Novel homozygous BMP9 nonsense mutation causes pulmonary arterial hypertension: a case report.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare, progressive, fatal vascular disorder. Genetic predisposition plays vital roles in the development of PAH, with most mutations being identified in genes involved in the transforming growth factor beta (TGF-ß) signaling pathways. Defects in the BMP9 gene have been documented in hereditary hemorrhagic telangiectasia (HHT), the most common inherited vascular disorder, which is occasionally associated with PAH. Selective enhancement of endothelial BMPR2 with BMP9 reverses pulmonary arterial hypertension. CASE PRESENTATION: We report the case of a 5-year-old Hispanic boy who was diagnosed with severe PAH and right heart failure at 3 years of age. During his stay in the pediatric intensive care unit, treatment was initiated with inhaled nitric oxide and intravenous epoprostenol; he subsequently was transitioned to treprostinil, sildenafil, and prophylactic enoxaparin. Now, two years later, the child is asymptomatic on sildenafil, bosentan, subcutaneous treprostinil, and warfarin. Genetic screening revealed a novel homozygous nonsense mutation in the BMP9 gene (c.76C > T; p.Gln26Ter). The child had no telangiectasias or arteriovenous malformations; family history also was negative. Subsequent parental testing showed both parents were heterozygous for the same mutation, indicating that the child inherited the BMP9 mutant allele from each parent. CONCLUSION: To our knowledge, this is the first report of a BMP9 mutation in a patient with PAH. The homozygous nonsense mutation may account for the early onset and severity of PAH in this patient and also fit the 'two-hit' model we proposed previously. The absence of clinical symptoms for PAH in the parents may be due to incomplete penetrance or various expressivities of the BMP9 mutations. Our study expands the spectrum of phenotypes related to BMP9 mutations.

Hereditary pulmonary arterial hypertension burden in pediatrics: A single referral center experience.

Introduction: Hereditary pulmonary arterial hypertension (HPAH) is a rare yet serious type of pulmonary arterial hypertension (PAH). The burden in the pediatric population remains high yet underreported. The objective of this study is to describe the distribution of mutations found on targeted PAH panel testing at a large pediatric referral center. Methods: Children with PAH panel administered by the John Welsh Cardiovascular Diagnostic Laboratory at Texas Children's Hospital and Baylor College of Medicine in Houston, Texas between October 2012 to August 2021 were included into this study. Medical records were retrospectively reviewed for clinical correlation. Results: Sixty-six children with PAH underwent PAH genetic testing. Among those, 9 (14%) children were found to have pathogenic mutations, 16 (24%) children with variant of unknown significance and 41 (62%) children with polymorphism (classified as likely benign and benign). BMPR2 mutation was the most common pathogenic mutation, seen in 6 of the 9 children with detected mutations. Hemodynamic studies showed higher pulmonary vascular resistance among those with pathogenic mutations than those without (17.4 vs. 4.6 Wood units). All children with pathogenic mutations had severe PAH requiring triple therapy. There were tendencies for higher lung transplantation rate but lower mortality among those with pathogenic mutations. Conclusions: Abnormalities on genetic testing are not uncommon among children with PAH, although majority are of unclear significance. However, children with pathogenic mutations tended to present with more severe PAH requiring aggressive medical and surgical therapies. Genetic testing should be routinely considered due to consequences for treatment and prognostic implications. Larger scale population studies and registries are warranted to characterize the burden of HPAH in the pediatric population specifically.

Ammonia-oxidizing bacteria rather than ammonia-oxidizing archaea dominate nitrification in a nitrogen-fertilized calcareous soil.

Microbe-driven nitrification is a key process that affects nitrogen (N) utilization by plants and N loss to the environment in agro-ecosystems. Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are important microorganisms that dominate the ammonia oxidation process (the first and rate-limiting step of nitrification). Calcareous soils are widely distributed, accounting for more than 30% of the Earth's land. However, the effects of long-term N fertilization on the potential nitrification rate (PNR) and on AOA and AOB in calcareous soils are poorly understood. In this study, we comprehensively assessed the effects of N application (applied at five rates as urea with 0, 73.5, 105, 136.5 and 250 kg N ha-1 for 12 years) on soil chemical characteristics, PNR, N use efficiency (NUE) and the community characteristics of AOB and AOA in a calcareous soil. N application rate affected AOB beta diversity more than that of AOA. Compared to no N control, N application significantly decreased the relative abundance of Group I.1b clade A of AOA and Nitrosospira cluster 3a.2 of AOB, but increased Nitrosomonas cluster 7 of AOB. The relative abundance of Nitrosospira cluster 3a.2 of AOB was negatively correlated with PNR. A structural equation model showed a direct effect of N application rate on the content of soil organic matter and nitrate, the alpha and beta diversity of AOA and AOB. Nitrate and AOB beta diversity were the key factors affecting PNR. Overall, the alpha, beta diversity and community composition of AOB contribute more to PNR than AOA in calcareous soils with high organic matter content. Understanding the relationship between the characteristics of AOA and AOB in calcareous soils and PNR will help to improve NUE.

