Endothelin-1 combined with extracellular matrix proteins promotes the adhesion and chemotaxis of amelanotic melanocytes from human hair follicles in vitro.

During the repigmentation of vitiliginous skin, amelanotic melanocytes (AMMCs) migrate from the outer root sheath (ORS) of the hair follicles into depigmented skin. It has been shown that endothelin-1 (ET-1) is an important cytokine in the migration of epidermal melanocytes, produced by keratinocytes particularly after irradiation with ultraviolet B (UVB). To further examine the role of ET-1 on the migration of AMMCs, we investigated the effects of ET-1 to the adhesion and chemotaxis of human AMMCs combined with extracellular matrix proteins (ECMP) and observed the effects on the actin and tubulin cytoskeleton of AMMC by ET-1. Human AMMCs were treated with different concentrations of ET-1 (0.1-100 nM) to observe adhesion on culture dishes coated with fibronectin (FN), laminin (LN) and collagen IV (CIV). In addition, chemotaxis on FN, LN and CIV coated micropore filters, with various concentrations of ET-1 as attractants, was investigated using a Boyden chemotaxis chamber. Cellular microfilaments and microtubules were immunostained with Rhodamine labeled actin and FITC labeled beta-tubulin. The effects of ET-1 on cytoskeleton were observed with laser confocal microscopy. The study demonstrated that ET-1 increases human AMMCs adhesion on FN in a dose-dependent manner, but minor increases are found on the coated surface with LN and CIV. ET-1 also induces chemotaxis of AMMCs on CIV, LN and FN in a dose-dependent manner. The greatest effect was seen with CIV. Minor chemotactic effects were observed with non-coated surfaces. A concentration of >or=10nM ET-1 induced an apparent increase in stress fibers underneath the cell membrane, but no effects were found on tubulin. ET-1 has various effects on the adhesion and chemotaxis of AMMCs on various ECMP, which could be partly due to a modulation and reorganization of the actin cytoskeleton.