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Loss-of-function thrombospondin-1 mutations in familial pulmonary hypertension.

ABSTRACT: Most patients with familial pulmonary arterial hypertension (FPAH) carry mutations in the bone morphogenic protein receptor 2 gene (BMPR2). Yet carriers have only a 20% risk of disease, suggesting that other factors influence penetrance. Thrombospondin-1 (TSP1) regulates activation of TGF-? and inhibits endothelial and smooth muscle cell proliferation, pathways coincidentally altered in pulmonary arterial hypertension (PAH). To determine whether a subset of FPAH patients also have mutations in the TSP1 gene (THBS1) we resequenced the type I repeats of THBS1 encoding the TGF-? regulation and cell growth inhibition domains in 60 FPAH probands, 70 nonfamilial PAH subjects, and in large control groups. We identified THBS1 mutations in three families: a novel missense mutation in two (Asp362Asn), and an intronic mutation in a third (IVS8+255 G/A). Neither mutation was detected in population controls. Mutant 362Asn TSP1 had less than half of the ability of wild-type TSP1 to activate TGF-?. Mutant 362Asn TSP1 also lost the ability to inhibit growth of pulmonary arterial smooth muscle cells and was over threefold less effective at inhibiting endothelial cell growth. The IVS8+255 G/A mutation decreased and/or eliminated local binding of the transcription factors SP1 and MAZ but did not affect RNA splicing. These novel mutations implicate THBS1 as a modifier gene in FPAH. These THBS1 mutations have implications in the genetic evaluation of FPAH patients. However, since FPAH is rare, these data are most relevant as evidence for the importance of TSP1 in pulmonary vascular homeostasis. Further examination of THBS1 in the pathogenesis of PAH is warranted.

SUBMITTER: Maloney JP

PROVIDER: S-EPMC3311532 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature

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Loss-of-function thrombospondin-1 mutations in familial pulmonary hypertension.

Maloney James P JP Stearman Robert S RS Bull Todd M TM Calabrese David W DW Tripp-Addison Megan L ML Wick Marilee J MJ Broeckel Ulrich U Robbins Ivan M IM Wheeler Lisa A LA Cogan Joy D JD Loyd James E JE

American journal of physiology. Lung cellular and molecular physiology 20111223 6

Most patients with familial pulmonary arterial hypertension (FPAH) carry mutations in the bone morphogenic protein receptor 2 gene (BMPR2). Yet carriers have only a 20% risk of disease, suggesting that other factors influence penetrance. Thrombospondin-1 (TSP1) regulates activation of TGF-β and inhibits endothelial and smooth muscle cell proliferation, pathways coincidentally altered in pulmonary arterial hypertension (PAH). To determine whether a subset of FPAH patients also have mutations in t ...[more]

PMID: 22198906

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Project description:Background Dilated cardiomyopathy (DCM), characterized by progressive left ventricular enlargement and systolic dysfunction, is the most common type of cardiomyopathy and a leading cause of heart failure and cardiac death. Accumulating evidence underscores the critical role of genetic defects in the pathogenesis of DCM, and >250 genes have been implicated in DCM to date. However, DCM is of substantial genetic heterogeneity, and the genetic basis underpinning DCM remains elusive in most cases. Methods and Results By genome-wide scan with microsatellite markers and genetic linkage analysis in a 4-generation family inflicted with autosomal-dominant DCM, a new locus for DCM was mapped on chromosome 15q13.1-q13.3, a 4.77-cM (≈3.43 Mbp) interval between markers D15S1019 and D15S1010, with the largest 2-point logarithm of odds score of 5.1175 for the marker D15S165 at recombination fraction (θ)=0.00. Whole-exome sequencing analyses revealed that within the mapping chromosomal region, only the mutation in the KLF13 gene, c.430G>T (p.E144X), cosegregated with DCM in the family. In addition, sequencing analyses of KLF13 in another cohort of 266 unrelated patients with DCM and their available family members unveiled 2 new mutations, c.580G>T (p.E194X) and c.595T>C (p.C199R), which cosegregated with DCM in 2 families, respectively. The 3 mutations were absent from 418 healthy subjects. Functional assays demonstrated that the 3 mutants had no transactivation on the target genes ACTC1 and MYH7 (2 genes causally linked to DCM), alone or together with GATA4 (another gene contributing to DCM), and a diminished ability to bind the promoters of ACTC1 and MYH7. Add, the E144X-mutant KLF13 showed a defect in intracellular distribution. Conclusions This investigation indicates KLF13 as a new gene predisposing to DCM, which adds novel insight to the molecular pathogenesis underlying DCM, implying potential implications for prenatal prevention and precision treatment of DCM in a subset of patients.

Project description:BACKGROUND:Germline mutations in the BRIP1 gene have been described as conferring a moderate risk for ovarian cancer (OC), while the role of BRIP1 in breast cancer (BC) pathogenesis remains controversial. METHODS:To assess the role of deleterious BRIP1 germline mutations in BC/OC predisposition, 6341 well-characterized index patients with BC, 706 index patients with OC, and 2189 geographically matched female controls were screened for loss-of-function (LoF) mutations and potentially damaging missense variants. All index patients met the inclusion criteria of the German Consortium for Hereditary Breast and Ovarian Cancer for germline testing and tested negative for pathogenic BRCA1/2 variants. RESULTS:BRIP1 LoF mutations confer a high OC risk in familial index patients (odds ratio (OR)?=?20.97, 95% confidence interval (CI)?=?12.02-36.57, P?<?0.0001) and in the subgroup of index patients with late-onset OC (OR?=?29.91, 95% CI?=?14.99-59.66, P?<?0.0001). No significant association of BRIP1 LoF mutations with familial BC was observed (OR?=?1.81 95% CI?=?1.00-3.30, P?=?0.0623). In the subgroup of familial BC index patients without a family history of OC there was also no apparent association (OR?=?1.42, 95% CI?=?0.70-2.90, P?=?0.3030). In 1027 familial BC index patients with a family history of OC, the BRIP1 mutation prevalence was significantly higher than that observed in controls (OR?=?3.59, 95% CI?=?1.43-9.01; P?=?0.0168). Based on the negative association between BRIP1 LoF mutations and familial BC in the absence of an OC family history, we conclude that the elevated mutation prevalence in the latter cohort was driven by the occurrence of OC in these families. Compared with controls, predicted damaging rare missense variants were significantly more prevalent in OC (P?=?0.0014) but not in BC (P?=?0.0693) patients. CONCLUSIONS:To avoid ambiguous results, studies aimed at assessing the impact of candidate predisposition gene mutations on BC risk might differentiate between BC index patients with an OC family history and those without. In familial cases, we suggest that BRIP1 is a high-risk gene for late-onset OC but not a BC predisposition gene, though minor effects cannot be excluded.

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Dataset Information

Loss-of-function thrombospondin-1 mutations in familial pulmonary hypertension.

Publications

Loss-of-function thrombospondin-1 mutations in familial pulmonary hypertension.

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