Abstract
Purpose: :
Our previous work demonstrated that IL-1β, a major proinflammatory cytokine, induces production of FGF-2 through PI 3-kinase and p38. We further investigated whether the NF-ΚB pathway participates in FGF-2 induction by IL-1β and its effect on cell migration and proliferation in corneal endothelial cells (CECs).
Methods: :
Scratch-induced directional migration assay was used to measure migratory rates. Cell proliferation was measured by MTT assay. NF-ΚB activity was measured using transcription assay kit. Pharmacological inhibitors were used to block PI 3-kinase, p38, ERK1/2, or NF-ΚB.
Results: :
We investigated whether IL-1β induced cell migration and proliferation. Brief stimulation with IL-1β or culture with conditioned media acquired from IL-1β treated cells induced cell migration and proliferation; however, these inductions were completely blocked by the neutralizing antibody to FGF-2, suggesting the involvement of FGF-2 induced by IL-1β. It was also defined that activation of PI 3-kinase and p38 was involved in cell migration, while cell proliferation was simultaneously stimulated by ERK1/2 and PI 3-kinase. We further investigated whether NF-ΚB participates in the induction pathway of FGF-2 by IL-1β. The NF-ΚB activity induced by IL-1β stimulation was 4-fold that of DMEM-cultured cells. The NF-ΚB activity was completely blocked by inhibition of PI 3-kinase and p38. Blocking of the NF-ΚB pathway by sulfasalazine, a specific NF-ΚB inhibitor, greatly decreased the IL-1β-induced FGF-2 production (63%), indicating that the NF-ΚB pathway activated by IL-1β through PI 3-kinase and p38 is involved in FGF-2 production.
Conclusions: :
These findings suggest that CECs utilize NF-ΚB as a major transcription factor to produce FGF-2 by IL-1β stimulation through PI 3-kinase and p38. The IL-1β-induced FGF-2 facilitates cell migration via PI 3-kinase and p38, while it stimulates cell proliferation using PI 3-kinase and ERK1/2 in parallel pathways.
Keywords: signal transduction • cornea: endothelium • cornea: basic science