Purpose:
Nerve growth factor (NGF) has been reported to be involved in cellular functions such as cell growth, proliferation, angiogenesis and also corneal wound healing. We aimed to investigated multiple signaling pathways to elucidate the possible action mechanism through which NGF might play a crucial role in the biological effects of corneal epithelial cells.
Methods:
Human corneal epithelial cells were obtained and cultured in vitro. The cells at passage one were stimulated with recombinant NGF for the time periods indicated at the concentration of 25ng/ml, or underwent a dose-dependent treatment for 1 hour. The PI3K and MEK1/2 signaling pathways were then determined. The phosphorylation of Akt and Erk1/2 were detected by Western blot analysis using an anti-phospho-Akt or anti-phospho-Erk1/2 antibody respectively.
Results:
Upon the time-dependent treatment with recombinant NGF in figure 1, both levels of phospho-Akt (p-Akt) and phospho-Erk (p-Erk) were increased within 10 minutes, reached a maximum after 60 min and remained high even after 2 hous. As presented in figure 2 of dose-dependent treatment, NGF caused an increased phosphorylation of PI3K/Akt and MAPK pathways at a concentration of 5 ng/ml. The maximal effect was observed at 25 ng/ml, but then increasing concentration of NGF induced the down-regulation of their phosphorylation level.
Conclusions:
Our findings suggested the possible mechanism through which NGF was involved in corneal physiopathology. PI3K/Akt and MAPK pathways were revealed for the first time to be activated by NGF in corneal epithelial cells. Several studies have showed that NGF promoted the corneal epithelial healing rate. The data presented here provided one more evidence that NGF might be a potential new medicine used in wide-spectrum corneal diseases. The different periods of time or dose treatment that we tried in the study also gave a suggested treatment condition of NGF for further studies.
Keywords: growth factors/growth factor receptors • cornea: basic science • cytokines/chemokines