Summary Acquisition and maintenance of vascular smooth muscle fate is essential for the morphogenesis and function of the circulatory system. Loss of contractile properties or changes in the identity of vascular smooth muscle cells (vSMC) can result in structural alterations associated with aneurysms and vascular wall calcification. Here we report that maturation of sclerotome-derived vSMC depends on a transcriptional switch between mouse embryonic days 13 and 14.5. At this time, Notch/Jag1-mediated repression of sclerotome transcription factors Pax1, Scx and Sox9 is necessary to fully enable vSMC maturation. Specifically, Notch signaling in vSMC antagonizes sclerotome and cartilage transcription factors, and promotes upregulation of contractile genes. In the absence of the Notch ligand Jag1, vSMC acquire a chondrocytic transcriptional repertoire that can lead to ossification. Importantly, our findings suggest that sustained Notch signaling is essential throughout vSMC life to maintain contractile function, prevent vSMC reprogramming and promote vascular wall integrity.

A bout 0.9% of human neonates are born with congenital heart disease (CHD). CHD can arise from genetic and epigenetic abnormalities that affect the tight control of specification, proliferation, and migration of cardiac progenitors/myocytes.1,2 During cardiogenesis, cardiac progenitors/myocytes proliferate in two waves: primitive heart tube shows highest proliferative activity at arterial and venous poles where latemigrating second heart field progenitors are recruited. 3,4 Then, after the completion of looping, the working myocytes reinitiate mitotic activity, resulting in the ballooning of chambers at late gestational stages. 3,5 Non-ballooning regions, mainly mediastinal myocardium, 6,7 are distinct from appendage myocardium in their morphology, expression profile, 8 and ionic currents. Nkx2-5 is a cardiac homeobox transcription factor that is expressed in a broad range of cardiac sublineages, from the early committed cardiac progenitors through the adult cardiomyocytes, and plays a pivotal role in the regulation of cardiac, vascular, and hematopoietic lineages. 4,[10][11][12][13][14][15] Human heterozygous mutations of NKX2-5 are associated with a spectrum of CHDs including septal defects, conotruncal malformations, hypoplastic left heart, and atrioventricular (AV) conduction block. In agreement with observations in patients, mouse genetics has revealed the complexity of the role of Nkx2-5. [16][17][18][19] Germline deletion of Nkx2-5 gene results in cardiac lethality at the early stages with defects in the myocardial wall thickening, trabeculation, and endocardial cushion formation, suggesting a pro-mitotic role of Nkx2-5. 4,12,13 Recent studies have shown that Nkx2-5 also plays a critical role at chamber ballooning stages. 3,5 Mutant mouse models with genetic deficiency or dysfunction of Nkx2-5 after midgestational stages lead to atrial septal defect (ASD) and conduction defects. [20][21][22][23][24] Despite common phenotypes, however, these studies show partially inconsistent results as to cardiomyocyte growth. Although the temporary controlled global deletion of Nkx2-5 after midgestational stage results in thin hypomorphic ventricle, 24 ventricular-specific deletion of Nkx2-5 shows hypertrophic ventricle with hypertrabeculation. 22 These apparently conflicting results can be, in part, due to the differential regulation of physiological cardiac growth in spatiotemporarily Rationale: Tight control of cardiomyocyte proliferation is essential for the formation of four-chambered heart.Although human mutation of NKX2-5 is linked to septal defects and atrioventricular conduction abnormalities, early lethality and hemodynamic alteration in the mutant models have caused controversy as to whether Nkx2-5 regulates cardiomyocyte proliferation. diverse cardiac subpopulation. In addition, the secondary effect by altered pump function in Nkx2-5 mutants may be another factor that complicates the interpretation of the phenotypes of mouse models mentioned above. In fact, hemodynamics by itself is known to be an indepen...

