Skin aging: A role for telomerase and telomere dynamics?

Skin is a complex tissue composed of two very different compartments - the continuously renewing epidermis made up mostly by keratinocytes and the underlying matrix-rich dermis with the resting fibroblasts as its major cellular components. Both compartments are tightly interconnected and a paracrine mutual interaction is essential for epidermal growth, differentiation, and tissue homeostasis. Skin aging is commonly viewed as wrinkle formation, hair greying, and impaired wound healing. Nevertheless, the epidermis as the outermost shield needs to remain intact in order to guarantee an inside-out and outside-in barrier function throughout life time of a human being. Furthermore, the epidermis is one of the few regenerative tissues that express telomerase, the ribonucleoprotein complex that can counteract telomere erosion, one of the presently mostly favoured potential mechanisms causing cellular aging. This raises the question whether in the epidermis telomerase is able to counteract telomere erosion and thereby to prevents a telomere-dependent aging process and consequently which part of the skin is responsible for the most obvious changes associated with skin aging.