STATs in Cell Mobility and Polarity during Morphogenetic Movement

Abstract

The signal transducer and activator of transcription (STAT) molecules mediate biological actions, such as cell proliferation, differentiation, and survival, in various biological processes in response to cytokines (1–3). In skin-wound healing, Stat3 is required for the migration but not the proliferation of keratinocytes (4), showing that Stat3 plays a crucial role in cell migration. Stat3 knockout (stat3-/-) mice die before 8.5 days postcoitum (5), indicating that Stat3 plays a role in the early development of the mouse embryo. During zebrafish gastrulation, Stat3 is activated in the dorsal organizer, and its activity is essential for convergence and extension movements, but is not required for early cell-fate specification. These requirements are cell-autonomous for the anterior migration of dorsal organizer cells, and non-cell-autonomous for the convergence of neighboring cells (6). Morphogenetic functions for STAT signaling pathways have also been described for Drosophila and Dictyostelium. The Drosophila JAK/STAT pathway functions in border cell migration during oogenesis (7), and the establishment of planar polarity during eye development (8). Dictyostelium STAT is required for normal chemotaxis during early development, and for the correct movement of prestalk cells during terminal differentiation (9). These observations raised the possibility that the role of STAT signaling in morphogenetic movements is conserved throughout evolution. In this review, we discuss what is known about STAT signaling requirements in morphogenetic movement processes, in particular, the role of STATs in the cell-autonomous epithelial-mesenchymal transition and the non-cellautonomous establishment of planar cell polarity.