transforming-growth-factor-beta and Eye-Abnormalities

Ocular anterior segment dysgenesis (ASD) refers to a collection of developmental disorders affecting the anterior structures of the eye. Although a number of genes have been implicated in the etiology of ASD, the underlying pathogenetic mechanisms remain unclear. Mutations in genes encoding collagen type IV alpha 1 (COL4A1) and alpha 2 (COL4A2) cause Gould syndrome, a multi-system disorder that often includes ocular manifestations such as ASD and glaucoma. COL4A1 and COL4A2 are abundant basement membrane proteins that provide structural support to tissues and modulate signaling through interactions with other extracellular matrix proteins, growth factors, and cell surface receptors. In this study, we used a combination of histological, molecular, genetic and pharmacological approaches to demonstrate that altered TGFβ signaling contributes to ASD in mouse models of Gould syndrome. We show that TGFβ signaling was elevated in anterior segments from Col4a1 mutant mice and that genetically reducing TGFβ signaling partially prevented ASD. Notably, we identified distinct roles for TGFβ1 and TGFβ2 in ocular defects observed in Col4a1 mutant mice. Importantly, we show that pharmacologically promoting type IV collagen secretion or reducing TGFβ signaling ameliorated ocular pathology in Col4a1 mutant mice. Overall, our findings demonstrate that altered TGFβ signaling contributes to COL4A1-related ocular dysgenesis and implicate this pathway as a potential therapeutic target for the treatment of Gould syndrome.

Topics: Animals; Basement Membrane; Collagen Type IV; Eye; Eye Abnormalities; Mice; Mutation; Transforming Growth Factor beta

Ocular mal-development results in heterogeneous and frequently visually disabling phenotypes that include coloboma and microphthalmia. Due to the contribution of bone morphogenetic proteins to such processes, the function of the paralogue Growth Differentiation Factor 3 was investigated. Multiple mis-sense variants were identified in patients with ocular and/or skeletal (Klippel-Feil) anomalies including one individual with heterozygous alterations in GDF3 and GDF6. These variants were characterized, individually and in combination, through integrated biochemical and zebrafish model organism analyses, demonstrating appreciable effects with western blot analyses, luciferase based reporter assays and antisense morpholino inhibition. Notably, inhibition of the zebrafish co-orthologue of GDF3 accurately recapitulates patient phenotypes. By demonstrating the pleiotropic effects of GDF3 mutation, these results extend the contribution of perturbed BMP signaling to human disease and potentially implicate multi-allelic inheritance of BMP variants in developmental disorders.

Topics: Amino Acid Sequence; Animals; Cell Line; Eye Abnormalities; Female; Growth Differentiation Factor 3; Humans; Male; Molecular Sequence Data; Muscle, Skeletal; Mutation; Pedigree; Sequence Alignment; Transforming Growth Factor beta; Zebrafish; Zebrafish Proteins

Although it is well known that flounder form external asymmetry by migration of one eye at metamorphosis, the control system that forms this asymmetry is unknown. To help elucidate this mechanism, we here describe the embryogenesis and expression profiles of the Nodal-pathway genes in the Japanese flounder, Paralichthys olivaceus. We also perform a comparative study of the laterality of the expression of these genes in sinistral (P. olivaceus) and dextral (Verasper variegatus) flounders. In P. olivaceus, Kupffer's vesicle forms at the 2-somite stage, after which left-sided expression of spaw starts at the 8-somite stage. Left-sided expression of pitx2 occurs in the gut field at the 15-somite to high-pec stages, in the heart field at the 21-somite stage, and in the dorsal diencephalon at the 27-somite to high-pec stages. In response to left-sided pitx2 expression, the heart, gut, and diencephalon begin asymmetric organogenesis at the pharyngula (heart) and the long-pec (gut and diencephalon) stages, whereas the eyes do not show signs of asymmetry at these stages. In both sinistral and dextral flounders, the Nodal-pathway genes are expressed at the left side of the dorsal diencephalon and left lateral-plate mesoderm. Considering these data together with our previous finding that reversal of eye laterality occurs to some extent in the P. olivaceus mutant reversed, in which embryonic pitx2 expression is randomized, we propose that although the Nodal pathway seems to function to fix eye laterality, embryonic expression of these genes does not act as a direct positional cue for eye laterality.

Topics: Animals; Embryo, Nonmammalian; Eye Abnormalities; Flounder; Gene Expression Regulation, Developmental; Left-Right Determination Factors; Metamorphosis, Biological; Nodal Protein; Transforming Growth Factor beta; Zebrafish Proteins

Development of the eye depends partly on the periocular mesenchyme derived from the neural crest (NC), but the fate of NC cells in mammalian eye development and the signals coordinating the formation of ocular structures are poorly understood.. Here we reveal distinct NC contributions to both anterior and posterior mesenchymal eye structures and show that TGFbeta signaling in these cells is crucial for normal eye development. In the anterior eye, TGFbeta2 released from the lens is required for the expression of transcription factors Pitx2 and Foxc1 in the NC-derived cornea and in the chamber-angle structures of the eye that control intraocular pressure. TGFbeta enhances Foxc1 and induces Pitx2 expression in cell cultures. As in patients carrying mutations in PITX2 and FOXC1, TGFbeta signal inactivation in NC cells leads to ocular defects characteristic of the human disorder Axenfeld-Rieger's anomaly. In the posterior eye, NC cell-specific inactivation of TGFbeta signaling results in a condition reminiscent of the human disorder persistent hyperplastic primary vitreous. As a secondary effect, retinal patterning is also disturbed in mutant mice.. In the developing eye the lens acts as a TGFbeta signaling center that controls the development of eye structures derived from the NC. Defective TGFbeta signal transduction interferes with NC-cell differentiation and survival anterior to the lens and with normal tissue morphogenesis and patterning posterior to the lens. The similarity to developmental eye disorders in humans suggests that defective TGFbeta signal modulation in ocular NC derivatives contributes to the pathophysiology of these diseases.

