Presentation on Ras-opothies (LEOPARD syndrome & NF1) and novel approaches for treatment. Presented at Cardiology 2011, 15th Annual Update on Pediatric and Congenital Cardiovascular Disease.
24. Rescue of Nf1 mKO cardiac hypertrophy with NF1 GRD
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31. Marin, et al., JCI (in press) LEOPARD syndrome mice have enlarged hearts Wild type LS/+
32. Rapamycin rescues LS/+ cardiac hypertrophy LS/+ LS/+ rapamycin * * HW/BW Ratio Marin, et al., JCI (in press) Wild type
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38. Acknowledgements Past support: a Young Investigator Award from the Children’s Tumor Foundation , a Physician Scientist Development Award (K08) from the NHLBI ; Current support: a Basil O’Connor scholarship from the March of Dimes Foundation , a cardiovascular research grant from the W.W. Smith Charitable Trust , and grants from the CHOP Cardiac Center Scientific Review Committee . Ismat Lab Almedia McCoy Timothy Macatee MCRC Core Facilities Histology Core (MM Lu) Transgenic Core (D Zhu) Physiology Core (T Wang*) Penn Core Facilities Flow Cytometry & Cell Sorting Small Animal Imaging Microarray Core Facility Collaborators & Others Jonathan Epstein (Penn) Aaron Gitler (Penn) Elizabeth Goldmuntz (CHOP) Tyler Jacks (MIT) Maria Kontaridis (BIDH-HMS) Thomas Look (DFCI) Arun Padmanabhan (Penn) Luis Parada (UTSW) Nancy Ratner (Cincinnati) Xin Zhang (IUPUI) Yuan Zhu (Michigan)
Hinweis der Redaktion
The mouse model of Neurofibromatosis, in which the disease gene, Nf1, has been “knocked-out”, demonstrates embryonically lethal cardiovascular defects in the homozygous mutant state. They die in mid-gestation from a series of cardiovascular defects, arising in large part from defects involving endothelial tissues. The cardiovascular failure, demonstrated by the large pericardial effusion in panel B (*), is a manifestation of this series of defects. Most notable from among these abnormalities are enlarged endocardial cushions resulting from abnormal endothelial to mesenchymal transformation, (dashed line, panel B), ventricular septal defects (arrows, panel D) and malrotation of the cardiac outflow tract, and a thinned, non-compacted ventricular myocardium (arrowheads, panel F).
NF1 encodes neurofibromin, a large protein expressed ubiquitously throughout development. The bulk of neurofibromin is of unknown function, but a small domain, known as the GAP-related domain (or GRD) shares homology with several Ras-GTPase activating proteins, or GAPs. GAPs downregulate the activity of Ras protooncogenes.
We constructed a “knock-in” mouse in which a cre-dependant NF1 GRD is knocked into the Rosa26 locus. In this construct, the GRD is preceded by a STOP signal flanked by loxP sites. DNA sequences between loxP sites are removed by cre-recombinase activity. This “floxed” STOP sequence would prevent the expression of the NF1 GRD, except if removed by cre. In this set of experiments, mice expressing cre ubiquitously (under the control of a CMV promoter) would have global expression of the GRD protein throughout development.