VEGF is essential for hypoxia-inducible factor-mediated neovascularization but dispensable for endothelial sprouting

Although our understanding of the molecular regulation of adult neovascularization has advanced tremendously, vascular-targeted therapies for tissue ischemia remain suboptimal. The master regulatory transcription factors of the hypoxia-inducible factor (HIF) family are attractive therapeutic targets because they coordinately up-regulate multiple genes controlling neovascularization. Here, we used an inducible model of epithelial HIF-1 activation, the TetON-HIF-1 mouse, to test the requirement for VEGF in HIF-1 mediated neovascularization. TetON-HIF-1, K14-Cre, and VEGF^(flox/flox) alleles were combined to create TetON-HIF-1:VEGFΔ mice to activate HIF-1 and its target genes in adult basal keratinocytes in the absence of concomitant VEGF. HIF-1 induction failed to produce neovascularization in TetON-HIF-1:VEGFΔ mice despite robust up-regulation of multiple proangiogenic HIF targets, including PlGF, adrenomedullin, angiogenin, and PAI-1. In contrast, endothelial sprouting was preserved, enhanced, and more persistent, consistent with marked reduction in Dll4-Notch-1 signaling. Optical-resolution photoacoustic microscopy, which provides noninvasive, label-free, high resolution, and wide-field vascular imaging, revealed the absence of both capillary expansion and arteriovenous remodeling in serially imaged individual TetON-HIF-1:VEGFΔ mice. Impaired TetON-HIF-1:VEGFΔ neovascularization could be partially rescued by 12-O-tetradecanoylphorbol-13-acetate skin treatment. These data suggest that therapeutic angiogenesis for ischemic cardiovascular disease may require treatment with both HIF-1 and VEGF

Conditional HIF-1α Expression Produces a Reversible Cardiomyopathy

The response to hypoxia in tissues is regulated by the heterodimeric transcription factor Hypoxia Inducible Factor-1 (HIF-1).We have created a strain of mice with inducible cardiomyocyte-specific expression of a mutated, oxygen-stable, form of HIF-1alpha. Cardiac function steadily decreased with transgene expression, but recovered after the transgene was turned off. Using long-oligo microarrays, we identified 162 transcripts more than 3-fold dysregulated in these hearts after transgene expression. Among the down-regulated genes the transcript for SERCA was reduced 46% and the protein 92%. This led us to an evaluation of calcium flux that showed diminished reuptake of cytoplasmic calcium in myocytes from these hearts, suggesting a mechanism for cardiac dysfunction.These results provide a deeper understanding of transcriptional activity of HIF in the heart, and show that enhanced HIF-1 activity is sufficient to cause contractile dysfunction in the adult heart. HIF is stabilized in the myocardium of patients with ischemic cardiomyopathy, and our results suggest that HIF could be contributing directly to the contractile dysfunction in this disease

VEGF is essential for hypoxia-inducible factor-mediated neovascularization but dispensable for endothelial sprouting

Although our understanding of the molecular regulation of adult neovascularization has advanced tremendously, vascular-targeted therapies for tissue ischemia remain suboptimal. The master regulatory transcription factors of the hypoxia-inducible factor (HIF) family are attractive therapeutic targets because they coordinately up-regulate multiple genes controlling neovascularization. Here, we used an inducible model of epithelial HIF-1 activation, the TetON-HIF-1 mouse, to test the requirement for VEGF in HIF-1 mediated neovascularization. TetON-HIF-1, K14-Cre, and VEGF^(flox/flox) alleles were combined to create TetON-HIF-1:VEGFΔ mice to activate HIF-1 and its target genes in adult basal keratinocytes in the absence of concomitant VEGF. HIF-1 induction failed to produce neovascularization in TetON-HIF-1:VEGFΔ mice despite robust up-regulation of multiple proangiogenic HIF targets, including PlGF, adrenomedullin, angiogenin, and PAI-1. In contrast, endothelial sprouting was preserved, enhanced, and more persistent, consistent with marked reduction in Dll4-Notch-1 signaling. Optical-resolution photoacoustic microscopy, which provides noninvasive, label-free, high resolution, and wide-field vascular imaging, revealed the absence of both capillary expansion and arteriovenous remodeling in serially imaged individual TetON-HIF-1:VEGFΔ mice. Impaired TetON-HIF-1:VEGFΔ neovascularization could be partially rescued by 12-O-tetradecanoylphorbol-13-acetate skin treatment. These data suggest that therapeutic angiogenesis for ischemic cardiovascular disease may require treatment with both HIF-1 and VEGF

Aortic Complications Associated With Pregnancy in Marfan Syndrome: The NHLBI National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139073/1/jah31693.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139073/2/jah31693_am.pd

Bicuspid and unicuspid aortic valves: Different phenotypes of the same disease? Insight from the GenTAC Registry

