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Shwachman-Diamond syndrome (SDS) is a rare and clinically heterogeneous bone marrow (BM) failure syndrome caused by mutations in the Shwachman-Bodian-Diamond syndrome (SBDS) gene. Although SDS was described more than 50 years ago, its molecular pathogenesis is poorly understood due, in part, to the rarity and heterogeneity of the affected hematopoietic progenitors. To address this, we used single-cell RNA sequencing to profile scant hematopoietic stem and progenitor cells from patients with SDS. We generated a single-cell map of early lineage commitment and found that SDS hematopoiesis was left-shifted with selective loss of granulocyte-monocyte progenitors. Transcriptional targets of transforming growth factor beta (TGF-[beta]) were dysregulated in SDS hematopoietic stem cells and multipotent progenitors, but not in lineage-committed progenitors. TGF-[beta] inhibitors (AVID200 and SD208) increased hematopoietic colony formation of SDS patient BM. Finally, TGF-[beta]3 and other TGF-[beta] pathway members were elevated in SDS patient blood plasma. These data establish the TGF-[beta] pathway as a candidate biomarker and therapeutic target in SDS and translate insights from single-cell biology into a potential therapy., Introduction Shwachman-Diamond syndrome (SDS) is an inherited bone marrow (BM) failure syndrome associated with biallelic, hypomorphic mutations in the Shwachman-Bodian-Diamond syndrome (SBDS) gene. SBDS is a pleiotropic protein that facilitates [...]

Bone morphogenetic protein (BMP) signaling has been linked to the development of pulmonary hypertension (PH). Inhibitors of differentiation (ID) proteins (ID1-4) are a family of basic helix-loop-helix transcription factors that are downstream targets of the BMP signaling pathway, but the role that ID proteins play in the development of PH is unknown. To address this, we evaluated pulmonary expression of ID proteins in a mouse model of hypoxia-induced PH. There is selective induction of ID1 and ID3 expression in hypoxic pulmonary vascular smooth muscle cells (VSMCs) in vivo, and ID1 and ID3 expression are increased by hypoxia in cultured pulmonary VSMCs in a BMP-dependent fashion. ID4 protein is barely detectable in the mouse lung, and while ID2 is induced in hypoxic peripheral VSMCs in vivo, it is not increased by hypoxia or BMP signaling in cultured pulmonary VSMCs. In addition, the PH response to chronic hypoxia is indistinguishable between wild type and Id1 null mice. This is associated with a compensatory increase in ID3 but not ID2 expression in pulmonary VSMCs of Id1 null mice. These findings indicate that ID1 is dispensable for mounting a normal pulmonary vascular response to hypoxia, but suggest that ID3 may compensate for loss of ID1 expression in pulmonary VSMCs. Taken together, these findings indicate that ID1 and ID3 expression are regulated in a BMP-dependent fashion in hypoxic pulmonary VSMCs, and that ID1 and ID3 may play a cooperative role in regulating BMP-dependent VSMC responses to chronic hypoxia. hypoxia; bone morphogenetic protein signaling; ID1; ID2; ID3; vascular smooth muscle cells; endothelial cells doi: 10.1152/ajpregu.00866.2009.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2010.06.015 Byline: Gabriele Amore (a), Fernando Casares (b) Keywords: Drosophila; Eye; Gene regulatory network; Cell proliferation; Cell specification Abstract: Organ development is a complex process in which the activity of scores of interacting transcription factors and signaling pathways need to be integrated with proliferative growth. Developmental gene regulatory networks (GRNs) allow capturing essential regulatory pathways at a systems-level and provide an effective way of approaching such complexity. However typical GRNs studies focus on very early embryonic stages (usually pre-gastrulation) or late stages, when there is little or no cell proliferation, and therefore do not consider how organ growth is integrated in the developmental process. This can be conveniently investigated in the Drosophila melanogaster eye primordium. Here we present a working model meant to illustrate how during a critical period, the second larval stage, changes in cells' proliferative pattern are coordinated with the initiation of the Retinal Determination (RD) gene program. Such changes are regulated in response to two different sources of signal (Wnt1/wg and BMP2/4/dpp) produced by the anterior and posterior ends of the primordium, respectively. The dpp signaling is necessary to trigger the RD program. However in order for it to be effective, cells receiving Dpp have to be out of the wg signaling range. This is obtained thanks to the proliferative growth that precedes the onset of RD expression. With this network model many of the gene regulatory steps previously known to participate in growth and patterning are linked. Analysis of the model highlights a few essential regulatory principles, as well as poses new questions. In addition, these principles might operate during the growth and patterning of other organs. Author Affiliation: (a) Animal Physiology and Evolutionary Laboratory-Stazione Zoologica Anton Dohrn, Napoli, Italy (b) Centro Andaluz de Biologia del Desarrollo (CABD), Seville, Spain Article History: Received 30 April 2010; Revised 3 June 2010; Accepted 8 June 2010

