Prenatal features, associated co-morbidities and clinical course of agenesis of the ductus venosus in the current era.

OBJECTIVES: Agenesis of the ductus venosus (ADV) has been associated with additional anomalies in up to 83% of cases. We sought to investigate characteristics, co-morbidities and outcomes of ADV in the current era. We hypothesized that rates of cardiac and non-cardiac diagnoses and survival would be higher, due to advances in genetic testing, prenatal diagnosis and surveillance. METHODS: A retrospective series of cases diagnosed at our institution from 2007 to 2018 were identified by searching our database. Cardiac and obstetric charts were reviewed for cardiac and extra-cardiac anomalies, genetic results and outcomes. RESULTS: Fourteen cases were diagnosed at a mean gestational age of 23.9 weeks (range 13-33). All had associated genetic, cardiac or extra-cardiac anomalies. Eight (57%) had cardiac anomalies and one other developed cardiomyopathy by 6 months. Extra-cardiac anomalies were present in 93% (13/14) and genetic diagnoses made in 75% (6/8) of those tested. Cardiac output Z-scores were >2 in 60% (6/10) prior to delivery. Two had hydrops, there was one intra-uterine death, 13 live-births and two neonatal deaths. CONCLUSION: Our cohort had more associated diagnoses and a lower mortality than previously reported. In our experience, high output occurs frequently, however with a relatively low risk of hydrops and intrauterine death.

Co-exposure to an Aryl Hydrocarbon Receptor Endogenous Ligand, 6-Formylindolo[3,2-b]carbazole (FICZ), and Cadmium Induces Cardiovascular Developmental Abnormalities in Mice.

6-Formylindolo[3,2-b]carbazole (FICZ) is a signal substance and an endogenous activator of aryl hydrocarbon receptor (AHR). Cadmium (Cd) is an environmental pollutant that can activate both AHR and Wnt/ß-catenin signaling pathways. We aimed to determine how dysregulated signaling through AHR-Wnt/ß-catenin cross-talk can influence mice heart development. Mice fetuses were exposed to Cd alone or in combination with FICZ in gestation day (GD) 0. In GD18, fetuses were harvested and randomly divided into two parts for stereological and molecular studies. Stereological and tessellation results revealed that when fetuses were co-exposed with FICZ and Cd, abnormalities were synergistically raised. In the presence of FICZ, mRNA expression levels of Wnt/ß-catenin target genes significantly enhanced, especially when animals co-treated with FICZ and Cd. Based on these findings, we propose that chemical pollutants can interfere with the normal function of AHR that has a physiological role in regulating Wnt/ß-catenin during cardiogenesis.

Loss of CXCL12/CXCR4 signalling impacts several aspects of cardiovascular development but does not exacerbate Tbx1 haploinsufficiency.

The CXCL12-CXCR4 pathway has crucial roles in stem cell homing and maintenance, neuronal guidance, cancer progression, inflammation, remote-conditioning, cell migration and development. Recently, work in chick suggested that signalling via CXCR4 in neural crest cells (NCCs) has a role in the 22q11.2 deletion syndrome (22q11.2DS), a disorder where haploinsufficiency of the transcription factor TBX1 is responsible for the major structural defects. We tested this idea in mouse models. Our analysis of genes with altered expression in Tbx1 mutant mouse models showed down-regulation of Cxcl12 in pharyngeal surface ectoderm and rostral mesoderm, both tissues with the potential to signal to migrating NCCs. Conditional mutagenesis of Tbx1 in the pharyngeal surface ectoderm is associated with hypo/aplasia of the 4th pharyngeal arch artery (PAA) and interruption of the aortic arch type B (IAA-B), the cardiovascular defect most typical of 22q11.2DS. We therefore analysed constitutive mouse mutants of the ligand (CXCL12) and receptor (CXCR4) components of the pathway, in addition to ectodermal conditionals of Cxcl12 and NCC conditionals of Cxcr4. However, none of these typical 22q11.2DS features were detected in constitutively or conditionally mutant embryos. Instead, duplicated carotid arteries were observed, a phenotype recapitulated in Tie-2Cre (endothelial) conditional knock outs of Cxcr4. Previous studies have demonstrated genetic interaction between signalling pathways and Tbx1 haploinsufficiency e.g. FGF, WNT, SMAD-dependent. We therefore tested for possible epistasis between Tbx1 and the CXCL12 signalling axis by examining Tbx1 and Cxcl12 double heterozygotes as well as Tbx1/Cxcl12/Cxcr4 triple heterozygotes, but failed to identify any exacerbation of the Tbx1 haploinsufficient arch artery phenotype. We conclude that CXCL12 signalling via NCC/CXCR4 has no major role in the genesis of the Tbx1 loss of function phenotype. Instead, the pathway has a distinct effect on remodelling of head vessels and interventricular septation mediated via CXCL12 signalling from the pharyngeal surface ectoderm and second heart field to endothelial cells.

