WNT gene family

Researchers have identified 19 genes in the WNT gene family. These genes provide instructions for making similar proteins that participate in chemical signaling pathways in the body. Some WNT proteins are specific to certain cells and tissues.

WNT proteins are ligands, which means they can attach (bind) to other proteins called receptors. A ligand and its receptor fit together like a key in a lock. WNT proteins bind with receptors called Frizzled proteins on the surface of cells. This binding triggers a multi-step process within the cell that allows a molecule called beta-catenin to move into the nucleus, where it activates certain genes. The association of WNT proteins with Frizzled receptors, and the subsequent effects on beta-catenin, are known as the canonical WNT signaling pathway. This pathway promotes the growth and division (proliferation) of cells and helps determine the specialized functions a cell will have (differentiation).

WNT signaling is known to be involved in many aspects of embryonic development. The WNT signaling pathway controls the activity of genes needed at specific times during development, and it regulates the interactions between cells as organs and tissues are forming. Mutations that disrupt the functions of WNT genes during embryonic development have been found to cause birth defects. In adult tissues, WNT signaling plays a role in the maintenance and renewal of stem cells, which are cells that help repair tissue damage and can give rise to other types of cells. Studies suggest that abnormal WNT signaling is associated with many human diseases, including cancer and degenerative diseases such as osteoarthritis.

Although most studies have focused on the canonical WNT signaling pathway, WNT proteins also have other functions. For example, noncanonical WNT signaling is involved in determining the position of various components within cells (cell polarity), regulating the migration of nerve cells, and directing the development of the heart during the earliest stages of embryonic development. Noncanonical WNT signaling is not well understood, however.