marshall, Kwoon Y Wong, Chamila N Rupasinghe, Rakesh Tiwari, Xiwu Zhao, Eren D Berberoglu, Christopher Sinkler, Jenney Liu, Icksoo Lee, Keykavous Parang, Mark R Spaller, Maik Hüttemann, Dennis J Goebel
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 290 Issue 36 Pg. 22030-48 (Sep 04 2015) ISSN: 1083-351X [Electronic] United States
• PMID: 26100636 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• CN2097
• Disks Large Homolog 4 Protein
• Dlg4 protein, mouse
• Excitatory Amino Acid Agonists
• Membrane Proteins
• Neuroprotective Agents
• Peptides
• Peptides, Cyclic
• Reactive Oxygen Species
• Receptors, N-Methyl-D-Aspartate
• polyarginine
• N-Methylaspartate
• Guanylate Kinases

Topics

• Animals
• Blotting, Western
• Cell Death (drug effects)
• Disks Large Homolog 4 Protein
• Excitatory Amino Acid Agonists (pharmacology)
• Guanylate Kinases (metabolism)
• HEK293 Cells
• Humans
• Male
• Membrane Potential, Mitochondrial (drug effects)
• Membrane Proteins (metabolism)
• Microscopy, Fluorescence
• Mitochondria (drug effects, metabolism, physiology)
• Mitochondrial Membranes (drug effects, physiology)
• N-Methylaspartate (pharmacology)
• Neuroprotective Agents (metabolism, pharmacology)
• Peptides (metabolism, pharmacology)
• Peptides, Cyclic (metabolism, pharmacology)
• Protein Binding
• Rats, Sprague-Dawley
• Reactive Oxygen Species (metabolism)
• Receptors, N-Methyl-D-Aspartate (metabolism)
• Retina (cytology, drug effects, metabolism)
• Retinal Ganglion Cells (drug effects, metabolism)
• Retinal Neurons (drug effects, metabolism)
• Stress, Physiological (drug effects, physiology)