{"id":263,"date":"2014-05-08T20:00:06","date_gmt":"2014-05-08T18:00:06","guid":{"rendered":"http:\/\/news.embl.de\/?p=263"},"modified":"2024-03-26T00:23:56","modified_gmt":"2024-03-25T23:23:56","slug":"1405_remodelling","status":"publish","type":"post","link":"https:\/\/www.embl.org\/news\/science\/1405_remodelling\/","title":{"rendered":"Remodelling the cell"},"content":{"rendered":"\n

As cells get bigger, they obviously need to create more membrane, but sculpting the cell into a defined shape also requires tightening and contracting parts of the membrane too. Coordinating these processes is essential for cells to acquire their correct form. New research from Stefano De Renzis\u2019 group<\/a> at EMBL Heidelberg has begun to show how this is achieved, as reported in a paper published this week in the Journal of Cell Biology<\/em>. Stefano\u2019s group studies the way cells change shape as embryos grow and develop, and the signals cells rely on to make sure they change shape appropriately. In recent experiments, Stefano and colleagues looked at how the embryo of the fruit fly Drosophila<\/em> goes from being a \u2018syncitium\u2019 \u2014 a giant cell with many nuclei \u2014 to a collection of 6000 individual cells, each with one nucleus. \u201cDuring this process, the surface area of the embryo\u2019s cell membranes increases 30-fold, as membranes grow around each nucleus to define a new cell,\u201d says Stefano. This entails expanding the membrane in some places, and tightening it in others to give the cells their shape \u2014 and coordinating these two processes. Using tools developed by Carsten Schultz\u2019s lab<\/a> (see factbox<\/a>), Alessandra Reversi, postdoctoral fellow in the De Renzis group, found that this is achieved by altering the ratios of the different building blocks of cell membranes, in particular two kinds of molecules: phosphatidylinositol 4,5-bisphosphate (PIP2<\/sub>) and phosphatidylinositol (3,4,5)-triphosphate (PIP3<\/sub>). High levels of PIP2<\/sub> relative to PIP3<\/sub> lead to contraction of the membrane; by contrast, high levels of PIP3<\/sub> prevent this contraction and allow the membrane to expand. PIP molecules do not themselves cause contraction of the membrane, however. Instead, networks of actomoysin, which are made up of actin and myosin proteins and are attached to the cell membrane, do this hard work.<\/p>\n\n\n\n

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