Chronic kidney diseases are characterized by progressive tubulointerstitial fibrosis, and TGF[beta]1 plays a crucial role in its development. Bone morphogenic protein 7 (BMP 7), another member of the TGF superfamily, antagonized the profibrotic effects of TGF[beta]1, including epithelial mesenchymal transition and E-cadherin loss, in the previous studies from animal models. We investigated the effect of BMP 7 on TGF[beta]1-mediated E-cadherin loss in two different transformed human adult proximal tubule epithelia. We found that BMP 7 not only failed to prevent TGF[beta]1-mediated E-cadherin loss but itself downregulated E-cadherin levels and that it had an additive effect with TGF[beta]1 in inducing E-cadherin loss. The downregulation of E-cadherin by BMP 7 was mediated through the Smad1/5 pathway. BMP 7-mediated E-cadherin loss was not followed by de novo [alpha]-smooth muscle actin ([alpha]-SMA) expression (a marker of myofibroblastic phenotype), which was due to the concurrent induction of Inhibitor of DNA binding 1 (Idl, a basic helix loop helix class transcriptional regulator) through a non-Smad pathway. Concurrent treatment of BMP 7 and TGF[beta]1 prevented TGF[beta]1-mediated [alpha]-SMA induction. In summary, our results suggest that E-cadherin loss, the key feature of epithelial mesenchymal transition, will not necessarily be followed by total phenotype change; rather, cells may undergo some loss of phenotypic marker in a ligand-dependent manner and participate in reparative processes. The inhibition of de novo expression of [alpha]-SMA could explain the antifibrotic effect of BMP 7. Id1 might play a crucial role in maintaining proximal tubule epithelial cell phenotype and its signaling regulation could be a potential therapeutic target. BMP 7; E-cadherin; renal proximal tubule epithelia; [alpha]-smooth muscle actin doi: 10.1152/ajprenal.90539.2008.

Cardiomyocytes derived from human embryonic stem (ES) cells are a potential source for cell-based therapy for heart diseases. We studied the effect of bone morphogenetic protein (BMP)-4 in the presence of fetal bovine serum (FBS) on cardiac induction from human H1 ES cells during embryoid body (EB) development. Suspension culture for 4 days with 20% FBS produced the best results for the differentiation of early mesoderm and cardiomyocytes. The addition of Noggin reduced the incidence of beating EBs from 23.6% to 5.3%, which indicated the involvement of BMP signaling in the spontaneous cardiac differentiation. In this condition, treatment with 12.5-25 ng/ml BMP-4 during the 4-day suspension optimally promoted the cardiomyocyte differentiation. The incidence of beating EBs at 25 ng/ml BMP-4 reached 95.8% on day 6 of expansion and then plateaued until day 20. In real-time PCR analysis, the cardiac development-related genes MESP1 and Nkx2.5 were upregulated in the EB outgrowths by 25 ng/ml BMP-4. The activation of BMP signaling in EBs was confirmed by the increase in the phosphorylation of Smadl/5/8 and by the nuclear localization of phospho-Smadl/5/8 and Smad4. The addition of 150 ng/ml Noggin considerably decreased the incidence of beating EBs and Nkx2.5 expression, and Noggin alone increased Nestin expression and neural differentiation in EB outgrowths. The cardiomyocytes induced by 25 ng/ml BMP-4 showed proper cell biological characteristics and a course of differentiation as judged from isoproterenol administration, gene expression, protein assay, immunoreactivity, and subcellular structures. No remarkable change in the extent of apoptosis and proliferation in the cardiomyocytes was observed by BMP-4 treatment. These findings showed that BMP-4 in combination with FBS at the appropriate time and concentrations significantly promotes cardiomyocyte induction from human ES cells. fetal bovine serum; early mesoderm; Noggin; cardiomyogenesis; differentiation

