Histochemical Localization of Catalase in Cultured Lens Epithelial Cells

Mancini, Michael A.; Unakar, Nalin J.; Giblin, Frank J.; Reddan, John R.

doi:10.1159/000266901

Cited by 7 publications

(4 citation statements)

References 8 publications

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“…The condition is due to the failure of lens fiber cells in the bow region to differentiate properly into the clear fiber state and to the improper involution of cells from the anterior epithelium directly into the underlying cortex, resulting in cataractous opacities 111. Lens epithelial cells that were constantly exposed to 0·05 mM H 2 O 2 for 1–3 h exhibited damaged mitochondria 112…”

Section: Discussionmentioning

confidence: 99%

Mitochondria induce oxidative stress, generation of reactive oxygen species and redox state unbalance of the eye lens leading to human cataract formation: disruption of redox lens organization by phospholipid hydroperoxides as a common basis for cataract disease

Babizhayev¹

2011

Cell Biochemistry & Function

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The aging eye appears to be at considerable risk from oxidative stress. Lipid peroxidation (LPO) is one of the mechanisms of cataractogenesis, initiated by enhanced promotion of oxygen free radicals in the eye fluids and tissues and impaired enzymatic and non-enzymatic antioxidant defenses of the crystalline lens. The present study proposes that mitochondria are one of the major sources of reactive oxygen species (ROS) in mammalian and human lens epithelial cells and that therapies that protect mitochondria in lens epithelial cells from damage and reduce damaging ROS generation may potentially ameliorate the effects of free radical-induced oxidation that occur in aging ocular tissues and in human cataract diseases. It has been found that rather than complete removal of oxidants by the high levels of protective enzyme activities such as superoxide dismutase (SOD), catalase, lipid peroxidases in transparent lenses, the lens conversely, possess a balance between peroxidants and antioxidants in a way that normal lens tends to generate oxidants diffusing from lenticular tissues, shifting the redox status of the lens to become more oxidizing during both morphogenesis and aging. Release of the oxidants (O(2)(-)·, H(2)O(2) , OH·, and lipid hydroperoxides) by the intact lenses in the absence of respiratory inhibitors indicates that these metabolites are normal physiological products inversely related to the lens life-span potential (maturity of cataract) generated through the metal-ion catalyzed redox-coupled pro-oxidant activation of the lens reductants (ascorbic acid, glutathione). The membrane-bound phospholipid (PL) hydroperoxides escape detoxification by the lens enzymatic reduction. The lens cells containing these species would be vulnerable to peroxidative attack which trigger the PL hydroperoxide-dependent chain propagation of LPO and other damages in membrane (lipid and protein alterations). The increased concentrations of primary LPO products (diene conjugates, lipid hydroperoxides) and end fluorescent LPO products were detected in the lipid moiety of the aqueous humor samples obtained from patients with cataract as compared to normal donors. Since LPO is clinically important in many of the pathological effects and aging, new therapeutic modalities, such as patented N-acetylcarnosine prodrug lubricant eye drops, should treat the incessant infliction of damage to the lens cells and biomolecules by reactive lipid peroxides and oxygen species and "refashion" the affected lens membranes in the lack of important metabolic detoxification of PL peroxides. Combined in ophthalmic formulations with N-acetylcarnosine, mitochondria-targeted antioxidants are promising to become investigated as a potential tool for treating a number of ROS-related ocular diseases, including human cataracts.

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Section: Discussionmentioning

confidence: 99%

Mitochondria induce oxidative stress, generation of reactive oxygen species and redox state unbalance of the eye lens leading to human cataract formation: disruption of redox lens organization by phospholipid hydroperoxides as a common basis for cataract disease

Babizhayev¹

2011

Cell Biochemistry & Function

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“…It is not surprising that, like major anti-oxidative enzymes (Fujiwara et al 1992; Mancini et al 1989; Reddan et al 1996), most of GLOI is localized in the epithelium, as this is the most metabolically active part of the lens (Bhat 2001). It is likely that much of MGO is produced here and that it might require high levels of GLOI for metabolism.…”

Section: Discussionmentioning

confidence: 99%

Glyoxalase I activity and immunoreactivity in the aging human lens

et al. 2009

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Glyoxalase I (GLOI) is the first enzyme of the glyoxalase system that catalyzes the metabolism of reactive dicarbonyls, such as methylglyoxal (MGO). During aging and cataract development, human lens proteins are chemically modified by MGO, which is likely due to inadequate metabolism of MGO by the glyoxalase system. In this study, we have determined the effect of aging on GLOI activity and the immunoreactivity and morphological distribution of GLOI in the human lens. A monoclonal antibody was developed against human GLOI. GLOI immunoreactivity was strongest in the anterior epithelial cells and weaker in rest of the lens. Cultured human lens epithelial cells showed immunostaining throughout the cytoplasm. In the human lens, GLOI activity and immunoreactivity both decreased with age. We believe that this would lead to promotion of MGO-modification in aging lens proteins.

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“…The organelles are randomly distributed within the cytosol and often localize adjacent to the nucleus ( Fig. 3B and C) [41]. Frequently, they were found closely attached to microtubules, suggesting their active movement within LECs [35,36,42].…”

Section: Discussionmentioning

confidence: 99%

Synthesis of plasmalogens in eye lens epithelial cells

et al. 1999

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The present paper describes cloning and sequencing of the mouse cDNA encoding dihydroxyacetonephosphate acyltransferase (DAPAT), the peroxisomal key enzyme of plasmalogen (PM) biosynthesis. Using monospecific antibodies, we localized DAPAT and alkyl dihydroxyacetonephosphate synthase to peroxisomes of mouse lens epithelial cells (LECs) and determined their enzymatic activity. By electrospray ionization mass spectrometry of mouse lens lipid extracts, we identified phosphatidyl ethanolamine including plasmenyl ethanolamine species as major constituents. Our data demonstrate the capacity of LECs to synthesize PMs and the high coincidence between deficiency of PM and early manifestation of cataract in patients with peroxisomal disorders suggests that ether-bonded lipids may play an important role in maintaining lens transparency.z 1999 Federation of European Biochemical Societies.

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Histochemical Localization of Catalase in Cultured Lens Epithelial Cells

Cited by 7 publications

References 8 publications

Mitochondria induce oxidative stress, generation of reactive oxygen species and redox state unbalance of the eye lens leading to human cataract formation: disruption of redox lens organization by phospholipid hydroperoxides as a common basis for cataract disease

Mitochondria induce oxidative stress, generation of reactive oxygen species and redox state unbalance of the eye lens leading to human cataract formation: disruption of redox lens organization by phospholipid hydroperoxides as a common basis for cataract disease

Glyoxalase I activity and immunoreactivity in the aging human lens

Synthesis of plasmalogens in eye lens epithelial cells

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