Depressive symptoms and socioeconomic status among the labor force: Evidence from China's representative sample.

OBJECTIVES: The purpose of this paper is to describe the prevalence of depressive symptoms in the Chinese labor force; to explore the relationship between depressive symptoms and socioeconomic status among the Chinese labor force, including both the structural determinants and the intermediary determinants of health inequities; and to identify vulnerable populations who would benefit from intervention measures. METHODS: Data were from the China Labor-Force Dynamics Survey (CLDS) 2016. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to assess depressive symptoms. The World Health Organization's theoretical framework of the social determinants of health was adopted to analyze the relationship between social determinants and depressive symptoms. RESULTS: Of the participants in the research from the Chinese labor force, 17.34% were identified as having depressive symptoms. Depression was significantly related to socioeconomic factors such as hukou status (p < 0.05 in the age < 45 model), education (p < 0.01 in all five models), employment (p < 0.05 in the male model), income (p < 0.05 in all five models), and self-assessed social class position (p < 0.01 in all five models). Intermediary factors were also related to depressive symptoms, such as gender (p < 0.001 in the overall model), age (p < 0.05 in the overall model), marriage (p < 0.05 in the female model), occupational exposure (p < 0.01 in the overall model), exercise (p < 0.05 in all five models), and health insurance (p < 0.05 in the overall model). The results showed that low socioeconomic status was associated with an increased risk of depression and there were some gradient changes in the distribution of depressive symptoms in socioeconomic status. CONCLUSIONS: The findings showed that depression symptoms are significantly related to structural determinants and intermediary determinants in China's labor force. There are some gradient changes in the distribution of depressive symptoms among people of different socioeconomic status. Low socioeconomic status is associated with increased risk of depression. Women, older people, and single and divorced people are the relative vulnerable groups in China's labor force.

Soil Microbial Composition and phoD Gene Abundance Are Sensitive to Phosphorus Level in a Long-Term Wheat-Maize Crop System.

Microbes associated with phosphorus (P) cycling are intrinsic to soil P transformation and availability for plant use but are also influenced by the application of P fertilizer. Nevertheless, the variability in soil P in the field means that integrative analyses of soil P cycling, microbial composition, and microbial functional genes related to P cycling remain very challenging. In the present study in the North China Plain, we subjected the bacterial and fungal communities to amplicon sequencing analysis and characterized the alkaline phosphatase gene (phoD) encoding bacterial alkaline phosphatase in a long-term field experiment (10 years) with six mineral P fertilization rates up to 200 kg P ha-1. Long-term P fertilization increased soil available P, inorganic P, and total P, while soil organic P increased until the applied P rate reached 25 kg ha-1 and then decreased. The fungal alpha-diversity decreased as P rate increased, while there were no significant effects on bacterial alpha-diversity. Community compositions of bacteria and fungi were significantly affected by P rates at order and family levels. The number of keystone taxa decreased from 10 to 3 OTUs under increasing P rates from 0 to 200 kg ha-1. The gene copy numbers of the biomarker of the alkaline phosphatase phoD was higher at moderate P rates (25 and 50 kg ha-1) than at low (0 and 12.5 kg ha-1) and high (100 and 200 kg ha-1) rates of P fertilization, and was positively correlated with soil organic P concentration. One of the keystone taxa named BacOTU3771 belonging to Xanthomonadales was positively correlated with potential functional genes encoding enzymes such as glycerophosphoryl diester phosphodiesterase, acid phosphatase and negatively correlated with guinoprotein glucose dehydrogenase. Altogether, the results show the systematic effect of P gradient fertilization on P forms, the microbial community structure, keystone taxa, and functional genes associated with P cycling and highlight the potential of moderate rates of P fertilization to maintain microbial community composition, specific taxa, and levels of functional genes to achieve and sustain soil health.

Variant R94C in TNNT2-Encoded Troponin T Predisposes to Pediatric Restrictive Cardiomyopathy and Sudden Death Through Impaired Thin Filament Relaxation Resulting in Myocardial Diastolic Dysfunction.

