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Circulation Research Sep 2008Congenital heart diseases are traditionally considered to be multifactorial in pathogenesis resulting from environmental and genetic interactions that determine...
Congenital heart diseases are traditionally considered to be multifactorial in pathogenesis resulting from environmental and genetic interactions that determine penetrance and expressivity within a genetically predisposed family. Recent evidence suggests that genetic contributions have been significantly underestimated. However, single gene defects occur only in a minority of cases, and multigenetic causes of congenital heart diseases have not been fully demonstrated. Here, we show that interactions between alleles of 3 Pbx genes, which encode homeodomain transcription factors, are sufficient to determine the phenotypic presentation of congenital heart diseases in mice. A major role is served by Pbx1, whose inactivation results in persistent truncus arteriosus. Reduction or absence of Pbx2 or Pbx3 leads to Pbx1 haploinsufficiency and specific malformations that resemble tetralogy of Fallot, overriding aorta with ventricular septal defect, and bicuspid aortic valves. Disruption of Meis1, which encodes a Pbx DNA-binding partner, results in cardiac anomalies that resemble those caused by Pbx mutations. Each of the observed cardiac defects represents developmental abnormalities affecting distinct stages of cardiac outflow tract development and corresponds to specific types of human congenital heart disease. Thus, varied deficiencies in the Pbx gene family produce a full spectrum of cardiac defects involving the outflow tract, providing a framework for determining multigenetic causes of congenital heart anomalies.
Topics: Alleles; Animals; Heart Defects, Congenital; Homeodomain Proteins; Humans; Mice; Mice, Knockout; Myeloid Ecotropic Viral Integration Site 1 Protein; Neoplasm Proteins; Pre-B-Cell Leukemia Transcription Factor 1; Proto-Oncogene Proteins; Transcription Factors
PubMed: 18723445
DOI: 10.1161/CIRCRESAHA.108.175489 -
Developmental Biology Jul 2008Here we report that mouse embryos homozygous for a gene trap insertion in the fibulin-1 (Fbln1) gene are deficient in Fbln1 and exhibit cardiac ventricular wall thinning...
Here we report that mouse embryos homozygous for a gene trap insertion in the fibulin-1 (Fbln1) gene are deficient in Fbln1 and exhibit cardiac ventricular wall thinning and ventricular septal defects with double outlet right ventricle or overriding aorta. Fbln1 nulls also display anomalies of aortic arch arteries, hypoplasia of the thymus and thyroid, underdeveloped skull bones, malformations of cranial nerves and hemorrhagic blood vessels in the head and neck. The spectrum of malformations is consistent with Fbln1 influencing neural crest cell (NCC)-dependent development of these tissues. This is supported by evidence that Fbln1 expression is associated with streams of cranial NCCs migrating adjacent to rhombomeres 2-7 and that Fbln1-deficient embryos display patterning anomalies of NCCs forming cranial nerves IX and X, which derive from rhombomeres 6 and 7. Additionally, Fbln1-deficient embryos show increased apoptosis in areas populated by NCCs derived from rhombomeres 4, 6 and 7. Based on these findings, it is concluded that Fbln1 is required for the directed migration and survival of cranial NCCs contributing to the development of pharyngeal glands, craniofacial skeleton, cranial nerves, aortic arch arteries, cardiac outflow tract and cephalic blood vessels.
Topics: Animals; CD4 Antigens; Calcium-Binding Proteins; Cerebrovascular Circulation; Chromosome Mapping; Crosses, Genetic; Endoplasmic Reticulum; Fetal Heart; Genotype; Heart Ventricles; Immunohistochemistry; Mice; Mice, Knockout; Morphogenesis; Neural Crest; Polymerase Chain Reaction; beta-Galactosidase
PubMed: 18538758
DOI: 10.1016/j.ydbio.2008.04.029 -
Molecular and Cellular Biology Mar 2008The Cdc42-like GTPase Wnt responsive Cdc42 homolog 1 (Wrch1) has several atypical features; it has an N-terminal proline-rich extension that confers binding to SH3...
The Cdc42-like GTPase Wnt responsive Cdc42 homolog 1 (Wrch1) has several atypical features; it has an N-terminal proline-rich extension that confers binding to SH3 domains, and it harbors an extremely high intrinsic nucleotide exchange activity, which overrides the normal GTPase activity. As a result, Wrch1 resides mainly in the active, GTP-loaded conformation under normal cellular conditions. We have previously shown that ectopic expression of Wrch1 in fibroblasts resulted in an altered cell morphology visible as a formation of filopodia, a loss of stress fibers, and a reduction in focal adhesions. Here, we show that Wrch1 binds to the nonreceptor tyrosine kinase Pyk2. The interaction required Wrch1 to be in a GTP conformation and also required an intact N-terminal proline-rich extension as well as an intact effector loop. Wrch1 requires Pyk2 in imposing the cytoskeletal effects, seen as the formation of filopodia, since treatment of cells with a Pyk2-specific small interfering RNA abrogated this response. Interestingly, we found that the presence and activity of Src were needed for the formation of a Wrch1-Pyk2 complex as well as for the Wrch1-induced formation of filopodia. We propose a model in which Pyk2 and Src function to coordinate the Wrch1-dependent effects on cytoskeletal dynamics.
