Figure 4: Direct binding of oridonin to HSF1.
From: Oridonin Triggers Chaperon-mediated Proteasomal Degradation of BCR-ABL in Leukemia
(a) Oridonin decreased the level of TSH in vitro and in cellulo. Left, cells lysates were incubated with oridonin at 37 °C for 10 minutes before DTNB reaction was performed to determine the TSH level. Right, cells were treated with oridonin for 2 hours and lysed for DTNB reaction. (b) Oridonin oxidized the thiols in GSH and synthesized peptides of HSF1. Peptides (2 mM) were incubated with oridonin at 37 °C for 10 minutes before DTNB was added. P1 to P5 represent peptides contain cysteines at position 36, 103, 153, 373 and 378 of HSF1, respectively. (c) ESI-MS showing the interaction between oridonin and HSF1. Peptide (P3) containing the cysteine 153 was incubated with DMSO (upper) or oridonin (lower) at a 1:1 molar ratio at room temperature for 10 minutes and loaded for ESI-MS.
