transforming-growth-factor-beta and Craniofacial-Abnormalities

Craniofacial development is a complex process involving several signaling pathways, including the one regulated by the TGF-beta (TGF-β) superfamily of growth factors. Isoforms of TGF-β play a vital part in embryonic development, notably in craniofacial patterning. Consequently, pathogenic variants in their coding genes may result in a variety of orofacial and craniofacial malformations. Here, we review the impact of genetic variability of TGF-β signaling biomarkers in major disorders, including palatal and lip clefts, dental anomalies, and craniofacial syndromes, such as the Loeys-Dietz syndrome (LDS) and Camurati-Engelmann disease. Cleft lip and cleft palate are associated with missense mutations in the TGFB1 and TGFB3 genes, while mutations in the LTBP3 gene encoding TGF-β binding protein 3 may cause selective tooth agenesis. Oligodontia may also be caused by TGFB1-inactivating mutations and/or by variations in the GREM2 gene, which disrupt the activity of gremlin 2, a TGF-β/bone morphogenetic protein (BMP4) signaling antagonist. CED may be caused by mutations in the TGFB1 gene, while the TGF-β-related genetic background of LDS consists mostly of TGFBR1 and TGFBR2 mutations, which may also impact the above syndromes' vascular manifestations. The potential utility of the TGF-β signaling pathway factors as biomarkers that correlate genetics with clinical outcome of craniofacial malformations is discussed.

Topics: Biomarkers; Craniofacial Abnormalities; Humans; Loeys-Dietz Syndrome; Receptors, Transforming Growth Factor beta; Signal Transduction; Transforming Growth Factor beta

Between 2 and 10 years of age, the developing craniofacial skeleton poses a significant reconstructive challenge. Local autogenous bone is largely unavailable, distant bone grafts are fraught with significant morbidity and limited yield, and alloplastic materials are incompatible with the growing calvarium and facial skeleton. Bone morphogenetic protein (BMP) 2, a member of a class of proteins first noticed in the 1960s to promote bone deposition in soft tissues, offers a potential solution to the bone shortage historically faced by the pediatric craniofacial surgeon. A review of English language literature was conducted from the 1960s to the present.Attention was focused on BMP-2's osteoinductive mechanism, basic science and translational laboratory findings, and multidisciplinary clinical experiences. Bone morphogenetic protein 2 has been embraced by spine surgeons, is gaining in popularity for long-bone repair, and is making its way into the plastic surgery literature. Bone morphogenetic protein 2 may provide a basis for an off-the-shelf tissue-engineered bone construct that is compatible with the growing craniofacial skeleton while free from the morbidities of distant graft harvest. Questions remain, however, regarding the safety and efficacy of this compound in the context of pediatric craniofacial surgery. In an effort to facilitate the clinician's risk-benefit analysis of this emerging technology, we present a primer on the basic science of BMP-2, a discussion of possible morbidities associated with its use, a review of laboratory and clinical trials with this substance to date, and an analysis of strategies to maximize its efficacy in craniofacial surgery.

Topics: Animals; Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins; Bone Regeneration; Core Binding Factor Alpha 1 Subunit; Craniofacial Abnormalities; Craniotomy; Humans; Osteoblasts; Osteogenesis; Recombinant Proteins; Signal Transduction; Skull; Smad Proteins, Inhibitory; Transforming Growth Factor beta

Topics: Activin Receptors; Activins; Animals; Bone Morphogenetic Proteins; Craniofacial Abnormalities; Embryonic Development; Embryonic Induction; Face; Growth Substances; Head; Inhibins; Ligands; Mice; Neural Crest; Receptors, Transforming Growth Factor beta; Signal Transduction; Transforming Growth Factor beta

Topics: Abnormalities, Multiple; Animals; Camurati-Engelmann Syndrome; Chromosome Aberrations; Chromosomes, Human, Pair 5; Cloning, Molecular; Craniofacial Abnormalities; Humans; Mutation; Peptide Fragments; Polydactyly; Protein Precursors; Syndrome; Transforming Growth Factor beta; Transforming Growth Factor beta1

