High-level expression of the Mnb/Dyrk1A gene in brain and heart during ratearly development

We previously isolated human MNB/DYRK1A cDNA from "the Down syndrome critic al region" of human chromosome 21 (Shindoh et al., 1996, Biochem. Biophy's. Res. Commun. 225: 92-99). As described herein, we prepared a polyclonal an ti-MNB/DYRK1A antibody and used it in a Western blot assay to assess the ex pression of the MNB/DYRKIA protein during rat development. The MNB/DYRK1A p rotein was expressed strongly not only in the brain but also in other tissu es from embryonic rats. At the early postnatal stage, expression of the pro tein was high in the central nervous system and heart, but low in liver, lu ng, spleen, and kidney. The level of MNB/DYRK1A protein in all tissues stud ied gradually decreased with postnatal growth. Similarly, Northern blot ana lysis revealed that a major 6.0-kb transcript of the Mnb/Dyrk1A gene was ex pressed at a high level in the brain during the early postnatal period but that its level was low in the adult. The finding that the MNB/DYRK1A protei n is expressed strongly in the central nervous system and heart may indicat e a significant role for this protein in the development of these organs. ( C) 1999 Academic Press.