Questioning the function of neuroligin

By making knockout mice, Frederique Varoqueaux at the Max Planck Institute of Experimental Medicine in Germany and his colleagues revealed that neuroligin, a cell adhesion molecule, may not be essential for synaptogenesis. ¹ "It hints that our current understanding is probably incorrect or at the very least incomplete," says Faculty of 1000 member Venkatesh Murthy at Harvard University.

"Neuroligins have been proposed to be important to initiate synapses in the mammalian brain. All the experiments that have been done to test this hypothesis have been in cultured neurons... but it's never been tested by just removing the gene from the animal.

"When you take out the three dominant isoforms of neuroligins from the mouse genome, there doesn't seem to be a very big effect on the number of synapses in native tissues and cultured networks. One possibility is that when you have mixed populations of cells, the ones that don't have neuroligins are somehow severely punished in some sort of a competitive manner. But in this case it is uniform knockout so no cell has the protein. One thing we need to do is take neurons out of the knockout mice and mix it with wild type neurons in a culture... we can't dismiss this molecule's role in neurogenesis just yet."