Figure 2.

Separation of dendrites and axons from soma using microfluidic chambers (MFC). (a) Diagram of an MFC showing the somal (left) and neuritic sides (right) connected by microgrooves with a length of 150 ± 25 µm and a width of 10 µm. The somal side contains cell bodies, dendrites (green) and axons (red). The neuritic side contains only axons and dendrites. The microgrooves do not allow the entry of the cell bodies so that only the neurites can pass through from the somal to the neuritic side. (b) Schematic of the side view of an MFC showing fluidic isolation. The somal side is shaded in dark gray and the neuritic side in yellow. Fluidic isolation is achieved by removing a small volume of medium (~ 80 µl) from the neuritic side, generating a flow of liquid from the somal to the neuritic side (orange arrow). This prevents back diffusion of molecules from the neuritic to the somal side. (c-e) Schematics of the treatments and its effects in a neuron cultured in an MFC. In the absence of protein degradation inhibitors of autophagy and the proteasome, MAPT (red) sorts mainly into the axons and MAP2 (green) into the somatodendritic compartment (c). When protein degradation inhibitors are applied on the neuritic side, there is an increased fraction of dendrites on the neuritic side with MAPT accumulation (yellow) accompanied by loss of spines (d). In the presence of translation inhibitors on the neuritic side, no MAPT missorting into the dendrites is observed (e).