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)-alpha 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 physiological regulation of both HIF factors with slightly greater normoxic dysregulation of HIF-2alpha. Differentiated Vhl(2B/2B)-derived teratomas overexpressed joint HIF targets Vegf and EglN3 but not the HIF-1alpha-specific target Pfk1. Vhl(2B/2B) teratomas additionally displayed a growth advantage over Vhl(-/-)-derived teratomas, suggestive of a tight connection between perturbations in the degree and ratio of HIF-1alpha and HIF-2alpha stabilization and cell growth. Vhl(2B/2B) mice displayed mid-gestational embryonic lethality, whereas adult Vhl(2B/+) mice exhibited susceptibility to carcinogen-promoted renal neoplasia compared with wild-type littermates at 12 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.

Association of HLA antigen BW35 with severe Graves' ophthalmopathy.

Human leukocyte antigens (HLA) in patients with Graves' disease were investigated according to the ophthalmic classification system of the American Thyroid Association. All prior HLA studies of Graves' disease have disregarded the patients' specific ophthalmic manifestations. Examination of 18 A and 34 B loci antigens disclosed an increased frequency (corrected P = 0.002, relative risk = 13.1) of HLA-BW35 in patients improving with oral corticosteroids who have severe extraocular muscle and orbital inflammation (class 4-5) when compared to a geographically and racially matched control population. No statistically significant associations were found when patients without ophthalmic manifestations or with other categories of Graves' ophthalmopathy were compared to controls. The association of severe Graves' ophthalmopathy with HLA-BW35 may provide immunologic evidence to explain both the unpredictable association of the orbital and thyroid disturbances of Graves' disease as well as the unpredictable response of the orbital inflammation to oral corticosteroids.