Figure 1.

STAU1 expression affects neuronal differentiation in SH-SY5Y cells. (a) Differentiation of SH-SY5Y cells was induced by adding 50 μM retinoic acid for the indicated number of days. The nucleus (DAPI, blue) and the expression of the presynaptic marker, synaptophysin (SYP, green), were visualized by immunofluorescence microscopy. (b,c) As (a), except that protein and gene expressions were determined by western blot (b) and RT-qPCR (c). (d and e) SH-SY5Y cells that were transiently transfected with STAU1-specific siRNA or control siRNA were differentiated by the addition of retinoic acid. The number of the column is the mean value compared to that of day 0 of differentiation. (f,g) SH-SY5Y cells were transiently transfected with C-terminally HA-tagged STAU1⁵⁵ (STAU1⁵⁵-HA₃) or an empty vector (–) as a control, and then differentiation was induced. The expression of STAU1 and SYP during the differentiation period was detected by western blot (d,f) and RT-qPCR (e and g). (h) Immunofluorescence was used to visualize SYP and DAPI at day 7 of differentiation with or without depletion of STAU1 (siSTAU1) or overexpression of STAU1 (STAU1⁵⁵-HA₃). (i) The dendritic lengths in (a) at the indicated days were measured during differentiation (n=50). (j) Similar to (i), except that the dendritic length was measured at day 7 of differentiation in STAU1-depleted or STAU1⁵⁵-HA₃-overexpressing SH-SY5Y cells in (h) (n=60). The protein level was normalized to the level of calnexin, and the relative levels of proteins at day 0 of differentiation were set to 1.0. The mRNA level was normalized to the level of U6 snRNA, and the relative levels of mRNAs at day 0 of differentiation were set to 1.0. Insets in (a) and (h) represent the higher magnification of the indicated field. **P<0.01