Ras-cuing the Heart (Cardiology 2011)

Fraz Ahmed Ismat, MDClinical Associate in Pediatrics, Division of Cardiology

The Children’s Hospital of Philadelphia

Ras-cuing the Heart

Nf1 in Cardiovascular Development & Disease

Nf1-/- embryos die of cardiovascular failure

Jacks T. et al., Nat Gen 1994

Nf1-/- hearts have a lethal series of defects

wild typee13.5

Nf1 -/-

e13.5

Gitler, et al., Nat Gen 2003

Disease-causing mutations occur throughout NF1

… but only the NF1 GAP-Related Domain (GRD) has a well-described function

NF1 GRD downregulates activated Ras

Ismat et al., JCI 2006

GRD expression rescues Nf1-/- embryonic heart defects

NF1 GRD expression rescues pericardial effusion ( ), enlarged endocardial cushion (arrows), and myocardial thinning (arrowheads).

*

Ismat et al., JCI 2006

GRD rescued Nf1-/- mice die soon after birth

Nf1+/+ 13 17 27

Nf1+/+, GRDk/+ 13 17 13

Nf1+/+, CMV-cre+ 13 17 15

Nf1+/+, GRDk/+, CMV-cre+ 13 17 17

Nf1+/- 26 35 22

Nf1+/-, GRDk/+ 26 35 40

Nf1+/-, CMV-cre+ 26 35 37

Nf1+/-, GRDk/+, CMV-cre+ 26 35 32

Nf1-/- 13 0 0

Nf1-/-, GRDk/+ 13 0 0

Nf1-/-, CMV-cre+ 13 0 0

Nf1-/-, GRDk/+, CMV-cre+ 13 0 5*

Genotype Mendelian Expected Observed

* All rescued Nf1-/- mice died on the first postpartum day.Ismat et al., JCI 2006

Late mortality in Nf1 myocardial knockout

n=23

n=20

Progressive cardiac hypertrophy & fibrosis in Nf1mKO

Cardiac dilation & reduced shortening in Nf1mKO

Rescue of Nf1mKO cardiac hypertrophy with NF1 GRD

Hypertrophic occlusive vasculopathy in NF1

Kanter et al., J Peds 2006

“Normal” arteries in Nf1 smooth muscle knock-out (Nf1smKO)

No anatomical differences seen in elastin (A, B) and smooth muscle α-actin staining (C, D)

between wild type and Nf1smKO arteries.

Xu & Ismat et al., Circ 2007

Elevated blood pressures in Nf1smKO mice

Junwang Xu & Tao Wang

Nf1smKO injury-induced intimal hyperplasia rescued by GRD

Xu & Ismat et al., Circ 2007

Tidyman & RauenCurrent Opinion in Genetics & Development2009, 19:230–236

(PTPN 1 1 )

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 LabAlmedia McCoyTimothy Macatee

MCRC Core FacilitiesHistology Core (MM Lu)Transgenic Core (D Zhu)Physiology Core (T Wang*)

Penn Core FacilitiesFlow Cytometry & Cell SortingSmall Animal ImagingMicroarray Core Facility

Collaborators & Others

Jonathan Epstein (Penn)Aaron Gitler (Penn)Elizabeth Goldmuntz (CHOP)Tyler Jacks (MIT)Maria Kontardis (BIDH-HMS)Thomas Look (DFCI)Arun Padmanabhan (Penn)Luis Parada (UTSW)Nancy Ratner (Cincinnati)Xin Zhang (IUPUI)Yuan Zhu (Michigan)