Recombinant human bone morphogenetic protein-2 (rhBMP-2) and bioceramic are the widely used bioactive factors in treatment of bone defects, but these easily cause side effects because of uncontrollable local concentration. In this study, rhBMP-2 was grafted on the surface of mesoporous bioglass nanoparticles (MBGNs) with an amide bond and then photo-cross-linked together with methacrylate gelatin (GelMA); in this way, a GelMA/MBGNs-rhBMP-2 hydrogel membrane was fabricated to release rhBMP-2 in a controllable program during the early bone regeneration period and then release calcium and silicon ions to keep promoting osteogenesis instead of rhBMP-2 in a long term. In this way, rhBMP-2 can keep releasing for 4 weeks and then the ions keep releasing after 4 weeks; this process is matched to early and late osteogenesis procedures. In vitro study demonstrated that the early release of rhBMP-2 can effectively promote local cell osteogenic differentiation in a short period, and then, the inorganic ions can promote cell adhesion not only in the early stage but also keep promoting osteogenic differentiation for a long period. Finally, the GelMA/MBGNs-rhBMP-2 hydrogel shows a superior capacity in long-term osteogenesis and promoting bone tissue regeneration in rat calvarial critical size defect. This GelMA/MBGNs-rhBMP-2 hydrogel demonstrated a promising strategy for the controllable and safer use of bioactive factors such as rhBMP-2 in artificial periosteum to accelerate bone repairing.

Topics: Animals; Bone Morphogenetic Protein 2; Bone Regeneration; Calcium; Cell Adhesion; Craniofacial Abnormalities; Delayed-Action Preparations; Drug Delivery Systems; Gelatin; Humans; Hydrogels; Nanoparticles; Osteogenesis; Periosteum; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Silicon; Transforming Growth Factor beta

Xq25q26 duplication syndrome has been reported in individuals with clinical features such as short stature, intellectual disability, syndromic facial appearance, small hands and feet, and genital abnormalities. The symptoms are related to critical chromosome regions including Xq26.1-26.3. In this particular syndrome, no patient with congenital heart disease was previously reported. Here, we report a 6-year-old boy with typical symptoms of Xq25q26 duplication syndrome and double outlet right ventricle (DORV) with pulmonary atresia (PA). He had the common duplicated region of Xq25q26 duplication syndrome extending to the distal region including the MOSPD1 locus. MOSPD1 regulates transforming growth factor beta (TGFβ) 2,3 and may be responsible for cardiac development including DORV. In the patient's lymphocytes, mRNA expression of TGFβ2 was lower than control, and might cause DORV as it does in TGFβ2-deficient mice. Therefore, MOSPD1 is a possible candidate gene for DORV, probably in combination with GPC3. Further studies of the combined functions of MOSPD1 and GPC3 are needed, and identification of additional patients with MOSPD1 and GPC3 duplication should be pursued.

Topics: Child; Chromosome Duplication; Chromosomes, Human, X; Craniofacial Abnormalities; Double Outlet Right Ventricle; Dwarfism; Ear; Glypicans; Humans; Intellectual Disability; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Neck; Sex Chromosome Aberrations; Sex Chromosome Disorders; Thorax; Transforming Growth Factor beta; Trisomy

Bone morphogenetic protein 2 (BMP2) in chromosomal region 20p12 belongs to a gene superfamily encoding TGF-β-signaling proteins involved in bone and cartilage biology. Monoallelic deletions of 20p12 are variably associated with cleft palate, short stature, and developmental delay. Here, we report a cranioskeletal phenotype due to monoallelic truncating and frameshift BMP2 variants and deletions in 12 individuals from eight unrelated families that share features of short stature, a recognizable craniofacial gestalt, skeletal anomalies, and congenital heart disease. De novo occurrence and autosomal-dominant inheritance of variants, including paternal mosaicism in two affected sisters who inherited a BMP2 splice-altering variant, were observed across all reported families. Additionally, we observed similarity to the human phenotype of short stature and skeletal anomalies in a heterozygous Bmp2-knockout mouse model, suggesting that haploinsufficiency of BMP2 could be the primary phenotypic determinant in individuals with predicted truncating variants and deletions encompassing BMP2. These findings demonstrate the important role of BMP2 in human craniofacial, skeletal, and cardiac development and confirm that individuals heterozygous for BMP2 truncating sequence variants or deletions display a consistent distinct phenotype characterized by short stature and skeletal and cardiac anomalies without neurological deficits.

