title: In vitro secretomics study of pterygium-derived fibroblasts by iTRAQ-based quantitative proteomics strategy.
abstract: Pterygium is a triangular shaped ocular fibrous surface lesion growing from conjunctiva towards central cornea, causing ocular irritation, astigmatism, and visual disturbance. The condition is characterized by epithelial proliferation, fibrovascular growth, chronic inflammation, and prominent extracellular matrix remodeling. Studies have suggested that aberrant extracellular proteins secreted by fibroblasts lead to abnormal matrix production and tissue invasion contributing to the development of the disease. In this study, secreted proteins collected from paired pterygium and conjunctival fibroblasts in vitro were identified and quantified by LC-MS iTRAQ-based analysis, in which 433 proteins common to all samples were identified. Among these proteins, 48.0% (208) were classified as classically secreted proteins, 17.1% (74) were exported out of the cells via non-classical secretion pathways, and 31.2% (135) were exosome proteins. A minority (3.7%) was not previously known to be secreted, or might be contaminants. 31 and 27 proteins were found up- or down-regulated in the conditioned media of pterygium fibroblasts relative to the media of control cells, respectively. Molecular function analysis showed that these proteins either belonged to catalytic proteins, structural molecules or were involved with receptor activities and protein binding. Further pathway analysis revealed that these proteins were involved in ECM-receptor interaction, focal adhesion, cancer-related, p53 signaling, complement and coagulation, and TGF-beta signaling pathways. These molecules identified may serve as extracellular ligands to activate intracellular pathways, possibly serving as potential therapeutic targets.
authors.affiliation: Ocular Surface Research Group, Singapore Eye Research Institute, Singapore.
authors.forename: Aihua
authors.initials: A
authors.lastname: Hou
authors.affiliation: Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Kai Pong
authors.initials: KP
authors.lastname: Law
authors.affiliation: Ocular Surface Research Group, Singapore Eye Research Institute, Singapore.
authors.forename: Min Qi
authors.initials: MQ
authors.lastname: Tin
authors.affiliation: Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Yoon Pin
authors.initials: YP
authors.lastname: Lim
authors.affiliation: Ocular Surface Research Group, Singapore Eye Research Institute, Singapore; Duke-NUS Graduate Medical School, Singapore; Singapore National Eye Center, Singapore; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Electronic address: Louis.tong.h.t@snec.com.sg.
authors.forename: Louis
authors.initials: L
authors.lastname: Tong
mesh_terms: D000368:Aged; D015153:Blotting, Western; D002448:Cell Adhesion; D002478:Cells, Cultured; D003228:Conjunctiva / Q000378:metabolism* / Q000473:pathology; D017077:Culture Media, Conditioned; D005136:Eye Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D040901:Proteomics / Q000379:methods*; D011625:Pterygium / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger; D015398:Signal Transduction
chemical_list: D017077:Culture Media, Conditioned; D005136:Eye Proteins; D012333:RNA, Messenger
keywords: Fibroblast; LC-MS/MS; Pterygium; Quantitative proteomics; Secretomics; iTRAQ