Darier disease : a disease model of impaired calcium homeostasis in the skin.

The importance of extracellular calcium in epidermal differentiation and intra-epidermal cohesion has been recognized for many years. Darier disease (DD) was the first genetic skin disease caused by abnormal epidermal calcium homeostasis to be identified. DD is characterized by loss of cell-to-cell adhesion and abnormal keratinization. DD is caused by genetic defects in ATP2A2 encoding the sarco/endoplasmic reticulum Ca(2+)-ATPase isoform 2 (SERCA2). SERCA2 is a calcium pump of the endoplasmic reticulum (ER) transporting Ca(2+) from the cytosol to the lumen of ER. ATP2A2 mutations lead to loss of Ca(2+) transport by SERCA2 resulting in decreased ER Ca(2+) concentration in Darier keratinocytes. Here, we review the role of SERCA2 pumps and calcium in normal epidermis, and we discuss the consequences of ATP2A2 mutations on Ca(2+) signaling in DD. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.