The R200W mutation in the von Hippel–Lindau (VHL) tumor suppressor protein (pVHL) is unique in that it is not associated with tumor development, but rather with Chuvash polycythemia, a heritable disease characterized by elevated hematocrit and increased serum levels of erythropoietin and VEGF. Previous studies have implicated hypoxia-inducible factor–1α (HIF-1α) signaling in this disorder, although the effects of this mutation on pVHL function are not fully understood. In order to explore the mechanisms underlying the development of this polycythemia, we generated mice homozygous for the R200W mutation (VhlR/R). VhlR/R mice developed polycythemia highly similar to the human disease. The activity of HIF proteins, specifically the HIF-2α isoform, was upregulated in ES cells and tissues from VhlR/R mice. Furthermore, we observed a striking phenotype in VhlR/R spleens, with greater numbers of erythroid progenitors and megakaryocytes and increased erythroid differentiation of VhlR/R splenic cells in vitro. These findings suggest that enhanced expression of key HIF-2α genes promotes splenic erythropoiesis, resulting in the development of polycythemia in VhlR/R mice. This mouse model is a faithful recapitulation of this VHL-associated syndrome and represents a useful tool for studying polycythemias and investigating potential therapeutics.
Michele M. Hickey, Jennifer C. Lam, Natalie A. Bezman, W. Kimryn Rathmell, M. Celeste Simon
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. All accepted letters will be posted on our website within one week of acceptance. We reserve the right to edit any letter for length, content, and clarity. Authors of all accepted letters will be asked to preview any changes. Authors will be notified by e-mail if their letters were not accepted. As this is a final decision, no appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at email@example.com.