Molecular mechanisms of de novo lumen formation

A lumen arising de novo creates a space between or within cells where no space existed before.De novo lumen formation has been studied in several model systems. Despite apparent differences, there are many cell biological commonalities that now justify a unifying overview.A major mechanism of de novo lumen formation is the delivery of membrane material to the apical plasma membrane of the lumen-forming cell, which must be incorporated in a spatially structured manner.Lumen formation can be subdivided into three steps: determining the site of lumen initiation, enlarging the apical domain, and the maturation and stabilization of the lumen.The major cellular machineries needed for tube construction are cell polarity determinants, vesicle-trafficking systems and the cytoskeleton.Although there is currently a good understanding of how material is delivered to the apical membrane during the creation of tubes, an important open question is how the membrane is given its spatial structure.