Silica nanoparticles inhibit macrophage activity and angiogenesis via VEGFR2-mediated MAPK signaling pathway in zebrafish embryos.

The safety evaluation of silica nanoparticles (SiNPs) are getting great attention due to its widely-used in food sciences, chemical industry and biomedicine. However, the adverse effect and underlying mechanisms of SiNPs on cardiovascular system, especially on angiogenesis is still unclear. This study was aimed to illuminate the possible mechanisms of SiNPs on angiogenesis in zebrafish transgenic lines, Tg(fli-1:EGFP) and Albino. SiNPs caused the cardiovascular malformations in a dose-dependent manner via intravenous microinjection. The incidences of cardiovascular malformations were observed as: Pericardial edema > Bradycardia > Blood deficiency. The area of subintestinal vessels (SIVs) was significant reduced in SiNPs-treated groups, accompanied with the weaken expression of vascular endothelial cells in zebrafish embryos. Using neutral red staining, the quantitative number of macrophage was declined; whereas macrophage inhibition rate was elevated in a dose-dependent way. Furthermore, SiNPs significantly decreased the mRNA expression of macrophage activity related gene, macrophage migration inhibitory factor (MIF) and the angiogenesis related gene, vascular endothelial growth factor receptor 2 (VEGFR2). The protein levels of p-Erk1/2 and p-p38 MAPK were markedly decreased in zebrafish exposed to SiNPs. Our results implicate that SiNPs inhibited the macrophage activity and angiogenesis via the downregulation of MAPK singaling pathway.

Incidence of an Aberrant Right Subclavian Artery on Second-Trimester Sonography in an Unselected Population.

OBJECTIVES: The aim of this study was to assess the incidence of an aberrant right subclavian artery (ARSA) among an unselected population during second-trimester sonography and to review the importance of this conotruncal variant as a marker of Down syndrome. METHODS: The presence or absence of an ARSA was assessed in an unselected population of 1913 second-trimester fetuses. RESULTS: Among the 1913 patients, an ARSA was detected in 20 fetuses (1.04%), all with a normal karyotype. Thirteen of 20 fetuses had an isolated ARSA, and 7 of them were nonisolated. Associated abnormal sonographic findings were an intracardiac echogenic focus (n = 3), a choroid plexus cyst (n = 1), pyelectasis (n = 1) and tetralogy of Fallot (n = 2). One of the cases of tetralogy of Fallot was also associated with a persistent left superior vena cava, a persistent right umbilical vein, hydrocephalus, rhombencephalosynapsis, and unilateral renal agenesis. There were only 2 fetuses with Down syndrome in this group, and both of them had a normal origin of the right subclavian artery. CONCLUSIONS: In an unselected population, an ARSA may be seen less frequently than in a high-risk population and may not be related to Down syndrome. An isolated ARSA is not a sufficient indication for karyotype analysis; it can be managed with noninvasive prenatal testing rather than invasive testing.

