Identification of two secreted phospholipases A(2) in human epidermis

Phospholipases A(2) are enzymes that catalyze the release of fatty acids fr om the sn-2 position of phospholipids. Fatty acids have been suggested to p lay a key role in the barrier function of the epidermis. The aim of this st udy was to identify and characterize the type of secretory phospholipase A( 2) expressed in human epidermis. We report the molecular cloning of two sec retory phospholipase A(2) in the human epidermis. The first enzyme is ident ical to human pancreatic type IB phospholipase A(2). Western blots revealed a 14 kDa protein localized in the soluble fraction. The second phospholipa se A(2) is identical to human synovial type IIA enzyme and is localized in the membrane fraction. By semiquantitative reverse transcription-polymerase chain reaction performed on horizontal sections of the epidermis, we found that the mRNAs of both phospholipases A(2) were expressed mainly in the ba sal layers of the epidermis. Our data thus provide evidence for the express ion of two secretory phospholipases A(2) in human epidermis. The different localization of these two secretory proteins strongly suggests that each en zyme might have a specific role in skin physiology and probably in the barr ier function. Taken together, these data validate the reverse transcription -polymerase chain reaction technique performed on thin sections as a first approach to detect gene expression in different layers of the epidermis.