Expression analysis of glycogen synthase kinase-3 in human tissues

Human glycogen synthase kinase-3 (GSK-3) is a multisubstrate, proline-direc ted kinase that phosphorylates tau, beta-amyloid and neurofilaments. In thi s study, the expression levels of the two GSK-3 isoforms, alpha and beta, R NA and proteins in different human tissues were examined. Northern analysis demonstrated that GSK-3 alpha is encoded by a 2.6-kb mRNA and GSK-3 beta b y 8.3- and 2.8-kb mRNAs. The two GSK-3 beta mRNA species were variably expr essed in different tissues. Northern and quantitative polymerase chain reac tion demonstrated that both GSK-3 alpha and GSK-3 beta mRNA were prominentl y expressed in testis, thymus, prostate and ovary but were low in adult lun g and kidney. Western blot analysis showed that the 51-kDa GSK3 alpha prote in was highly expressed in lung, ovary, kidney and testis, whereas the 46-k Da GSK-3 alpha protein was highly expressed in lung, kidney and brain. The differential expression of GSK-3 alpha and GSK-3 beta mRNA and proteins and the lack of relationship between transcription and translation in some tis sues indicate that GSK-3 alpha and GSK-3 beta are subject to different mean s of regulation.