The human Descemet's membrane and lens capsule: Protein composition and biomechanical properties. (December 2020)

• Record Type: Journal Article
• Authors: Halfter, Willi; Moes, Suzette; Halfter, Kathrin; Schoenenberger, Monica S.; Monnier, Christophe A.; Kalita, Joanna; Asgeirsson, Daphne; Binggeli, Tatjana; Jenoe, Paul; Scholl, Hendrik P.N.; Henrich, Paul Bernhard
• Is Part Of: Experimental eye research. Volume 201(2020)
• Publication Date: 2020-12
• Subjects: Basement membrane -- Diabetes -- Collagen IV -- Laminin -- Nidogens -- Perlecan -- Collagens -- Proteomics -- Mass spectrometry -- Atomic force microscopy; BM basement membrane -- DM Descemet's membrane -- LC Lens capsule -- ECM extracellular matrix -- LC/MS liquid chromatography/mass spectrometry -- LN laminin -- AFM Atomic Force Microscopy; Ophthalmology -- Periodicals; Eye -- Periodicals; Œil -- Périodiques; Ophthalmology; Periodicals; Electronic journals; 612.8405
• DOI: 10.1016/j.exer.2020.108326
• Languages: English
• ISSNs: 0014-4835

Abstract

Abstract: The Descemet's membrane (DM) and the lens capsule (LC) are two ocular basement membranes (BMs) that are essential in maintaining stability and structure of the cornea and lens. In this study, we investigated the proteomes and biomechanical properties of these two materials to uncover common and unique properties. We also screened for possible protein changes during diabetes. LC-MS/MS was used to determine the proteomes of both BMs. Biomechanical measurements were conducted by atomic force microscopy (AFM) in force spectroscopy mode, and complemented with immunofluorescence microscopy. Proteome analysis showed that all six existing collagen IV chains represent 70% of all LC-protein, and are thus the dominant components of the LC. The DM on the other hand is predominantly composed of a single protein, TGF-induced protein, which accounted for around 50% of all DM-protein. Four collagen IV-family members in DM accounted for only 10% of the DM protein. Unlike the retinal vascular BMs, the LC and DM do not undergo significant changes in their protein compositions during diabetes. Nanomechanical measurements showed that the endothelial/epithelial sides of both BMs are stiffer than their respective stromal/anterior-chamber sides, and both endothelial and stromal sides of the DM were stiffer than the epithelial and anterior-chamber sides of the LC. Long-term diabetes did not change the stiffness of the DM and LC. In summary, our analyses show that the protein composition and biomechanical properties of the DM and LC are different, i.e., the LC is softer than DM despite a significantly higher concentration of collagen IV family members. This finding is unexpected, as collagen IV members are presumed to be responsible for BM stiffness. Diabetes had no significant effect on the protein composition and the biomechanical properties of both the DM and LC. Highlights: Using mass pectrometry the protein composition of the lens capsule (LC) and the Descemet's membrane (DM) was determined. Atomic Force Microscopy was utilized to investigate the biomechanical properties of the LC and the DM. The protein composition of the LC and DM show significant differences. The DM is stiffer than the LC. The protein composition and the stiffness of DM and LC do not change following long-term diabetes.