Retinoid X receptor gamma signaling accelerates CNS remyelination

The molecular basis of CNS myelin regeneration (remyelination) is poorly understood. Here we generate a comprehensive transcriptional profile of the separate stages of spontaneous remyelination following focal demyelination in the rat CNS. White matter tracts in the rat caudal cerebellar peduncles were focally demyelinated using 0.1% ethidium bromide, the lesions were isolated using laser capture microdissection at 5, 14 and 28 days postlesion, followed by RNA extraction and Illumina beadarray analysis of differentially expressed transcripts. We found transcripts encoding retinoid acid receptor RXR-gamma is highly differentially expressed during remyelination, and that oligodendrocyte lineage cells express RXR-gamma in rat tissues undergoing remyelination and in active and remyelinated MS lesions. RXR-gamma knockdown by RNA interference or RXR-specific antagonists severely inhibit oligodendrocyte differentiation in culture. In RXR-gamma deficient mice, adult oligodendrocyte precursor cells efficiently repopulate lesions following demyelination, but display delayed differentiation into mature oligodendrocytes. Administration of the RXR agonist 9-cis-retinoic acid to demyelinated cerebellar slice cultures and to aged rats following demyelination results in more remyelinated axons. RXR-gamma is therefore a positive regulator of endogenous oligodendrocyte precursor cell differentiation and remyelination, and may be a pharmacological target for CNS regenerative therapy. 9 Samples analysed, 3 different time points each with 3 biological replicates.