Topics: Animals; Aorta; Cell Line; Cells, Cultured; Cytoskeleton; Endothelial Cells; Endothelium, Vascular; Female; Fibroblasts; Focal Adhesion Kinase 2; Humans; Immunohistochemistry; Kidney; Mice; Mice, Knockout; Mutation; Plasmids; Pregnancy; Protein Conformation; Proto-Oncogene Proteins pp60(c-src); Pseudopodia; RNA, Small Interfering; Swine; Transfection; Two-Hybrid System Techniques; cdc42 GTP-Binding Protein
PubMed: 18086875
DOI: 10.1128/MCB.00201-07 -
Developmental Biology Aug 2007Msx1 and Msx2 are highly conserved, Nk-related homeodomain transcription factors that are essential for a variety of tissue-tissue interactions during vertebrate...
Msx1 and Msx2 are highly conserved, Nk-related homeodomain transcription factors that are essential for a variety of tissue-tissue interactions during vertebrate organogenesis. Here we show that combined deficiencies of Msx1 and Msx2 cause conotruncal anomalies associated with malalignment of the cardiac outflow tract (OFT). Msx1 and Msx2 play dual roles in outflow tract morphogenesis by both protecting secondary heart field (SHF) precursors against apoptosis and inhibiting excessive proliferation of cardiac neural crest, endothelial and myocardial cells in the conotruncal cushions. During incorporation of SHF precursors into the OFT myocardium, ectopic apoptosis in the Msx1-/-; Msx2-/- mutant SHF is associated with reduced expression of Hand1 and Hand2, which from work on Hand1 and Hand2 mutants may be functionally important in the inhibition of apoptosis in Msx1/2 mutants. Later during aorticopulmonary septation, excessive proliferation in the OFT cushion mesenchyme and myocardium of Msx1-/-; Msx2-/- mutants is associated with premature down-regulation of p27(KIP1), an inhibitor of cyclin-dependent kinases. Diminished accretion of SHF precursors to the elongating OFT myocardium and excessive accumulation of mesenchymal cells in the conotruncal cushions may work together to perturb the rotation of the truncus arteriosus, leading to OFT malalignment defects including double-outlet right ventricle, overriding aorta and pulmonary stenosis.
Topics: Animals; Apoptosis; Body Patterning; Bone Morphogenetic Protein 2; Bone Morphogenetic Protein 4; Bone Morphogenetic Proteins; Cell Movement; Cell Proliferation; Cell Survival; Cyclin-Dependent Kinase Inhibitor p27; DNA-Binding Proteins; Female; Fetal Heart; Gene Expression Regulation, Developmental; Genes, Homeobox; Heart Defects, Congenital; Homeodomain Proteins; MSX1 Transcription Factor; Male; Mice; Mice, Inbred BALB C; Mice, Knockout; Mutation; Neural Crest; Pregnancy; Signal Transduction; Transforming Growth Factor beta
PubMed: 17601530
DOI: 10.1016/j.ydbio.2007.05.037 -
The Journal of Veterinary Medical... Jan 2007A 5-month-old female Korean Sapsaree dog was presented with severe ascites, cyanosis, respiratory difficulty and exercise intolerance. Diagnostic imaging studies...
A 5-month-old female Korean Sapsaree dog was presented with severe ascites, cyanosis, respiratory difficulty and exercise intolerance. Diagnostic imaging studies revealed a dextropositioned and over-riding aorta, pulmonary valvular stenosis, ventricular and atrial septal defects, and right ventricular hypertrophy. Based on these findings, the dog was diagnosed as a case of tetralogy of Fallot with atrial septal defect (pentalogy of Fallot). The dog was medically managed by use of diuretics and vasodilators and an occasional phlebotomy.
