Aggrelyte-2 promotes protein solubility and decreases lens stiffness through lysine acetylation and disulfide reduction: Implications for treating presbyopia.

Abstract

Aging proteins in the lens become increasingly aggregated and insoluble, contributing to presbyopia. In this study, we investigated the ability of aggrelyte-2 (N,S-diacetyl-L-cysteine methyl ester) to reverse the water insolubility of aged human lens proteins and to decrease stiffness in cultured human and mouse lenses. Water-insoluble proteins (WI) of aged human lenses (65-75 years) were incubated with aggrelyte-2 (500 μM) for 24 or 48 h. A control compound that lacked the S-acetyl group (aggrelyte-2C) was also tested. We observed 19%-30% solubility of WI upon treatment with aggrelyte-2. Aggrelyte-2C also increased protein solubility, but its effect was approximately 1.4-fold lower than that of aggrelyte-2. The protein thiol contents were 1.9- to 4.9-fold higher in the aggrelyte-2- and aggrelyte-2C-treated samples than in the untreated samples. The LC-MS/MS results showed Nε -acetyllysine (AcK) levels of 1.5 to 2.1 nmol/mg protein and 0.6 to 0.9 nmol/mg protein in the aggrelyte-2- and aggrelyte-2C-treated samples. Mouse (C57BL/6J) lenses (incubated for 24 h) and human lenses (incubated for 72 h) with 1.0 mM aggrelyte-2 showed significant decreases in stiffness with simultaneous increases in soluble proteins (human lenses) and protein-AcK levels, and such changes were not observed in aggrelyte-2C-treated lenses. Mass spectrometry of the solubilized protein revealed AcK in all crystallins, but more was observed in α-crystallins. These results suggest that aggrelyte-2 increases protein solubility and decreases lens stiffness through acetylation and disulfide reduction. Aggrelyte-2 might be useful in treating presbyopia in humans.

• Authors: Sudipta Panja, Rooban B Nahomi, Johanna Rankenberg, Cole R Michel, Hanmant Gaikwad, Mi-Hyun Nam, Ram H Nagaraj
• Journal: Aging cell (Aging Cell) Vol. 22 Issue 4 Pg. e13797 (04 2023) ISSN: 1474-9726 [Electronic] England
• PMID: 36823285 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural)
• Copyright: © 2023 The Authors. Aging Cell published by Anatomical Society and John Wiley & Sons Ltd.

Chemical References

• Lysine
• Crystallins
• Water
• Disulfides

Topics

• Humans
• Animals
• Mice
• Aged
• Lysine (metabolism)
• Presbyopia (metabolism)
• Solubility
• Chromatography, Liquid
• Acetylation
• Mice, Inbred C57BL
• Tandem Mass Spectrometry
• Lens, Crystalline (metabolism)
• Crystallins (analysis, metabolism)
• Water (analysis, metabolism)
• Disulfides (analysis, metabolism)