title: 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.affiliation: From the Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, Rhode Island, 02912.
authors.forename: John
authors.initials: J
authors.lastname: Marshall
authors.affiliation: the Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan 48105.
authors.forename: Kwoon Y
authors.initials: KY
authors.lastname: Wong
authors.affiliation: the Geisel School of Medicine at Dartmouth, Department of Pharmacology and Toxicology, and Norris Cotton Cancer Center, Lebanon, New Hampshire 03756.
authors.forename: Chamila N
authors.initials: CN
authors.lastname: Rupasinghe
authors.affiliation: the Chapman University School of Pharmacy, Irvine, California 92618.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Tiwari
authors.affiliation: the Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan 48105.
authors.forename: Xiwu
authors.initials: X
authors.lastname: Zhao
authors.affiliation: the Department of Anatomy and Cell Biology and.
authors.forename: Eren D
authors.initials: ED
authors.lastname: Berberoglu
authors.affiliation: Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201, and.
authors.forename: Christopher
authors.initials: C
authors.lastname: Sinkler
authors.affiliation: Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201, and.
authors.forename: Jenney
authors.initials: J
authors.lastname: Liu
authors.affiliation: the College of Medicine, Dankook University, Cheonan-si, Chungcheongnam-do, 330-714, Republic of Korea.
authors.forename: Icksoo
authors.initials: I
authors.lastname: Lee
authors.affiliation: the Chapman University School of Pharmacy, Irvine, California 92618.
authors.forename: Keykavous
authors.initials: K
authors.lastname: Parang
authors.affiliation: the Geisel School of Medicine at Dartmouth, Department of Pharmacology and Toxicology, and Norris Cotton Cancer Center, Lebanon, New Hampshire 03756.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Spaller
authors.affiliation: Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201, and.
authors.forename: Maik
authors.initials: M
authors.lastname: Hüttemann
authors.affiliation: the Department of Anatomy and Cell Biology and dgoebel@med.wayne.edu.
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Goebel
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016923:Cell Death / Q000187:drug effects; D000076122:Disks Large Homolog 4 Protein; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D051528:Guanylate Kinases / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects*; D008565:Membrane Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000502:physiology; D016202:N-Methylaspartate / Q000494:pharmacology*; D018696:Neuroprotective Agents / Q000378:metabolism / Q000494:pharmacology; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology*; D010456:Peptides, Cyclic / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism; D055351:Retinal Neurons / Q000187:drug effects* / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects / Q000502:physiology
chemical_list: C550069:CN2097; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D018690:Excitatory Amino Acid Agonists; D008565:Membrane Proteins; D018696:Neuroprotective Agents; D010455:Peptides; D010456:Peptides, Cyclic; D017382:Reactive Oxygen Species; D016194:Receptors, N-Methyl-D-Aspartate; C015462:polyarginine; D016202:N-Methylaspartate; D051528:Guanylate Kinases
keywords: N-methyl-d-aspartate receptor (NMDA receptor, NMDAR); apoptosis; mitochondrial membrane potential; necrosis (necrotic death); neuroprotection; retina; retinal ganglion cells