Figure 3.

IGF-1 stimulates HIF-1α accumulation through a transcriptional and translational mechanism. A, Representative immunoblots and corresponding densitometric analysis showing HIF-1α protein levels in hippocampal neuron cultures from IGF-1 (300 ng/ml) treatment for 6 h with or without actinomycin D (Act D) (1 μm), cycloheximide (CHX) (10 μm), or anisomycin (Ani) (2 μm). B, Representative immunoblots and corresponding densitometric analysis showing HIF-1α protein stability in hippocampal neuron cultures treated with IGF-1 or DFO. Hippocampal neuronal cultures were treated with IGF-1 (300 ng/ml) or DFO (100 μm) treatment for 6 h, after which cycloheximide was added for 30–90 min. Total protein was isolated and expression of HIF-1α was analyzed by Western blotting. Data are presented as mean ± SEM. *p < 0.05 compared with the vehicle (0.1% DMSO)-treated control group by unpaired Student's t test.