Bone morphogenic protein (BMP) signaling is essential for the coordinated assembly of the synapse, but we know little about how BMP signaling is modulated in neurons. Our findings indicate that the Nemo (Nmo) kinase modulates BMP signaling in motor neurons. nmo mutants show synaptic structural defects at the Drosophila melanogaster larval neuromuscular junction, and providing Nmo in motor neurons rescues these defects. We show that Nmo and the BMP transcription factor Mad can be coimmunoprecipitated and find a genetic interaction between nmo and Mad mutants. Moreover, we demonstrate that Nmo is required for normal distribution and accumulation of phosphorylated Mad in motor neurons. Finally, our results indicate that Nmo phosphorylation of Mad at its N terminus, distinct from the BMP phosphorylation site, is required for normal function of Mad. Based on our findings, we propose a model in which phosphorylation of Mad by Nmo ensures normal accumulation and distribution of Mad and thereby fine tunes BMP signaling in motor neurons.

Wnt signaling increases bone mass by stimulating osteoblast lineage commitment and expansion and forms the basis for novel anabolic therapeutic strategies being developed for osteoporosis. These strategies include derepression of Wnt signaling by targeting secreted Wnt pathway antagonists, such as sclerostin. However, such therapies are associated with safety concerns regarding an increased risk of osteosarcoma, the most common primary malignancy of bone. Here, we analyzed 5 human osteosarcoma cell lines in a high-throughput screen for epigenetically silenced tumor suppressor genes and identified Wnt inhibitory factor 1 (WIF1), which encodes an endogenous secreted Wnt pathway antagonist, as a candidate tumor suppressor gene. In vitro, WIF1 suppressed [beta]-catenin levels in human osteosarcoma cell lines, induced differentiation of human and mouse primary osteoblasts, and suppressed the growth of mouse and human osteosarcoma cell lines. Wif1 was highly expressed in the developing and mature mouse skeleton, and, although it was dispensable for normal development, targeted deletion of mouse Wif1 accelerated development of radiation-induced osteosarcomas in vivo. In primary human osteosarcomas, silencing of WIF1 by promoter hypermethylation was associated with loss of differentiation, increased [beta]-catenin levels, and increased proliferation. These data lead us to suggest that derepression of Wnt signaling by targeting secreted Wnt antagonists in osteoblasts may increase susceptibility to osteosarcoma., Introduction Osteosarcoma is the most common primary malignancy of bone, and the third most common cancer in adolescents (1). Risk factors for osteosarcoma include states associated with increased osteoblast proliferation, [...]

Retinal ganglion cells form orderly topographic connections with the tectum, establishing a continuous neural representation of visual space. Mapping along the dorsal--ventral axis requires interactions between EphB and ephrin-B cell-surface molecules expressed as countergradients in both retina and tectum. We have discovered that the diffusible TGF [beta]-related factor Radar (Gdf6a) is necessary and sufficient for activation of dorsal markers, such as Bmp4, Tbx5, Tbx2b, and Ephrin-B2, and suppression of the ventral marker Vax2 in the zebrafish retina. Radar mutant axons innervate only the dorsal half of the tectum, where they form a compressed retinotectal map. Wild-type cells transplanted into the dorsal retina are able to rescue the dorsal identity of nearby mutant cells. Moreover, Radar overexpression 'dorsalizes' retinal ganglion cell identity in the ventral retina. We conclude that Radar is near the top of a signaling cascade that establishes dorsal--ventral positional information in the retina and controls the formation of the retinotectal map. patterning | eye development | ocular coloboma | bone morphogenetic protein | rectum