Topics: Animals; Bone and Bones; Bone Morphogenetic Protein 2; Child; Child, Preschool; Chromosomes, Human, Pair 20; Cleft Palate; Craniofacial Abnormalities; Developmental Disabilities; Disease Models, Animal; Dwarfism; Female; Haploinsufficiency; Heart; Heart Defects, Congenital; Humans; Infant; Male; Mice; Mice, Knockout; Transforming Growth Factor beta

The Pierre Robin Sequence (PRS), consisting of cleft palate, glossoptosis and micrognathia, is a common human birth defect. However, how this abnormality occurs remains largely unknown. Here we report that neural crest cell (NCC)-specific knockout of transferrin receptor (Tfrc), a well known transferrin transporter protein, caused micrognathia, cleft palate, severe respiratory distress and inability to suckle in mice, which highly resemble human PRS. Histological and anatomical analysis revealed that the cleft palate is due to the failure of palatal shelves elevation that resulted from a retarded extension of Meckel's cartilage. Interestingly, Tfrc deletion dramatically suppressed both transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signaling in cranial NCCs-derived mandibular tissues, suggesting that Tfrc may act as a facilitator of these two signaling pathways during craniofacial morphogenesis. Together, our study uncovers an unknown function of Tfrc in craniofacial development and provides novel insight into the etiology of PRS.

Topics: Animals; Bone Morphogenetic Proteins; Cell Differentiation; Cell Movement; Cell Proliferation; Chondrogenesis; Cleft Palate; Craniofacial Abnormalities; Gene Deletion; Mandible; Mice; Morphogenesis; Mutation; Neural Crest; Osteogenesis; Receptors, Transferrin; Signal Transduction; Transforming Growth Factor beta; Wnt Proteins

Multiple assessment methods are available to evaluate the performance of engineered scaffolds in accepted bone healing animal models. Evaluation and comparison of these methods can aid in the planning of future animal studies, as well as, inform clinical assessments as the engineered scaffolds translate into clinical studies and applications. To evaluate multiple bone assessment techniques, bone regrowth potential of tyrosine-derived polycarbonate (TyrPC) scaffolds loaded with various dosages of recombinant human bone morphogenetic protein-2 (rhBMP-2) (0, 10, 25, and 50 μg) was assessed after 16 weeks in vivo in a rabbit calvarial model. Traditional X-ray radiography and micro-computed tomography (micro-CT) analyses were used to quantify the volume and density of regenerated bone. Histomorphometric analysis was performed as the traditional gold standard of evaluation. While these techniques are fairly standard in bone tissue engineering, we also investigated 64-slice CT, a tool more commonly used clinically, for comparison and to guide translational efforts. The 64-slice CT scans were carried out at 4 and 16 weeks to monitor temporal bone healing patterns. Study results indicated a clear dose-dependent response of increasing regenerated bone volume with rhBMP-2 loaded on the TyrPC scaffolds after 16 weeks of implantation. Significantly more bone formation was observed at the highest dose of rhBMP-2 (50 μg), which is 25-50% of the previously recommended dose (100-200 μg) for this defect. A significant difference was observed between the lowest and highest doses using radiographs (p<0.001), micro-CT (p=0.002), and CT (p<0.001) and a high correlation was found between techniques (R(2) values between 0.446 and 0.911). It was found that the number of animals required per group to detect significant dose effects ranged between 6 and 8 for the imaging methods while histomorphometric analysis would require 25 animals per group to detect similar differences (desired power=0.9, α=0.05). Radiographic analysis provided quantifiable % defect coverage and radio-opacity, micro-CT provided spatial volumetric and bone density measures, histomorphometry provided biological confirmation, and 64-slice CT allowed for establishing of clinically relevant translational guidelines. These methodologies allow for a standardized and comprehensive description of bone regeneration and provide guidelines for the planning of future preclinical and clinical studies.