Aberrant Right Subclavian Artery: Correlation Between Fetal and Neonatal Abnormalities and Abnormal Genetic Screening or Testing.

OBJECTIVES: To determine whether fetuses with an isolated aberrant course of the right subclavian artery (ARSA) have increased risk for chromosomal abnormalities, including trisomy 21 or 22q11 deletion. METHODS: We performed a retrospective chart review of all fetuses with antenatally diagnosed ARSA. Data were collected from fetal anatomic surveys, fetal echocardiograms, noninvasive trisomy 21 screening programs, invasive genetic studies, and neonatal records. RESULTS: Seventy-nine fetuses with ARSA were identified at 20.3 ± 3.8 weeks' gestation. Forty-eight fetuses underwent chromosomal evaluation. Of those, seven had trisomy 21. Four other fetuses had unusual karyotype abnormalities. All fetuses with genetic anomalies had additional aberrant ultrasound findings. There were three spontaneous fetal deaths (trisomy 21-2 and Wolf-Hirshhorn-1). Nine pregnancies were terminated because of abnormalities and one died as a result of hypoplastic left heart syndrome. No neonate was found or suspected to have 22q11.2 deletion. The ARSA was isolated in 43 fetuses; all had unremarkable neonatal outcomes, and none were readmitted within 6 months after discharge. CONCLUSIONS: As an apparently isolated finding, ARSA is benign and not associated with trisomy 21 or 22q11.2 deletion. The finding of ARSA, however, warrants a detailed fetal ultrasound. All fetuses with ARSA and genetic anomalies had additional ultrasound findings.

Essential role of the TFIID subunit TAF4 in murine embryogenesis and embryonic stem cell differentiation.

TAF4 (TATA-binding protein-associated factor 4) and its paralogue TAF4b are components of the TFIID core module. We inactivated the murine Taf4a gene to address Taf4 function during embryogenesis. Here we show that Taf4a(-/-) embryos survive until E9.5 where primary germ layers and many embryonic structures are identified showing Taf4 is dispensable for their specification. In contrast, Taf4 is required for correct patterning of the trunk and anterior structures, ventral morphogenesis and proper heart positioning. Overlapping expression of Taf4a and Taf4b during embryogenesis suggests their redundancy at early stages. In agreement with this, Taf4a(-/-) embryonic stem cells (ESCs) are viable and comprise Taf4b-containing TFIID. Nevertheless, Taf4a(-/-) ESCs do not complete differentiation into glutamatergic neurons and cardiomyocytes in vitro due to impaired preinitiation complex formation at the promoters of critical differentiation genes. We define an essential role of a core TFIID TAF in differentiation events during mammalian embryogenesis.

Genetic and Developmental Basis of Cardiovascular Malformations.

Cardiovascular malformations (CVMs) are the most common birth defect, occurring in 1% to 5% of all live births. Genetic, epigenetic, and environmental factors all influence the development of CVMs, and an improved understanding of the causation of CVMs is a prerequisite for prevention. Cardiac development is a complex, multistep process of morphogenesis that is under genetic regulation. Although the genetic contribution to CVMs is well recognized, the genetic causes of human CVMs are still identified infrequently. This article discusses the key genetic concepts characterizing human CVMs, their developmental basis, and the critical developmental and genetic concepts underlying their pathogenesis.

p21-Activated Kinase 2 Regulates Endothelial Development and Function through the Bmk1/Erk5 Pathway.

