TGF-{beta}2 induces senescence-associated changes in human trabecular meshwork cells.
OBJECTIVE
Recent studies have revealed an accumulation of senescent cells in the outflow pathways in primary open-angle glaucoma (POAG). Transforming growth factor (TGF)-β2 is thought to be involved in the pathologic changes of the trabecular meshwork (TM) of POAG eyes. The goal of this study was to determine whether TGF-β2 triggers senescence-associated changes in human TM cells in vitro.


METHODS
Cultured human TM cells were exposed to 1.0 ng/mL TGF-β2 for 12, 24, and 48 hours. Senescence-associated β-galactosidase (SA-β-Gal) activity was investigated by histochemical staining. Lipid peroxidation was assessed after TGF-β2 treatment. Levels of apolipoprotein J (Apo J), SM22, and osteonectin (SPARC) mRNA were determined by real-time PCR analysis. Furthermore, the effects of antioxidants on these TGF-β2-mediated changes were tested. Induction of senescence-related signal transduction proteins (p16, p21, and pRb) was examined by real-time PCR and Western blot analysis.


RESULTS
TGF-β2 increased SA-β-Gal activity, lipid peroxidation, and the mRNA expressions of Apo J, SM22, and SPARC. These TGF-β2-induced changes were attenuated by antioxidants. TGF-β2 increased p16 mRNA and protein expression, which was paralleled by a downregulation of pRb protein. There was no effect on p21 mRNA and protein expression after exposure to TGF-β2.


CONCLUSIONS
TGF-β2 induces senescence-associated TM changes and activates the senescence-related p16-pRb signal transduction pathway in vitro. Thus, minimizing TGF-β2 levels may help to prevent the ageing process in the TM as seen in POAG.
Yu
Alice L
AL
Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany.
Birke
Kerstin
K
Moriniere
Jerome
J
Welge-Lüssen
Ulrich
U
D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects*; D051152:Clusterin / Q000235:genetics; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics; D006801:Humans; D015227:Lipid Peroxidation; D008840:Microfilament Proteins / Q000235:genetics; D009124:Muscle Proteins / Q000235:genetics; D009363:Neoplasm Proteins / Q000235:genetics; D015676:Osteonectin / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D016160:Retinoblastoma Protein / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014129:Trabecular Meshwork / Q000187:drug effects* / Q000378:metabolism; D053781:Transforming Growth Factor beta2 / Q000494:pharmacology*; D001616:beta-Galactosidase / Q000378:metabolism
D015415:Biomarkers; C493956:CDKN1A protein, human; C000614131:CDKN2A protein, human; C495242:CLU protein, human; D051152:Clusterin; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D008840:Microfilament Proteins; D009124:Muscle Proteins; D009363:Neoplasm Proteins; D015676:Osteonectin; D012333:RNA, Messenger; D016160:Retinoblastoma Protein; D053781:Transforming Growth Factor beta2; C051615:transgelin; D001616:beta-Galactosidase