ORCID Profile
0000-0002-3511-5620
Current Organisations
Hong Kong Polytechnic University Shenzhen Research Institute
,
The Hong Kong Polytechnic University
,
PolyU Academy for Interdisciplinary Research (PAIR)
,
Centre for Eye and Vision Research Limited
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Publisher: Springer Science and Business Media LLC
Date: 11-2016
Publisher: MDPI AG
Date: 11-2022
Abstract: 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.
Publisher: MDPI AG
Date: 29-04-2021
DOI: 10.3390/IJMS22094721
Abstract: Most of the previous myopic animal studies employed a single-candidate approach and lower resolution proteomics approaches that were difficult to detect minor changes, and generated limited systems-wide biological information. Hence, a complete picture of molecular events in the retina involving myopic development is lacking. Here, to investigate comprehensive retinal protein alternations and underlying molecular events in the early myopic stage, we performed a data-independent Sequential Window Acquisition of all Theoretical Mass Spectra (SWATH) based proteomic analysis coupled with different bioinformatics tools in pigmented guinea pigs after 4-day lens-induced myopia (LIM). Myopic eyes compared to untreated contralateral control eyes caused significant changes in refractive error and choroid thickness (p 0.05, n = 5). Relative elongation of axial length and the vitreous chamber depth were also observed. Using pooled s les from all in iduals (n = 10) to build a species-specific retinal ion library for SWATH analysis, 3202 non-redundant proteins (with 24,616 peptides) were identified at 1% global FDR. For quantitative analysis, the 10 in idual retinal s les (5 pairs) were analyzed using a high resolution Triple-TOF 6600 mass spectrometry (MS) with technical replicates. In total, 37 up-regulated and 21 down-regulated proteins were found significantly changed after LIM treatment (log2 ratio (T/C) 0.26 or −0.26 p ≤ 0.05). Data are accepted via ProteomeXchange with identifier PXD025003. Through Ingenuity Pathways Analysis (IPA), “lipid metabolism” was found as the top function associated with the differentially expressed proteins. Based on the protein abundance and peptide sequences, expression patterns of two regulated proteins (SLC6A6 and PTGES2) identified in this pathway were further successfully validated with high confidence (p 0.05) using a novel Multiple Reaction Monitoring (MRM) assay on a QTRAP 6500+ MS. In summary, through an integrated discovery and targeted proteomic approach, this study serves as the first report to detect and confirm novel retinal protein changes and significant biological functions in the early LIM mammalian guinea pigs. The study provides new workflow and insights for further research to myopia control.
Publisher: Spandidos Publications
Date: 08-02-2018
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 06-06-2018
Publisher: American Chemical Society (ACS)
Date: 22-02-2006
DOI: 10.1021/PR050280N
Abstract: Proteomics approach as a research tool has gained popularity in a growing number of basic and clinical researches. However, proteomic research has yet to gain significant momentum in eye research. Hence, we decided to build a retinal proteome database using postnatal retinal tissue from chick, a commonly used animal model in eye research. Employing 2-D gels with the coverage of 3-10 pH gradients, we were able to resolve hundreds of proteins from young chick retinae. Among them, 155 high abundant proteins were identified by Peptide Mass Fingerprinting (PMF) after the Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS). These proteins were then classified according to their functions. Making use of the retinal database, we were able to identify several differentially expressed proteins that might be involved in early retinal development by comparing the 2-DE maps of chick retinal tissues (3, 10, and 20 days after hatching). With the current proteomics approach, we not only documented the most abundant soluble proteins in the chick retinal tissue, but also demonstrated the dynamic protein expression changes during early ocular development. This represents one of the first steps in building a complete protein database in chick retinae which is applicable to the study of eye diseases from a few selected protein candidates to the whole proteome. Proteomic technology may provide a high throughput platform for advancing eye research in the feasible future.
Publisher: American Chemical Society (ACS)
Date: 09-10-2007
DOI: 10.1021/PR0701097
Abstract: The lens-induced myopia (LIM) in response to concave lens (negative lens) is a well established animal model for studying myopia development. However, the exact visual and neurochemical signaling mechanisms involving myopic eye growth are yet to be elucidated. The feasibility of applying a novel two-dimensional fluorescence difference gel electrophoresis technique for global protein profilings and a search for differential protein expressions in LIM were explored in the present study. Two-dimensional polyacrylamide gel electrophoresis was performed employing a "minimal Lysine labeling" approach and a reverse CyeDye experimental protocol using retinal tissue from chicks. The retinal protein profiles between myopic and control eyes were found to be very similar. More than a thousand protein spots could be detected on a 2D gel. Sixteen and ten protein spots were found to be up-regulated and down-regulated respectively in the myopic eyes according to our preset criteria with the inclusion of an internal pool standard. About 65% of those filtered spots could be successfully identified by peptide mass fingerprinting by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry . Most of the differentially expressed proteins were found to be related to cytoskeletal or oxidative functions. According to the prediction of subcellular locations, most of them (about 84%) were classified as cytoplasmic proteins. The cellular functions for those differentially expressed proteins were reported and their possible involvements in the compensated eye growth were discussed. We have optimized a workable protocol for the study of the differential retinal protein expressions in the LIM using 2D-DIGE approach which was shown to have a number of advantages over the traditional 2D electrophoresis technique.