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2008.10.015 Byline: Tetsuya Akamatsu, Ahmad Azlina, Nunuk Purwanti, Mileva Ratko Karabasil, Takahiro Hasegawa, Chenjuan Yao, Kazuo Hosoi Keywords: Subtilisin-like proprotein convertase; PACE4; Branching morphogenesis; Water channel; AQP5; Submandibular gland; siRNA Abstract: The submandibular gland (SMG) develops through the epithelial-mesenchymal interaction mediated by many growth/differentiation factors including activin and BMPs, which are synthesized as inactive precursors and activated by subtilisin-like proprotein convertases (SPC) following cleavage at their R-X-K/R-R site. Here, we found that Dec-RVKR-CMK, a potent inhibitor of SPC, inhibited the branching morphogenesis of the rat embryonic SMG, and caused low expression of a water channel AQP5, in an organ culture system. Dec-RVKR-CMK also decreased the expression of PACE4, a SPC member, but not furin, another SPC member, suggesting the involvement of PACE4 in the SMG development. Heparin, which is known to translocate PACE4 in the extracellular matrix into the medium, and an antibody specific for the catalytic domain of PACE4, both reduced the branching morphogenesis and AQP5 expression in the SMG. The inhibitory effects of Dec-RVKR-CMK were partially rescued by the addition of recombinant BMP2, whose precursor is one of the candidate substrates for PACE4 in vivo. Further, the suppression of PACE4 expression by siRNAs resulted in decreased expression of AQP5 and inhibition of the branching morphogenesis in the present organ culture system. These observations suggest that PACE4 regulates the SMG development via the activation of some growth/differentiation factors. Author Affiliation: Department of Molecular Oral Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15, Kuramoto-cho, Tokushima-shi, Tokushima 770-8504, Japan Article History: Received 18 December 2007; Revised 3 October 2008; Accepted 3 October 2008

Fibrodysplasia ossificans progressiva (FOP) is a congenital disorder of progressive and widespread postnatal ossification of soft tissues (1-4) and is without known effective treatments. Affected individuals harbor conserved mutations in the ACVR1 gene that are thought to cause constitutive activation of the bone morphogenetic protein (BMP) type I receptor, activin receptor-like kinase-2 (ALK2) (5). Here we show that intramuscular expression in the mouse of an inducible transgene encoding constitutively active ALK2 (caALK2), resulting from a glutamine to aspartic acid change at amino acid position 207, leads to ectopic endochondral bone formation, joint fusion and functional impairment, thus phenocopying key aspects of human FOP. A selective inhibitor of BMP type I receptor kinases, LDN-193189 (ref. 6), inhibits activation of the BMP signaling effectors SMAD1, SMAD5 and SMAD8 in tissues expressing caALK2 induced by adenovirus specifying Cre (Ad.Cre). This treatment resulted in a reduction in ectopic ossification and functional impairment. In contrast to localized induction of caALK2 by Ad.Cre (which entails inflammation), global postnatal expression of caALK2 (induced without the use of Ad.Cre and thus without inflammation) does not lead to ectopic ossification. However, if in this context an inflammatory stimulus was provided with a control adenovirus, ectopic bone formation was induced. Like LDN-193189, corticosteroid treatment inhibits ossification in Ad.Cre-injected mutant mice, suggesting caALK2 expression and an inflammatory milieu are both required for the development of ectopic ossification in this model. These results support the role of dysregulated ALK2 kinase activity in the pathogenesis of FOP and suggest that small molecule inhibition of BMP type I receptor activity may be useful in treating FOP and heterotopic ossification syndromes associated with excessive BMP signaling., Individuals with FOP typically present within the first decade of life with progressive ectopic calcification of muscles and connective tissues after physical trauma, surgery, viral illness or myositis (1-4). FOP [...]

