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. 2007 Feb 15;117(3):648–658. doi: 10.1172/JCI29715

Figure 6. The unique cochaperone CHIP is essential for Hsp90 inhibitor–mediated tau degradation and regulates the levels of other chaperones as well as Hsp90.

Figure 6

(A) HeLa cells transfected with Hsp90 siRNA were subsequently transfected with V5-tau with or without myc-CHIP. Tau accumulated when Hsp90 expression was reduced; however, this accumulation was abrogated by CHIP and the amount of coimmunoprecipitated tau/CHIP complexes increased in the absence of Hsp90. (B) Chaperone protein levels were assessed in CHIP–/– brain tissue by Western blot analysis. The absence of CHIP and elevation in total tau levels were confirmed. Both Hsp40 and Hsp90 levels were decreased. In addition, the non–HSF1-mediated cochaperone, Hop, was also significantly decreased in CHIP–/– mice. P23 levels remained unchanged compared to GAPDH levels. (C) Quantification was assessed by standard densitometry. Error bars represent SD of the 4 CHIP–/– mice. **P < 0.01; ***P < 0.001 versus CHIP+/+.