Immunohistological localization of the myelinating cell‐specific receptor LPA1

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Abstract
LPA1 (also termed Edg‐2 or VZG‐1) is a G‐protein–coupled receptor for lysophosphatidic acid and its gene transcripts have been found selectively expressed by mature myelin‐producing cells. We have raised in rabbit a polyclonal antibody against a sequence unique to LPA1 and common to rat, mouse, and human orthologues. In Western blots, LPA1 immunoreactivity appeared as 44–53 kDa bands in extracts from recombinant RH7777 cells expressing LPA1, mouse purified oligodendrocytes, or human white matter, but not from wild‐type RH7777 cells or purified astrocytes. In glial cultures, LPA1 immunoreactivity was restricted to oligodendrocytes, appeared at cell membrane and processes, colocalized with myelin basic protein, and appeared before myelin/oligodendrocyte glycoprotein. In slices of rat and human brains, LPA1 immunoreactivity was found in myelinated tracts, as well as in oligodendrocyte somata and their myelinating fibers. Immunoreactivities of LPA1 and myelin basic protein colocalized in the brain, but oligodendrocyte soma showed stronger signals for LPA1 than myelinated fibers, whereas the reverse was true for myelin basic protein. These results strengthen the view that LPA1 is involved in myelin formation or maintenance. GLIA 38:126–136, 2002.