ABSTRACT
Avellino corneal dystrophy(ACD) is an autosomal dominant eye disorder caused by mutation of R124H in the transforming growth factor-beta induced gene (TGFBI) on chromosome 5,which was responsible for accumulating of abnormal TGFBI.Although the underlying mechanism by which mutations cause abnormal TGFBI deposition is not yet clear,but we have a better understanding of the etiology and possible pathogenesis of corneal dystrophy with the rapid development of human genetics and molecular biology,and summarizes the current achievement of this disease and understand the roles of TGFBI and its interaction with Periostin,which may contribute to further research in ACD.
ABSTRACT
Corneal dystrophy represents a group of inherited corneal diseases with progressive accumulation of deposits in different layers of cornea,resulting in loss of corneal transparency and visual impairment,or even blindness.Initial classification of corneal dystrophy was upon involved cornea layer,and it is insufficient for some multi-layer lesion.With the current progress in molecular genetics,researchers proposed a new classifying way based on genetic information of corneal dystrophy.A revised classification has been recommended by the International Committee for Classification of Corneal Dystrophies (IC3D).The clinical manifestation,histological and genetic basis of the disease are integrated in the classification system,so it is regarded as to be more scientific and reasonable.Recent years,our laboratory performed genetic screen on some Chinese pedigrees with corneal dystrophy,mainly focusing on the corneal dystrophy-associated genes such as human transforming growth factor beta induced (TGFBI) gene,which reveals the relationship of the different mutations on TGFBI gene with clinical phenotypes.Our studies further indicated that the corneal dystrophy classification method based on molecular level is a more scientific and practicable method.Some updated information on the clinical phenotypes and molecular aspects of corneal dystrophy were provided here aimed to offer the aid to the differential diagnosis and management of these diseases.
ABSTRACT
Background Clinical studies indicated that the pathogenesis of most corneal dystrophy is associated with the mutation of the transforming growth factor beta-induced (TGFBI) gene.However,the molecular mechanism of mutated TGFBI gene in corneal dystrophy is unclear. Objective The present study was to investigate the expression of the TGFBI gene in human corneal tissue and cells in vitro.MethodsHuman corneal epithelial cells and keratocytes were cultured and passaged,and donor corneal tissue was obtained for the section preparation.RT-PCR was used to detect the expression of TGFBI mRNA in human corneal tissue and cells.Immunofluorescence was used to test the expression of the TGFBI protein in the human corneal tissue,and immunohistochemistry was used to test the expression of the TGFBI protein in human corneal epithelial cells and corneal stromal cells.ResultsRT-PCR analysis showed that TGFBI mRNA could be detected as a 1274 bp band in human corneal tissue and corneal stromal cells,but no TGFBI mRNA was observed in corneal epithelial cells.Immunofluorescence assay revealed that corneal stromal cells were positive ly expressed for the TGFBI protein,but the corneal epithelial cells did not express the TGFBI protein.Immunohistochemistry indicated that the expression of TGFBI was detected the red fluoressence in the cytoplasm of corneal stromal cells;however,no positive response was found in corneal epithelial cells.ConclusionsThe expression of the TGFBI gene occurs in human corneal stromal cells but not in the corneal epithelial cells.This result might be of helpful for studying the function and role of TGFBI gene in pathogenesis of corneal dystrophy.
ABSTRACT
Background The human transforming growth factor beta-induced gene (TGFBI) is the first determined pathogenic gene to corneal dystrophy.But the molecular genetic mechanism is completely unknown.The study of concerning role of TGFBI is very important for us understand the physiological function of cornea,and the pathogenesis of corneal dystrophy.Objective The vector of human transforming growth factor beta-induced gene (TGFBI) in eukaryotic expression was constructed and transfected into the human corneal epithelial cells in order to explore its influence on the growth of human corneal epithelial cells.Methods Total RNA was extracted from normal donor cornea tissue and cDNA was obtained by reverse transcription.TGFBI cDNA was synthesized by reverse transcription-PCR and cloned into pCMV-N-HA vector and identified by sequencing with PCR and EcoRV,XhoI double restriction endonuclease.The cells were grouped into recombinant pCMV-N-HA-TGFBI plasmid group,pCMVN-HA plasmid group,non-transfected group and pGFP-C2 transfected group.The recombinant pCMV-N-HA-TGFBI plasmid was transfected to human corneal epithelial cells and identified by observing the expression of enhanced green fluorescence protein(EGFP) in the cells.The TGFBI mRNA and proteins were harvested from the cells for real-time PCR analysis and Western blot assay respectively in 58 hours after transfection.The growth of the transfected cells was assessed by Cell Counting Kit-8.The expressions of matrix metalloproteinase(MMP) and tissue inhibitors of matrix metalloproteinase (TIMP) proteins and their mRNA in transfected cells were detected using SYBR fluorescence realtime PCR analysis and Western blot assay.Results The sequencing result of pCMV-N-HA-TGFBI positive clone plasmid showed that amplified TGFBI eDNA inserted into the vector at the correct sequence.EGFP was expressed in transfected cells in 48 hours after transfer of pGFP-C2 with the transfer efficacy 70％.The expression intensity of TGFBI mRNA was significantly higher in recombinant pCMV-N-HA-TGFBI plasmid group compared with pCMV-N-HA plasmid group and non-transfected group,and TGFBI protein was expressed in recombinant pCMV-N-HA-TGFBI plasmid group.No significant difference was found in the A450value among recombinant pCMV-N-HA-TGFBI plasmid group,pCMV-N-HA plasmid group and non-transfected group ( F=3.34,P＞0.05 ).The mRNA level of MMP1,MMP3in the transfected cells was significant elevated but that of TIMP1 was declined in the recombinant pCMV-N-HA-TGFBI plasmid group compared with pCMV-N-HA plasmid group and non-transfected group (all P ＜ 0.05 ).Meanwhile,the expressions of MMP1,MMP3 and TIMP1 proteins appeared the same tendency( all P＜0.05).Conclusions Eukaryotic expression vector harboring human TGFBI eDNA can be successfully constructed and efficiently overexpressed in human corneal epithelial cells.TGFBI gene is involved in the physical and pathological conditions of human corneal epithelial cells by regulating the activity of MMP1,MMP3 and TIMP1.The results offer a new approach for the study of the role of TGFBI in pathogenesis of corneal transparency.