scholarly journals VHL tumor suppressor regulates Cl−/HCO3− exchange and Na+/H+ exchange activities in renal carcinoma cells

2001 ◽  
Vol 5 (3) ◽  
pp. 119-128 ◽  
Author(s):  
S. ANANTH KARUMANCHI ◽  
LIANWEI JIANG ◽  
BERTRAND KNEBELMANN ◽  
ALAN K. STUART-TILLEY ◽  
SETH L. ALPER ◽  
...  

Mutations in the von Hippel-Lindau (VHL) tumor suppressor gene are thought to play a critical role in the pathogenesis of both sporadic and VHL disease-associated clear-cell renal carcinomas (RCC). Differential display-PCR identified the AE2 anion exchanger as a candidate VHL target gene. AE2 mRNA and polypeptide levels were approximately threefold higher in 786-O VHL cells than in 786-O Neo cells. In contrast, Cl−/HCO3− exchange activity in 786-O VHL cells was 50% lower than in 786-O Neo cells. Since resting intracellular pH (pHi) values were indistinguishable, we postulated that Na+/H+ exchange activity (NHE) might be similarly reduced in 786-O VHL cells. NHE-mediated pHi recovery from acid load was less than 50% that in 786-O Neo cells, whereas hypertonicity-stimulated, amiloride-sensitive NHE was indistinguishable in the two cell lines. The NHE3 mRNA level was higher in 786-O VHL than 786-O Neo cells, but NHE1 mRNA levels did not differ. AE2 and NHE3 are the first transcripts reported to be upregulated by pVHL. Elucidation of mechanisms responsible for downregulation of both ion exchange activities will require further investigation.

2004 ◽  
Vol 22 (24) ◽  
pp. 4991-5004 ◽  
Author(s):  
William Y. Kim ◽  
William G. Kaelin

Germline inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene causes the von Hippel-Lindau hereditary cancer syndrome, and somatic mutations of this gene have been linked to the development of sporadic hemangioblastomas and clear-cell renal carcinomas. The VHL tumor suppressor protein (pVHL), through its oxygen-dependent polyubiquitylation of hypoxia-inducible factor (HIF), plays a central role in the mammalian oxygen-sensing pathway. This interaction between pVHL and HIF is governed by post-translational prolyl hydroxylation of HIF in the presence of oxygen by a conserved family of Egl-nine (EGLN) enzymes. In the absence of pVHL, HIF becomes stabilized and is free to induce the expression of its target genes, many of which are important in regulating angiogenesis, cell growth, or cell survival. Moreover, preliminary data indicate that HIF plays a critical role in pVHL-defective tumor formation, raising the possibility that drugs directed against HIF or its downstream targets (such as vascular endothelial growth factor) might one day play a role in the treatment of hemangioblastoma and renal cell carcinoma. On the other hand, clear genotype-phenotype correlations are emerging in VHL disease and can be rationalized if pVHL has functions separate from its control of HIF.


2016 ◽  
Vol 36 (12) ◽  
pp. 1803-1817 ◽  
Author(s):  
Fumihiko Okumura ◽  
Keiji Uematsu ◽  
Stuart D. Byrne ◽  
Mie Hirano ◽  
Akiko Joo-Okumura ◽  
...  

pVHL, the protein product of the von Hippel-Lindau (VHL) tumor suppressor gene, is a ubiquitin ligase that targets hypoxia-inducible factor α (HIF-α) for proteasomal degradation. Although HIF-α activation is necessary for VHL disease pathogenesis, constitutive activation of HIF-α alone did not induce renal clear cell carcinomas and pheochromocytomas in mice, suggesting the involvement of an HIF-α-independent pathway in VHL pathogenesis. Here, we show that the transcription factor B-Myb is a pVHL substrate that is degraded via the ubiquitin-proteasome pathway and that vascular endothelial growth factor (VEGF)- and/or platelet-derived growth factor (PDGF)-dependent tyrosine 15 phosphorylation of B-Myb prevents its degradation. Mice injected with B-Myb knockdown 786-O cells developed dramatically larger tumors than those bearing control cell tumors. Microarray screening of B-Myb-regulated genes showed that the expression of HIF-α-dependent genes was not affected by B-Myb knockdown, indicating that B-Myb prevents HIF-α-dependent tumorigenesis through an HIF-α-independent pathway. These data indicate that the regulation of B-Myb by pVHL plays a critical role in VHL disease.


Blood ◽  
2009 ◽  
Vol 113 (25) ◽  
pp. 6449-6460 ◽  
Author(s):  
Ellen van Rooijen ◽  
Emile E. Voest ◽  
Ive Logister ◽  
Jeroen Korving ◽  
Thorsten Schwerte ◽  
...  

Abstract We have generated 2 zebrafish lines carrying inactivating germline mutations in the von Hippel-Lindau (VHL) tumor suppressor gene ortholog vhl. Mutant embryos display a general systemic hypoxic response, including the up-regulation of hypoxia-induced genes by 1 day after fertilization and a severe hyperventilation and cardiophysiologic response. The vhl mutants develop polycythemia with concomitantly increased epo/epor mRNA levels and erythropoietin signaling. In situ hybridizations reveal global up-regulation of both red and white hematopoietic lineages. Hematopoietic tissues are highly proliferative, with enlarged populations of c-myb+ hematopoietic stem cells and circulating erythroid precursors. Chemical activation of hypoxia-inducible factor signaling recapitulated aspects of the vhl−/− phenotype. Furthermore, microarray expression analysis confirms the hypoxic response and hematopoietic phenotype observed in vhl−/− embryos. We conclude that VHL participates in regulating hematopoiesis and erythroid differentiation. Injections with human VHLp30 and R200W mutant mRNA demonstrate functional conservation of VHL between mammals and zebrafish at the amino acid level, indicating that vhl mutants are a powerful new tool to study genotype-phenotype correlations in human disease. Zebrafish vhl mutants are the first congenital embryonic viable systemic vertebrate animal model for VHL, representing the most accurate model for VHL-associated polycythemia to date. They will contribute to our understanding of hypoxic signaling, hematopoiesis, and VHL-associated disease progression.


Author(s):  
Thomas Connor ◽  
Patrick H. Maxwell

Von Hippel–Lindau (VHL) disease is a dominantly inherited familial cancer syndrome caused by germline mutations in the VHL tumour suppressor gene. The most frequent manifestations of VHL disease are retinal and central nervous system haemangioblastomas, clear cell renal cell carcinomas, and phaeochromocytomas. Genetic testing and active screening for clinical manifestations is now started in childhood and has greatly improved the prognosis for patients with VHL disease. The VHL protein plays a critical role in regulating the cellular response to changes in oxygen tension. Loss of VHL function results in constitutive activation of a range of angiogenic and metabolic pathways. New drug therapies have been developed that reverse some of the cellular consequences of VHL loss of function in kidney cancer.


1995 ◽  
Vol 61 (3) ◽  
pp. 437-438 ◽  
Author(s):  
Yi Sun ◽  
Allan Hildesheim ◽  
Hua Li ◽  
Anne P. Lanier ◽  
Ya Cao ◽  
...  

2005 ◽  
Vol 25 (8) ◽  
pp. 3163-3172 ◽  
Author(s):  
Erinn B. Rankin ◽  
Debra F. Higgins ◽  
Jacqueline A. Walisser ◽  
Randall S. Johnson ◽  
Christopher A. Bradfield ◽  
...  

ABSTRACT Patients with germ line mutations in the VHL tumor suppressor gene are predisposed to the development of highly vascularized tumors within multiple tissues. Loss of pVHL results in constitutive activation of the transcription factors HIF-1 and HIF-2, whose relative contributions to the pathogenesis of the VHL phenotype have yet to be defined. In order to examine the role of HIF in von Hippel-Lindau (VHL)-associated vascular tumorigenesis, we utilized Cre-loxP-mediated recombination to inactivate hypoxia-inducible factor-1α (Hif-1α) and arylhydrocarbon receptor nuclear translocator (Arnt) genes in a VHL mouse model of cavernous liver hemangiomas and polycythemia. Deletion of Hif-1α did not affect the development of vascular tumors and polycythemia, nor did it suppress the increased expression of vascular endothelial growth factor (Vegf) and erythropoietin (Epo). In contrast, phosphoglycerokinase (Pgk) expression was substantially decreased, providing evidence for target gene-dependent functional redundancy between different Hif transcription factors. Inactivation of Arnt completely suppressed the development of hemangiomas, polycythemia, and Hif-induced gene expression. Here, we demonstrate genetically that the development of VHL-associated vascular tumors in the liver depends on functional ARNT. Furthermore, we provide evidence that individual HIF transcription factors may play distinct roles in the development of specific VHL disease manifestations.


1996 ◽  
Author(s):  
R Nakashima ◽  
T Enomoto ◽  
M Fujita ◽  
K Yoshino ◽  
H Wada ◽  
...  

2015 ◽  
Vol 139 (2) ◽  
pp. 263-268 ◽  
Author(s):  
Clarissa Cassol ◽  
Ozgur Mete

von Hippel–Lindau (VHL) disease is an autosomal dominant disorder caused by heterozygous mutations in the VHL tumor suppressor gene that is characterized by the occurrence of multiple endocrine and nonendocrine lesions. This review focuses on the endocrine manifestations of VHL disease. Pancreatic neuroendocrine proliferations (ductuloinsular complexes, islet dysplasia, endocrine microadenoma, and neuroendocrine tumors), pheochromocytomas, and extra-adrenal paragangliomas are important endocrine manifestations of VHL disease. They frequently display characteristic clinical, biochemical, and histopathologic features that, although not pathognomonic, can be helpful in suggesting VHL disease as the underlying etiology and distinguishing these tumors from sporadic cases. Recent improvements in treatment and outcomes of renal cell carcinomas have allowed pancreatic neuroendocrine tumors to emerge as a significant source of metastatic disease, making the accurate recognition and classification of these neoplasms by the pathologist of utmost importance to determine prognosis, treatment, and follow-up strategies for affected patients.


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