Proteomic Profiling Revealed Mitochondrial Dysfunction in Photoreceptor Cells under Hyperglycemia.

Diabetic retinopathy (DR) was identified as a leading cause of blindness and vision impairment in 2020. In addition to vasculopathy, DR has been found to involve retinal neurons, including amacrine cells and retinal ganglion cells. Despite possessing features that are susceptible to diabetic conditions, photoreceptor cells have received relatively little attention with respect to the development of DR. Until recently, studies have suggested that photoreceptors secret proinflammatory molecules and produce reactive oxygen species that contribute to the development of DR. However, the effect of hyperglycemia on photoreceptors and its underlying mechanism remains elusive. In this study, the direct effect of high glucose on photoreceptor cells was investigated using a 661w photoreceptor-like cell line. A data-independent sequential window acquisition of all theoretical mass spectra (SWATH)-based proteomic approach was employed to study changes induced by high glucose in the proteomic profile of the cells. The results indicated that high glucose induced a significant increase in apoptosis and ROS levels in the 661w cells, with mitochondrial dysfunction among the major affected canonical pathways. The involvement of mitochondrial dysfunction was further supported by increased mitochondrial fission and reduced mitochondrial bioenergetics. Collectively, these findings provide a biological basis for a possible role of photoreceptors in the pathogenesis of DR.

Transcriptional profiling of the chick retina identifies down-regulation of VIP and UTS2B genes during early lens-induced myopia.

Gene expression of the chick retina was examined during the early development of lens-induced myopia (LIM) using whole transcriptome sequencing. Monocular treatment of the right eyes with -10 diopter (D) lenses was performed on newly born chicks for one day (LIM-24) or two days (LIM-48), while the contralateral eyes without lenses served as controls. Myopia development was confirmed by demonstrating significant elongation of the optical axis in lens-treated eyes compared to untreated control eyes. RNA was extracted and RNA-seq was performed using the Illumina HiSeqTM 2000 platform. Data analysis was carried out on a Partek® Flow platform. Using screening criteria of ≥1.30-fold change and a false discovery rate <1%, 11 (five down-regulated and six up-regulated) and 35 differentially expressed genes (six down-regulated and twenty-nine up-regulated) were identified at 24 hours and 48 hours, respectively. Using another cohort for validation, Quantitative PCR confirmed significant changes in the expression of VIP and UTS2B mRNA (P <0.05) after only 24 hours of LIM treatment and numerical changes in the expression for PCGF5 and FOXG1, which were consistent with transcriptome sequencing but did not reach statistical significance. These data suggest that concerted changes of retinal gene expression may be instrumental in the initiation of axial elongation and myopia development.

High-pH reversed-phase fractionated neural retina proteome of normal growing C57BL/6 mouse.

The retina is a key sensory tissue composed of multiple layers of cell populations that work coherently to process and decode visual information. Mass spectrometry-based proteomics approach has allowed high-throughput, untargeted protein identification, demonstrating the presence of these proteins in the retina and their involvement in biological signalling cascades. The comprehensive wild-type mouse retina proteome was prepared using a novel sample preparation approach, the suspension trapping (S-Trap) filter, and further fractionated with high-pH reversed phase chromatography involving a total of 28 injections. This data-dependent acquisition (DDA) approach using a Sciex TripleTOF 6600 mass spectrometer identified a total of 7,122 unique proteins (1% FDR), and generated a spectral library of 5,950 proteins in the normal C57BL/6 mouse retina. Data-independent acquisition (DIA) approach relies on a large and high-quality spectral library to analyse chromatograms, this spectral library would enable access to SWATH-MS acquisition to provide unbiased, multiplexed, and quantification of proteins in the mouse retina, acting as the most extensive reference library to investigate retinal diseases using the C57BL/6 mouse model.

Corneal proteome and differentially expressed corneal proteins in highly myopic chicks using a label-free SWATH-MS quantification approach.

Myopia, or short-sightedness, is a highly prevalent refractive disorder in which the eye's focal length is too short for its axial dimension in its relaxed state. High myopia is associated with increased risks of blinding ocular complications and abnormal eye shape. In addition to consistent findings on posterior segment anomalies in high myopia (e.g., scleral remodeling), more recent biometric and biomechanical data in myopic humans and animal models also indicate anterior segment anomalies (e.g., corneal biomechanical properties). Because the cornea is the anterior-most ocular tissue, providing essential refractive power and physiological stability, it is important to understand the biochemical signaling pathway during myopia development. This study first aimed to establish the entire chicken corneal proteome. Then, using the classical form deprivation paradigm to induce high myopia in chicks, state-of-the-art bioinformatics technologies were applied to identify eight differentially expressed proteins in the highly myopic cornea. These results provide strong foundation for future corneal research, especially those using chicken as an animal model for myopia development.

Human tear proteome dataset in response to daily wear of water gradient contact lens using SWATH-MS approach.

