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Abstract #21668 Published in IGR 10-3
Neuroprotection in glaucoma using calpain-1 inhibitors: Regional differences in calpain-1 activity in the trabecular meshwork, optic nerve and implications for therepeutics
Govindarajan B; Laird J; Sherman R; Salomon RG; Bhattacharya SKCNS and Neurological Disorders - Drug Targets 2008; 7: 295-304
Glaucoma is a group of irreversible blinding eye diseases affecting over 70 million people worldwide. Systemic delivery of calpain-1 inhibitors was proposed as a neuroprotection strategy for the prevention of progressive optic nerve damage in glaucoma. We present a general review of calpain-1 and an account of vast differences in processing of calpain-1 in the trabecular meshwork (TM) and the optic nerve. Calpain-1 accumulates in the glaucomatous TM tissues in vivo. However, calpain-1 activity is substantially lower in the glaucomatous TM compared to controls, apparently owing to partial degradation, and modification by lipid oxidation products such as iso [4]leviglandin E2 (iso ([4]LGE2). Treatment of calpain-1 with iso [4]LGE2 in vitro results in covalent modification, inactivation, and resistance to protease digestion. Iso [4]LGE2-modified calpain-1 appeared to undergo ubiquitination in the TM by cellular degradation machinery mediated by ubch1-2, ubch5,6 and E6-AP, E2 and E3 enzymes respectively. In the TM, iso [4]LGE2-modified calpain-1 loading impairs the cellular proteasome activity consistent with competitive inhibition and formation of suicidal high molecular weight aggregates. In contrast, higher calpain-1 activity, that appears to be under translational control, was observed in glaucomatous optic nerve compared to control. Therapeutic neuroprotection strategies using calpain-1 inhibitors will require consideration of such anatomic differences in its activity and biosynthesis.
Dr. S.K. Bhattacharya, Bascom Palmer Eye Institute, University of Miami, 1638 NW 10th Avenue, Miami, FL 33136, USA. sbhattacharya@med.miami.edu
Classification:
11.8 Neuroprotection (Part of: 11 Medical treatment)
11.14 Investigational drugs; pharmacological experiments (Part of: 11 Medical treatment)
5.3 Other (Part of: 5 Experimental glaucoma; animal models)