Topics: Animals; Cell Movement; Cells, Cultured; Eye Abnormalities; Forkhead Transcription Factors; Homeobox Protein PITX2; Homeodomain Proteins; Lens, Crystalline; Mice; Mice, Mutant Strains; Neural Crest; Nuclear Proteins; Rats; Signal Transduction; Stem Cells; Transcription Factors; Transforming Growth Factor beta

In humans, low peak bone mass is a significant risk factor for osteoporosis. We report that LRP5, encoding the low-density lipoprotein receptor-related protein 5, affects bone mass accrual during growth. Mutations in LRP5 cause the autosomal recessive disorder osteoporosis-pseudoglioma syndrome (OPPG). We find that OPPG carriers have reduced bone mass when compared to age- and gender-matched controls. We demonstrate LRP5 expression by osteoblasts in situ and show that LRP5 can transduce Wnt signaling in vitro via the canonical pathway. We further show that a mutant-secreted form of LRP5 can reduce bone thickness in mouse calvarial explant cultures. These data indicate that Wnt-mediated signaling via LRP5 affects bone accrual during growth and is important for the establishment of peak bone mass.

Topics: Adaptor Proteins, Signal Transducing; Adult; Animals; Animals, Outbred Strains; Bone Density; Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins; Child; Child, Preschool; Chlorocebus aethiops; Chromosomes, Human, Pair 11; COS Cells; Culture Media, Conditioned; Dishevelled Proteins; DNA, Complementary; Eye; Eye Abnormalities; Female; Genes, Recessive; Heterozygote; Humans; LDL-Receptor Related Proteins; Low Density Lipoprotein Receptor-Related Protein-5; Male; Mesoderm; Mice; Mice, Inbred C57BL; Organ Culture Techniques; Osteoblasts; Osteoporosis; Phosphoproteins; Proteins; Proto-Oncogene Proteins; Receptors, LDL; Recombinant Fusion Proteins; Recombinant Proteins; Signal Transduction; Skull; Species Specificity; Stromal Cells; Syndrome; Transfection; Transforming Growth Factor beta; Wnt Proteins; Wnt-5a Protein; Wnt2 Protein; Wnt3 Protein; Wnt4 Protein; Zebrafish Proteins

Ventral structures in the central nervous system are patterned by signals emanating from the underlying mesoderm as well as originating within the neuroectoderm. Mutations in the zebrafish, Danio rerio, are proving instrumental in dissecting these midline signals. The cyclops mutation leads to a loss of medial floor plate and to severe deficits in ventral forebrain development, leading to cyclopia. Here, we report that the cyclops locus encodes the nodal-related protein Ndr2, a member of the transforming growth factor type beta superfamily of factors. The evidence includes identification of a missense mutation in the initiation codon and rescue of the cyclops phenotype by expression of ndr2 RNA, here renamed "cyclops." Thus, in interaction with other molecules implicated in these processes such as sonic hedgehog and one-eyed-pinhead, cyclops is required for ventral midline patterning of the embryonic central nervous system.

Topics: Alleles; Amino Acid Sequence; Animals; Base Sequence; Body Patterning; Central Nervous System; DNA Primers; DNA, Complementary; Eye Abnormalities; Gene Expression Regulation, Developmental; Molecular Sequence Data; Mutation; Nodal Signaling Ligands; Phenotype; Proteins; Signal Transduction; Transforming Growth Factor beta; Zebrafish; Zebrafish Proteins

While generating bcl2 alpha transgenic mice, we found some F2 offspring of one of the transgenic lines which were very small and had closed eyes at the time of weaning. These pups died within 1 month after birth. In order to determine the molecular basis of this phenotype, we screened a genomic library of the above transgenic line with a transgene-specific probe and found that the Bmp7 gene, a member of the TGF beta superfamily, was inactivated by insertional mutagenesis due to transgene integration. The Bmp7 homozygous null condition in mice is a postnatal lethal mutation and is associated with various developmental defects: holes in the basisphenoid bone and the xyphoid cartilage, retarded ossification of bones, fused ribs and vertebrae, underdeveloped neural arches of the lumbar and sacral vertebrae, polydactyly of the hind limbs, a kinked tail, a reduced number of nephrons, polycystic kidney, lack of retinal pigmentation, and retarded lens development. These findings indicate that BMP7 is an important signaling molecule for normal development of the mammalian skeleton, kidney, and eye. Academic Press

Topics: Abnormalities, Multiple; Animals; Animals, Newborn; Base Sequence; Bone and Bones; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins; DNA Primers; Eye Abnormalities; Female; Genes, bcl-2; Homozygote; Kidney; Male; Mice; Mice, Knockout; Mutagenesis, Insertional; Phenotype; Polymerase Chain Reaction; Pregnancy; 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

In summary, the generation of BMP-7-deficient mice has provided additional evidence that this family of growth factors regulate many morphogenetic processes including but not limited to skeletal development. In particular our experiments demonstrate that BMP 7 acts as an early inducer of glomeruli formation, and that it is required for skeletal patterning and lens formation. Our results not only demonstrate that BMP 7 is involved in the differentiation of several organs during development, but also raise the hypothesis that mutations in the Bmp 7 gene itself or in the genetic pathway could be responsible for several human genetic diseases in which glomerulus formation is impaired.

Topics: Animals; Anophthalmos; Bone and Bones; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins; Eye Abnormalities; Humans; Kidney; Mice; Mice, Knockout; Morphogenesis; Mutation; Polydactyly; Proteins; Toes; Transforming Growth Factor beta