Topics: Animals; Bone Morphogenetic Protein 2; Bone Regeneration; Craniofacial Abnormalities; Dose-Response Relationship, Drug; Female; Humans; Imaging, Three-Dimensional; Rabbits; Recombinant Proteins; Regenerative Medicine; Tomography, X-Ray Computed; Transforming Growth Factor beta

Otitis media with effusion (OME) is the most common cause of hearing loss in children and tympanostomy to alleviate the condition remains the commonest surgical intervention in children in the developed world. Chronic and recurrent forms of OM are known to have a very significant genetic component, however, until recently little was known of the underlying genes involved. The identification of mouse models of chronic OM has indicated a role of transforming growth factor beta (TGFβ) signalling and its impact on responses to hypoxia in the inflamed middle ear. We have, therefore, investigated the role of TGFβ signalling and identified and characterized a new model of chronic OM carrying a mutation in the gene for transforming growth interacting factor 1 (Tgif1). Tgif1 homozygous mutant mice have significantly raised auditory thresholds due to a conductive deafness arising from a chronic effusion starting at around 3 weeks of age. The OM is accompanied by a significant thickening of the middle ear mucosa lining, expansion of mucin-secreting goblet cell populations and raised levels of vascular endothelial growth factor, TNF-α and IL-1β in ear fluids. We also identified downstream effects on TGFβ signalling in middle ear epithelia at the time of development of chronic OM. Both phosphorylated SMAD2 and p21 levels were lowered in the homozygous mutant, demonstrating a suppression of the TGFβ pathway. The identification and characterization of the Tgif mutant supports the role of TGFβ signalling in the development of chronic OM and provides an important candidate gene for genetic studies in the human population.

Topics: Animals; Craniofacial Abnormalities; Cytokines; Disease Models, Animal; Ear, Middle; Epithelial Cells; Female; Genotype; Hair Cells, Auditory; Hearing Loss; Homeodomain Proteins; Homozygote; Male; Mice; Mice, Knockout; Mutation; Otitis Media; Phenotype; Placenta; Pregnancy; Repressor Proteins; Signal Transduction; Transforming Growth Factor beta

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 β1 integrin conditional mutant mice, and therefore support that, in neural crest-derived cells, ILK and Pinch1 act as cytoplasmic effectors of β1 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.

Topics: Actin Cytoskeleton; Animals; Aorta, Thoracic; Aortic Aneurysm; Cardiovascular Abnormalities; Cell Differentiation; Cell Movement; Cell Proliferation; Craniofacial Abnormalities; Embryo Loss; Embryo, Mammalian; Gene Deletion; Integrases; Mice; Mice, Mutant Strains; Morphogenesis; Neural Crest; Organ Specificity; Phenotype; Protein Serine-Threonine Kinases; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta; Wnt Proteins

Cranial neural crest cells form much of the facial skeleton, and abnormalities in their development lead to severe birth defects. In a novel zebrafish protein trap screen, we identified an RNA-binding protein, Rbms3, that is transiently expressed in the cytoplasm of condensing neural crest cells within the pharyngeal arches. Morphants for rbms3 displayed reduced proliferation of prechondrogenic crest and significantly altered expression for chondrogenic/osteogenic lineage markers. This phenotype strongly resembles cartilage/crest defects observed in Tgf-βr2:Wnt1-Cre mutants, which suggests a possible link with TGF-β signaling. Consistent with this are the findings that: (a) Rbms3 stabilized a reporter transcript with smad2 3' untranslated region, (b) RNA immunoprecipitation with full-length Rbms3 showed enrichment for smad2/3, and (c) pSmad2 levels were reduced in rbms3 morphants. Overall, these results suggest that Rbms3 posttranscriptionally regulates one of the major pathways that promotes chondrogenesis, the transforming growth factor β receptor (TGF-βr) pathway.

