Role of Epidermal Growt h Factor signaling in epidermal homeostasis of Danio rerio (zebrafish)

Abstract

The epidermis covers the entire organism forming a barrier between the external environment and the organism. It averts any mechanical, biological or chemical attack from the environment. Epidermis is not a static but a dynamic barrier wherein the old dying cells are replaced constantly by new ones, so study of epidermal homeostasis is of vital importance. Growth factors like egf and fgf have been known to be involved in the maintenance of epidermal homeostasis. However it is not clear whether any of these factors play any role in the early embryonic epidermis, which is just a bilayered epithelium, and whether there is a layer specific requirement of these factors. Here, I have investigated this issues using zebrafish larval epidermis as a model. In this study, I show that EGF signaling is active in epidermis and has a role in regulating cell proliferation. By blocking the activity of the EGF receptors using an inhibitor I see decreased proliferation specifically in the periderm, the outermost epidermal layer. Also the cross-sectional area of the peridermal cells increases in these embryos as compared to the wild type. Thus, the results indicate that EGF signaling is essential to maintain proliferation and optimal surface area in the periderm.