Osteoporosis results from an imbalance in skeletal remodeling that favors bone resorption over bone formation. Bone matrix is degraded by osteoclasts, which differentiate from myeloid precursors in response to the cytokine RANKL. To gain insight into the transcriptional regulation of bone resorption during growth and disease, we generated a conditional knockout of the transcription factor nuclear factor of activated T cells c1 (Nfatc1). Deletion of Nfatc1 in young mice resulted in osteopetrosis and inhibition of osteoclastogenesis in vivo and in vitro. Transcriptional profiling revealed NFATc1 as a master regulator of the osteoclast transcriptome, promoting the expression of numerous genes needed for bone resorption. In addition, NFATc1 directly repressed osteoclast progenitor expression of osteoprotegerin, a decoy receptor for RANKL previously thought to be an osteoblast-derived inhibitor of bone resorption. "Cherubism mice", which carry a gain-of-function mutation in SH3-domain binding protein 2 (Sh3bp2), develop osteoporosis and widespread inflammation dependent on the proinflammatory cytokine, TNF-[alpha]. Interestingly, deletion of Nfatc1 protected cherubism mice from systemic bone loss but did not inhibit inflammation. Taken together, our study demonstrates that NFATc1 is required for remodeling of the growing and adult skeleton and suggests that NFATc1 may be an effective therapeutic target for osteoporosis associated with inflammatory states., Introduction Osteoporosis, the most common pathologic condition resulting from excessive bone destruction, afflicts 10 million Americans over the age of 50 and results in 1.5 million fractures annually (1), (2). [...]

Patients with familial pulmonary arterial hypertension inherit heterozygous mutations of the type 2 bone morphogenetic protein (BMP) receptor BMPR2. To explore the cellular mechanisms of this disease, we evaluated the pulmonary vascular responses to chronic hypoxia in mice carrying heterozygous hypomorphic Bmpr2 mutations ([Bmpr2.sup.[DELTA]Ex2/+]). These mice develop more severe pulmonary hypertension after prolonged exposure to hypoxia without an associated increase in pulmonary vascular remodeling or proliferation compared with wild-type mice. This is associated with defective endothelial-dependent vasodilatation and enhanced vasoconstriction in isolated intrapulmonary artery preparations. In addition, there is a selective decrease in hypoxia-induced, BMP-dependent, endothelial nitric oxide synthase expression and Smad signaling in the intact lungs and in cultured pulmonary microvascular endothelial cells from [Bmpr2.sup.[DELTA]Ex2/+] mutant mice. These findings indicate that the pulmonary endothelium is a target of abnormal BMP signaling in [Bmpr2.sup.[DELTA]Ex2/+] mutant mice and suggest that endothelial dysfunction contributes to their increased susceptibility to hypoxic pulmonary hypertension. bone morphogenetic protein receptors; endothelial dysfunction; pulmonary hypertension; endothelial nitric oxide synthase

Human colonic epithelial cell renewal, proliferation, and differentiation are stringently controlled by numerous regulatory pathways. To identify genetic programs of human colonic epithelial cell differentiation in vivo as well as candidate marker genes that define colonic epithelial stem/progenitor cells and the stem cell niche, we applied gene expression analysis of normal human colon tops and basal crypts by using expression microarrays with 30,000 genes. Nine hundred and sixty-nine cDNA clones were found to be differentially expressed between human colon crypts and tops. Pathway analysis revealed the differential expression of genes involved in cell cycle maintenance and apoptosis, as well as genes in bone morphogenetic protein (BMP), Notch, Wnt, EPH, and MYC signaling pathways. BMP antagonists gremlin 1, gremlin 2, and chordin-like 1 were found to be expressed by colon crypts. In situ hybridization and RT-PCR confirmed that these BMP antagonists are expressed by intestinal cryptal myofibroblasts and smooth muscle cells at the colon crypt. In vitro analysis demonstrated that gremlin 1 partially inhibits Caco-2 cell differentiation upon confluence and activates Wnt signaling in normal rat intestinal epithelial cells. Collectively, the expression data set provides a comprehensive picture of human colonic epithelial cell differentiation. Our study also suggests that BMP antagonists are candidate signaling components that make up the intestinal epithelial stem cell niche. gremlin | expression profiling microarray | crypt maturation program | myofibroblast