p21-activated kinases (Paks) have been shown to regulate cytoskeleton rearrangements, cell proliferation, attachment, and migration in a variety of cellular contexts, including endothelial cells. However, the role of endothelial Pak in embryo development has not been reported, and currently, there is no consensus on the endothelial function of individual Pak isoforms, in particular p21-activated kinase 2 (Pak2), the main Pak isoform expressed in endothelial cells. In this work, we employ genetic and molecular studies that show that Pak2, but not Pak1, is a critical mediator of development and maintenance of endothelial cell function. Endothelial depletion of Pak2 leads to early embryo lethality due to flawed blood vessel formation in the embryo body and yolk sac. In adult endothelial cells, Pak2 depletion leads to severe apoptosis and acute angiogenesis defects, and in adult mice, endothelial Pak2 deletion leads to increased vascular permeability. Furthermore, ubiquitous Pak2 deletion is lethal in adult mice. We show that many of these defects are mediated through a newly unveiled Pak2/Bmk1 pathway. Our results demonstrate that endothelial Pak2 is essential during embryogenesis and also for adult blood vessel maintenance, and they also pinpoint the Bmk1/Erk5 pathway as a critical mediator of endothelial Pak2 signaling.

The impact of high-salt exposure on cardiovascular development in the early chick embryo.

In this study, we show that high-salt exposure dramatically increases chick mortality during embryo development. As embryonic mortality at early stages mainly results from defects in cardiovascular development, we focused on heart formation and angiogenesis. We found that high-salt exposure enhanced the risk of abnormal heart tube looping and blood congestion in the heart chamber. In the presence of high salt, both ventricular cell proliferation and apoptosis increased. The high osmolarity induced by high salt in the ventricular cardiomyocytes resulted in incomplete differentiation, which might be due to reduced expression of Nkx2.5 and GATA4. Blood vessel density and diameter were suppressed by exposure to high salt in both the yolk sac membrane (YSM) and chorioallantoic membrane models. In addition, high-salt-induced suppression of angiogenesis occurred even at the vasculogenesis stage, as blood island formation was also inhibited by high-salt exposure. At the same time, cell proliferation was repressed and cell apoptosis was enhanced by high-salt exposure in YSM tissue. Moreover, the reduction in expression of HIF2 and FGF2 genes might cause high-salt-suppressed angiogenesis. Interestingly, we show that high-salt exposure causes excess generation of reactive oxygen species (ROS) in the heart and YSM tissues, which could be partially rescued through the addition of antioxidants. In total, our study suggests that excess generation of ROS might play an important role in high-salt-induced defects in heart and angiogenesis.

Requirement of DLG1 for cardiovascular development and tissue elongation during cochlear, enteric, and skeletal development: possible role in convergent extension.

The Dlg1 gene encodes a member of the MAGUK protein family involved in the polarization of epithelial cells. Null mutant mice for the Dlg1 gene (Dlg1-/- mice) exhibit respiratory failure and cyanosis, and die soon after birth. However, the cause of this neonatal lethality has not been determined. In the present study, we further examined Dlg1-/- mice and found severe defects in the cardiovascular system, including ventricular septal defect, persistent truncus arteriosus, and double outlet right ventricle, which would cause the neonatal lethality. These cardiovascular phenotypes resemble those of mutant mice lacking planar cell polarity (PCP) genes and support a recent notion that DLG1 is involved in the PCP pathway. We assessed the degree of involvement of DLG1 in the development of other organs, as the cochlea, intestine, and skeleton, in which PCP signaling has been suggested to play a role. In the organ of Corti, tissue elongation was inhibited accompanied by disorganized arrangement of the hair cell rows, while the orientation of the stereocilia bundle was normal. In the sternum, cleft sternum, abnormal calcification pattern of cartilage, and disorganization of chondrocytes were observed. Furthermore, shortening of the intestine, sternum, and long bones of the limbs was observed. These phenotypes of Dlg1-/- mice involving cellular disorganization and insufficient tissue elongation strongly suggest a defect in the convergent extension movements in these mice. Thus, our present results provide a possibility that DLG1 is particularly required for convergent extension among PCP signaling-dependent processes.

Requisite role for Nck adaptors in cardiovascular development, endothelial-to-mesenchymal transition, and directed cell migration.