Topics: Amino Acid Sequence; Animals; Apoptosis; Blotting, Western; Cartilage; Cell Differentiation; Cell Proliferation; Chondrogenesis; Craniofacial Abnormalities; Embryo, Nonmammalian; Fluorescent Antibody Technique; Gene Expression Regulation, Developmental; Immunoprecipitation; In Situ Hybridization; Molecular Sequence Data; Neural Crest; Real-Time Polymerase Chain Reaction; Receptors, Transforming Growth Factor beta; Reverse Transcriptase Polymerase Chain Reaction; RNA Processing, Post-Transcriptional; RNA-Binding Proteins; RNA, Messenger; Signal Transduction; Transforming Growth Factor beta; Zebrafish; Zebrafish Proteins

Topics: Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins; Bone Regeneration; Bone Resorption; Craniofacial Abnormalities; Humans; Ossification, Heterotopic; Osteogenesis; Recombinant Proteins; Skull; Spinal Canal; Spine; Transforming Growth Factor beta

Pinch1, an adaptor protein composed of 5 LIM domains, has been suggested to play an important role in multiple cellular processes. We found that Pinch1 is highly expressed in neural crest cells and their derivatives. To examine the requirement for Pinch1 in neural crest development, we generated neural crest conditional Pinch1 knockout mice using the Wnt1-Cre/loxP system. Neural crest conditional Pinch1 mutant embryos die perinatally from severe cardiovascular defects with an unusual aneurysmal common arterial trunk. Pinch1 mutants also exhibit multiple deficiencies in cranial neural crest-derived structures. Fate mapping demonstrated that initial migration of neural crest cells to the pharyngeal arch region occurs normally in the mutant embryos. However, in the cardiac outflow tract of mutants, neural crest cells exhibited hyperplasia and failed to differentiate into smooth muscle. Markedly increased apoptosis is observed in outflow tract cushions of mutants between embryonic days 11.5 and 13.5, likely contributing to the observed defects in cushion/valve remodeling and ventricular septation. Expression of transforming growth factor-beta(2), which plays a crucial role in outflow tract development, was decreased or absent in the outflow tract of the mutants. The decrease in transforming growth factor-beta(2) expression preceded neural crest cell death. Together, our results demonstrate that Pinch1 plays an essential role in neural crest development, perhaps in part through transforming growth factor-beta signaling.

Topics: Adaptor Proteins, Signal Transducing; Animals; Cardiovascular Abnormalities; Cells, Cultured; Craniofacial Abnormalities; DNA-Binding Proteins; Female; Gene Expression Regulation, Developmental; LIM Domain Proteins; Membrane Proteins; Mice; Mice, Knockout; Mutation; Neural Crest; Signal Transduction; Transforming Growth Factor beta

GDF-8 (myostatin) is a negative growth regulator of skeletal muscle, and myostatin-deficient mice are hypermuscular. Muscle size and force production are thought to influence growth of the craniofacial skeleton. To test this relationship, we compared masticatory muscle size and craniofacial dimensions in myostatin-deficient and wild-type CD-1 control mice. Myostatin-deficient mice had significantly (p < 0.01) greater body (by 18%) and masseter muscle weight (by 83%), compared with wild-type controls. Significant differences (p < 0.05) were noted for cranial vault length, maxillary length, mandibular body length, and mandibular shape index. Significant correlations were noted between masseter muscle weight and mandibular body length (r = 0.68; p < 0.01), cranial vault length (r = -0.57; p < 0.05), and the mandibular shape index (r = -0.56; p < 0.05). Masticatory hypermuscularity resulted in significantly altered craniofacial morphology, probably through altered biomechanical stress. These findings emphasize the important role that masticatory muscle function plays in the ontogeny of the cranial vault, the maxilla, and, most notably, the mandible.

