Wnt signaling pathway

The Wnt signaling pathway is one of many signal transduction pathways can respond by cells to external signals. The signal path is named after its ligands " Wnt ", a signaling protein that plays an important role in the development of various animal cells as a local mediator. " Wnt " consists of Wg for Wingless and Int -1. The Wingless -type designation comes from observations with the fruit fly Drosophila melanogaster, in which mutations in the wingless gene lead to a variant of the wingless flies. The int gene in mice promotes the development of breast cancer if its expression by the integration of the mouse mammary tumor virus (MMTV ), a retrovirus in the vicinity of the INT1 gene (now Wnt -1) is activated.

At the signal transduction of the Wnt signaling pathway numerous proteins are involved. It is essential for normal embryonic development ( embryonic development ), and is also observed in certain types of cancer. According to current knowledge, the Wnt protein binds to the receptor Frizzled (together with the co-receptor LRP), which the protein Dishevelled is activated, which in turn inhibiting a protein complex (consisting of GSK- 3β ( a kinase ), the tumor suppressor protein APC and Axin protein -1) acts, which normally degrades β -catenin. Since the degradation of β -catenin is inhibited accumulates this in the cytoplasm and in the nucleus. In the nucleus, the β -catenin forms a protein complex with TCF and activates specific target genes.

Wnt signaling and APC gene ( Adenomatous polyposis coli protein )

The APC gene is a tumor suppressor gene which has been first found mutated in a particular type of cancer. However, this gene can mutate in other cancers. The gene coding for the APC protein, which is involved in the Wnt signaling pathway in the degradation of β -catenin.