Cyclophilin A Is Required for Retinoic Acid-induced Neuronal Differentiation in p19 Cells

Stable transfectants with expression of small interfering RNA for targeting cyclophilin A ( CypA ) in p19 cells lose their potential for retinoic acid (RA)-induced neuronal differentiation but not Me 2 SO-induced mesodermal differentiation. This difference suggests that CypA is specifically required for the RA-induced neuronal pathway. In addition to the loss of RA-induced RA receptor β expression and retinoic acid response element (RARE)-binding activity, a dramatic reduction in RA-induced RARE-mediated luciferase activity in the CypA knockdown cell line suggests that CypA affects RARE-mediated regulation of gene expression. Silent mutation of target sequences confirms the specificity of RNA interference in p19 embryonal carcinoma cells. Collectively, our data reveal that a novel function of CypA is required in the processing of RA-induced neuronal differentiation in p19 embryonal carcinoma cells.