The von Hippel-Lindau tumor suppressor regulates programmed cell death 5-mediated degradation of Mdm2.
Functional loss of the von Hippel-Lindau (VHL) tumor suppressor protein (pVHL), which is part of an E3-ubiquitin ligase complex, initiates most inherited and sporadic clear-cell renal cell carcinomas (ccRCC). Genetic inactivation of the TP53 gene in ccRCC is rare, suggesting that an alternate mechanism alleviates the selective pressure for TP53 mutations in ccRCC. Here we use a zebrafish model to describe the functional consequences of pVHL loss on the p53/Mdm2 pathway. We show that p53 is stabilized in the absence of pVHL and becomes hyperstabilized upon DNA damage, which we propose is because of a novel in vivo interaction revealed between human pVHL and a negative regulator of Mdm2, the programmed cell death 5 (PDCD5) protein. PDCD5 is normally localized at the plasma membrane and in the cytoplasm. However, upon hypoxia or loss of pVHL, PDCD5 relocalizes to the nucleus, an event that is coupled to the degradation of Mdm2. Despite the subsequent hyperstabilization and normal transcriptional activity of p53, we find that zebrafish vhl(-/-) cells are still as highly resistant to DNA damage-induced cell cycle arrest and apoptosis as human ccRCC cells. We suggest this is because of a marked increase in expression of birc5a, the zebrafish homolog of Survivin. Accordingly, when we knock down Survivin in human ccRCC cells we are able to restore caspase activity in response to DNA damage. Taken together, our study describes a new mechanism for p53 stabilization through PDCD5 upon hypoxia or pVHL loss, and reveals new clinical potential for the treatment of pathobiological disorders linked to hypoxic stress.
Hubrecht Institute for Developmental Biology and Stem Cell Research, KNAW and University Medical Center Utrecht, Utrecht, The Netherlands.
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PB
Essers
Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands.
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TD
Klasson
Hubrecht Institute for Developmental Biology and Stem Cell Research, KNAW and University Medical Center Utrecht, Utrecht, The Netherlands.
T C
TC
Pereboom
1] Department of Human Genetics, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands [2] Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands.
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DA
Mans
Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands.
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M
Nicastro
Center for Ophthalmic Research, Medical Proteome Center, Eberhard-Karls University Tuebingen, Tuebingen, Germany.
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K
Boldt
Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands.
R H
RH
Giles
Hubrecht Institute for Developmental Biology and Stem Cell Research, KNAW and University Medical Center Utrecht, Utrecht, The Netherlands.
A W
AW
MacInnes
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D002292:Carcinoma, Renal Cell / Q000235:genetics* / Q000473:pathology; D002467:Cell Nucleus / Q000235:genetics; D004249:DNA Damage / Q000235:genetics; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000096:biosynthesis; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D059748:Proteolysis; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism*; D000077022:Survivin; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000096:biosynthesis
D051017:Apoptosis Regulatory Proteins; C541681:Birc5a protein, zebrafish; D051034:Inhibitor of Apoptosis Proteins; D009363:Neoplasm Proteins; C117283:PDCD5 protein, human; D000077022:Survivin; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D029961:Zebrafish Proteins; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; C497446:VHL protein, human