The proposed research will use genetically engineered stem cells capable of autoregulating their differentiation into insulin-producing beta cells by incorporating artificial cell-cell communication and carefully regulated multistep differentiation. The overall goal is to model an artificial tissue homeostasis system which contains regulatory elements that will allow cells to detect stem cell and beta cell populations and differentiate appropriately depending on cell population thresholds. Steps toward this goal will be carried out by controlling the differentiation of mES into pancreatic beta cells in vitro. The proposal integrates the multidisciplinary areas of synthetic, computational, and developmental biology; biological and tissue engineering; and modeling/computational and stem cell biology. Signaling elements are used in the first step of differentiation (ES cells into endoderm) where the native alpha-fetoprotein (AFP) is used to regulate expression of red fluorescent protein and allows for the visualization of mES transition into endoderm by cells) is?nfluorescence microscopy. The second step of differentiation (into beta visualized by GFP expression (from the Mouse Insulin Promoter (MIP)), which is caused by natural insulin production. These experimental observations will direct the forward-engineering of the synthetic autoregulating system.