Background Pediatric-onset restrictive cardiomyopathy (RCM) is associated with high mortality, but underlying mechanisms of disease are under investigated. RCM-associated diastolic dysfunction secondary to variants in TNNT2-encoded cardiac troponin T (TNNT2) is poorly described. Methods and Results Genetic analysis of a proband and kindred with RCM identified TNNT2-R94C, which cosegregated in a family with 2 generations of RCM, ventricular arrhythmias, and sudden death. TNNT2-R94C was absent among large, population-based cohorts Genome Aggregation Database (gnomAD) and predicted to be pathologic by in silico modeling. Biophysical experiments using recombinant human TNNT2-R94C demonstrated impaired cardiac regulation at the molecular level attributed to reduced calcium-dependent blocking of myosin's interaction with the thin filament. Computational modeling predicted a shift in the force-calcium curve for the R94C mutant toward submaximal calcium activation compared within the wild type, suggesting low levels of muscle activation even at resting calcium concentrations and hypercontractility following activation by calcium. Conclusions The pathogenic TNNT2-R94C variant activates thin-filament-mediated sarcomeric contraction at submaximal calcium concentrations, likely resulting in increased muscle tension during diastole and hypercontractility during systole. This describes the proximal biophysical mechanism for development of RCM in this family.

Concomitant presentation of Anderson-Tawil syndrome and myasthenia gravis in an adult patient: A case report.

Andersen-Tawil syndrome (ATS) is an autosomal dominant, multisystem channelopathy characterized by periodic paralysis, ventricular arrhythmias and distinctive dysmorphic facial or skeletal features. The disorder displays marked intrafamilial variability and incomplete penetrance. Myasthenia gravis (MG) is an autoimmune disorder that demonstrates progressive fatigability, in which the nicotinic acetylcholine receptor (AChR) at neuromuscular junctions is the primary autoantigen. The present study reports a rare case of a 31-year-old woman with a history of morbid obesity and periodic weakness, who presented with hemodynamic instability, cardiogenic shock and facial anomalies. Laboratory results revealed hypokalemia and an elevated anti-AChR antibody expression levels. Electrocardiography demonstrated prolonged QT-interval, ST-elevation, and subsequent third-degree atrioventricular block. Neurological examination revealed bilateral ptosis, horizontal diplopia, dysarthria and generalized weakness. No mutations in the potassium channel inwardly rectifying subfamily J member 2 gene were detected in the present case. The patient was treated with oral potassium supplementation and an acetylcholinesterase inhibitor (pyridostigmine), after which the symptoms were improved. To the best of our knowledge, the present case report was the first to describe concomitant presentation of both ATS and MG, which represents a diagnostic and therapeutic challenge.

Inhibition of Sp1 functions by its sequestration into PML nuclear bodies.

Promyelocytic leukemia nuclear bodies (PML NBs) are comprised of PML and a striking variety of its associated proteins. Various cellular functions have been attributed to PML NBs, including the regulation of gene expression. We report here that induced expression of PML recruits Sp1 into PML NBs, leading to the reduction of Sp1 transactivation function. Specifically, Chromatin immunoprecipitation (ChIP) assay demonstrated that induced expression of PML significantly diminishes the amount of Sp1 binding to its target gene promoter, immunofluorescence staining showed dramatic increase in the co-localization between PML and Sp1 upon induction of PML expression, moreover, PML and Sp1 co-fractionated in the core nuclear matrix. Our study further showed that PML promotes SUMOylation of Sp1 in a RING-motif-dependent manner, SUMOylation of Sp1 facilitates physical interaction between Sp1 and PML and recruitment of Sp1 into the PML NBs, the SUMO binding motif of PML was also important for its interaction with Sp1. The results of this study demonstrate a novel mechanism by which PML regulates gene expression through sequestration of the transcription factor into PML NBs.

Functional changes in pulmonary arterial endothelial cells associated with BMPR2 mutations.

