Developmental Expression of Wnt Signaling Factors in Mouse Brain

The Wnt signaling pathway has been implicated in a variety of biological events inducing neurogenesis. In this study, we aim to investigate the expression pattern of various components of the Wnt pathway including b-catenin and its partners LEF-1/TCF-4, GSK-3β and their nuclear target genes such as c-myc and cyclin D1 during mouse brain development. We performed a series of Western blot and immunohistochemistry of brain cortex, brainstem, and cerebellum which revealed differential accumulation of these proteins in different types of brain cells including neurons, astrocytes, and oligodendrocytes at different developmental stages. Intense cytoplasmic immunolabeling of β-catenin in 5 day old neurons throughout the cortex and brainstem significantly decreased as the brain developed, whereas the level of GSK-3β, the protein that phosphorylates β-catenin and causes its destabilization, increased during brain maturation. On the other hand, high level accumulation of LEF-1 and TCF-4 in neurons and astrocytes at ...