Evolutionary diversifications are commonly attributed to the continued modifications of a conserved genetic toolkit of developmental pathways, such that complexity and convergence in organismal forms are assumed to be due to similarity in genetic mechanisms or environmental conditions. This approach, however, confounds the causes of organismal development with the causes of organismal differences and, as such, has only limited utility for addressing the cause of evolutionary change. Molecular mechanisms that are closely involved in both developmental response to environmental signals and major evolutionary innovations and diversifications are uniquely suited to bridge this gap by connecting explicitly the causes of within-generation variation with the causes of divergence of taxa. Developmental pathways of bone formation and a common role for bone morphogenetic proteins (BMPs) in both epigenetic bone remodeling and the evolution of major adaptive diversifications provide such opportunity. We show that variation in timing of ossification can result in similar phenotypic patterns through epigenetically induced changes in gene expression and propose that both genetic accommodation of environmentally induced developmental pathways and flexibility in development across environments evolve through heterochronic shifts in bone maturation relative to exposure to unpredictable environments. We suggest that such heterochronic shifts in ossification can not only buffer development under fluctuating environments while maintaining epigenetic sensitivity critical for normal skeletal formation, but also enable epigenetically induced gene expression to generate specialized morphological adaptations. We review studies of environmental sensitivity of BMP pathways and their regulation of formation, remodeling, and repair of cartilage and bone to examine the hypothesis that BMP-mediated skeletal adaptations are facilitated by evolved reactivity of BMPs to external signals. Surprisingly, no empirical study to date has identified the molecular mechanism behind developmental plasticity in skeletal traits. We outline a conceptual framework for future studies that focus on mediation of phenotypic plasticity in skeletal development by the patterns of BMP expression.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2007.02.038 Byline: Jun Liang, Ling Yu, Jianghua Yin, Cathy Savage-Dunn Keywords: sma-9; BMP; Schnurri; Transcriptional repressor; Transcriptional activator; DNA microarray; Gene regulation; Body size Abstract: In the nematode Caenorhabditis elegans, the BMP-related growth factor DBL-1 regulates body size and male tail morphogenesis via a conserved receptor/Smad signaling pathway. Smads are transcription factors, but rely on transcription cofactors for appropriate regulation of target genes in response to TGF-[beta]- and BMP-related signals. In the DBL-1 pathway, sma-9 encodes multiple zinc finger transcription factors homologous to Drosophila Schnurri, which functions in Dpp/BMP signaling. We have studied the molecular functions of SMA-9 as a model for transcription cofactor-dependent regulation of gene expression. Using SMA-9 fusions to known transcriptional activators and repressors, we demonstrate that SMA-9 acts primarily as a transcriptional repressor in body size regulation in vivo. In contrast, both activator and repressor functions contribute to male tail patterning. We further show that different SMA-9 regions have intrinsic repressor and activator activities using a yeast transcription assay. We use microarray analysis to identify transcriptional target genes in body size regulation. Consistent with the importance of repression in mediating body size regulation, we find more repressed genes than activated genes in this pool. Finally, we identify five transcriptional targets with body size and/or male tail patterning phenotypes, including transcription factors related to Runx and fos and signaling molecules related to hedgehog and patched. Our results thus suggest that SMA-9 products function differentially as transcriptional repressors and activators in DBL-1/BMP pathway regulated body size and male tail morphogenesis. Author Affiliation: Department of Biology, Queens College, and Biochemistry PhD Program, the Graduate School and University Center, the City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367, USA Article History: Received 1 September 2006; Revised 9 January 2007; Accepted 27 February 2007