Topics: Animals; Diuretics; Dog Diseases; Dogs; Electrocardiography; Female; Phlebotomy; Tetralogy of Fallot; Vasodilator Agents
PubMed: 17283405
DOI: 10.1292/jvms.69.73 -
American Journal of Physiology. Heart... Feb 2007On the basis of our previous studies on RhoA signaling in smooth muscle cells (SMC), we hypothesized that RhoA-mediated nuclear translocalization of the... (Comparative Study)
Comparative Study
On the basis of our previous studies on RhoA signaling in smooth muscle cells (SMC), we hypothesized that RhoA-mediated nuclear translocalization of the myocardin-related transcription factors (MRTFs) was important for regulating SMC phenotype. MRTF-A protein and MRTF-B message were detected in aortic SMC and in many adult mouse organs that contain a large SMC component. Both MRTFs upregulated SMC-specific promoter activity as well as endogenous SM22alpha expression in multipotential 10T1/2 cells, although to a lesser extent than myocardin. We used enhanced green fluorescent protein (EGFP) fusion proteins to demonstrate that the myocardin factors have dramatically different localization patterns and that the stimulation of SMC-specific transcription by certain RhoA-dependent agonists was likely mediated by increased nuclear translocation of the MRTFs. Importantly, a dominant-negative form of MRTF-A (DeltaB1/B2) that traps endogenous MRTFs in the cytoplasm inhibited the SM alpha-actin, SM22alpha, and SM myosin heavy chain promoters in SMC and attenuated the effects of sphingosine 1-phosphate and transforming growth factor (TGF)-beta on SMC-specific transcription. Our data confirmed the importance of the NH(2)-terminal RPEL domains for regulating MRTF localization, but our analysis of MRTF-A/myocardin chimeras and myocardin RPEL2 mutations indicated that the myocardin B1/B2 region can override this signal. Gel shift assays demonstrated that myocardin factor activity correlated well with ternary complex formation at the SM alpha-actin CArGs and that MRTF-serum response factor interactions were partially dependent on CArG sequence. Taken together, our results indicate that the MRTFs regulate SMC-specific gene expression in at least some SMC subtypes and that regulation of MRTF nuclear localization may be important for the effects of selected agonists on SMC phenotype.
Topics: Active Transport, Cell Nucleus; Animals; Aorta, Thoracic; Cell Differentiation; Cell Nucleus; Cells, Cultured; Lysophospholipids; Microfilament Proteins; Muscle Proteins; Muscle, Smooth, Vascular; Mutation; Myocytes, Smooth Muscle; Nuclear Proteins; Phenotype; Platelet-Derived Growth Factor; Promoter Regions, Genetic; RNA, Messenger; Rats; Serum Response Factor; Sphingosine; Time Factors; Trans-Activators; Transcription, Genetic; Transfection; Transforming Growth Factor beta; rhoA GTP-Binding Protein
PubMed: 16997888
DOI: 10.1152/ajpheart.00864.2006 -
Developmental Biology Aug 2005Several syndromes characterized by defects in cardiovascular and craniofacial development are associated with a hemizygous deletion of chromosome 22q11 in humans and... (Comparative Study)
Comparative Study
Several syndromes characterized by defects in cardiovascular and craniofacial development are associated with a hemizygous deletion of chromosome 22q11 in humans and involve defects in pharyngeal arch and neural crest cell development. Recent efforts have focused on identifying 22q11 deletion syndrome modifying loci. In this study, we show that mouse embryos deficient for Gbx2 display aberrant neural crest cell patterning and defects in pharyngeal arch-derived structures. Gbx2(-/-) embryos exhibit cardiovascular defects associated with aberrant development of the fourth pharyngeal arch arteries including interrupted aortic arch type B, right aortic arch, and retroesophageal right subclavian artery. Other developmental abnormalities include overriding aorta, ventricular septal defects, cranial nerve, and craniofacial skeletal patterning defects. Recently, Fgf8 has been proposed as a candidate modifier for 22q11 deletion syndromes. Here, we demonstrate that Fgf8 and Gbx2 expression overlaps in regions of the developing pharyngeal arches and that they interact genetically during pharyngeal arch and cardiovascular development.
