The protection of rat retinal ganglion cells from ischemia/reperfusion injury by the inhibitory peptide of mitochondrial μ-calpain.
Intracellular Ca(2+)-dependent cysteine proteases such as calpains have been suggested as critical factors in retinal ganglion cell (RGC) death. However, it is unknown whether mitochondrial calpains are involved in RGC death. The purpose of the present study was to determine whether the inhibition of mitochondrial μ-calpain activity protects against RGC death during ischemia/reperfusion (I/R) injury. This study used a well-established rat model of experimental acute glaucoma involving I/R injury. A specific peptide inhibitor of mitochondrial μ-calpain, Tat-μCL, was topically applied to rats via eye drops three times a day for 5 days after I/R. RGC death was determined by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. The truncation of apoptosis-inducing factor (AIF) was determined by western blot analyses. Retinal morphology was determined after staining with hematoxyline and eosin. In addition, the number of Fluoro Gold-labeled RGCs in flat-mounted retinas was used to determine the percentage of surviving RGCs after I/R injury. After 1 day of I/R, RGC death was observed in the ganglion cell layer. Treatment with Tat-μCL eye drops significantly prevented the death of RGCs and the truncation of AIF. After 5 days of I/R, RGC death decreased by approximately 40%. However, Tat-μCL significantly inhibited the decrease in the retinal sections and flat-mounted retinas. The results suggested that mitochondrial μ-calpain is associated with RGC death during I/R injury via truncation of AIF. In addition, the inhibition of mitochondrial μ-calpain activity by Tat-μCL had a neuroprotective effect against I/R-induced RGC death.
Department of Chemistry and Biological Sciences, Faculty of Science and Engineering, Iwate University, Morioka, Japan; Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan. Electronic address: tozaki@iwate-u.ac.jp.
Taku
T
Ozaki
Department of Biological Chemistry, Faculty of Agriculture, Iwate University, Morioka, Japan.
Tetsuro
T
Yamashita
Department of Chemistry and Biological Sciences, Faculty of Science and Engineering, Iwate University, Morioka, Japan.
Hiroshi
H
Tomita
Department of Chemistry and Biological Sciences, Faculty of Science and Engineering, Iwate University, Morioka, Japan.
Eriko
E
Sugano
Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan; Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
Sei-Ichi
S
Ishiguro
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051033:Apoptosis Inducing Factor / Q000037:antagonists & inhibitors / Q000378:metabolism; D015153:Blotting, Western; D002154:Calpain / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005901:Glaucoma / Q000378:metabolism / Q000503:physiopathology; D018613:Microscopy, Confocal; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009883:Ophthalmic Solutions; D010455:Peptides / Q000008:administration & dosage / Q000138:chemical synthesis / Q000494:pharmacology*; D020011:Protective Agents / Q000008:administration & dosage / Q000138:chemical synthesis / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism* / Q000503:physiopathology; D012160:Retina / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000378:metabolism
D051033:Apoptosis Inducing Factor; D024101:Mitochondrial Proteins; D009883:Ophthalmic Solutions; D010455:Peptides; D020011:Protective Agents; D002154:Calpain; C449002:mu-calpain
Apoptosis; Apoptosis-inducing factor; Glaucoma; Ischemia/reperfusion injury; Mitochondrial calpain; Retinal ganglion cell