Topics: Animals; Cephalometry; Craniofacial Abnormalities; Dental Stress Analysis; Male; Masseter Muscle; Maxillofacial Development; Mice; Mice, Mutant Strains; Myostatin; Organ Size; Transforming Growth Factor beta

Msx and Dlx homeoproteins control the morphogenesis and organization of craniofacial skeletal structures, specifically those derived from the pharyngeal arches. In vitro Msx and Dlx proteins have opposing transcriptional properties and form heterodimeric complexes via their homeodomain with reciprocal functional repression. In this report we examine the skeletal phenotype of Msx1; Dlx5 double knock-out (DKO) mice in relationship with their expression territories during craniofacial development. Co-expression of Dlx5 and Msx1 is only observed in embryonic tissues in which these genes have independent functions, and thus direct protein interactions are unlikely to control morphogenesis of the cranium. The DKO craniofacial phenotypes indicate a complex interplay between these genes, acting independently (mandible and middle ear), synergistically (deposition of bone tissue) or converging on the same morphogenetic process (palate growth and closure). In the latter case, the absence of Dlx5 rescues in part the Msx1-dependent defects in palate growth and elevation. At the basis of this effect, our data implicate the Bmp (Bmp7, Bmp4)/Bmp antagonist (Follistatin) signal: in the Dlx5(-/-) palate changes in the expression level of Bmp7 and Follistatin counteract the reduced Bmp4 expression. These results highlight the importance of precise spatial and temporal regulation of the Bmp/Bmp antagonist system during palate closure.

Topics: Animals; Base Sequence; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins; Craniofacial Abnormalities; DNA, Complementary; Ear, Middle; Facial Bones; Gene Expression Regulation, Developmental; Homeodomain Proteins; Mandible; Mice; Mice, Knockout; Mice, Transgenic; MSX1 Transcription Factor; Palate; Phenotype; Signal Transduction; Skull; Transforming Growth Factor beta

The murine frontal bone derives entirely from the cranial neural crest (CNC) and consists of the calvarial (lateral) aspect that covers the frontal lobe of brain and the orbital aspect that forms the roof of bony orbit. TGFbeta and FGF signaling have important regulatory roles in postnatal calvarial development. Our previous study has demonstrated that conditional inactivation of Tgfbr2 in the neural crest results in severe defects in calvarial development, although the cellular and molecular mechanisms by which TGFbeta signaling regulates the fate of CNC cells during frontal bone development remain unknown. Here, we show that TGFbeta IIR is required for proliferation of osteoprogenitor cells in the CNC-derived frontal bone anlagen. FGF acts downstream of TGFbeta signaling in regulating CNC cell proliferation, and exogenous FGF2 rescues the cell proliferation defect in the frontal primordium of Tgfbr2 mutant. Furthermore, the CNC-derived frontal primordium requires TGFbeta IIR to undergo terminal differentiation. However, this requirement is restricted to the developing calvarial aspect of the frontal bone, whereas the orbital aspect forms despite the ablation of Tgfbr2 gene, implying a differential requirement for TGFbeta signaling during the development of various regions of the frontal bone. This study demonstrates the biological significance of TGFbeta-mediated FGF signaling cascade in regulating frontal bone development, suggests that TGFbeta functions as a morphogen in regulating the fate of the CNC-derived osteoblast and provides a model for investigating abnormal craniofacial development.

Topics: Animals; Cell Proliferation; Cell Survival; Craniofacial Abnormalities; Disease Models, Animal; Female; Fibroblast Growth Factors; Frontal Bone; Gene Expression Regulation, Developmental; Homeodomain Proteins; Humans; Mice; Mice, Knockout; Mice, Transgenic; Multipotent Stem Cells; Neural Crest; Nuclear Proteins; Pregnancy; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Signal Transduction; Transforming Growth Factor beta; Twist-Related Protein 1

Ligands of the transforming growth factor-beta (TGF-beta) superfamily are involved in numerous developmental and disease processes. TGF-beta, activins, and nodal ligands operate through the highly homologous Smad2 and Smad3 intracellular mediators. Smad2 mutants exhibit early embryonic lethality, while Smad3 mutants are viable, but show a plethora of postnatal phenotypes, including immune dysfunction and skeletal abnormalities. Previously, we have shown that the Smad2 and Smad3 genes function cooperatively during liver morphogenesis. Here we show that Smad2 and Smad3 are required at a full dosage for normal embryonic development. Animals lacking one allele of each gene exhibit a variably penetrant phenotype in which structures in the anterior and ventral midline are reduced or lost; additionally, we demonstrate that this craniofacial defect and the previously reported hepatic phenotypes are both due to defects in the definitive endoderm. A reduction of endodermal gene expression as well as a failure to displace the visceral endoderm occurs despite the formation of a normal foregut pocket. This precedes any defects in anterior patterning and likely causes the abnormalities observed in craniofacial and midline development, as well as hepatogenesis.

