June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
α-Crystallin chaperone mimetic small molecules as a paradigm for cataract prevention by inhibition of lens γ-crystallin aggregation
Author Affiliations & Notes
  • Vincent M Monnier
    Pathology, Case Western Reserve University, Cleveland, Ohio, United States
  • Sidra Islam
    Pathology, Case Western Reserve University, Cleveland, Ohio, United States
  • Michael Do
    Pathology, Case Western Reserve University, Cleveland, Ohio, United States
  • Brett Frank
    Pathology, Case Western Reserve University, Cleveland, Ohio, United States
  • Samuel G Wheeler
    Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States
  • Xingjun Fan
    Cell Biology and Anatomy, Medical College of Georgia, Augusta, Georgia, United States
  • Kirsten J Lampi
    Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States
  • David R Sell
    Pathology, Case Western Reserve University, Cleveland, Ohio, United States
  • Footnotes
    Commercial Relationships   Vincent Monnier Revel Pharmaceuticals, Code C (Consultant/Contractor); Sidra Islam None; Michael Do None; Brett Frank None; Samuel Wheeler None; Xingjun Fan None; Kirsten Lampi None; David Sell None
  • Footnotes
    Support  NEI Grant EY02929
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 17. doi:
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      Vincent M Monnier, Sidra Islam, Michael Do, Brett Frank, Samuel G Wheeler, Xingjun Fan, Kirsten J Lampi, David R Sell; α-Crystallin chaperone mimetic small molecules as a paradigm for cataract prevention by inhibition of lens γ-crystallin aggregation. Invest. Ophthalmol. Vis. Sci. 2022;63(7):17.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : γ-Crystallins play a major role in maintaining age-related lens transparency. Their destabilization by mutations and physical chemical insults is strongly associated with cataract. Therefore, drugs that increase their stability should have anti-cataract properties. To this end we have screened 2560 drugs and natural compounds for their ability to suppress H2O2 and/or heat mediated aggregation of bovine γ-crystallins and various recombinant human and mouse γ-crystallins.

Methods : Protein unfolding, aggregation and binding affinity were determined using absorption, fluorescence and CD spectroscopy, dynamic light scattering, transmission electron microscopy and fluorescence quenching. Protein binding sites were determined using AutodockVIna.

Results : The top two drugs, Closantel (C), an antihelmintic drug, and Gambogic Acid (G), a xanthonoid compound prevented or attenuated to variable degree thermal-induced protein unfolding when tested against Human or Mouse recombinant crystallins such as deamidated HγS mutants, wild-type HγD & MγS and their respective mutants W43R, R14C and R58H, and F9S/OPJ. Binding studies using fluorescence quenching and ANS method revealed static binding of drugs C & G to hydrophobic sites of medium to low affinity ranging from -5.9 to -7.9 kcal/mol (HγD) and -4.1 to -8.2 kcal/mol (MγS) with Kb values ranging from 1.34x105 to 6.1 x 105 M-1(HγD) and 0.073 x105 to 1.38 x105 M-1 (MγS). Molecular docking to HγD and other γ-crystallin revealed two binding sites, one in the “NC-pocket” including residues in the 50-150 sequence of HgD, and one in the “NC-tail” spanning residues 56-61 from the N-terminal to the residues 168-174 in C-terminal domain. Several of these binding sites overlapped with those of the protective α-crystallin mini-chaperone peptide “MAC”.

Conclusions : These results support the existence of a new class of α-crystallin mimetic drugs with chaperone effect and anti-cataract potential whereby Closantel and Gambogic acid emerge as the most promising candidate compounds. However, their binding activity to gamma crystallins is relatively low and it remains to be tested whether inhibtion of gamma crystallin aggregation can prevent cataract formation in appropriate congenital or environmentally induced animal models of cataract.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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