Byline: Amanda R. Crowley (1), Sheilendra S. Mehta (1), Mark J. Hembree (1), Barry L. Preuett (1), Krishna L. Prasadan (1), Susan W. Sharp (1), Hooi Yew (1), Christopher R. McFall (1), Christina L. Benjes (1), Sidhartha S. Tulachan (1), George K. Gittes (1), Charles L. Snyder (1) Keywords: Esophageal atresia; Tracheoesophageal fistula; Bone morphogenetic protein; Branching; Morphogenesis Abstract: The organogenesis of esophageal atresia with tracheoesophageal fistula (EA/TEF) remains unknown. The fistula tract appears to develop from a non-branching trifurcation of the embryonic lung bud. The non-branching growth of the fistula differs from the other lung buds and suggests a deficiency in bone morphogenetic protein (BMP) signaling, since BMPs are critical to proper lung development and branching. With IRB approval, portions of newborn human proximal esophageal pouch and distal fistula samples were recovered at the time of surgical repair of EA/TEF. The tissues were processed for immunohistochemistry. Commercially available fetal tissues were used as controls. In control tissues, BMP ligands (BMP 2, 4, and 7) were all present in the esophagus but absent in the trachea. BMPRIA was absent in both tissues. BMPRIB was detected in trachea but not in esophagus and BMPRII was detected in esophagus but not in trachea. In the EA/TEF specimens, all BMP ligands were present in the proximal esophageal pouch but absent in the fistula tract. BMPRIA and BMPRIB were not detected in either tissue. However, BMPRII was found in both fistula tract and proximal pouch. The submucosa of the fistula appears to maintain a mixed (identical neither to lung, esophagus, or trachea) BMP signaling pattern, providing one mechanism which could potentially explain the esophageal dismotility and lack of lung branching seen in the fistula/distal esophagus. Author Affiliation: (1) Laboratory for Surgical Organogenesis, Department of Surgery, Children's Mercy Hospital, 2401 Gillham Road, Kansas City, MO, 64108, USA Article History: Registration Date: 09/11/2005 Accepted Date: 21/10/2005 Online Date: 29/11/2005

Studies show that Bone Morphogenetic Protein 7 (BMP7) restricts the number of high Notch1/Hes1 activity domains and inhibits prostate epithelium branching morphogenesis. A mouse model is presented.

Functional inactivation of divergent bone morphogenetic proteins (BMPs) causes discrete disturbances during mouse development. BMP4-deficient embryos display mesodermal patterning defects at early post-implantation stages, whereas loss of BMP7 selectively disrupts kidney and eye morphogenesis. Whether these distinct phenotypes simply reflect differences in expression domains, or alternatively intrinsic differences in the signaling properties of these ligands remains unknown. To address this issue, we created embryos exclusively expressing BMP4 under control of the BMP7 locus. Surprisingly, this novel knock-in allele efficiently rescues kidney development. These results demonstrate unequivocally that these structurally divergent BMP family members, sharing only minimal sequence similarity can function interchangeably to activate all the essential signaling pathways for growth and morphogenesis of the kidney. Thus, we conclude that partially overlapping expression patterns of BMPs serve to modulate strength of BMP signaling rather than create discrete fields of ligands with intrinsically different signaling properties. Keywords: Bone morphogenetic protein; BMP; Kidney development

In the early Drosophila embryo, Bone morphogenetic protein (BMP) activity is positively and negatively regulated by the BMP-binding proteins Short gastrulation (Sog) and Twisted gastrulation (Tsg). We show here that a similar mechanism operates during crossvein formation, utilizing Sog and a new member of the tsg gene family, encoded by the crossveinless (cv) locus. The initial specification of crossvein fate in the Drosophila wing requires signaling mediated by Dpp and Gbb, two members of the BMP family, cv is required for the promotion of BMP signaling in the crossveins. Large sog clones disrupt posterior crossvein formation, suggesting that Sog and Cv act together in this context. We demonstrate that sog and cv can have both positive and negative effects on BMP signaling in the wing. Moreover, Cv is functionally equivalent to Tsg, since Tsg and Cv can substitute for each other's activity. We also confirm that Tsg and Cv have similar biochemical activities: Sog/Cv complex binds a Dpp/Gbb heterodimer with high affinity. Taken together, these studies suggest that Sog and Cv promote BMP signaling by transporting a BMP heterodimer from the longitudinal veins into the crossvein regions. Keywords: Drosophila; Pupal wing; Decapentaplegic; Glass bottom boat; Heterodimer

