Cellular expression and subcellular localization of autotaxin, a lysophosphatidic acid-generating enzyme, in the adult and developing mouse brain.

Autotaxin (ATX) is a lysophosphatidic acid-producing enzyme. In this study, we describe the cellular expression and subcellular localization of ATX in the mouse brain, thereby providing a fundamental framework for understanding lysophosphatidic acid signaling in vivo. High expression levels of ATX in the choroid plexus were observed in both developing and adult brains. ATX was localized predominantly at the cerebrospinal fluid (CSF)-facing apical side of choroid plexus epithelial cells, suggesting preferential secretion of ATX towards the CSF. High ATX expression was detected in oligodendrocytes and low-to-moderate levels were detected in neurons and astrocytes. ATX was preferentially localized in vesicle- and endoplasmic reticulum-rich regions of the cytoplasm. In the embryonic and early postnatal brain, ATX immunolabeling was intensely detected in neuronal perikarya and processes, whereas it was faint in the radial glia/astrocyte lineage. A marked upregulation of ATX in oligodendrocytes was observed during the active myelination stage that persisted into adulthood. The highly regulated, cell type-dependent expression of ATX suggests that ATX is a key regulatory factor for lysophosphatidic acid signaling in brain development and function.