AS SIMPLE AS APC

By controlling protein degradation, the anaphase-promoting complex/cyclosome (APC/C) is crucial to the normal functioning of the cell cycle in many different organisms. Dr Andrea Brand and colleagues at the Gurdon Institute of Cancer and Developmental Biology in Cambridge have shown, unexpectedly, that the APC/C also plays an important role at synapses, the junctions between neurons, and hence in nervous system function.

The activity of neurons is very finely controlled. An important aspect of this control, it has recently become clear, comes from tight regulation of protein levels within cells. One way this can be achieved is through the ubiquitin system, which tags proteins for degradation within the cell.

Not much is known about this process in neurons, but it has been studied for many years in dividing cells. A key component is the APC/C complex of proteins. Dr Brand and colleagues looked to see if this complex might also be active in neurons at the neuromuscular synapses, where nerve meets muscle, in the fruit fly Drosophila.

They found that the APC/C has two highly significant effects – on the size of synapses and the transmission of signals across them. The APC/C acts on muscle cells, regulating the number of receptors for glutamate, a neurotransmitter released by neurons innervating the muscle.

The discovery of APC/C activity at the synapse opens up a new area of study of this key aspect of animal biology.

External links

• van Roessel P et al. Independent regulation of synaptic size and activity by the anaphase promoting complex. Cell 2004;119(5):707–18.