Figure 4. HCN1_ΔSNL truncation mutant shows defective trafficking to CA1 distal dendrites.

Images of CA1 region from hippocampal slices from HCN1 KO mouse expressing EGFP-HCN1 (A) or EGFP-HCN1_ΔSNL (B). EGFP-tagged channel fluorescence (left column) and as green (right column). Staining for MAP2 dendritic marker (middle column) and as red (right). Note that full-length EGFP-HCN1 was trafficked efficiently to distal apical dendrites whereas EGFP-HCN1_ΔSNL showed even dendritic distribution, with relatively high expression in soma and proximal apical and basal dendrites. Scale bar is 200 μm. (C) Higher magnification z-series projections showing fluorescence signals for EGFP-HCN1, EGFP-HCN1_ΔSNL, and co-expressed DsRed2. Scale bar is 10 μm. (D) EGFP and DsRed2 fluorescence intensities were measured along somato-dendritic axis in soma and apical dendrites of individual cells. Mean EGFP signal averaged from individual dendrites was normalized by DsRed2 signal and plotted as function of distance from somatic layer for neurons expressing EGFP-HCN1 (black) or EGFP-HCN1_ΔSNL (red). (Solid lines: means; dashed lines: SEM).