170 likes | 656 Views
VHL & von Hippel-Lindau syndrome. By: Michelle Ostrowski. http://www.highlighthealth.com/wp-content/uploads/2007/09/ubiquitination.png. DEGRADATION VIA UBIQUITINATION. http://www.crombes.hr/ifmbe-news/ifmbe-news.iee.org/ifmbe-news/nov2004/images/nobelfig02.gif.
E N D
VHL & von Hippel-Lindau syndrome By: Michelle Ostrowski
http://www.highlighthealth.com/wp-content/uploads/2007/09/ubiquitination.pnghttp://www.highlighthealth.com/wp-content/uploads/2007/09/ubiquitination.png DEGRADATION VIA UBIQUITINATION http://www.crombes.hr/ifmbe-news/ifmbe-news.iee.org/ifmbe-news/nov2004/images/nobelfig02.gif
http://www.hindawi.com/floats/720840/figures/720840.fig.001.jpghttp://www.hindawi.com/floats/720840/figures/720840.fig.001.jpg VHL = E3 component
E3 Ubiquitin Ligase Complex + Substrate http://www.hindawi.com/floats/720840/figures/720840.fig.001.jpg
Effects of Oxygen Levels Enzyme: Proline hydroxylase Downstream: EPO VEGF PDGF TGF-α (angiogenesis & erythropoeisis) http://www.nature.com/nm/journal/v11/n9/images/nm0905-925-F1.jpg
VHL NON-FUNCTIONAL??? • Oxygen levels have no effect • VHL cannot bind HIF-1α • HIF-1 α is not degraded, binds to HIF-1β • HIF initiates transcription of downstream genes • Angiogenesis and erythropoeisis stimulated
HOW DOES THIS RELATE TO CANCER? • Loss of regulation • Angiogenesis = growth of blood vessels • Erythropoeisis = stimulates production of RBCs • Tumors need extra nutrients & an increased blood supply to grow http://onctalk.com/wp-content/uploads/2008/01/hallmarks-of-ca.jpg
What Actually Happens in the ORGANISM??? VHL -/- mice die as embryos day 10.5- 12.5 lack of placental vasculogenesis VHL +/- mice phenotypically normal 15+ months w/o spontaneous Targeted inactivation of specific tissues??? - similar clinical features as those seen in humans… good model organism http://www.bugmanrochester.com/pest_mice.jpg http://www.pnas.org/content/94/17/9102.full http://www.hesca.org/past_meetings/dallas/images/bio59.jpg
ROLE IN HUMAN CANCERS FAMILIAL CASES: SPORADIC CASES: http://www.vhl.org/gifs/0ba3soma.gif http://www.vhl.org/gifs/0ba4gona.gif
Von Hippel-Lindau syndrome Cerebellar Hemangioblastoma Retinal Angiomata • Incidence of 1 in 35,000 • Autosomal dominant • VHL tumor suppressor • Type 1, 2A, 2B, 2C • Estimated penetrance of 80-90% by 65 yrs http://hmg.oxfordjournals.org/content/vol10/issue7/images/large/DDE08901.jpeg
WHY DO TUMORS TEND TO DEVELOP IN CERTAIN LOCATIONS MORE FREQUENTLY THAN IN OTHERS? • VHL expressed throughout the body (development + adulthood) • Expression higher in specific tissues (Brain, urogenital system, spinal cord, sensory ganglia, eyes, bronchial epithelium) http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=608537
Bibliography • http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=608537 • http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=193300 • Weinberg, Robert A. The Biology of Cancer. New York: Garland Science, Taylor & Francis Group, LLC, 2007. (241-246, 225) • Gnarra, James R.Defective placental vasculogenesis causes embryonic lethality in VHL-deficient mice. PNAS August 19, 1997 vol. 94 no. 17 9102-9107 http://www.pnas.org/content/94/17/9102.full • Franke, Gerlind. Alu-Alu Recombination Underlies the Vast Majority of Large VHL Germline Deletions: Molecular Characterization and Genotype-Phenotype Correlations in VHL Patients. Human Mutation, Vol. 30, No 0, 1-11, 2009 • Clifford, Steven C. The pVHL-associated SCF ubiquitin ligase complex: Molecular genetic analysis of elongin B and C, Rbx1 and HIF-1a in renal cell carcinoma.Oncogene (2001) 20, 5067-5074. <http://www.nature.com/onc/journal/v20/n36/pdf/1204602a.pdf>