Primary angle closure glaucoma is characterized by altered extracellular matrix homeostasis in the iris

Creation of a Plant Metabolite Spectral Library for Untargeted and Targeted Metabolomics

Large-scale high throughput metabolomic technologies are indispensable components of systems biology in terms of discovering and defining the metabolite parts of the system. However, the lack of a plant metabolite spectral library limits the metabolite identification of plant metabolomic studies. Here, we have created a plant metabolite spectral library using 544 authentic standards, which increased the efficiency of identification for untargeted metabolomic studies. The process of creating the spectral library was described, and the mzVault library was deposited in the public repository for free download. Furthermore, based on the spectral library, we describe a process of creating a pseudo-targeted method, which was applied to a proof-of-concept study of Arabidopsis leaf extracts. As authentic standards become available, more metabolite spectra can be easily incorporated into the spectral library to improve the mzVault package.

Thrombospondin-1 Signaling Through the Calreticulin/LDL Receptor Related Protein 1 Axis: Functions and Possible Roles in Glaucoma

Thrombospondin-1 (TSP-1) is a matricellular extracellular matrix protein. Matricellular proteins are components of the extracellular matrix (ECM) that regulate key cellular functions and impact ECM organization, but which lack direct primary structural roles in the ECM. TSP-1 expression is upregulated in response to injury, hypoxia, growth factor stimulation, inflammation, glucose, and by reactive oxygen species. Relevant to glaucoma, TSP-1 is also a mechanosensitive molecule upregulated by mechanical stretch. TSP-1 expression is increased in ocular remodeling in glaucoma in both the trabecular meshwork and in the optic nerve head. The exact roles of TSP-1 in glaucoma remain to be defined, however. It plays important roles in cell behavior and in ECM remodeling during wound healing, fibrosis, angiogenesis, and in tumorigenesis and metastasis. At the cellular level, TSP-1 can modulate cell adhesion and migration, protease activity, growth factor activity, anoikis resistance, apoptosis, and collagen secretion and matrix assembly and cross-linking. These multiple functions and macromolecular and receptor interactions have been ascribed to specific domains of the TSP-1 molecule. In this review, we will focus on the cell regulatory activities of the TSP-1 N-terminal domain (NTD) sequence that binds to cell surface calreticulin (Calr) and which regulates cell functions via signaling through Calr complexed with LDL receptor related protein 1 (LRP1). We will describe TSP-1 actions mediated through the Calr/LRP1 complex in regulating focal adhesion disassembly and cytoskeletal reorganization, cell motility, anoikis resistance, and induction of collagen secretion and matrix deposition. Finally, we will consider the relevance of these TSP-1 functions to the pathologic remodeling of the ECM in glaucoma.

Global and Comparative Proteome Signatures in the Lens Capsule, Trabecular Meshwork, and Iris of Patients With Pseudoexfoliation Glaucoma

Pseudoexfoliation (PXF) is characterized by the accumulation of the exfoliative material in the eye and high rates of blindness if left untreated. Pseudoexfoliation glaucoma (PXG) is generally diagnosed too late due to its asymptomatic nature, necessitating the development of new effective screening tools for the early diagnosis of the disease. Thus, the increasing prevalence of this disease due to an aging population has demanded the identification of suitable biomarkers for the early detection of the disease or detection of the onset of glaucoma in the eyes with PXF. We applied a proteomics strategy based on a high-throughput screening method for the determination of proteins involving PXF and PXG pathogenesis. The lens capsule (LC), iris, and trabecular meshwork (TM) samples with PXF and PXG were taken by surgical trabeculectomy, and control samples were taken from the donor corneal buttons obtained from the institutional eye bank to characterize the proteome profile. Peptides from the LC were analyzed using liquid chromatography with tandem mass spectrometry (LC-MS/MS). The protein of interest and cytokine/chemokine profiles were verified using immunohistochemistry and the bio-plex kit assay, respectively. There were a total of 1433 proteins identified in the human LC, of which 27 proteins were overexpressed and eight proteins were underexpressed in PXG compared with PXF. Overexpressed proteins such as fibromodulin, decorin, lysyl oxidase homolog 1, collagen alpha-1(I) chain, collagen alpha-3(VI) chain, and biglycan were the major components of the extracellular matrix (ECM) proteins involved in cell-matrix interactions or ECM proteoglycans and the assembly and cross-linking of collagen fibrils. The ECM composition and homeostasis are altered in glaucoma. Thus, quantitative proteomics is a method to discover molecular markers in the eye. Monitoring these events can help evaluate disease progression in future studies.