Development begins with a ball of generic stem cells capable of becoming any type of cell. Stem cells become precursor cells, which can change into a limited number of cell types. By the end of the developmental stage, cells are committed to just one cellular future. Scientists knew that Wnt proteins were involved in early cell development, but the U-M study is the first to identify the importance of Wnts in fat cell formation. Tissue samples from experimental and control mice in the U-M study show how expression of Wnt blocks formation of adipocytes.
Fat cells develop in tissue grown from preadipocyte cells.
Understanding this developmental pathway could help scientists learn how and why obesity develops. When Wnt protein binds to a cell membrane receptor, it sets off a chain of biochemical signals, according to Ross. Signals are passed from one messenger molecule to another until they reach the cell nucleus where they either turn on or turn off genes that regulate development. Ross demonstrated Wnt's power to control cell differentiation by blocking proteins in this signaling pathway to interrupt the Wnt signal. After just a few days, myoblasts already on their way to differentiating into muscle cells spontaneously switched gears and became fat cells instead.