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P. S. Reinach, F. Zhang, N. Furtado; Transient Receptor Potential Vanilloid 1 (TRPV1) Activation Promotes Human Corneal Epithelial Cell Migration. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3166.
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TRPV1 is a vanilloid subtype of the transient receptor potential protein superfamily. This isoform is a subunit of a non-selective cation channel mediating downstream responses to either heat, low pH, or noxious stimuli. TRPV1 activation mediates in hepatoblastoma cells enhances migration through increases in calcium influx. We show here in human corneal epithelial (HCE) cells that TRPV1 activation elicits such a response.
Scratch wound assay was performed to determine the dose dependent effects of a TRPV1 agonist, capsaicin ( i.e 0.1, 1 and 10 µM) over a 24 h period on SV40-immortalized human corneal epithelial (HCE) cell migration. HCE cells were cultured in DMEM supplemented with 5 ng/ml EGF and 10% FBS and then exposed to serum-free medium overnight. A TRPV1 antagonist, capsazepine (1 µM, 5 µM and 10 µM), was used to validate capsaicin selectivity. An epidermal growth factor receptor (EGFR) inhibitor tyrphostin AG 1478 (1 µM), and AKT inhibitors (LY 294002, 1 µM and wortmannin, 0.05 µM), delineated downstream proximal signaling. Phosphorylation of AKT was analyzed by Western blotting.
Capsaicin at 0.1, 1 and 10 µM hastened wound rates by up to 2.5-fold. Capsazepine inhibited such enhancement in a dose-dependent manner. At 10 µM, the wound closure rate fell below the control rate. Subsequent to inhibition of EGFR or blocking AKT activation, TRPV1-mediated enhancement of migration was diminished by 78% and 72%, respectively. Capsaicin 1 µM induced time dependent biphasic increases in pAKT formation which reached a maximal 2- fold increase above the baseline condition after 15 min.
Capsaicin induced TRPV1 receptor stimulation accelerates cell migration through EGFR transactivation and pAKT formation. These results suggest that corneal epithelial wound healing rates can be increased through TRPV1 stimulation.
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