Journal: Cell Cycle
Article Title: AMPK-HDAC5 pathway facilitates nuclear accumulation of HIF-1α and functional activation of HIF-1 by deacetylating Hsp70 in the cytosol
doi: 10.1080/15384101.2015.1055426
Figure Lengend Snippet: HDAC5 deacetylates Hsp70, attenuates Hsp70-HIF-1α interaction but enhances Hsp90-HIF-1α interaction. ( A ) Hep3B cells were treated as indicated and lysates were immunoprecipitated with anti-HIF-1α. The same blot was firstly used to detect Hsp90 and Hsp70, and then HIF-1α. MG132 (5 μM) was added to balance HIF-1α levels. ( B ) Hep3B cells were co-transfected with 2 μg of HA-HIF-1α and 2 μg of flag-HDAC5. Cell lysates were immunoprecipitated with anti-HIF-1α followed by detecting coimmunoprecipitated Hsp90 and Hsp70. ( C ) Hep3B cells were transfected with control or HDAC5 siRNA and exposed to 1% O2 in the presence of MG132 (5 μM) for 6 h. Cell lysates were immunoprecipitated with anti-acetyl-lysine antibody. Precipitated Hsp90 and Hsp70 were detected sequentially by Western blotting. ( D-E ) HDAC5 deacetylates Hsp70 in cultured cells. D. Hep3B cells were co-transfected with flag-HDAC5 and Flag-Hsp70, or Flag-HDAC3 and Flag-Hsp70. 5% of cell lysates were used to detect indicated proteins (left), and remaining cell lysates were immunoprecipitated with anti-Hsp70 or non-specific IgG. Acetyl-K and Flag-Hsp70 were detected sequentially. E. Hep3B cells were transfected with wt-HDAC5 or HDAC5C698/H704A mutant. Cell lysates were immunoprecipitated with anti-Hsp70 followed by examining Acetyl-K proteins and Hsp70. ( F ) HDAC5 directly deacetylates Hsp70 in vitro . Hep3B cells were transfected with Flag-Hsp70. Flag-Hsp70 was purified by immunoprecipitation with anti-flag antibody, and incubated with or without 60 ng of recombinant GST-HDAC5 (rHDAC5) at 37 °C for 30 min in deacetylase buffer. Acetylated Hsp70 and total Hsp70 were detected sequentially. ( G ) Overexpression of Hsp70 impairs HIF-1α accumulation, which is reversed by HDAC5. Cells were transfected with 2 μg of HA-HIF-1α. In addition, the following plasmids were cotransfected: (1) 2 μg control vector; (2) 1 μg Flag-Hsp70, 1 μg control vector; (3) 1 μg Flag-HDAC5, 1 μg control vector; and (4) 1 μg Flag-Hsp70 and 1 μg of Flag-HDAC5. (H) Schematic representing Hsp70 acetylation sites. ( I ) HDAC5 deacetylates Hsp70 at K559/561. From left to right, Hep3B cells were transfected with: 1. control siRNA + Hsp70 WT; 2. HDAC5 siRNA + Hsp70 WT; 3. control siRNA + Hsp70 K559/561R; 4. HDAC5 siRNA + Hsp70 K559/561R. Cells were exposed to 1% O2 for 6 h. Cell lysates were immunoprecipitated with anti-acetyl-K. ( J ) Deacetylation of Hsp70 at K559/561 enhances the stabilization of HIF-1α. Cells were transfected with empty vectors, Hsp70 or K559/561R as indicated and exposed to 1% O2 for 6 h. Hsp70 was immunoprecipitated with anti-Flag and associated HIF-1α was detected by Western blotting.
Article Snippet: The antibodies and sources are: Anti-HIF-1α polyclonal antibody (NB100-519): Novus (Littleton, CO); Anti-HDAC4 (#2072), anti-HDAC5 (#2082), anti-AMPKα (#2532) and anti-phospho-AMPKα(Thr172) (#2535S): Cell Signaling Technology (Danvers, MA); Anti-acetyl-K: Cell Signaling Technology (#9441) and Stressgen (#12210519); Anti-flag (050M6000) and anti-α-tubulin (081M4861), horseradish peroxidase-coupled secondary antibodies: Sigma-Aldrich.
Techniques: Immunoprecipitation, Transfection, Control, Western Blot, Cell Culture, Mutagenesis, In Vitro, Purification, Incubation, Recombinant, Histone Deacetylase Assay, Over Expression, Plasmid Preparation