Development of the cardiovascular system is critically dependent on the ability of endothelial cells (ECs) to reorganize their intracellular actin architecture to facilitate migration, adhesion, and morphogenesis. Nck family cytoskeletal adaptors function as key mediators of actin dynamics in numerous cell types, though their role in EC biology remains largely unexplored. Here, we demonstrate an essential requirement for Nck within ECs. Mouse embryos lacking endothelial Nck1/2 expression develop extensive angiogenic defects that result in lethality at about embryonic day 10. Mutant embryos show immature vascular networks, with decreased vessel branching, aberrant perivascular cell recruitment, and reduced cardiac trabeculation. Strikingly, embryos deficient in endothelial Nck also fail to undergo the endothelial-to-mesenchymal transition (EnMT) required for cardiac valve morphogenesis, with loss of Nck disrupting expression of major EnMT markers, as well as suppressing mesenchymal outgrowth. Furthermore, we show that Nck-null ECs are unable to migrate downstream of vascular endothelial growth factor and angiopoietin-1, and they exhibit profound perturbations in cytoskeletal patterning, with disorganized cellular projections, impaired focal adhesion turnover, and disrupted actin-based signaling. Our collective findings thereby reveal a crucial role for Nck as a master regulator within the endothelium to control actin cytoskeleton organization, vascular network remodeling, and EnMT during cardiovascular development.

[Aberrant right subclavian artery (ARSA)--a new sonographic marker for chromosomal aberrations in the second trimester--preliminary observations]. / Bladzaca prawa tetnica podobojczykowa--nowy marker aberracji chromosomowych w badaniu USG drugiego trymestru--wstepne obserwacje na materiale wlasnym.

OBJECTIVES: Presentation of our own, preliminary experiences in the assessment of the right subclavian artery's (RSA) position during the second trimester scan. MATERIAL AND METHODS: Since January 2012 our center has started to conduct the assessment of the position of the right subclavian artery in the second trimester scan. Patients who were diagnosed with an aberrant right subclavian artery (ARSA) were referred to invasive method of prenatal diagnosis. Abnormal karyotype and microdeletion 22q11 were analyzed. Detailed echocardiography was conducted in each case. RESULTS: Between January 2012 and September 2013 we diagnosed 19 cases of ARSA. There were three cases of congenital heart defect (15.8%; 3/19) (ventricular septal defect--VSD, n=2, atrioventricular septal defect--AVSD, n=1). Two out of 17 cases showed an abnormal karyotype (11.8%; 2/17)--46,XY del(5) (q15q31) and 47,XX+18. No 22q11.2 deletions were observed. Two patients did not consent to invasive methods of prenatal diagnosis. CONCLUSIONS: The position of the right subclavian artery (RSA) should be routinely assessed during the second trimester of ultrasound screening. The presence of ARSA increases the risk for abnormal karyotype in the fetus and therefore, all patients who are diagnosed with ARSA should be referred to the reference center.

Bicuspid aortic valve morphology and associated cardiovascular abnormalities in fetal Turner syndrome: a pathomorphological study.

INTRODUCTION: Bicuspid aortic valve (BAV) is common in Turner syndrome (TS). In adult TS, 82-95% of BAVs have fusion of the right and left coronary leaflets. Data in fetal stages are scarce. The purpose of this study was to gain insight into aortic valve morphology and associated cardiovascular abnormalities in a fetal TS cohort with adverse outcome early in development. MATERIAL AND METHODS: We studied post-mortem heart specimens of 36 TS fetuses and 1 TS newborn. RESULTS: BAV was present in 28 (76%) hearts. BAVs showed fusion of the right and left coronary leaflet (type 1 BAV) in 61%, and fusion of the right coronary and non-coronary leaflet (type 2 BAV) in 39%. There were no significant differences in occurrence of additional cardiovascular abnormalities between type 1 and type 2 BAV. However, all type 2 BAV hearts showed ascending aorta hypoplasia and tubular hypoplasia of the B segment, as opposed to only 55 and 64% of type 1 BAV hearts, respectively. DISCUSSION: The proportion of type 2 BAV seems higher in TS fetuses than in adults. Fetal type 2 BAV hearts all had severe aortic pathology, possibly contributing to a worse prognosis of type 2 than type 1 BAV in TS.

