Cell Biology

Developmental Fusogen

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Science  13 Oct 2006:
Vol. 314, Issue 5797, pp. 225
DOI: 10.1126/science.314.5797.225c

Occasionally during development, two cells must fuse; for example, during the formation of muscle, myoblasts fuse with one another to form myotubes. This fusion of neighboring plasma membranes to form syncytia containing multiple nuclei must be very carefully regulated. The nematode Caenorhabditis elegans contains a number of syncytial tissues, and a protein termed EFF-1 is known to be a part of this fusion machinery. Podbilewicz et al. find by expression in heterologous cell lines that the EFF-1 transmembrane protein can drive the fusion of a variety of cells. The mechanism of fusion promoted by EFF-1 involves the formation of a hemifusion intermediate wherein the outer leaflets of the two plasma membranes merge before mixing of cytosolic components has occurred. For productive fusion to occur, the EFF-1 protein needs to be expressed at the surface of both partner cells, both in vitro and in intact worms. This homotypic interaction between proteins in two fusing membrane partners is a variant on the established themes in membrane fusion: In intracellular membrane fusion events, different proteins are needed in each membrane for successful fusion, whereas in virally mediated fusion, only one of the membranes needs to carry the fusogen. — SMH

Dev. Cell 11, 471 (2006).

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