Topics: Animals; Blotting, Western; Cells, Cultured; Craniofacial Abnormalities; DNA Primers; DNA-Binding Proteins; Endoderm; Gene Expression Regulation, Developmental; Histological Techniques; In Situ Hybridization; Mice; Mice, Mutant Strains; Models, Biological; Signal Transduction; Smad2 Protein; Smad3 Protein; Trans-Activators; Transforming Growth Factor beta; Xenopus; Xenopus Proteins

We report a 56-year-old woman, mainly suffering from painful legs and the inability to run. Radiologically, marked sclerosis and hyperostosis of the skull bones is present resulting in macrocephaly. Most tubular bones of the limbs, as well as the clavicles, are affected by sclerosis. By mutation analysis of the TGFB1, SOST and LRP5 genes, we were able to exclude the diagnoses of Camurati-Engelmann disease, Van Buchem disease, sclerosteosis, high-bone-mass trait and endosteal hyperostosis (Worth type). We believe this patient represents one of the very few examples of adult craniodiaphyseal dysplasia with a mild form of the disease and moderate facial changes.

Topics: Adaptor Proteins, Signal Transducing; Bone Morphogenetic Proteins; Camurati-Engelmann Syndrome; Craniofacial Abnormalities; Female; Genetic Markers; Humans; Hyperostosis; LDL-Receptor Related Proteins; Low Density Lipoprotein Receptor-Related Protein-5; Middle Aged; Receptors, LDL; Severity of Illness Index; Skull; Transforming Growth Factor beta; Transforming Growth Factor beta1

The TGF-betas are multifunctional proteins whose activities are believed to be controlled by interaction with the latent TGF-beta binding proteins (LTBPs). In spite of substantial effort, the precise in vivo significance of this interaction remains unknown. To examine the role of the Ltbp-3, we made an Ltbp-3-null mutation in the mouse by gene targeting. Homozygous mutant animals develop cranio-facial malformations by day 10. At 2 mo, there is a pronounced rounding of the cranial vault, extension of the mandible beyond the maxilla, and kyphosis. Histological examination of the skulls from null animals revealed ossification of the synchondroses within 2 wk of birth, in contrast to the wild-type synchondroses, which never ossify. Between 6 and 9 mo of age, mutant animals also develop osteosclerosis and osteoarthritis. The pathological changes of the Ltbp-3-null mice are consistent with perturbed TGF-beta signaling in the skull and long bones. These observations give support to the notion that LTBP-3 is important for the control of TGF-beta action. Moreover, the results provide the first in vivo indication for a role of LTBP in modulating TGF-beta bioavailability.

Topics: Adaptor Proteins, Signal Transducing; Animals; Bone and Bones; Bone Remodeling; Carrier Proteins; Craniofacial Abnormalities; Gene Deletion; Gene Targeting; In Situ Hybridization; Latent TGF-beta Binding Proteins; Mice; Mice, Knockout; Osteoarthritis; Osteosclerosis; RNA, Messenger; Skull; Transforming Growth Factor beta

There is growing evidence that implicates a role for Sonic hedgehog (SHH) in morphogenesis of the craniofacial complex. Mutations in human and murine SHH cause midline patterning defects that are manifested in the head as holoprosencephaly and cyclopia. In addition, teratogens such as jervine, which inhibit the response of tissues to SHH, also produce cyclopia. Thus, the loss of SHH signaling during early stages of neural plate patterning has a profound influence of craniofacial morphogenesis. However, the severity of these defects precludes analyses of SHH function during later stages of craniofacial development. We have used an embryonic chick system to study the role of SHH during these later stages of craniofacial development. Using a combination of surgical and molecular experiments, we show here that SHH is essential for morphogenesis of the frontonasal and maxillary processes (FNP and MXPs), which give rise to the mid- and upper face. Transient loss of SHH signaling in the embryonic face inhibits growth of the primordia and results in defects analogous to hypotelorism and cleft lip/palate, characteristics of the mild forms of holoprosencephaly. In contrast, excess SHH leads to a mediolateral widening of the FNP and a widening between the eyes, a condition known as hypertelorism. In severe cases, this widening is accompanied by facial duplications. Collectively, these experiments demonstrate that SHH has multiple and profound effects on the entire spectrum of craniofacial development, and perturbations in SHH signaling are likely to underlie a number of human craniofacial anomalies.

