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.

Descemet膜（DM）和晶状体囊（LC）是两个眼基膜（BMs），对维持角膜和晶状体的稳定性和结构至关重要。在这项研究中，我们调查了这两种材料的蛋白质组学和生物力学特性，以揭示共同的和独特的特性。我们还筛查了糖尿病期间可能的蛋白质变化。LC-MS / MS用于确定两种BM的蛋白质组。生物力学测量通过原子力显微镜（AFM）在力谱模式下进行，并辅以免疫荧光显微镜。蛋白质组分析表明，所有六个现有的胶原IV链占所有LC蛋白的70％，因此是LC的主要成分。DM则主要由单一蛋白TGF诱导的蛋白组成，约占所有DM蛋白的50％。DM中的四个胶原IV家族成员仅占DM蛋白的10％。与视网膜血管BMs不同，LC和DM在糖尿病期间蛋白质组成没有明显变化。纳米力学测量表明，两种BM的内皮/上皮侧均比其各自的基质/前侧硬，而DM的内皮和基质侧均比LC的上皮和前侧硬。长期糖尿病并没有改变DM和LC的强度。总而言之，我们的分析表明DM和LC的蛋白质组成和生物力学特性不同，在糖尿病期间，LC和DM的蛋白质组成没有明显变化。纳米力学测量表明，两种BM的内皮/上皮侧均比其各自的基质/前侧硬，而DM的内皮和基质侧均比LC的上皮和前侧硬。长期糖尿病并没有改变DM和LC的强度。总而言之，我们的分析表明DM和LC的蛋白质组成和生物力学特性不同，在糖尿病期间，LC和DM的蛋白质组成没有明显变化。纳米力学测量表明，两种BM的内皮/上皮侧均比其各自的基质/前侧硬，而DM的内皮和基质侧均比LC的上皮和前侧硬。长期糖尿病并没有改变DM和LC的强度。总而言之，我们的分析表明DM和LC的蛋白质组成和生物力学特性不同，DM的内皮侧和基质侧均比LC的上皮侧和前室侧硬。长期糖尿病并没有改变DM和LC的强度。总而言之，我们的分析表明DM和LC的蛋白质组成和生物力学特性不同，DM的内皮侧和基质侧均比LC的上皮侧和前室侧硬。长期糖尿病并没有改变DM和LC的强度。总而言之，我们的分析表明DM和LC的蛋白质组成和生物力学特性不同，也就是说，尽管胶原IV家族成员的浓度明显较高，但LC比DM软。这一发现是出乎意料的，因为胶原IV成员被认为是造成BM僵硬的原因。糖尿病对DM和LC的蛋白质组成和生物力学特性均无明显影响。