Fig 2: Pharmacological inhibition of Akt by triciribine leads to an increased INa current density in HEK-293 cells expressing Nav1.6. (A) Representative traces of INa currents recorded from HEK-Nav1.6 cells treated for 60 min either with DMSO (0.1%) (black) or 30 µM triciribine (red). (B) Current–voltage relationship showing increased peak INa current densities in triciribine-treated HEK-Nav1.6 cells (red, n = 11) compared to DMSO control (black, n = 11). (C) Peak current density at voltage step of −10 mV in DMSO and triciribine-treated HEK-Nav1.6 cells. A 60 min treatment with triciribine (30 µM) significantly increased the Nav1.6-mediated peak INa current density (n = 11 in both group; ** p = 0.0076 with Student’s unpaired t-test). (D,E). Voltage dependence of INa activation (D) and steady-state inactivation (E) in DMSO and triciribine-treated HEK-Nav1.6 cells. Treatment with triciribine did not affect voltage dependence of INa activation or steady-state inactivation. Inset shows the inactivation protocol (scale bars: 20 mv/100 ms). Box plot shows: Range (Perc 25, 75), Mean, Median, Min, and Max. Results are summarized in Table 1.

Fig 3: Mislocalization of axonal domain proteins following adult-onset sulfatide depletion. (A) An axon from a CTL mouse demonstrates proper ion channel and axonal domain protein organization in the spinal cord with Nav1.6 (green) localized to the node of Ranvier, Caspr1 (blue) localized to the paranode and Kv1.1 (red) localized to the juxtaparanode. Common, but not exclusive, pathologies observed included (B) Kv1.1 invading the paranodal region (white arrows); (C) elongated sodium channel domain (white star) and heminode (white bracket) (note: z-stack collected encompassed entirety of fluorescence and absent paranode was not the result of exclusion of z-stack); (D) elongated Caspr1 localization (white brackets); (E) combination of several pathologies including binodal sodium channels clusters (yellow stars) and intermixing of Kv1.1 channels and Caspr1 (white star). (F) Quantification of protein organization revealed preservation of protein domains at 3 months PI but a significant loss of axonal domain organization at 6 and 11 months PI. Data are presented as mean ± standard error; ** p < 0.01 **** p < 0.0001. Scale bars = 5 µm.