BMP signaling during bone pattern determination in the developing limb

Development ◽  
1996 ◽  
Vol 122 (11) ◽  
pp. 3557-3566 ◽  
Author(s):  
Y. Kawakami ◽  
T. Ishikawa ◽  
M. Shimabara ◽  
N. Tanda ◽  
M. Enomoto-Iwamoto ◽  
...  
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Kinase Domain ◽  
Distal Region ◽  
Bmp Signaling ◽  
Dominant Negative ◽  
Limb Bud ◽  
Type I ◽  
Posterior Limb ◽  
Receptor Complexes ◽  
Limb Mesenchyme

To examine the role of BMP signaling during limb pattern formation, we isolated chicken cDNAs encoding type I (BRK-1 and BRK-2) and type II (BRK-3) receptors for bone morphogenetic proteins. BRK-2 and BRK-3, which constitute dual-affinity signaling receptor complexes for BMPs, are co-expressed in condensing precartilaginous cells, while BRK-1 is weakly expressed in the limb mesenchyme. BRK-3 is also expressed in the apical ectodermal ridge and interdigital limb mesenchyme. BRK-2 is intensely expressed in the posterior-distal region of the limb bud. During digit duplication by implanting Sonic hedgehog-producing cells, BRK-2 expression is induced anteriorly in the new digit forming region as observed for BMP-2 and BMP-7 expression in the limb bud. Dominant-negative effects on BMP signaling were obtained by over-expressing kinase domain-deficient forms of the receptors. Chondrogenesis of limb mesenchymal cells is markedly inhibited by dominant-negative BRK-2 and BRK-3, but not by BRK-1. Although the bone pattern was not disturbed by expressing individual dominant-negative BRK independently, preferential distal and posterior limb truncations resulted from co-expressing the dominant-negative forms of BRK-2 and BRK-3 in the whole limb bud, thus providing evidence that BMPs are essential morphogenetic signals for limb bone patterning.

scholarly journals The Bone Morphogenetic Protein Type Ib Receptor Is a Major Mediator of Glial Differentiation and Cell Survival in Adult Hippocampal Progenitor Cell Culture

2004 ◽  
Vol 15 (8) ◽  
pp. 3863-3875 ◽  
Author(s):  
A. Brederlau ◽  
R. Faigle ◽  
M. Elmi ◽  
A. Zarebski ◽  
S. Sjöberg ◽  
...  
Keyword(s):  
Cell Survival ◽  
Bone Morphogenetic Protein ◽  
Cell Fate ◽  
Bone Morphogenetic Proteins ◽  
Bmp Signaling ◽  
Dominant Negative ◽  
Type I ◽  
Protein Receptor ◽  
Morphogenetic Protein ◽  
Mediate Cell

Bone morphogenetic proteins (BMPs) act as growth regulators and inducers of differentiation. They transduce their signal via three different type I receptors, termed activin receptor-like kinase 2 (Alk2), Alk3, or bone morphogenetic protein receptor Ia (BMPRIa) and Alk6 or BMPRIb. Little is known about functional differences between the three type I receptors. Here, we have investigated consequences of constitutively active (ca) and dominant negative (dn) type I receptor overexpression in adult-derived hippocampal progenitor cells (AHPs). The dn receptors have a nonfunctional intracellular but functional extracellular domain. They thus trap BMPs that are endogenously produced by AHPs. We found that effects obtained by overexpression of dnAlk2 and dnAlk6 were similar, suggesting similar ligand binding patterns for these receptors. Thus, cell survival was decreased, glial fibrillary acidic protein (GFAP) expression was reduced, whereas the number of oligodendrocytes increased. No effect on neuronal differentiation was seen. Whereas the expression of Alk2 and Alk3 mRNA remained unchanged, the Alk6 mRNA was induced after impaired BMP signaling. After dnAlk3 overexpression, cell survival and astroglial differentiation increased in parallel to augmented Alk6 receptor signaling. We conclude that endogenous BMPs mediate cell survival, astroglial differentiation and the suppression of oligodendrocytic cell fate mainly via the Alk6 receptor in AHP culture.

scholarly journals Structural basis for ALK2/BMPR2 receptor complex signaling through kinase domain oligomerization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Christopher Agnew ◽  
Pelin Ayaz ◽  
Risa Kashima ◽  
Hanna S. Loving ◽  
Prajakta Ghatpande ◽  
...  
Keyword(s):  
Md Simulations ◽  
Kinase Domain ◽  
Structural Basis ◽  
Type I ◽  
Type Ii ◽  
Exchange Mass Spectrometry ◽  
Receptor Complexes ◽  
Bmp Receptors ◽  
Morphogenetic Protein ◽  
Smad Proteins