Deletion of yes-associated protein (YAP) specifically in cardiac and vascular smooth muscle cells reveals a crucial role for YAP in mouse cardiovascular development.

RATIONALE: Our previous study has shown that yes-associated protein (YAP) plays a crucial role in the phenotypic modulation of vascular smooth muscle cells (SMCs) in response to arterial injury. However, the role of YAP in vascular SMC development is unknown. OBJECTIVE: The goal of this study was to investigate the functional role of YAP in cardiovascular development in mice and determine the mechanisms underlying YAP's actions. METHODS AND RESULTS: YAP was deleted in cardiomyocytes and vascular SMCs by crossing YAP flox mice with SM22α-Cre transgenic mice. Cardiac/SMC-specific deletion of YAP directed by SM22α-Cre resulted in perinatal lethality in mice because of profound cardiac defects including hypoplastic myocardium, membranous ventricular septal defect, and double outlet right ventricle. The cardiac/SMC-specific YAP knockout mice also displayed severe vascular abnormalities including hypoplastic arterial wall, short/absent brachiocephalic artery, and retroesophageal right subclavian artery. Deletion of YAP in mouse vascular SMCs induced expression of a subset of cell cycle arrest genes including G-protein-coupled receptor 132 (Gpr132). Silencing Gpr132 promoted SMC proliferation, whereas overexpression of Gpr132 attenuated SMC growth by arresting cell cycle in G0/G1 phase, suggesting that ablation of YAP-induced impairment of SMC proliferation was mediated, at least in part, by induction of Gpr132 expression. Mechanistically, YAP recruited the epigenetic repressor histone deacetylase-4 to suppress Gpr132 gene expression via a muscle CAT element in the Gpr132 gene. CONCLUSIONS: YAP plays a critical role in cardiac/SMC proliferation during cardiovascular development by epigenetically regulating expression of a set of cell cycle suppressors.

Mice generated by in vitro fertilization exhibit vascular dysfunction and shortened life span.

Children conceived by assisted reproductive technologies (ART) display a level of vascular dysfunction similar to that seen in children of mothers with preeclamspia. The long-term consequences of ART-associated vascular disorders are unknown and difficult to investigate in healthy children. Here, we found that vasculature from mice generated by ART display endothelial dysfunction and increased stiffness, which translated into arterial hypertension in vivo. Progeny of male ART mice also exhibited vascular dysfunction, suggesting underlying epigenetic modifications. ART mice had altered methylation at the promoter of the gene encoding eNOS in the aorta, which correlated with decreased vascular eNOS expression and NO synthesis. Administration of a deacetylase inhibitor to ART mice normalized vascular gene methylation and function and resulted in progeny without vascular dysfunction. The induction of ART-associated vascular and epigenetic alterations appeared to be related to the embryo environment; these alterations were possibly facilitated by the hormonally stimulated ovulation accompanying ART. Finally, ART mice challenged with a high-fat diet had roughly a 25% shorter life span compared with control animals. This study highlights the potential of ART to induce vascular dysfunction and shorten life span and suggests that epigenetic alterations contribute to these problems.

Inactivation of Cdc42 in neural crest cells causes craniofacial and cardiovascular morphogenesis defects.

