Lens epithelium-derived growth factor relieves transforming growth factor-beta1-induced transcription repression of heat shock proteins in human lens epithelial cells.
Lens epithelium-cell derived growth factor (LEDGF) is a transcriptional activator. It protects the cells by binding to cis-stress response ((A/T)GGGG(T/A)), and heat shock (HSE; nGAAn) elements in the stress genes and activating their transcription. Transforming growth factor-beta (TGF-beta) has been implicated in the control of tissue homeostasis, terminal differentiation, and apoptosis. Here we provide evidence that TGF-beta1 down-regulates LEDGF expression and diminishes its affinity for DNA during TGF-beta1-induced phenotypic changes and apoptosis in human lens epithelial cells. Surprisingly, TGF-beta1 treatment for 48 h markedly decreased the LEDGF, Hsp27, and alphaB-crystallin promoter activities with the decrease of abundance of LEDGF mRNA and protein. Deletion mutants of the LEDGF promoter showed that one TGF-beta1 inhibitory element (TIE) like sequence nnnTTGGnnn (-444 to -433) contributed to this negative regulation. Mutation of TIE (TTGG to TATT) abolished the down-regulation of the LEDGF promoter. Gel mobility and supershift assays showed that LEDGF in the nuclear extracts of TGF-beta1-treated human lens epithelial cells did not bind to stress-response elements and HSE. The TGF-beta1-induced down-regulation of LEDGF, Hsp27, and alphaB-crystallin promoters activity was reversed by cotransfection with a plasmid expressing LEDGF. Because overexpression of LEDGF was able to relieve TGF-beta1 and/or stress-induced changes, it would be a candidate molecule to postpone age-related degenerating disorders.
Sharma
Preeti
P
Center for Ophthalmic Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Fatma
Nigar
N
Kubo
Eri
E
Shinohara
Toshimichi
T
Chylack
Leo T
LT
Singh
Dhirendra P
DP
D001483:Base Sequence; D019070:Cell Lineage; D004247:DNA; D015536:Down-Regulation / Q000502:physiology*; D004847:Epithelial Cells / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D007908:Lens, Crystalline / Q000166:cytology / Q000378:metabolism*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D016212:Transforming Growth Factor beta / Q000502:physiology*
D006360:Heat-Shock Proteins; D036341:Intercellular Signaling Peptides and Proteins; D016212:Transforming Growth Factor beta; C119380:lens epithelium-derived growth factor; D004247:DNA