Potential prophylactic effect of chemical chaperones for alleviation of endoplasmic reticulum stress in experimental diabetic cataract

Background Imbalance between protein synthesis and endoplasmic reticulum (ER) capacity to modify and fold proteins lead to the accumulation of unfolded proteins resulting in ER stress and apoptosis. Chaperones are major defense molecules assisting in protein folding, transport, and cellular signalin...

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Published in:	Bulletin of the National Research Centre Vol. 43; no. 1; pp. 1 - 15
Main Authors:	Abdel-Ghaffar, Amany, Elhossary, Ghada G., Mahmoud, Atef M., Elshazly, Amany H. M., Hassanin, Olfat A., Saleh, Anisa, Mansour, Sahar M., Metwally, Fatma G., Hanafy, Laila K., Karam, Sawsan H., Amer, Hager E., Samy, Nadia A., Ata, Ahmed Mostafa
Format:	Journal Article
Language:	English
Published:	Berlin/Heidelberg Springer Berlin Heidelberg 25-04-2019 Springer Nature B.V SpringerOpen
Subjects:	4-PBA Apoptosis Biochemical analysis Biochemical tests Blood Caspase-12 Cataract Cataracts Chaperones Chemical compounds Diabetes Diabetes mellitus Endoplasmic reticulum ER stress Humanities and Social Sciences Insulin Lenses Markers multidisciplinary Parameters Pathogenesis Pharmacology Phenylbutyric acid Protein biosynthesis Protein folding Protein synthesis Protein transport Proteins Science Science (multidisciplinary) Tauroursodeoxycholic acid Trimethylamine TUDCA Vascular endothelial growth factor TMAO Cataract 4-PBA Diabetes mellitus TUDCA ER stress Chaperones
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Summary:	Background Imbalance between protein synthesis and endoplasmic reticulum (ER) capacity to modify and fold proteins lead to the accumulation of unfolded proteins resulting in ER stress and apoptosis. Chaperones are major defense molecules assisting in protein folding, transport, and cellular signaling. ER stress plays a major role in the pathogenesis of diabetes mellitus (DM) and its complications, e.g., diabetic cataract. In the present investigation, the chemical chaperones 4-phenylbutyric acid (4-PBA), tauroursodeoxycholic acid (TUDCA), and trimethylamine N-oxide (TMAO) are used as potential therapeutic agents for alleviation of DM-induced ER stress and diabetic cataract in rats. Animals are subjected to biochemical analysis of blood and lenses for ER stress and apoptosis markers. Moreover, ophthalmologic examination and histopathologic examination of the lenses were done to confirm the results. Results Both ophthalmic and lens histopathologic examination revealed that treatment with 4-PBA and TUDCA retarded the occurrence of cataract markedly. Whereas, treatment with TMAO caused a partial improvement of cataract. Moreover, biochemical tests showed that both 4-PBA and TUDCA produced a remarkable improvement in the ER marker levels (VEGF and caspase-12), GSH, MDA, TAC levels in lens tissues. On the other hand, TMAO had no significant effect on these parameters. However, Western blot analysis of lens homogenates showed a suppressed expression of GRP78 and CHOP after treatment with 4-PBA, TUDCA, and TMAO. Moreover, all treated groups showed a significant improvement of lens soluble proteins and their UV spectra absorption. A significant improvement in fasting blood sugar, GSH, serum MDA, and TAC were noted in all treated groups. 4-PBA produced a significant decrease in insulin resistance, whereas TUDCA and TMAO showed insignificant change. Conclusion The present research found that the tested chaperones could be used as a therapeutic approach for clinically relevant disorders featuring ER dysfunction such as DM and for reducing its complications in the eye mainly cataract. However, TUDCA and 4-PBA were found to have a more potential efficacy in reducing most of the tested parameters as compared to TMAO.
ISSN:	2522-8307 2522-8307
DOI:	10.1186/s42269-019-0089-7