Oxidative stress-induced up-regulation of the chloride channel and Na+/Ca2+ exchanger during cataractogenesis in diabetic rats.
We have determined the abundance of the chloride channel, ClC-3, and Na(+)/Ca(2+) exchanger proteins in isolated rat lens cortex fiber cells by immunofluorescence method using polyclonal anti-ClC-3 antibodies and monoclonal antibodies against the canine cardiac Na(+)/Ca(2+) exchanger protein. These proteins were also quantified in the lens cortex of streptozotocin-injected rats by Western blots. Also, mRNA for ClC-3 was determined by Northern blot analysis. The isolated rat lens cortical fibers expressed basal levels of ClC-3 and Na(+)/Ca(2+) exchanger proteins. As compared to controls, the ClC-3 protein in the lens cortex of diabetic rats (blood glucose>400 mg%) increased by 2.5-fold in 7 days and 4.5-fold in 14 days. However, the ClC-3 protein decreased to near-normal values in 40 days. The changes in ClC-3 mRNA closely followed the protein levels. Similarly, as compared to controls, on Day 7, the Na(+)/Ca(2+) exchanger protein in the diabetic rat lens cortex increased by 3.5-fold and on Day14 by 5.5-fold. Subsequently, it decreased to control levels on Day 40. Treatment with the antioxidant, Trolox (2 mg/kg body weight), prevented the initial increase in ClC-3 and Na(+)/Ca(2+) exchanger proteins. The up-regulation of ClC-3 and Na(+)/Ca(2+) exchanger proteins during the early stages of diabetes and its prevention by antioxidants suggests that the proteins regulating ion transport may have a pathophysiological role in the development of diabetic cataracts.
Ramana
Kota V
KV
Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, 6-644 Basic Science Building, Galveston, TX 77555-0647, USA.
Chandra
Deepak
D
Wills
Nancy K
NK
Bhatnagar
Aruni
A
Srivastava
Satish K
SK
D008841:Actin Cytoskeleton / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015153:Blotting, Western / Q000379:methods; D002386:Cataract / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D018118:Chloride Channels / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D002839:Chromans / Q000494:pharmacology / Q000627:therapeutic use; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced; D004195:Disease Models, Animal; D005455:Fluorescent Antibody Technique / Q000379:methods; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006943:Hyperglycemia / Q000378:metabolism; D007904:Lens Cortex, Crystalline / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019831:Sodium-Calcium Exchanger / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D013311:Streptozocin / Q000008:administration & dosage / Q000009:adverse effects; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
D000911:Antibodies, Monoclonal; D018118:Chloride Channels; D002839:Chromans; D019831:Sodium-Calcium Exchanger; D013311:Streptozocin; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid