VHL Type 2B gene mutation moderates HIF dosage in vitro and in vivo

Von Hippel-Lindau (VHL) disease is caused by germline mutations in the VHL tumor suppressor gene, with Type 2B missense VHL mutations predisposing to renal cell carcinoma, hemangioblastoma, and pheochromocytoma. Type 2B mutant pVHL is predicted to be defective in hypoxia inducible factor (HIF)-α regulation. Murine embryonic stem (ES) cells in which the endogenous wild-type Vhl gene was replaced with the representative Type 2B VHL hotspot mutation R167Q (Vhl(2B/2B)) displayed preserved physiologic regulation of both HIF factors with slightly more normoxic dysregulation of HIF-2α. Differentiated Vhl(2B/2B)-derived teratomas over-expressed the joint HIF targets Vegf and EglN3 but not the HIF-1α-specific target Pfk1 and displayed a growth advantage over Vhl(-/-)-derived teratomas, suggestive of a tight connection between perturbations in the degree and ratio of HIF-1α and HIF-2α stabilization and cell growth. Vhl(2B/2B) mice displayed mid-gestational embryonic lethality, while adult Vhl(2B/+) mice exhibited susceptibility to carcinogen-promoted renal neoplasia compared with wild-type littermates at twelve months. Our experiments support a model in which the representative Type 2B R167Q mutant pVhl produces a unique profile of HIF dysregulation, thereby promoting tissue-specific effects on cell growth, development, and tumor predisposition.