Pulmonary vascular medial hypertrophy in primary pulmonary hypertension (PPH) is mainly caused by increased proliferation and decreased apoptosis in pulmonary artery smooth muscle cells (PASMCs). Mutations of the bone morphogenetic protein (BMP) receptor type II (BMP-RII) gene have been implicated in patients with familial and sporadic PPH. The objective of this study was to elucidate the apoptotic effects of BMPs on normal human PASMCs and to examine whether BMP-induced effects are altered in PASMCs from PPH patients. Using RT-PCR, we detected six isoforms of BMPs (BMP-1 through -6) and three subunits of BMP receptors (BMP-RIa, -Rib, and -RID in PASMCs. Treatment of normal PASMCs with BMP-2 or -7 (100-200 nM, 24-48 h) markedly increased the percentage of cells undergoing apoptosis. The BMP-2-mediated apoptosis in normal PASMCs was associated with a transient activation or phosphorylation of Smad1 and a marked downregulation of the antiapoptotic protein Bcl-2. In PASMCs from PPH patients, the BMP-2- or BMP-7-induced apoptosis was significantly inhibited compared with PASMCs from patients with secondary pulmonary hypertension. These results suggest that the antiproliferative effect of BMPs is partially due to induction of PASMC apoptosis, which serves as a critical mechanism to maintain normal cell number in the pulmonary vasculature. Inhibition of BMP-induced PASMC apoptosis in PPH patients may play an important role in the development of pulmonary vascular medial hypertrophy in these patients. hypertension; arteries; Smad; Bcl; transforming growth factor-[beta]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/S0012-1606(02)00022-2 Byline: Stephen H Settle (a), Ryan B Rountree (a), Abhishek Sinha (a), Abigail Thacker (a), Kay Higgins (a), David M Kingsley (a) Keywords: Growth/differentiation factors; Bone morphogenetic protein; Mouse mutation; Skeletal patterning; Joints; Craniosynostosis; Limb development Abstract: Growth/differentiation factors 5, 6, and 7 (GDF5/6/7) represent a distinct subgroup within the bone morphogenetic protein (BMP) family of secreted signaling molecules. Previous studies have shown that the Gdf5 gene is expressed in transverse stripes across developing skeletal elements and is one of the earliest known markers of joint formation during embryonic development. Although null mutations in this gene disrupt formation of some bones and joints in the skeleton, many sites are unaffected. Here, we show that the closely related family members Gdf6 and Gdf7 are expressed in different subsets of developing joints. Inactivation of the Gdf6 gene causes defects in joint, ligament, and cartilage formation at sites distinct from those seen in Gdf5 mutants, including the wrist and ankle, the middle ear, and the coronal suture between bones in the skull. Mice lacking both Gdf5 and Gdf6 show additional defects, including severe reduction or loss of some skeletal elements in the limb, additional fusions between skeletal structures, scoliosis, and altered cartilage in the intervertebral joints of the spinal column. These results show that members of the GDF5/6/7 subgroup are required for normal formation of bones and joints in the limbs, skull, and axial skeleton. The diverse effects on joint development and the different types of joints affected in the mutants suggest that members of the GDF family play a key role in establishing boundaries between many different skeletal elements during normal development. Some of the skeletal defects seen in single or double mutant mice resemble defects seen in human skeletal diseases, which suggests that these genes may be candidates that underlie some forms of carpal/tarsal coalition, conductive deafness, scoliosis, and craniosynostosis. Author Affiliation: (a) Department of Developmental Biology and Howard Hughes Medical Institute, Beckman Center B300, Stanford University School of Medicine, Stanford, CA 94305-5327, USA Article History: Received 12 September 2002; Revised 14 October 2002; Accepted 14 October 2002

Research has been conducted on Sonic hedgehog proteins. The hypothesis that these proteins induce factors allowing somatic cells to chondrify in response to the bone morphogenetic protein signals has been tested and the results are reported.

Research demonstrates that the signals for head and trunk formation during vertebrate development are governed by bone morphogenetic proteins (BMPs). Results show that mutations in BMP inhibitors limit BMP signaling, which in turn regulates the determinants that specifying vertebrate head and trunk development.