AbstractUpon ligand binding, bone morphogenetic protein (BMP) receptors form active tetrameric complexes, comprised of two type I and two type II receptors, which then transmit signals to SMAD proteins. The link between receptor tetramerization and the mechanism of kinase activation, however, has not been elucidated. Here, using hydrogen deuterium exchange mass spectrometry (HDX-MS), small angle X-ray scattering (SAXS) and molecular dynamics (MD) simulations, combined with analysis of SMAD signaling, we show that the kinase domain of the type I receptor ALK2 and type II receptor BMPR2 form a heterodimeric complex via their C-terminal lobes. Formation of this dimer is essential for ligand-induced receptor signaling and is targeted by mutations in BMPR2 in patients with pulmonary arterial hypertension (PAH). We further show that the type I/type II kinase domain heterodimer serves as the scaffold for assembly of the active tetrameric receptor complexes to enable phosphorylation of the GS domain and activation of SMADs.

scholarly journals Bone Morphogenetic Protein Receptor Complexes on the Surface of Live Cells: A New Oligomerization Mode for Serine/Threonine Kinase Receptors

2000 ◽  
Vol 11 (3) ◽  
pp. 1023-1035 ◽  
Author(s):  
Lilach Gilboa ◽  
Anja Nohe ◽  
Tanja Geissendörfer ◽  
Walter Sebald ◽  
Yoav I. Henis ◽  
...  
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Live Cells ◽  
Type I ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Receptor Complexes ◽  
Bmp Receptors ◽  
Protein Receptor

The bone morphogenetic proteins (BMPs) play important roles in embryogenesis and normal cell growth. The BMP receptors belong to the family of serine/threonine kinase receptors, whose activation has been investigated intensively for the transforming growth factor-β (TGF-β) receptor subfamily. However, the interactions between the BMP receptors, the composition of the active receptor complex, and the role of the ligand in its formation have not yet been investigated and were usually assumed to follow the same pattern as the TGF-β receptors. Here we demonstrate that the oligomerization pattern of the BMP receptors is different and is more flexible and susceptible to modulation by ligand. Using several complementary approaches, we investigated the formation of homomeric and heteromeric complexes between the two known BMP type I receptors (BR-Ia and BR-Ib) and the BMP type II receptor (BR-II). Coimmunoprecipitation studies detected the formation of heteromeric and homomeric complexes among all the BMP receptor types even in the absence of ligand. These complexes were also detected at the cell surface after BMP-2 binding and cross-linking. Using antibody-mediated immunofluorescence copatching of epitope-tagged receptors, we provide evidence in live cells for preexisting heteromeric (BR-II/BR-Ia and BR-II/BR-Ib) and homomeric (BR-II/BR-II, BR-Ia/ BR-Ia, BR-Ib/ BR-Ib, and also BR-Ia/ BR-Ib) oligomers in the absence of ligand. BMP-2 binding significantly increased hetero- and homo-oligomerization (except for the BR-II homo-oligomer, which binds ligand poorly in the absence of BR-I). In contrast to previous observations on TGF-β receptors, which were found to be fully homodimeric in the absence of ligand, the BMP receptors show a much more flexible oligomerization pattern. This novel feature in the oligomerization mode of the BMP receptors allows higher variety and flexibility in their responses to various ligands as compared with the TGF-β receptors.

scholarly journals The N domain of Smad7 is essential for specific inhibition of transforming growth factor-β signaling

2001 ◽  
Vol 155 (6) ◽  
pp. 1017-1028 ◽  
Author(s):  
Aki Hanyu ◽  
Yasuhiro Ishidou ◽  
Takanori Ebisawa ◽  
Tomomasa Shimanuki ◽  
Takeshi Imamura ◽  
...  
Keyword(s):  
Growth Factor ◽  
Bone Morphogenetic Proteins ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Amino Acid Sequences ◽  
Bmp Signaling ◽  
Type I ◽  
Specific Inhibition ◽  
Amino Terminal ◽  
Carboxy Terminal

