Differential patterns of expression of Eps15 and Eps15R during mouse embryogenesis

: Eps15 and Eps15R are related tyrosine kinase substrates, which have been implicated in endocytosis and synaptic vesicle recycling. Through the protein:protein interaction abilities of their EH domains, they establish a complex network of interactions with several proteins, including Numb, a protein necessary for neuronal cell fate specification. We analyzed the expression of Eps15 and Eps15R during murine development, at the time of active neurogenesis. The most striking difference was at the level of subcellular localization, with Eps15 present in the cytosol and on the plasma membrane, while Eps15R exhibited mainly a nuclear localization. Interesting topographical differences also emerged. In the 12.5 days post coitum neuroepithelium, Eps15 was expressed in the ventricular zone, which contains proliferating neuroblasts, whereas Eps15R was found only in postmitotic neurons. Conversely, both proteins were expressed in sensory and cranial ganglia. At later times, the expression of Eps15 and Eps15R was widely maintained in neuronal structures. In other tissues, Eps15 was first seen in the liver primordium and at low levels in choroid plexus, lung, kidney and intestine; later on the expression was maintained at high levels in epithelia. Nuclear staining of Eps15R was present in kidney, intestine, lung and liver, as well as in heart and pancreas.