Journal: Cellular and Molecular Life Sciences: CMLS
Article Title: Tip60-HDAC8-SMURF2-mediated β-TrCP1 degradation is a key mechanism for hypoxia-induced cell death and tissue injury
doi: 10.1007/s00018-025-05983-4
Figure Lengend Snippet: β-TrCP1 degradation is required for hypoxia-induced cell death and tissue injury. ( A ) HepG2 cells were transfected with siHDAC8 or siHDAC8 combined with siβ-TrCP1 or siCont. for 24 h. Cells were then exposed to 1% O 2 (Hyp) for the indicated times. Cell death was measured by PI staining assay. ( B ) HepG2 cells were transfected with Flag-Tip60 or Flag-Tip60 combined with siβ-TrCP1 or Flag empty vector for 24 h. Cells were then exposed to 1% O 2 (Hyp) for the indicated times. Cell death was measured by PI staining assay. ( C ) HepG2 cells were transfected with wild-type (WT) or K96Q- or K294Q-mutated Flag-β-TrCP1 for 24 h. Cells were then exposed to 1% O 2 (Hyp) for the indicated times. Cell death was measured by PI staining assay. ( D ) HepG2 cells were transfected with siSMURF2 or siSMUFR2 combined with siβ-TrCP1 or siCont. for 24 h. Cells were then exposed to 1% O 2 (Hyp) for the indicated times. Cell death was measured by PI staining assay. ( E ) HepG2 cells were transfected with Flag-β-TrCP1 or Flag empty vector for 24 h. Cells were then exposed to 1% O 2 for 72 h (Hyp) or not (Nor). WB assays were performed to measure the levels of the indicated proteins. ( F ) HepG2 cells were transfected with siβ-TrCP1 or siCont. for 24 h. Cells were then exposed to 1% O 2 for 72 h (Hyp) or not (Nor). WB assays were performed to measure the levels of the indicated proteins. ( G ) HepG2 cells were transfected with siβ-TrCP1, siβ-TrCP1 together with p53-specific siRNA (sip53), or siCont. for 24 h. Cells were then exposed to 1% O 2 (Hyp) for the indicated times or not (Nor). Cell death was measured by PI staining assay. ( H ) HepG2 cells were transfected with HA-tagged β-TrCP1 (HA-β-TrCP1), HA-β-TrCP1 together with Flag-tagged p53 (Flag-p53), or Flag empty vector (Cont.) for 24 h. Cells were then exposed to 1% O 2 (Hyp) for the indicated times or not (Nor). Cell death was measured by PI staining assay. ( I ) Wild-type (WT), Tip60-specific shRNA (shTip60)-containing AAV8-infected or shTip60-AAV8 combined with Flag-β-TrCP1-containing AAV8-infected mice were exposed to 7% O 2 for 72 h (Hyp) or not (Nor). Histological analyses of TUNEL, immunostaining for cleaved caspase 3 and H&E assays were performed on liver sections. DAPI staining was performed to detect the nuclei. ( J ) WT, shTip60-containing AAV8-infected or shTip60-AAV8 combined with Flag-β-TrCP1-containing AAV8-infected mice were exposed to Hyp for 72 h (+) or not (-) as indicated. Serum ALT and AST levels were measured ( n = 6). (K ) WT, β-TrCP1 −/− , and WT or β-TrCP1 −/− mice infected with HDAC8-specific shRNA (shHDAC8)-containing AAV8 were exposed to 7% O 2 for 72 h (Hyp) or not (Nor). Histological analyses of TUNEL, immunostaining for cleaved caspase 3 and H&E assays were performed on liver sections. DAPI staining was performed to detect the nuclei. ( L ) WT, β-TrCP1 −/− , and WT or β-TrCP1 −/− mice infected with shHDAC8-AAV8 were exposed to 7% O 2 for 72 h (Hyp) or not (Nor). Serum ALT and AST levels were measured ( n = 6). ( M ) WT, β-TrCP1 −/− and β-TrCP1 −/− mice infected with p53-specific shRNA (shp53)-containing AAV8 were exposed to 7% O 2 for 72 h (Hyp) or not (Nor). Histological analyses of TUNEL, immunostaining for cleaved caspase 3 and H&E assays were performed on liver sections. DAPI staining was performed to detect the nuclei. ( N ) WT, β-TrCP1 −/− or β-TrCP1 −/− mice infected with shp53-containing AAV8 were exposed to Hyp for 72 h (+) or not (-) as indicated. Serum ALT, AST and bilirubin levels were measured ( n = 6). ( O ) Working model. Under normoxic conditions, Tip60 is prolyl-hydroxylated and stabilized by PHD2, and then Tip60 acetylates β-TrCP1 to stabilize β-TrCP1, allowing cells with lower levels of p53. Under hypoxic conditions, impaired prolyl hydroxylation of Tip60 results in the degradation of Tip60, and HDAC8 is recruited to β-TrCP1, synergistically promoting a decrease in β-TrCP1 acetylation. Thus, more SMURF2 is recruited to β-TrCP1 and ubiquitinates β-TrCP1 to promote its degradation. Ultimately, p53 is accumulated, and cell death occurs. Data information: Bars and error bars represent mean ± SD, n = 4 independent repeats in ( A - D and H ), n = 3 independent repeats in ( G ), n = 6 independent repeats in ( J and L ). Two-tailed unpaired Student’s t test was performed. * p < 0.05; ** p < 0.01; *** p < 0.001
Article Snippet: His6-tagged HDAC8 (His6-HDAC8) proteins (Ag11692) were purchased from Proteintech (China).
Techniques: Transfection, Staining, Plasmid Preparation, shRNA, Infection, TUNEL Assay, Immunostaining, Two Tailed Test