Autophagy at the synapse.

As the sites of communication between neurons, synapses depend upon precisely regulated protein-protein interactions to support neurotransmitter release and reception. Moreover, neuronal synapses typically exist great distances (i.e. up to meters) away from cell bodies, which are the sources of new proteins and the major sites of protein degradation via lysosomes. Thus, synapses are uniquely sensitive to disruptions in proteostasis, and depend upon carefully orchestrated degradative mechanisms for the clearance of dysfunctional proteins. One of the primary cellular degradative pathways is macroautophagy, hereafter referred to as 'autophagy'. Although it has only recently become a focus of research in synaptic biology, emerging studies indicate that autophagy has essential functions at the synapse throughout an organism's lifetime. This review will discuss recent findings about the roles of synaptic autophagy, as well as some of the questions and issues to be considered in this field moving forward.