Topics: Animals; Beak; Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins; Chick Embryo; Craniofacial Abnormalities; Ectoderm; Embryonic Induction; Gene Expression Regulation, Developmental; Head; Hedgehog Proteins; Humans; Membrane Proteins; Oncogene Proteins; Patched Receptors; Proteins; Receptors, Cell Surface; Trans-Activators; Transcription Factors; Transforming Growth Factor beta; Zinc Finger Protein GLI1

Signalling by the transforming growth factor-beta (TGF-beta) superfamily of proteins depends on the phosphorylation and activation of SMAD proteins by heteromeric complexes of ligand-specific type I and type II receptors with serine/threonine-kinase activity. The vertebrate SMAD family includes at least nine members, of which Smad2 has been shown to mediate signalling by activin and TGF-beta. In Xenopus, Smad2 can induce dorsal mesoderm, mimicking Vg-1, activin and nodal. Here we investigate the function of Smad2 in mammalian development by generating two independent Smad2 mutant alleles in mice by gene targeting. We show that homozygous mutant embryos fail to form an organized egg cylinder and lack mesoderm, like mutant mice lacking nodal or ActRIB, the gene encoding the activin type-I receptor. About 20 per cent of Smad2 heterozygous embryos have severe gastrulation defects and lack mandibles or eyes, indicating that the gene dosage of Smad2 is critical for signalling. Mice trans-heterozygous for both Smad2 and nodal mutations display a range of phenotypes, including gastrulation defects, complex craniofacial abnormalities such as cyclopia, and defects in left-right patterning, indicating that Smad2 may mediate nodal signalling in these developmental processes. Our results show that Smad2 function is essential for early development and for several patterning processes in mice.

Topics: Abnormalities, Multiple; Animals; Body Patterning; Cell Line; Cloning, Molecular; Craniofacial Abnormalities; DNA-Binding Proteins; Embryo, Mammalian; Embryonic and Fetal Development; Facial Bones; Fetal Death; Gastrula; Gene Targeting; Mesoderm; Mice; Mice, Inbred C57BL; Mutagenesis; Nodal Protein; Proteins; Signal Transduction; Skull; Smad2 Protein; Stem Cells; Trans-Activators; Transforming Growth Factor beta

The growth and differentiation factor transforming growth factor-beta2 (TGFbeta2) is thought to play important roles in multiple developmental processes. Targeted disruption of the TGFbeta2 gene was undertaken to determine its essential role in vivo. TGFbeta2-null mice exhibit perinatal mortality and a wide range of developmental defects for a single gene disruption. These include cardiac, lung, craniofacial, limb, spinal column, eye, inner ear and urogenital defects. The developmental processes most commonly involved in the affected tissues include epithelial-mesenchymal interactions, cell growth, extracellular matrix production and tissue remodeling. In addition, many affected tissues have neural crest-derived components and simulate neural crest deficiencies. There is no phenotypic overlap with TGFbeta1- and TGFbeta3-null mice indicating numerous non-compensated functions between the TGFbeta isoforms.

Topics: Abnormalities, Multiple; Animals; Bone and Bones; Cleft Palate; Craniofacial Abnormalities; Cyanosis; Ear, Inner; Embryonic Induction; Epithelium; Eye Abnormalities; Genes, Homeobox; Heart Defects, Congenital; Mesoderm; Mice; Mice, Inbred C57BL; Mice, Knockout; Phenotype; Transforming Growth Factor beta; Tretinoin; Urogenital Abnormalities