Evaluation of differentially expressed genes identified in keratoconus
MOLECULAR VISION
Authors: Lee, Ji-Eun; Oum, Boo Sup; Choi, Hee Young; Lee, Seung Uk; Lee, Jong Soo
Abstract
Purpose: To identify the differentially expressed genes (DEGs) in the human keratocytes in keratoconus. Methods: Total RNA extracted from cultured corneal stromal fibroblasts from normal and keratoconic corneas were used for the synthesis of cDNA. DEGs were screened by an annealing control primer (TM)-based PCR method using GeneFishing (TM) DEG kits. The differentially expressed bands were sequenced and analyzed. The genes identified were further evaluated by reverse transcriptase PCR and quantitative real-time PCR. Results: Overexpression of bone morphogenetic protein 4 (BMP4), cofilin 1 (CFL1), and JAW1-related protein (MRVI1) and underexpression of actin, alpha 2 (ACTA2), gene rich cluster, and C 10 gene (GRCC10), tissue inhibitor of metalloproteinase 3 (TIMP3), tissue inhibitor of metalloproteinase 1 (TIMP1), and somatostatin receptor 1 (SSTR1) were verified, and these results were confirmed by reverse transcriptase PCR and quantitative real-time PCR. Conclusions: Eight genes were identified to be differentially expressed in keratoconus and related with apoptosis, the cytoskeleton, wound healing, and nerve fibers. The genes identified may be involved in the mechanism underlying stromal thinning; thus, they could be important and deserve further investigation.
Proteomic analysis of filaggrin deficiency identifies molecular signatures characteristic of atopic eczema
JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY
Authors: Elias, Martina S.; Long, Heather A.; Newman, Carla F.; Wilson, Paul A.; West, Andrew; McGill, Paul J.; Wu, Keith C.; Donaldson, Michael J.; Reynolds, Nick J.
Abstract
Background: Atopic eczema (AE) is characterized by skin barrier and immune dysfunction. Null mutations in filaggrin (FLG), a key epidermal barrier protein, strongly predispose to AE; however, the precise role of FLG deficiency in AE pathogenesis remains incompletely understood. Objectives: We sought to identify global proteomic changes downstream of FLG deficiency in human epidermal living skinequivalent (LSE) models and validate findings in skin of patients with AE. Methods: Differentially expressed proteins from paired control (nontargeting control short hairpin RNA [shNT]) and FLG knockdown (FLG knockdown short hairpin RNA [shFLG]) LSEs were identified by means of proteomic analysis (liquid chromatography-mass spectrometry) and Ingenuity Pathway Analysis. Expression of key targets was validated in independent LSE samples (quantitative RT-PCR and Western blotting) and in normal and AE skin biopsy specimens (immunofluorescence). Results: Proteomic analysis identified 17 (P <=.05) differentially expressed proteins after FLG knockdown, including kallikrein-7 (KLK7; 2.2-fold), cyclophilin A (PPIA; 0.9-fold), and cofilin-1 (CFL1, 1.3-fold). Differential protein expression was confirmed in shNT/shFLGLSEs; however, only KLK7 was transcriptionally dysregulated. Molecular pathways overrepresented after FLG knockdown included inflammation, protease activity, cell structure, and stress. Furthermore, KLK7 (1.8-fold) and PPIA (0.65-fold) proteins were differentially expressed in lesional biopsy specimens from patients with AE relative to normal skin. Conclusions: For the first time, we show that loss of FLG in the absence of inflammation is sufficient to alter the expression level of proteins relevant to the pathogenesis of AE. These include proteins regulating inflammatory, proteolytic, and cytoskeletal functions. We identify PPIA as a novel protein with levels that are decreased in clinically active AE skin and show that the characteristic upregulation of KLK7 expression in patients with AE occurs downstream of FLG loss. Importantly, we highlight disconnect between the epidermal proteome and transcriptome, emphasizing the utility of global proteomic studies.