Topics: Animals; Arteries; Body Patterning; Branchial Region; Fibroblast Growth Factor 8; Gene Expression Regulation, Developmental; Homeodomain Proteins; Immunohistochemistry; In Situ Hybridization; Mice; Microscopy, Confocal; Neural Crest
PubMed: 15996652
DOI: 10.1016/j.ydbio.2005.05.023 -
Developmental Biology Aug 2005Recent studies in chick and mouse embryos have identified a previously unrecognized secondary heart field (SHF), located in the ventral midline splanchnic mesenchyme,... (Comparative Study)
Comparative Study
Recent studies in chick and mouse embryos have identified a previously unrecognized secondary heart field (SHF), located in the ventral midline splanchnic mesenchyme, which provides additional myocardial cells to the outflow tract as the heart tube lengthens during cardiac looping. In order to further delineate the contribution of this secondary myocardium to outflow development, we labeled the right SHF of Hamburger-Hamilton (HH) stage 14 chick embryos via microinjection of DiI/rhodamine and followed the fluorescently labeled cells over a 96-h time period. These experiments confirmed the movement of the SHF into the outflow and its spiraling migration distally, with the right side of the SHF contributing to the left side of the outflow. In contrast, when the right SHF was labeled at HH18, the fluorescence was limited to the caudal wall of the lengthening aortic sac. We then injected a combination of DiI and neutral red dye, and ablated the SHF in HH14 or 18 chick embryos. Embryos were allowed to develop until day 9, and harvested for assessment of outflow alignment. Of the embryos ablated at HH14, 76% demonstrated cardiac defects including overriding aorta and pulmonary atresia, while none of the sham-operated controls were affected. In addition, the more severely affected embryos demonstrated coronary artery anomalies. The embryos ablated at HH18 also manifested coronary artery anomalies but maintained normal outflow alignment. Therefore, the myocardium added to the outflow by the SHF at earlier stages is required for the elongation and appropriate alignment of the outflow tract. However, at later stages, the SHF contributes to the smooth muscle component of the outflow vessels above the pulmonary and aortic valves which is important for the development of the coronary artery stems. This work suggests a role for the SHF in a subset of congenital heart defects that have overriding aorta and coronary artery anomalies, such as tetralogy of Fallot and double outlet right ventricle.
Topics: Animals; Carbocyanines; Chick Embryo; Fluorescent Dyes; Heart; Immunohistochemistry; In Situ Hybridization; Models, Biological; Morphogenesis; Myocardium; Pulmonary Atresia; Tetralogy of Fallot
PubMed: 15950213
DOI: 10.1016/j.ydbio.2005.05.003 -
Journal of Virology Jan 2005To override the diffusion-limited adsorption step of viral infection, we magnetically synchronized cell attachment. Human immunodeficiency virus type 1-based lentivirus...
To override the diffusion-limited adsorption step of viral infection, we magnetically synchronized cell attachment. Human immunodeficiency virus type 1-based lentivirus preparations were rendered magnetically reactive by association with magnetite nanoparticles, 50 nm in diameter. Application of a magnetic field resulted in immediate redistribution of the viral inoculum to the cell-associated state and completion of the productive adsorption process within 1 min. Independent of adsorption time, viral concentration, and diffusion rate, infection subsequently progressed by the receptor-mediated entry mechanism. Synchronization of this rate-limiting step of infection may now be applied to analyze isolated events in the viral replication sequence.
Topics: Adsorption; Animals; Aorta; Cells, Cultured; Endothelial Cells; Endothelium, Vascular; Lentivirus; Magnetics; Membrane Glycoproteins; Rats; Receptors, Virus; Viral Envelope Proteins; Virology
PubMed: 15596857
DOI: 10.1128/JVI.79.1.622-625.2005 -
Croatian Medical Journal Apr 2003A thirty-year-old man with the diagnosis of the tetralogy of Fallot and patent ductus arteriosus was admitted to our hospital because of a syncope. He reported no...
A thirty-year-old man with the diagnosis of the tetralogy of Fallot and patent ductus arteriosus was admitted to our hospital because of a syncope. He reported no previous symptoms. We diagnosed adult tetralogy of Fallot, which included all four characteristic anomalies: ventricular septal defect, overriding aorta, pulmonary artery stenosis, and right ventricular hypertrophy. The associated persistent ductus arteriosus and the presence of compensatory arteriovenous communications produced a continuous flow load on the left ventricle, which resulted in moderate left ventricular hypertrophy, but without symptoms of pulmonary congestion or cardiac decompensation. Anatomic diagnosis and hemodynamic assessment were established by transthoracic and transesophageal echocardiography, with incidental finding of a quadricuspid aortic valve. To the best of our knowledge, our case of the adult form of Fallot's tetralogy associated with both patent ductus arteriosus and quadricuspid aortic valve is the first one ever described. It is well known that patients with tetralogy of Fallot who do not undergo operation in childhood have short survival, which depends predominantly on the degree of pulmonary artery stenosis and early development of collateral circulation to the lungs. Long-term persistence of natural aortopulmonary anastomosis with systemic collateral circulation to the lungs and remodeling of the heart, with better hemodynamic balance as well as the presence of mild pulmonary artery stenosis probably enhanced the survival of our patient.
Topics: Adult; Aortic Valve; Croatia; Ductus Arteriosus, Patent; Echocardiography; Humans; Male; Palliative Care; Tetralogy of Fallot
PubMed: 12698517
DOI: No ID Found