Abstract
We have previously shown in rat brain that ABCA2, which belongs to the A subclass of ATP-binding cassette (ABC) transporter superfamily, is predominantly expressed in the cytoplasm of oligodendrocytes but not in GFAP+ astrocytes, CD11b+ microglia, or NG2+ progenitors. In addition, onset of ABCA2 expression in oligodendrocytes coincides with the appearance of myelin segments immunolabeled with myelin basic protein, implying a role of ABCA2 in transport of substances related to myelination processes. Consistently, expression of ABCA2 was detected in S100β+ Schwann cells in human and rat peripheral nerve. Unexpectedly, however, ABCA2 also was detected in S100β-weakly positive cells containing number of densely packed, thin axons in peripheral nerve, implying expression of ABCA2 in non-myelinating Schwann cells. Indeed, multiple immunolabeling with ABCA2, S100β, GFAP, and a zinc finger transcription factor Krox20, one of the most reliable makers for myelinating Schwann cells, revealed that ABCA2 is expressed not only in myelinating Schwann cells but also in non-myelinating Schwann cells. As number of non-myelinating axons are thinly wrapped by single non-myelinating Schwann cells, ABCA2 might contribute to transport of lipid components commonly required for surrounding myelinating and non-myelinating axons. [J Physiol Sci. 2006;56 Suppl:S170]
