Pyridoxamine Inhibits Maillard Reactions in Diabetic Rat Lenses

Padival, Simi; Nagaraj, Ram H.

doi:10.1159/000095773

Cited by 24 publications

(13 citation statements)

References 67 publications

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“…Indeed, MG acts as an aldehyde substrate of AR, which also requires GSH for enzymatic activity [37], although both enzyme systems appear to react differently to the diabetic milieu. For example in diabetic lens, GLO1 activity goes down, whereas AR is enhanced, and the AGE inhibitor pyridoxamine corrects both these responses [38]. In many tissues where GSH is high and AR activity low, the glyoxalase system may be the main detoxifier of MG [37].…”

Section: Discussionmentioning

confidence: 99%

Protection against methylglyoxal-derived AGEs by regulation of glyoxalase 1 prevents retinal neuroglial and vasodegenerative pathology

et al. 2011

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Aims/hypothesis Methylglyoxal (MG) is an important precursor for AGEs. Normally, MG is detoxified by the glyoxalase (GLO) enzyme system (including component enzymes GLO1 and GLO2). Enhanced glycolytic metabolism in many cells during diabetes may overpower detoxification capacity and lead to AGE-related pathology. Using a transgenic rat model that overexpresses GLO1, we investigated if this enzyme can inhibit retinal AGE formation and prevent key lesions of diabetic retinopathy. Methods Transgenic rats were developed by overexpression of full length GLO1. Diabetes was induced in wild-type (WT) and GLO1 rats and the animals were killed after 12 or 24 weeks of hyperglycaemia. N ε -(Carboxyethyl)lysine (CEL), N ε -(carboxymethyl)lysine (CML) and MG-derivedhydroimidazalone-1 (MG-H1) were determined by immunohistochemistry and by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MSMS).Müller glia dysfunction was determined by glial fibrillary acidic protein (GFAP) immunoreactivity and by spatial localisation of the potassium channel Kir4.1. Acellular capillaries were quantified in retinal flat mounts. Results GLO1 overexpression prevented CEL and MG-H1 accumulation in the diabetic retina when compared with WT diabetic counterparts (p<0.01). Diabetes-related increases in Müller glial GFAP levels and loss of Kir4.1 at the vascular end-feet were significantly prevented by GLO1 overexpression (p<0.05) at both 12-and 24-week time points. GLO1 diabetic animals showed fewer acellular capillaries than WT diabetic animals (p<0.001) at 24 weeks' diabetes.A.K. Berner, O. Brouwers and R. Pringle contributed equally to this study.Electronic supplementary material The online version of this article

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Section: Discussionmentioning

confidence: 99%

Protection against methylglyoxal-derived AGEs by regulation of glyoxalase 1 prevents retinal neuroglial and vasodegenerative pathology

et al. 2011

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“…Lengthened wound healing time and increased susceptibility to infection associated with aging and the progressive age-induced decline in kidney function are also examples of the results of protein glycation. Glycation on the optic lens results in cataracts [21]. When AGE-induced cross-linking occurs in proteins that form the cells' internal structures, cells lose the ability to transport chemical signals internally, impairing numerous cell functions.…”

Section: Discussionmentioning

confidence: 99%

A well-oxygenated cells environment may help to fight against protein glycation

Mercier¹,

Prost²,

Prost

2011

International Journal of Occupational Medicine and Environmental Health

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Objectives: Normoglycemic Wistar rats' Glycated Hemoglobin Levels (GHL) showed a time-dependent difference between control groups and those exposed to regular inhalation of peroxidizing extracts of turpentine. These extracts were able to optimize the oxygen permeation at the cellular level during and subsequently to a breathing session. The more the rats breathed turpentine peroxidized vapor, the lower their GHL was. This study was designed to confirm, in ex-vivo blood samples, the impact of peroxidizing extract on the GHL. Materials and Methods: Red blood cells were separated from plasmas by centrifugation. Plasmas were treated by peroxidizing and non-peroxidizing turpentine vapor or untreated (control), then combined with washed red blood cells three hours before evaluation. Glycation of hemoglobin proteins was quantified according to the Habeed's method. Results: The ex-vivo experiments showed that the peroxidizing terpenes reduced the GHL after a three-hour contact. So did oxidized terpenes. Controls and the volatile component of the expended essential oil showed the opposite results. Conclusion: Optimal oxygenation, especially when facilitated by the peroxidized volatile component of the essential oil of turpentine, can protect organisms (mammals in this study) from protein glycation. Optimizing oxygenation can also reduce the GHL of treated blood samples after three hours of incubation.

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“…Lenses were homogenized in ice-cold 10%TCA (trichloroacetic acid) and the GSH concentration was determined as previously described [34]. …”

Section: Methodsmentioning

confidence: 99%

Identification of peptides in human Hsp20 and Hsp27 that possess molecular chaperone and anti-apoptotic activities

Nahomi

DiMauro

Wang

et al. 2014

Biochemical Journal

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Previous studies have identified peptides in the ‘crystallin-domain’ of the small heat-shock protein (sHSP) α-crystallin with chaperone and anti-apoptotic activities. We found that peptides in heat-shock protein Hsp20 (G71HFSVLLDVKHFSPEEIAVK91) and Hsp27 (D93RWRVSLDVNHFAPDELTVK113) with sequence homology to α-crystallin also have robust chaperone and anti-apoptotic activities. Both peptides inhibited hyperthermic and chemically induced aggregation of client proteins. The scrambled peptides of Hsp20 and Hsp27 showed no such effects. The chaperone activities of the peptides were better than those from αA- and αB-crystallin. HeLa cells took up the FITC-conjugated Hsp20 peptide and, when the cells were thermally stressed, the peptide was translocated from the cytoplasm to the nucleus. The two peptides inhibited apoptosis in HeLa cells by blocking cytochrome c release from the mitochondria and caspase-3 activation. We found that scrambling the last four amino acids in the two peptides (KAIV in Hsp20 and KTLV in Hsp27) made them unable to enter cells and ineffective against stress-induced apoptosis. Intraperitoneal injection of the peptides prevented sodium-selenite-induced cataract formation in rats by inhibiting protein aggregation and oxidative stress. Our study has identified peptides from Hsp20 and Hsp27 that may have therapeutic benefit in diseases where protein aggregation and apoptosis are contributing factors.

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Pyridoxamine Inhibits Maillard Reactions in Diabetic Rat Lenses

Cited by 24 publications

References 67 publications

Protection against methylglyoxal-derived AGEs by regulation of glyoxalase 1 prevents retinal neuroglial and vasodegenerative pathology

Protection against methylglyoxal-derived AGEs by regulation of glyoxalase 1 prevents retinal neuroglial and vasodegenerative pathology

A well-oxygenated cells environment may help to fight against protein glycation

Identification of peptides in human Hsp20 and Hsp27 that possess molecular chaperone and anti-apoptotic activities

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