Whether it is an egg and sperm joining during fertilization or bone cells merging during development, cell fusion may start with a neighbourly poke.

Elizabeth Chen and her team at Johns Hopkins University in Baltimore, Maryland, found a way to induce fusion in a cell line that does not normally fuse. When proteins involved in membrane fusion and cytoskeletal remodelling were expressed in these cells, the cells pushed finger-like appendages from their membranes by linking up subunits of actin — a protein required for cell movement and structure. This allows proteins at the tips of the 'fingers' to make direct contact with adjacent cells. The authors suggest that such actin-based appendages may be a general mechanism used by cells to initiate fusion.

Science http://dx.doi.org/10.1126/science.1234781 (2013)