BackgroundUnicuspid aortic valve (UAV) is a rare disorder, often difficult to distinguish from bicuspid aortic valve (BAV). BAV and UAV share valve pathology such as the presence of a raphe, leaflet fusion, aortic stenosis, aortic regurgitation, and/or ascending aortic dilatation, but a comprehensive echocardiographic comparison of patients with UAV and BAV has not been previously performed.MethodsWe investigated UAV and BAV patients at an early stage of disease included in GenTAC, a national registry of genetically related aortic aneurysms and associated cardiac conditions. Clinical and echocardiographic data from the GenTAC Registry were compared between 17 patients with UAV and 17 matched‐controls with BAV.ResultsBaseline characteristics including demographics, clinical findings including family history of BAV and aortic aneurysm/coarctation, and echocardiographic variables were similar between BAV and UAV patients; aortic stenosis was more common and more severe in patients with UAV. This was evidenced by higher mean and peak gradient, smaller aortic valve area, and more advanced valvular degeneration (all P < .05). There were no significant differences in aortic dimensions, with a similar pattern of enlargement of the ascending aorta.ConclusionsThe similar baseline characteristics with more accelerated aortic valve degeneration and stenosis suggest that UAV represents an extreme in the spectrum of BAV syndromes. Therefore, it is reasonable to consider application of recommendations for the management of patients with BAV to those with the rarer UAV.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139976/1/chd12520.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139976/2/chd12520_am.pd

Cardiovascular Outcomes in Aortopathy: GenTAC Registry of Genetically Triggered Aortic Aneurysms and Related Conditions.

BACKGROUND: The GenTAC (Genetically Triggered Thoracic Aortic Aneurysm and Cardiovascular Conditions) Registry enrolled patients with genetic aortopathies between 2007 and 2016. OBJECTIVES: The purpose of this study was to compare age distribution and probability of elective surgery for proximal aortic aneurysm, any dissection surgery, and cardiovascular mortality among aortopathy etiologies. METHODS: The GenTAC study had a retrospective/prospective design. Participants with bicuspid aortic valve (BAV) with aneurysm (n = 879), Marfan syndrome (MFS) (n = 861), nonsyndromic heritable thoracic aortic disease (nsHTAD) (n = 378), Turner syndrome (TS) (n = 298), vascular Ehlers-Danlos syndrome (vEDS) (n = 149), and Loeys-Dietz syndrome (LDS) (n = 121) were analyzed. RESULTS: The 25% probability of elective proximal aortic aneurysm surgery was 30 years for LDS (95% CI: 18-37 years), followed by MFS (34 years; 95% CI: 32-36 years), nsHTAD (52 years; 95% CI: 48-56 years), and BAV (55 years; 95% CI: 53-58 years). Any dissection surgery 25% probability was highest in LDS (38 years; 95% CI: 33-53 years) followed by MFS (51 years; 95% CI: 46-57 years) and nsHTAD (54 years; 95% CI: 51-61 years). BAV experienced the largest relative frequency of elective surgery to any dissection surgery (254/33 = 7.7), compared with MFS (273/112 = 2.4), LDS (35/16 = 2.2), or nsHTAD (82/76 = 1.1). With MFS as the reference population, risk of any dissection surgery or cardiovascular mortality was lowest in BAV patients (HR: 0.13; 95% CI: 0.08-0.18; HR: 0.13; 95%: CI: 0.06-0.27, respectively). The greatest risk of mortality was seen in patients with vEDS. CONCLUSIONS: Marfan and LDS cohorts demonstrate age and event profiles congruent with the current understanding of syndromic aortopathies. BAV events weigh toward elective replacement with relatively few dissection surgeries. Nonsyndromic HTAD patients experience near equal probability of dissection vs prophylactic surgery, possibly because of failure of early diagnosis

Vertebral Tortuosity Is Associated With Increased Rate of Cardiovascular Events in Vascular Ehlers-Danlos Syndrome

Background Arterial tortuosity is associated with adverse events in Marfan and Loeys-Dietz syndromes but remains understudied in Vascular Ehlers-Danlos syndrome. Methods and Results Subjects with a pathogeni

Fine-mapping, novel loci identification, and SNP association transferability in a genome-wide association study of QRS duration in African Americans

