Shiseido Research Center, Yokohama, Kanagawa 236-8643, Japan.
Adv Exp Med Biol. 2011;704:847-60. doi: 10.1007/978-94-007-0265-3_44.
Epidermal keratinocytes are the epithelial cells of mammalian skin. At the basal layer of the epidermis, these cells proliferate strongly, and as they move towards the skin surface, differentiation proceeds. At the uppermost layer of the epidermis, keratinocytes undergo apoptosis and die, forming a thin, water-impermeable layer called the stratum corneum. Peripheral blood vessels do not reach the epidermis, but peripheral nerve fibers do penetrate into it. Until recently, it was considered that the main role of epidermal keratinocytes was to construct and maintain the water-impermeable barrier function. However, since the functional existence of TRPV1, which is activated by heat and low pH, in epidermal keratinocytes was identified, our understanding of the role of keratinocytes has changed enormously. It has been found that many TRP channels are expressed in epidermal keratinocytes, and play important roles in differentiation, proliferation and barrier homeostasis. Moreover, because TRP channels expressed in keratinocytes have the ability to sense a variety of environmental factors, such as temperature, mechanical stress, osmotic stress and chemical stimuli, epidermal keratinocytes might form a key part of the sensory system of the skin. The present review deals with the potential roles of TRP channels expressed in epidermal keratinocytes and focuses on the concept of the epidermis as an active interface between the body and the environment.
表皮角质形成细胞是哺乳动物皮肤的上皮细胞。在表皮的基底层，这些细胞强烈增殖，并且随着它们向皮肤表面移动，分化进行。在表皮的最上层，角质形成细胞经历凋亡并死亡，形成一层薄的、不透水的层，称为角质层。外周血管不能到达表皮，但外周神经纤维确实渗透到表皮中。直到最近，人们认为表皮角质形成细胞的主要作用是构建和维持不透水的屏障功能。然而，自从鉴定出 TRPV1 的功能存在以来，TRPV1 可被热和低 pH 值激活，我们对角质形成细胞作用的理解发生了巨大变化。已经发现许多 TRP 通道在表皮角质形成细胞中表达，并在分化、增殖和屏障稳态中发挥重要作用。此外，由于角质形成细胞中表达的 TRP 通道具有感知各种环境因素（如温度、机械应力、渗透压和化学刺激）的能力，表皮角质形成细胞可能形成皮肤感觉系统的关键部分。本综述讨论了表皮角质形成细胞中表达的 TRP 通道的潜在作用，并重点介绍了表皮作为身体和环境之间的主动界面的概念。