Mutations in SCN2A gene cause a variety of epilepsy syndromes. We report a novel SCN2A-associated epilepsy phenotype in monozygotic twins with tonic seizures soon after birth and a suppression-burst EEG pattern. We reviewed the medical records, EEG tracings, MRI, neuropathological findings, and performed whole genome sequencing (WGS) on Twin B’s DNA and Sanger sequencing (SS) on candidate gene mutations. Extensive neurometabolic evaluation and early neuroimaging studies were normal. Twin A died of an iatrogenic cause at 2 weeks of life. His neuropathologic examination was remarkable for dentato-olivary dysplasia and granule cell dispersion of the dentate gyrus. Twin B became seizure-free at 8 months and was off anti-epileptic drugs by 2 years. His brain MRI, normal at 2 months, revealed evolving brainstem and basal ganglia abnormalities at 8 and 15 months that resolved by 20 months. At 2.5 years, Twin B demonstrated significant developmental delay. Twin B’s WGS revealed a heterozygous variant c.788C>T predicted to cause p.Ala263Val change in SCN2A and confirmed to be de novo in both twins by SS. In conclusion, we have identified a de novo SCN2A mutation as the etiology for Ohtahara syndrome in monozygotic twins associated with a unique dentate-olivary dysplasia in the deceased twin.

Background Cardiac maturation during perinatal transition of heart is critical for functional adaptation to hemodynamic load and nutrient environment. Perturbation in this process has major implications in congenital heart defects (CHDs). Transcriptome programming during perinatal stages is important information but incomplete in current literature, particularly, the expression profiles of the long noncoding RNAs (lncRNAs) are not fully elucidated. Methods and Results From comprehensive analysis of transcriptomes derived from neonatal mouse heart left and right ventricles, a total of 45,167 unique transcripts were identified, including 21,916 known and 2,033 novel lncRNAs. Among these lncRNAs, 196 exhibited significant dynamic regulation along maturation process. By implementing parallel weighted gene co-expression network analysis (WGCNA) of mRNA and lncRNA datasets, several lncRNA modules coordinately expressed in a developmental manner similar to protein coding genes, while few lncRNAs revealed chamber specific patterns. Out of 2,262 lncRNAs located within 50 KBs of protein coding genes, 5% significantly correlate with the expression of their neighboring genes. The impact of Ppp1r1b-lncRNA on the corresponding partner gene Tcap was validated in cultured myoblasts. This concordant regulation was also conserved in human infantile hearts. Furthermore, the Ppp1r1b-lncRNA/Tcap expression ratio was identified as a molecular signature that differentiated CHD phenotypes. Conclusions The study provides the first high-resolution landscape on neonatal cardiac lncRNAs and reveals their potential interaction with mRNA transcriptome during cardiac maturation. Ppp1r1b-lncRNA was identified as a regulator of Tcap expression with dynamic interaction in postnatal cardiac development and CHDs.

We examined the effect of mild (Mi; ∼25%) and moderate (Mo; ∼50%) maternal calorie restriction (MCR) vs ad libitum-fed controls on placental glucose and leucine transport impacting fetal growth potential. We observed in MiMCR a compensatory increase in transplacental (TP) glucose transport due to increased placental glucose transporter isoform (GLUT)-3 but no change in GLUT1 protein concentrations. This change was paralleled by increased glut3 mRNA and 5-hydroxymethylated cytosines with enhanced recruitment of histone 3 lysine demethylase to the glut3 gene locus. To assess the biologic relevance of placental GLUT1, we also examined glut1 heterozygous null vs wild-type mice and observed no difference in placental GLUT3 and TP or intraplacental glucose and leucine transport. Both MCR states led to a graded decrease in TP and intraplacental leucine transport, with a decline in placental L amino acid transporter isoform 2 (LAT2) concentrations and increased microRNA-149 (targets LAT2) and microRNA-122 (targets GLUT3) expression in MoMCR alone. These changes were accompanied by a step-wise reduction in uterine and umbilical artery Doppler blood flow with decreased fetal left ventricular ejection fraction and fractional shortening. We conclude that MiMCR transactivates placental GLUT3 toward preserving TP glucose transport in the face of reduced leucine transport. This contrasts MoMCR in which a reduction in placental GLUT3 mediated glucose transport with a reciprocal increase in miR-122 expression was encountered. A posttranscriptional reduction in LAT2-mediated leucine transport also occurred with enhanced miR-149 expression. Both MCR states, although not affecting placental GLUT1, resulted in uteroplacental insufficiency and fetal growth restriction with compromised cardiovascular health.

