Figure 4.

Tat-RACK1 induces expression and secretion of BDNF in dissociated hippocampal neurons. A, Tat-RACK1 is transduced throughout the cell, including the nucleus. Cells were treated with vehicle or 1 μm Tat-RACK1 for 2 hr. HA-tagged Tat-RACK1 nuclear localization was visualized by confocal microscopy by the merged signal (yellow-orange) between the anti-HA antibody for the detection of Tat-RACK1 (green) and the nuclear marker TOTO-3 (red). Images are representative of ∼700 cells per treatment in five experiments. B, Tat-RACK1 induces BDNF expression in primary dissociated hippocampal neurons. Neurons were treated with 1 μm Tat-RACK 1 for the indicated times, and BDNF and GPDH expression were analyzed by RT-PCR. Histogramd epicts the mean ratio of BDNF:GPDH± SD; n = 3. ^*p < 0.05; ^**p < 0.01 compared with control. C, D, Tat-RACK1 increases the secretion of BDNF but not NGF in primary hippocampal neurons. Neurons were incubated without (control) or with increasing concentrations of Tat-RACK1 for 6 hr (C), or with 1 μm of Tat-RACK1, Tat-KIP²⁷, or the Tat-peptide for 6 hr (D), and BDNF (C, D) or NGF (D) secretion was determined. Histogram depicts the mean ± SD from three experiments that were conducted in triplicate after treatment with vehicle (control, white bar), Tat-RACK1 (black bar), Tat-KIP²⁷ (gray bar), or Tat-peptide (hatched bar). ^**p < 0.01 compared with control.