The electrocardiographic QRS duration, a measure of ventricular depolarization and conduction, is associated with cardiovascular mortality. While single nucleotide polymorphisms (SNPs) associated with QRS duration have been identified at 22 loci in populations of European descent, the genetic architecture of QRS duration in non-European populations is largely unknown. We therefore performed a genome-wide association study (GWAS) meta-analysis of QRS duration in 13,031 African Americans from ten cohorts and a transethnic GWAS meta-analysis with additional results from populations of European descent. In the African American GWAS, a single genome-wide significant SNP association was identified (rs3922844, P = 4 × 10−14) in intron 16 of SCN5A, a voltage-gated cardiac sodium channel gene. The QRS-prolonging rs3922844 C allele was also associated with decreased SCN5A RNA expression in human atrial tissue (P = 1.1 × 10−4). High density genotyping revealed that the SCN5A association region in African Americans was confined to intron 16. Transethnic GWAS meta-analysis identified novel SNP associations on chromosome 18 in MYL12A (rs1662342, P = 4.9 × 10−8) and chromosome 1 near CD1E and SPTA1 (rs7547997, P = 7.9 × 10−9). The 22 QRS loci previously identified in populations of European descent were enriched for significant SNP associations with QRS duration in African Americans (P = 9.9 × 10−7), and index SNP associations in or near SCN5A, SCN10A, CDKN1A, NFIA, HAND1, TBX5 and SETBP1 replicated in African Americans. In summary, rs3922844 was associated with QRS duration and SCN5A expression, two novel QRS loci were identified using transethnic meta-analysis, and a significant proportion of QRS–SNP associations discovered in populations of European descent were transferable to African Americans when adequate power was achieved

Investigation of gene-by-sex interactions for lipid traits in diverse populations from the population architecture using genomics and epidemiology study

Abstract Background High-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) levels are influenced by both genes and the environment. Genome-wide association studies (GWAS) have identified ~100 common genetic variants associated with HDL-C, LDL-C, and/or TG levels, mostly in populations of European descent, but little is known about the modifiers of these associations. Here, we investigated whether GWAS-identified SNPs for lipid traits exhibited heterogeneity by sex in the Population Architecture using Genomics and Epidemiology (PAGE) study. Results A sex-stratified meta-analysis was performed for 49 GWAS-identified SNPs for fasting HDL-C, LDL-C, and ln(TG) levels among adults self-identified as European American (25,013). Heterogeneity by sex was established when phet < 0.001. There was evidence for heterogeneity by sex for two SNPs for ln(TG) in the APOA1/C3/A4/A5/BUD13 gene cluster: rs28927680 (phet = 7.4x10-7) and rs3135506 (phet = 4.3x10-4), one SNP in PLTP for HDL levels (rs7679; phet = 9.9x10-4), and one in HMGCR for LDL levels (rs12654264; phet = 3.1x10-5). We replicated heterogeneity by sex in five of seventeen loci previously reported by genome-wide studies (binomial p = 0.0009). We also present results for other racial/ethnic groups in the supplementary materials, to provide a resource for future meta-analyses. Conclusions We provide further evidence for sex-specific effects of SNPs in the APOA1/C3/A4/A5/BUD13 gene cluster, PLTP, and HMGCR on fasting triglyceride levels in European Americans from the PAGE study. Our findings emphasize the need for considering context-specific effects when interpreting genetic associations emerging from GWAS, and also highlight the difficulties in replicating interaction effects across studies and across racial/ethnic groups

Fine mapping of QT interval regions in global populations refines previously identified QT interval loci and identifies signals unique to African and Hispanic descent populations

BACKGROUND: The electrocardiographically measured QT interval (QT) is heritable and its prolongation is an established risk factor for several cardiovascular diseases. Yet, most QT genetic studies have been performed in European ancestral populations, possibly reducing their global relevance. OBJECTIVE: To leverage diversity and improve biological insight, we fine mapped 16 of the 35 previously identified QT loci (46%) in populations of African American (n = 12,410) and Hispanic/Latino (n = 14,837) ancestry. METHODS: Racial/ethnic-specific multiple linear regression analyses adjusted for heart rate and clinical covariates were examined separately and in combination after inverse-variance weighted trans-ethnic meta-analysis. RESULTS: The 16 fine-mapped QT loci included on the Illumina Metabochip represented 21 independent signals, of which 16 (76%) were significantly (P-value≤9.1×10-5) associated with QT. Through sequential conditional analysis we also identified three trans-ethnic novel SNPs at ATP1B1, SCN5A-SCN10A, and KCNQ1 and three Hispanic/Latino-specific novel SNPs at NOS1AP and SCN5A-SCN10A (two novel SNPs) with evidence of associations with QT independent of previous identified GWAS lead SNPs. Linkage disequilibrium patterns helped to narrow the region likely to contain the functional variants at several loci, including NOS1AP, USP50-TRPM7, and PRKCA, although intervals surrounding SLC35F1-PLN and CNOT1 remained broad in size (>100 kb). Finally, bioinformatics-based functional characterization suggested a regulatory function in cardiac tissues for the majority of independent signals that generalized and the novel SNPs. CONCLUSION: Our findings suggest that a majority of identified SNPs implicate gene regulatory dysfunction in QT prolongation, that the same loci influence variation in QT across global populations, and that additional, novel, population-specific QT signals exist