Publisher: Springer Science and Business Media LLC
Date: 27-08-1970
DOI: 10.1038/S41597-021-00813-1
Abstract: 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 s le 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.
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 12-2007
DOI: 10.1167/IOVS.07-0383
Abstract: To determine the effects of simultaneously presented myopic and hyperopic defocus on the refractive development of chicks. A novel form of dual-power lens was designed. Normal chicks 7 to 8 days of age were fitted with a dual-power lens over one eye and a plano lens over the fellow (control) eye. Dual-power lenses of +20/-10, +10/-10, +5/-10, and plano/-10-D were tested, along with +10/-10-D lenses having differing ratios (50:50, 33:67, and 25:75) of surface area devoted to each power. Ocular refraction and axial ocular component dimensions were assessed after 6 days of lens wear, by retinoscopy and high-frequency ultrasound, respectively. In a separate experiment designed to test the effect of dual-power lens wear on the refractive development of myopic eyes, chicks were fitted with a dual-power +10/-10-D lens for 6 days, after myopia had been induced by 6 days of -10-D lens wear. For each of the dual-power lenses tested, the refractive end point of the treated eye was found to lie between the two optical powers of the lens (but with the response weighted in favor of the effect of myopic defocus). Refractive development appeared to be modulated by the sign, dioptric magnitude, and relative contribution (relative contrast) of the imposed optical defocuses through an integrative mechanism. Chicks with myopia induced by -10-D lens wear recovered when treated with a +10/-10-D dual-power lens. The chick retina can discern both the sign and the magnitude of optical defocus. Chick eyes were able to integrate blur cues from simultaneously presented images focused either side of the photoreceptors and to modulate their refractive development accordingly. This implies that the complex nature of defocus in the visual environment may play a critical role in the pathogenesis of myopia. The results suggest a rational method for arresting or reversing the development of myopia, which may be useful in the treatment of human myopia if the primate retina is also capable of responding to simultaneously presented opposing defocus cues.
Publisher: Elsevier BV
Date: 12-2018
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.JPROT.2018.03.023
Abstract: Myopia is generally regarded as a failure of normal emmetropization process, however, its underlying molecular mechanisms are unclear. To investigate the retinal protein profile changes during emmetropization, we studied differential protein expressions of ocular growth in young guinea pigs at 3 and 21 days old respectively, when significant axial elongation was detected (P < 0.001, n = 10). Independent pooled retinal s les of both eyes were subjected to SWATH mass spectrometry (MS) followed by bioinformatics analysis using cloud-based platforms. A comprehensive retina SWATH ion-library consisting of 3138 (22,871) unique proteins (peptides) at 1% FDR was constructed. 40 proteins were found to be significantly up-regulated and 8 proteins down-regulated during emmetropization (≥log2 of 0.43 with ≥2 peptides matched per protein P < 0.05). Using pathway analysis, the most significant pathway identifiable was 'phototransduction' (P = 1.412e-4). Expression patterns of 7 proteins identified in this pathway were further validated and confirmed (P < 0.05) with high-resolution Multiple Reaction Monitoring (MRM-HR) MS. Combining discovery and targeted proteomics approaches, this study for the first time comprehensively profiled protein changes in the guinea pig retina during normal emmetropization-associated eye growth. The findings of this study are also relevant to the myopia development, which is the result of failed emmetropization. Myopia is considered as a failure of emmetropization. However, the underlying biochemical mechanism of emmetropization, a visually guided process in which eye grows towards the optimal optical state of clear vision during early development, is not well understood. Retina is known as the key tissue to regulate this active eye growth. we studied eye growth of young guinea pigs and harvested their retinal tissues. A comprehensive SWATH ion library with identification of a total 3138 unique proteins were established, in which 48 proteins exhibited significant differential expressions between 3 and 21 days old. After MRM-HR confirmation, 'phototransduction' were found as the most active pathway during emmetropic eye growth. This study is the first in discovering key retinal protein players and pathways which are presumably orchestrated by biological mechanism(s) underlying emmetropization.
Location: China
Location: Hong Kong
No related grants have been discovered for Chuen Lam.