Neural crest cells (NCCs) are physically responsible for craniofacial skeleton formation, pharyngeal arch artery remodeling and cardiac outflow tract septation during vertebrate development. Cdc42 (cell division cycle 42) is a Rho family small GTP-binding protein that works as a molecular switch to regulate cytoskeleton remodeling and the establishment of cell polarity. To investigate the role of Cdc42 in NCCs during embryonic development, we deleted Cdc42 in NCCs by crossing Cdc42 flox mice with Wnt1-cre mice. We found that the inactivation of Cdc42 in NCCs caused embryonic lethality with craniofacial deformities and cardiovascular developmental defects. Specifically, Cdc42 NCC knockout embryos showed fully penetrant cleft lips and short snouts. Alcian Blue and Alizarin Red staining of the cranium exhibited an unfused nasal capsule and palatine in the mutant embryos. India ink intracardiac injection analysis displayed a spectrum of cardiovascular developmental defects, including persistent truncus arteriosus, hypomorphic pulmonary arteries, interrupted aortic arches, and right-sided aortic arches. To explore the underlying mechanisms of Cdc42 in the formation of the great blood vessels, we generated Wnt1Cre-Cdc42-Rosa26 reporter mice. By beta-galactosidase staining, a subpopulation of Cdc42-null NCCs was observed halting in their migration midway from the pharyngeal arches to the conotruncal cushions. Phalloidin staining revealed dispersed, shorter and disoriented stress fibers in Cdc42-null NCCs. Finally, we demonstrated that the inactivation of Cdc42 in NCCs impaired bone morphogenetic protein 2 (BMP2)-induced NCC cytoskeleton remodeling and migration. In summary, our results demonstrate that Cdc42 plays an essential role in NCC migration, and inactivation of Cdc42 in NCCs impairs craniofacial and cardiovascular development in mice.

High glucose level induces cardiovascular dysplasia during early embryo development.

The incidence of gestational diabetes mellitus (GDM) has increased dramatically amongst multiethnic population. However, how gestational diabetes mellitus damages the developing embryo is still unknown. In this study, we used yolk sac membrane (YSM) model to investigate angiogenesis in the developing chick embryo. We determined that in the presence of high glucose, it retarded the growth and extension of the embryonic vascular plexus and it also reduced the density of the vasculature in yolk sac membrane model. Using the same strategy, we used the chorioallantoic membrane (CAM) as a model to investigate the influence of high glucose on the vasculature. We established that high glucose inhibited development of the blood vessel plexus and the blood vessels formed had a narrower diameter than control vessels. Concurrent with the abnormal angiogenesis, we also examined how it impacted cardiogenesis. We determined the myocardium in the right ventricle and left atrium were significantly thicker than the control and also there was a reduction in glycogen content in cardiomyocytes. The high glucose also induced excess reactive oxygen species (ROS) production in the cardiomyocytes. We postulated that it was the excess reactive oxygen species that damaged the cardiomyocytes resulting in cardiac hyperplasia.

Deletion of integrin-linked kinase from neural crest cells in mice results in aortic aneurysms and embryonic lethality.

Neural crest cells (NCCs) participate in the remodeling of the cardiac outflow tract and pharyngeal arch arteries during cardiovascular development. Integrin-linked kinase (ILK) is a serine/threonine kinase and a major regulator of integrin signaling. It links integrins to the actin cytoskeleton and recruits other adaptor molecules into a large complex to regulate actin dynamics and integrin function. Using the Cre-lox system, we deleted Ilk from NCCs of mice to investigate its role in NCC morphogenesis. The resulting mutants developed a severe aneurysmal arterial trunk that resulted in embryonic lethality during late gestation. Ilk mutants showed normal cardiac NCC migration but reduced differentiation into smooth muscle within the aortic arch arteries and the outflow tract. Within the conotruncal cushions, Ilk-deficient NCCs exhibited disorganization of F-actin stress fibers and a significantly rounder morphology, with shorter cellular projections. Additionally, absence of ILK resulted in reduced in vivo phosphorylation of Smad3 in NCCs, which correlated with reduced αSMA levels. Our findings resemble those seen in Pinch1 and ß1 integrin conditional mutant mice, and therefore support that, in neural crest-derived cells, ILK and Pinch1 act as cytoplasmic effectors of ß1 integrin in a pathway that protects against aneurysms. In addition, our conditional Ilk mutant mice might prove useful as a model to study aortic aneurysms caused by reduced Smad3 signaling, as occurs in the newly described aneurysms-osteoarthritis syndrome, for example.