Pulmonary arterial hypertension (PAH) is a devastating disease characterized by abnormal remodeling of small, peripheral pulmonary arteries. Germline mutations in the bone morphogenetic protein receptor type 2 (BMPR2) gene are a major risk factor for developing PAH. At present, the correlation between the BMPR2 mutation and the patient's prognosis remains controversial despite several investigations. In this study, we explored the functional effects of four BMPR2 mutations to dissect the functional significance of the BMPR2 gene defect. Cellular immunofluorescence assay of four mutants (Tyr67Cys, Thr268fs, Ser863Asn, and Gln433X) revealed that the BMPR2 protein containing Thr268fs, Ser863Asn, or Gln433X exhibited abnormal subcellular localization. The BrdU incorporation and TUNEL assay suggested that any of the BMPR2 mutations Thr268fs, Ser863Asn, or Gln433X could improve endothelial cell apoptosis and decrease cell proliferation. All of the four mutants could inhibit nitric oxide (NO) synthesis in HLMVE cells, and ET-1 levels increased in the cells transfected with mutant Ser863Asn. Our results will improve the understanding of the genotype-phenotype correlations and mechanisms associated with BMPR2 mutations.

Dephosphorylation of phosphotyrosine on STAT1 dimers requires extensive spatial reorientation of the monomers facilitated by the N-terminal domain.

We report experiments that infer a radical reorientation of tyrosine-phosphorylated parallel STAT1 dimers to an antiparallel form. Such a change in structure allows easy access to a phosphatase. With differentially epitope-tagged molecules, we show that the two monomers of a dimer remain together during dephosphorylation although they most likely undergo spatial reorientation. Extensive single amino acid mutagenesis within crystallographically established domains, manipulation of amino acids in an unstructured tether that connects the N-terminal domain (ND) to the core of the protein, and the demonstration that overexpressed ND can facilitate dephosphorylation of a core molecule lacking an ND all support this model: When the tyrosine-phosphorylated STAT1 disengages from DNA, the ND dimerizes and somehow assists in freeing the reciprocal pY-SH2 binding between the monomers of the dimer while ND ND dimerization persists. The core of the monomers rotate allowing reciprocal association of the coiled:coil and DNA-binding domains to present pY at the two ends of an antiparallel dimer for ready dephosphorylation.

A role for PML3 in centrosome duplication and genome stability.

The promyelocytic leukemia gene (PML), which is disrupted by the chromosomal translocation t(15;17) in acute promyelocytic leukemia (APL), encodes a multifunctional protein involved in several important cellular functions. Herein, we demonstrate that PML is localized to centrosomes and that PML deficiency leads to centrosome amplification. By using PML isoform-specific antibodies, we found PML3-specific association with the centrosome and the pole of the mitotic spindle. PML3 deficiency leads to dysregulation of the centrosome duplication checkpoint. Furthermore, PML3 physically interacts with Aurora A and regulates its kinase activity. Specific knockdown of PML3 activates Cdk2/cyclin kinase activity. The results of this study implicate a direct role for PML3 in the control of centrosome duplication through suppression of Aurora A activation to prevent centrosome reduplication.

The glutathione-glutaredoxin system in Rhodobacter capsulatus: part of a complex regulatory network controlling defense against oxidative stress.

Mutants with defects in components of the glutathione-glutaredoxin (GSH/Grx) system of Rhodobacter capsulatus were constructed to study its role in defense against oxidative stress and the redox-dependent formation of photosynthetic complexes. The lack of the glutaredoxin 3 gene (grxC) or the glutathione synthetase B gene (gshB) resulted in lower growth rates under aerobic conditions and higher sensitivity to oxidative stress, confirming the role of the GSH/Grx system in oxidative stress defense. Both mutants are highly sensitive to disulfide stress, indicating a major contribution of the GSH/Grx system to the thiol-disulfide redox buffer in the cytoplasm. Like mutations in the thioredoxin system, mutations in the GSH/Grx system affected the formation of photosynthetic complexes, which is redox dependent in R. capsulatus. Expression of the genes grxC, gshB, grxA for glutaredoxin 1, and gorA for glutathione reductase, all encoding components of the GSH/Grx system, was not induced by oxidative stress. Other genes, for which a role in oxidative stress was established in Escherichia coli, acnA, fpr, fur, and katG, were strongly induced by oxidative stress in R. capsulatus. Mutations in the grxC, and/or gshB, and/or trxC (thioredoxin 2) genes affected expression of these genes, indicating an interplay of the different defense systems against oxidative stress. The OxyR and the SoxRS regulons control the expression of many genes involved in oxidative stress defense in E. coli in response to H2O2 and superoxide, respectively. Our data and the available genome sequence of R. capsulatus suggest that a SoxRS system is lacking but an alternative superoxide specific regulator exists in R. capsulatus. While the expression of gorA and grxA is regulated by H2O2 in E. coli this is not the case in R. capsulatus, indicating that the OxyR regulons of these two species are significantly different.