Expression analysis of BACE2 in brain and peripheral tissues

Beta-site amyloid precursor protein cleaving enzyme (BACE) is a novel trans membrane aspartic protease that possesses all the known characteristics of the beta-secretase involved in Alzheimer's disease (Vassar, R., Bennett, B. D., Babu-Khan, S., Kahn, S., Mendiaz, E. A., Denis, P., Teplow, D. B., Bos s, S., Amarante, P., Loeloff, R., Luo, Y., Fisher, S., Fuller, J., Edenson, S., Lile, J., Jarosinski, M. A., Biere, A. L., Curran, E., Burgess, T., Lo uis, J.-C., Collins, F., Treanor, J., Rogers, G., and Citron, M. (1999) Sci ence 286, 735-741). We have analyzed the sequence and expression pattern of a BACE homolog termed BACE2. BACE and BACE2 are unique among aspartic prot eases in that they possess a carboxyl-terminal extension with a predicted t ransmembrane region and together they define a new family. Northern analysi s reveals that BACE2 mRNA is expressed at low levels in most human peripher al tissues and at higher levels in colon, kidney, pancreas, placenta, prost ate, stomach, and trachea. Human adult and fetal whole brain and most adult brain subregions express very low or undetectable levels of BACE2 mRNA In addition, in situ hybridization of adult rat brain shows that BACE2 mRNA is expressed at very low levels in most brain regions. The very low or undete ctable levels of BACE2 mRNA in the brain are not consistent with the expres sion pattern predicted for beta-secretase.