Familial PAH. Genetics and pulmonary arterial hypertension. PAH and mutations in the bone morphogenetic protein type II receptor (BMPR-II)

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1 athology of vascular lesions in idiopathic pulmonary arterial hypertension Genetics and pulmonary arterial hypertension Concentric intimal lesion Nick Morrell British Heart Foundation rofessor of Cardiopulmonary Medicine University of Cambridge School of Clinical Medicine Addenbrooke s and apworth Hospitals Cambridge, UK lexiform lesion CD31 CD31 α-sma α-sma Atkinson et al. Circulation. 22;15: Familial AH Autosomal dominant Reduced gene penetrance Sex bias F>M AH and mutations in the bone morphogenetic protein type II receptor (BMR-II) Heterozygous germline mutations in BMR2,, encoding a TGF-β receptor, cause familial AH mutations detected in ~7% of families (The International H Consortium, Nat. Genetics 2; Deng et al. Am J. Hum. Genetics 2) Unaffected Obligate carrier Affected UK family 4 Association of sporadic AH with BMR2 mutations 15-26% of sporadics have mutations in BMR-II parental transmission and de novo mutation documented (Thomson et al. J. Med. Genet. 2 Newman et al. N. Engl. J. Med. 21) Clinical outcomes of pulmonary arterial hypertension in carriers of BMR2 mutation. Sztrymf et al. Am J Respir Crit Care Med. 28;177: Austin et al. Respiratory Research 29, 1:87

2 BM signaling Bone and cartilage formation BM ligand Clathrin coated pits Cell membrane BMR-II LIMK1 Tctex-1 BMR1A/B/ALK-1 Smad1/5/8 MAK Angiogenesis and vascular differentiation Bone morphogenetic proteins Embryonic mesoderm formation HC HC Smad4 neurogenesis ~2 family members form kda dimers cysteine knot structure Dorso- Ventral patterning Gene expression regulation Transcription Organogenesis kidney lung Tissue specific nature of BM signalling BMR-II Cell-specific responses to BMs depend on the expression profile of BM receptors and ligands Familial pulmonary arterial hypertension BM6 BM2 BM4 BM6 BM4 BM2 BM9/1 GDF5 BMR-IA (ALK3) BMR-IB (ALK6) Juvenile gastrointestinal polyposis Hereditary brachydactyly BMR -II ALK3 BMR -II ALK6 BMR -II ALK1 Upton et al. Mol harmacol. 28;73: David et al Blood. 27;19: BMR-II wild type Ligand binding and cysteine kinase domain mutations Non-cysteine kinase domain mutations Cytoplasmic tail domain mutations Chemical chaperones improve cell surface localization of ER-retained mutant BMR-II wtbmr-ii- 5 myc C118W- 5 myc Smads p38 MAK Smads Smads Control 4-phenylbutyrate Normal vascular homeostasis Rudarakanchana et al. Hum Mol Genet. 22;11:1517- Abnormal vascular cell function Sobolewski et al. Hum Mol Genet ;17(2):318-9

3 otential for therapeutic rescue of missfolded BMR-II proteins in familial AH? Familial and idiopathic AH are associated with reduced pulmonary vascular expression of BMR-II Normal lung Exon 3 frameshift mutation BMR-II positive tissue area (%) 5 # # + CD31 positive tissue area (%) 5 Normal SH H H BMR2 mutation Normal SH H H BMR2 mutation BMR-II CD31 Atkinson et al. Circulation. 22;15: Ubiquitin ligases e.g. Smurf1/2 Viral ubiquitin ligases BMR-II BMR-I Reduced expression of BMR-II and phospho-smad1/5 in monocrotaline-induced induced AH BMR-II transcription Smads 1/5 Failure of antiproliferative effects in vascular smooth muscle Cytokines e.g. TNF-α HHV-8 8 infection HIV-1 1 infection Autoimmune inflammation Durrington et al. J Biol Chem. 21;285(48): Long L, Crosby A, et al Circulation 29;119: Adenoviral delivery of BMR-II in the hypoxic rat model of pulmonary hypertension Detection of BMR-II II-myc in rat lung following adenoviral gene delivery Reynolds, A. M. et al. Am J hysiol 27; 292: L1182-L Reynolds, A. M. et al. Am J hysiol 27; 292: L1182-L

4 Adenoviral BMRII-myc attenuates hypoxic pulmonary hypertension in the rat ulmonary artery smooth muscle cells from HAH patients exhibit reduced Smad1 mediated growth suppression ASMC(Donor1) ASMC(R491W) p-smad1 t-smad1 p-p38 t-p38 p-p44/42 t-p44/ BM Luciferase activity (% of control) BM4 + + Control ASMCs Mutant ASMCs 1 Donor IAH Mutant AH 3H-thymidine incorporation (% of.1%fbs) 1 5 Reynolds, A. M. et al. Am J hysiol 27; 292: L1182-L %FBS BM-4 (ng/ml) Yang et al Circ Res ;96: Smad1 mediates the growth inhibitory effects Of BM-4 4 in proximal ASMCs Inhibitors of DNA binding (Id) genes control cell fate and differentiation Flag-Smad1 Control BM4 Flag-Smad1+DN Smad1+DN-Smad1 control BM4 A B C D E F G H Transfected proximal ASMC 3 H-Thymidine incorporation (% of.1%fbs) DN-Smad1.1%FBS 1 5 BM4 (ng/ml) Control Vector.1%FBS 1 5 BM4 (ng/ml) Yang et al Circ Res ;96: BM signaling pathway BMR-II BMR-I Mutation in BMR-II reduces transcription of Id genes in response to BMs Smads 1/5 Cell specific changes in gene transcription Id gene expression Vascular cell phenotype migration and proliferation Yang et al. Circ Res ; 96: Yang et al. Circ Res 28;12: Yang et al. Circ Res 28;12:

5 Reduced Id1 gene expression in lesions of heritable AH Id gene knockdown leads to loss of the growth inhibitory effects of BMs in ASMCs Yang et al. Circ Res 28;12: Lentiviral-mediated overexpression of Id1 suppresses serum-induced proliferation of human ASMCs Con Lentivector Lenti- Lentiviral transfection efficiency Id1 rostanoid GCR DGF RTK BMR-II BMR-I Id1 -actin Vector Lenti-GF cam ERK1/2 counts (x1,) Cell specific changes in gene transcription Vascular cell phenotype migration and proliferation Smads 1/5 Id gene expression Yang et al. Circ Res 28;12: Treprostinil inhibits progression of pulmonary hypertension and vascular remodeling in monocrotaline model of H Treprostinil restores psmad1/5 signaling and Id1 gene expression in monocrotaline model of H A B E C D F Con MCT/Saline MCT/Trep H&E EVG

6 otential role of BMR2 mutations in pulmonary arterial hypertension Mutant BMR-II Abnormal vascular development? Unstable vasculature 2nd hit Inflammation Critical reduction in BM signaling Abnormal TGF-β signaling Thanks to: Kings College London Richard Trembath University of Glasgow Mandy MacLean Andrew Baker Imperial College Martin Wilkins Harvard University Ken Bloch University of Giessen Ralph Schermuly