The last day of 2019 delivered the first report to the World Health Organization (WHO) about a group of cases of pneumonia of unknown etiology in Wuhan, China. Subsequent investigations identified the new comer, a novel coronavirus related to severe acute respiratory syndrome coronavirus (SARS-CoV) and thus was termed as SARS-CoV-2. Being very contagious, the new virus led the era of "COVID-19" which is the acronym of "coronavirus disease 2019," evoking an imminent threat to global health security with unprecedented devastating challenges to human kind. In this article, we provide a molecular overview on the SARS-CoV-2 virus and summarize tremendous efforts that have been made to develop a rapid confirmatory diagnostic test for COVID-19. The diagnostic performances of the available tests are analyzed based on the best current information from the early research.

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Christou H, Reslan OM, Mam V, Tanbe AF, Vitali SH, Touma M, Arons E, Mitsialis SA, Kourembanas S, Khalil RA. Improved pulmonary vascular reactivity and decreased hypertrophic remodeling during nonhypercapnic acidosis in experimental pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 302: L875-L890, 2012. First published January 27, 2012; doi:10.1152/ajplung.00293.2011.-Pulmonary hypertension (PH) is characterized by pulmonary arteriolar remodeling with excessive pulmonary vascular smooth muscle cell (VSMC) proliferation. This results in decreased responsiveness of pulmonary circulation to vasodilator therapies. We have shown that extracellular acidosis inhibits VSMC proliferation and migration in vitro. Here we tested whether induction of nonhypercapnic acidosis in vivo ameliorates PH and the underlying pulmonary vascular remodeling and dysfunction. Adult male Sprague-Dawley rats were exposed to hypoxia (8.5% O2) for 2 wk, or injected subcutaneously with monocrotaline (MCT, 60 mg/kg) to develop PH. Acidosis was induced with NH4Cl (1.5%) in the drinking water 5 days prior to and during the 2 wk of hypoxic exposure (prevention protocol), or after MCT injection from day 21 to 28 (reversal protocol). Right ventricular systolic pressure (RVSP) and Fulton's index were measured, and pulmonary arteriolar remodeling was analyzed. Pulmonary and mesenteric artery contraction to phenylephrine (Phe) and high KCl, and relaxation to acetylcholine (ACh) and sodium nitroprusside (SNP) were examined ex vivo. Hypoxic and MCT-treated rats demonstrated increased RVSP, Fulton's index, and pulmonary arteriolar thickening. In pulmonary arteries of hypoxic and MCT rats there was reduced contraction to Phe and KCl and reduced vasodilation to ACh and SNP. Acidosis prevented hypoxia-induced PH, reversed MCT-induced PH, and resulted in reduction in all indexes of PH including RVSP, Fulton's index, and pulmonary arteriolar remodeling. Pulmonary artery contraction to Phe and KCl was preserved or improved, and relaxation to ACh and SNP was enhanced in NH4Cl-treated PH animals. Acidosis alone did not affect the hemodynamics or pulmonary vascular function. Phe and KCl contraction and ACh and SNP relaxation were not different in mesenteric arteries of all groups. Thus nonhypercapnic acidosis ameliorates experimental PH, attenuates pulmonary arteriolar thickening, and enhances pulmonary vascular responsiveness to vasoconstrictor and vasodilator stimuli. Together with our finding that acidosis decreases VSMC proliferation, the results are consistent with the possibility that nonhypercapnic acidosis promotes differentiation of pulmonary VSMCs to a more contractile phenotype, which may enhance the effectiveness of vasodilator therapies in PH. pulmonary artery; pulmonary circulation; nitric oxide; vascular smooth muscle PULMONARY HYPERTENSION (PH) is a serious disease and a major and expanding public health problem with ϳ1,000 new patients diagnosed every year in the United States (6,20). PH is characterized by increased pulmonary arterial pre...