Developmental expression of OSP/claudin-11

Oligodendrocyte-specific protein (OSP/claudin-11) is a major component of C NS myelin and has been recently added to the claudin family of tight juncti on proteins. In this study, the developmental expression of OSP/ claudin-11 was determined using in situ hybridization, immunohistochemistry (IH), and Western blot analysis. OSP/claudin-11 mRNA was expressed in a bimodal fash ion. During prenatal development, OSP/claudin-11 mRNA was abundant in devel oping meninges, in areas adjacent to cartilage, and in mesoderm. In postnat al animals, OSP/claudin-11 was expressed primarily in developing oligodendr ocytes and to a lesser extent, in testes, Double-labeled IH using O2-A prog enitor cells revealed that OSP/claudin-11 expression occurs from the early progenitor stage and continues in mature oligodendrocytes. Electron microsc opic IH localized OSP/claudin-11 to laminar myelin in the adult CNS. Wester n blot analysis of OSP/claudin-11 in developing brain revealed the expressi on of two separate transcripts that were developmentally regulated. These d ata demonstrate that OSP/claudin-11 expression is highly regulated during d evelopment and, therefore, may play an important role in growth and differe ntiation of oligodendrocytes and other cells outside the CNS. (C) 2000 Wile y-Liss, Inc.