EMTASY · Common molecular pathways in epithelial-mesenchymal transition and left-right asymmetries

The majority of animals show an external bilateral symmetry, precluding the observation of multiple internal left-right (L/R) asymmetries which are fundamental for organ packaging and function. A prominent molecular pathway converging on and downstream of the Pitx2 transcription factor confers left-handed information in the left side of the embryo, with players expressed on the right ensuring that the left determinants are excluded. Therefore, conferring or excluding left identity in left and right hand sides, respectively, drives L/R asymmetry. Some indications suggest that a program actively specifying right–handed information could exist on the right. Our recent findings support this view. In a screening for novel regulators of the epithelial to mesenchymal transition (EMT), we have identified a transcription factor, EMT2, which similarly to well known factor Snail, it is an EMT inducer. The EMT is crucial for the development of tissues during embryonic development and for the progression of carcinomas to the invasive state. Strikingly, again as Snail, in addition to promote EMT, the EMT2 factor is predominantly expressed on the right side and may operate instructing L/R identity on the right-hand side of the embryo.With this background, our knowledge of the EMT and a series of genome-wide high-throughput approaches and a comprehensive functional analysis using the chick, the fish and the mouse as model systems we propose to reveal the putative molecular pathways conveying right-handed information and to reveal commonalities between L/R pathways and the EMT. In the long run, we aim at better understanding human pathologies that involve these morphogenetic and cellular processes, including pathological situs conditions (i.e. altered organ positioning) and cancer progression.