The endoplasmic reticulum and protein trafficking in dendrites and axons

Neurons are highly polarized cells whose dendrites and axons extend long distances from the cell body to form synapses that mediate neuronal communication. The trafficking of membrane lipids and proteins throughout the neuron is essential for the establishment and maintenance of cell morphology and synaptic function. However, the dynamic shape and spatial organization of secretory organelles, and their role in defining neuronal polarity and the composition of synapses, are not well delineated. In particular, the structure and function of the continuous and intricate network of the endoplasmic reticulum (ER) in neurons remain largely unknown. Here we review our current understanding of the ER in dendrites and axons, its contribution to local trafficking of neurotransmitter receptors, and the implications for synaptic plasticity and pathology.