1. Lactate Treatment Causes NF-κB Activation and CD44 Shedding in Cultured Trabecular Meshwork Cells
- Author
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M. J. Nolan, T. Koga, A.M. Miller, Paul A. Knepper, Xiang Shen, Beatrice Y.J.T. Yue, and John Choi
- Subjects
Adult ,Time Factors ,Cell Survival ,Blotting, Western ,Cell ,Enzyme-Linked Immunosorbent Assay ,Biology ,chemistry.chemical_compound ,Western blot ,Trabecular Meshwork ,Matrix Metalloproteinase 14 ,medicine ,Humans ,Lactic Acid ,Viability assay ,Cells, Cultured ,Dose-Response Relationship, Drug ,medicine.diagnostic_test ,CD44 ,Transcription Factor RelA ,Middle Aged ,Molecular biology ,Lactic acid ,Hyaluronan Receptors ,medicine.anatomical_structure ,chemistry ,Biochemistry ,Cell culture ,Cytoplasm ,biology.protein ,Trabecular meshwork - Abstract
PURPOSE To challenge human trabecular meshwork (TM) cells using lactate to mimic cell stress and observe the effects on cell viability, NF-kappaB, and membrane type 1 matrix metalloproteinase (MT1-MMP) expression and the ectodomain shedding of soluble (s)CD44. METHODS Human TM cells grown in 10% fetal calf serum (FCS) were incubated in 0.1% FCS with 1, 10, or 40 mM lactate or PBS for 5 and 30 minutes and 1, 3, and 6 hours. Cell viability was determined with trypan blue staining. NF-kappaB and MT1-MMP expression was evaluated through Western blot analysis of medium and the cytoplasmic and nuclear fractions. Media sCD44 concentration was determined by enzyme-linked immunosorbent assay and Western blot analysis. RESULTS The TM cell viability was significantly decreased after incubation for 3 hours with 40 mM lactate (P < 0.01) and 6 hours with 10 and 40 mM lactate (P < 0.001). Western blot analysis showed an increased NF-kappaB p50 and MT1-MMP expression and activity by 5 minutes in lactate-treated TM cells compared with that of control cells. At 6 hours, NF-kappaB p65 was increased in nuclear fraction of lactate-treated compared with control cells. Treatment with 1 mM lactate caused an increase in the media concentration of both the 32 and 55 kDa sCD44 at 3 (P < 0.05) and 6 hours (P < 0.01). CONCLUSIONS Lactate treatment resulted in dose- and time-dependent effects on human TM cell viability, translocation of NF-kappaB, and activation of MT1-MMP. Increased shedding of sCD44 occurred with the l mM dose of lactate. Lactate treatment of human TM cells in culture offers a useful cell model to examine the stress responses that occur in glaucoma.
- Published
- 2007