Water Gradient Contact Lens (WGCL) is a new generation material that combines the benefits of Silicone hydrogel (SiHy) and traditional hydrogel contact lenses by modifying the materials between the core and the surface. However, its impact on tear proteome has not been explored. Tears were collected on healthy young adults using Schirmer's strip at baseline, 1-week, and 1-month of WGCL lens wear (n=15) and age-matched untouched controls (n=10). Equal amounts of tears samples from individuals of WGCL and control groups were randomly pooled to form representative equal parts at each condition (n=3 for WGCL wear and age-matched untouched control group) at each condition (baseline, 1-week, and 1-month). Tears were prepared using the S-Trap sample preparation followed by the analysis of a TripleTOF 6600 mass spectrometer. Using Information-dependent acquisition (IDA), a total of 725 tear proteins (6760 distinct peptides) were identified in the constructed spectral library at 1% FDR. Using data-independent acquisition (SWATH-MS), data were analyzed and processed using PeakView (v2.2, SCIEX), with the top differentially expressed proteins at each time point (baseline, 1-week, and 1-month) presented. All acquired raw data (IDA and SWATH-MS) were submitted and published on the Peptide Atlas public repository (http://www.peptideatlas.org/) for general release (Data ID PASS01589).

Data on protein changes of chick vitreous during normal eye growth using data-independent acquisition (SWATH-MS).

Myopia is the most common refractive error which is estimated to affect half the population of the world by 2050. It has been suggested that it could be determined by multiple factors such as environmental and genetic, but the mechanism behind the cause of myopia is still yet to be identified. Vitreous humor (VH) is a transparent gelatin-like substance that takes up to 80% of the volume of the eye, making it the largest component of the eye. Although VH is the main contributor to axial elongation of the eye including normal eye growth (emmetropization) and myopia, the diluted nature of VH (made up of 99% of water) made it difficult for less abundant molecules to be identified and therefore often overlooked. Using the more sensitive label-free mass spectrometry approach with data-independent acquisition (SWATH-MS), we established a comprehensive VH proteome library in chick animal model and quantified possible protein biomarkers that are responsible for the axial elongation during emmetropization (7, 14, 21, 28 days after hatching, n = 48 eyes). Raw data files for both information-dependent acquisition (IDA) and data-independent acquisition (SWATH-MS) were uploaded on PeptideAtlas for public access (http://www.peptideatlas.org/PASS/PASS01258).

Combined retinal proteome datasets in response to atropine treatment using iTRAQ and SWATH-MS based proteomics approaches in guinea pig myopia model.

Atropine, a non-selective muscarinic antagonist, is known to slow down myopia progression in human adolescents and in several animal models. However, its underlying molecular mechanism is unclear. The present work built a monocular form-deprivation myopia (FDM) guinea pig model, using facemasks as well as atropine treatment on FDM eyes for 2 and 4 weeks. Retinal protein changes in response to the FDM and effects of topical administration of atropine were screened for the two periods using fractionated isobaric tags for a relative and absolute quantification (iTRAQ) approach coupled with nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS) (n=24, 48 eyes). Retinal tissues from another cohort receiving 4-weeks FDM with atropine treatment (n=12, 24 eyes) with more significant changes were subjected to sequential window acquisition of all theoretical mass spectra (SWATH-MS) proteomics for further protein target confirmation. A total of 1695 proteins (8875 peptides) and 5961 proteins (51871 peptides) were identified using iTRAQ and SWATH approaches, respectively. Using the Paragon algorithm in the ProteinPilotTM software, the three most significantly up-regulated and down-regulated proteins that were commonly found in both ITRAQ and SWATH experiments are presented. All raw data generated from the work were submitted and published in the Peptide Atlas public repository (http://www.peptideatlas.org/) for general release (Data ID PASS01507).

Data on corneal proteome and differentially expressed corneal proteins in highly myopic chicks using a data independent quantification approach.

Myopia is an abnormal refractive status, explained by an excessive ocular lengthening mostly in posterior segments. Although growing evidence of anterior segments, specifically altered corneal geometries with biomechanical properties in myopes have been reported, the mechanism behind is poorly understood. We hereby prepared experimentally induced highly myopic chicks to investigate the molecular basis of corneal remodeling by applying a novel proteomic approach integrated with information dependent acquisition (IDA) and data independent quantification (SWATH-MS) analysis. As a result, differentially expressed protein biomarkers that might be involved in structural changes were screened based on the first of its kind unique chicken corneal proteome. All generated raw data from IDA and SWATH-MS are accessible at Peptide Atlas public repository (http://www.peptideatlas.org/PASS/PASS01410) for general release.

Isotope-coded protein label based quantitative proteomic analysis reveals significant up-regulation of apolipoprotein A1 and ovotransferrin in the myopic chick vitreous.

This study used isotope-coded protein label (ICPL) quantitative proteomics and bioinformatics analysis to examine changes in vitreous protein content and associated pathways during lens-induced eye growth. First, the vitreous protein profile of normal 7-day old chicks was characterized by nano-liquid chromatography electrospray ionization tandem mass spectrometry. A total of 341 unique proteins were identified. Next, myopia and hyperopia were induced in the same chick by attaching -10D lenses to the right eye and +10D lenses to the left eye, for 3 and 7 days. Protein expression in lens-induced ametropic eyes was analyzed using the ICPL approach coupled to LCMS. Four proteins (cystatin, apolipoprotein A1, ovotransferrin, and purpurin) were significantly up-regulated in the vitreous after 3 days of wearing -10D lenses relative to +10D lens contralateral eyes. The differences in protein expression were less pronounced after 7 days when the eyes approached full compensation. In a different group of chicks, western blot confirmed the up-regulation of apolipoprotein A1 and ovotransferrin in the myopic vitreous relative to both contralateral lens-free eyes and hyperopic eyes in separate animals wearing +10D lenses. Bioinformatics analysis suggested oxidative stress and lipid metabolism as pathways involved in compensated ocular elongation.