Inhibitory Smads (I-Smads) repress signaling by cytokines of the transforming growth factor-β (TGF-β) superfamily. I-Smads have conserved carboxy-terminal Mad homology 2 (MH2) domains, whereas the amino acid sequences of their amino-terminal regions (N domains) are highly divergent from those of other Smads. Of the two different I-Smads in mammals, Smad7 inhibited signaling by both TGF-β and bone morphogenetic proteins (BMPs), whereas Smad6 was less effective in inhibiting TGF-β signaling. Analyses using deletion mutants and chimeras of Smad6 and Smad7 revealed that the MH2 domains were responsible for the inhibition of both TGF-β and BMP signaling by I-Smads, but the isolated MH2 domains of Smad6 and Smad7 were less potent than the full-length Smad7 in inhibiting TGF-β signaling. The N domains of I-Smads determined the subcellular localization of these molecules. Chimeras containing the N domain of Smad7 interacted with the TGF-β type I receptor (TβR-I) more efficiently, and were more potent in repressing TGF-β signaling, than those containing the N domain of Smad6. The isolated N domain of Smad7 physically interacted with the MH2 domain of Smad7, and enhanced the inhibitory activity of the latter through facilitating interaction with TGF-β receptors. The N domain of Smad7 thus plays an important role in the specific inhibition of TGF-β signaling.

XBMPRII, a novel Xenopus type II receptor mediating BMP signaling in embryonic tissues

Development ◽  
1998 ◽  
Vol 125 (3) ◽  
pp. 431-442 ◽  
Author(s):  
A. Frisch ◽  
C.V. Wright
Keyword(s):  
Cell Fate ◽  
Organizer Region ◽  
Bmp Signaling ◽  
Dominant Negative ◽  
Mesoderm Induction ◽  
Type I ◽  
Type Ii ◽  
Common Component ◽  
Activin Signaling

Bone Morphogenetic Proteins (BMPs) are potent regulators of embryonic cell fate that are presumed to initiate signal transduction in recipient cells through multimeric, transmembrane, serine/threonine kinase complexes made up of type I and type II receptors. BMPRII was identified previously in mammals as the only type II receptor that binds BMPs, but not activin or TGFbeta, in vitro. We report the cloning and functional analysis in vivo of its Xenopus homolog, XBMPRII. XBMPRII is expressed maternally and zygotically in an initially unrestricted manner. Strikingly, XBMPRII transcripts then become restricted to the mesodermal precursors during gastrulation. Expression is lower in the dorsal organizer region, potentially providing a mechanism to suppress the actions of BMP4 on dorsally fated tissues. Similar to the results seen for a truncated type I BMP receptor (tBR), a dominant-negative form of XBMPRII (tBRII) can dorsalize ventral mesoderm, induce extensive secondary body axes, block mesoderm induction by BMP4 and directly neuralize ectoderm, strongly suggesting that XBMPRII mediates BMP signals in vivo. However, although both tBRII and tBR can induce partial secondary axes, marker analysis shows that tBRII-induced axes are more anteriorly extended. Additionally, coinjection of tBRII and tBR synergistically increases the incidence of secondary axis formation. A truncated activin type II receptor (deltaXAR1) is known to block both activin and BMP signaling in vivo. Here we show that such crossreactivity does not occur for tBRII, in that it does not affect activin signaling. Furthermore, our studies indicate that the full-length activin type II receptor (XAR1) overcomes a block in BMP4 signaling imposed by tBRII, implicating XAR1 as a common component of BMP and activin signaling pathways in vivo. These data implicate XBMPRII as a type II receptor with high selectivity for BMP signaling, and therefore as a critical mediator of the effects of BMPs as mesodermal patterning agents and suppressors of neural fate during embryogenesis.

scholarly journals Regulatory Roles of Bone Morphogenetic Proteins and Glucocorticoids in Catecholamine Production by Rat Pheochromocytoma Cells

Endocrinology ◽  
2005 ◽  
Vol 146 (12) ◽  
pp. 5332-5340 ◽  
Author(s):  
Yoshihiro Kano ◽  
Fumio Otsuka ◽  
Masaya Takeda ◽  
Jiro Suzuki ◽  
Kenichi Inagaki ◽  
...  
Keyword(s):  
Tyrosine Hydroxylase ◽  
Pc12 Cells ◽  
Bone Morphogenetic Proteins ◽  
Bmp Signaling ◽  
Type I ◽  
Dependent Manner ◽  
Catecholamine Synthesis ◽  
Pheochromocytoma Cells ◽  
Dose Dependent Fashion ◽  
Dose Dependent

We here report a new physiological system that governs catecholamine synthesis involving bone morphogenetic proteins (BMPs) and activin in the rat pheochromocytoma cell line, PC12. BMP type I receptors, including activin receptor-like kinase-2 (ALK-2) (also referred to as ActRIA) and ALK-3 (BMPRIA), both type II receptors, ActRII and BMPRII, as well as the ligands BMP-2, -4, and -7 and inhibin/activin subunits were expressed in PC12 cells. PC12 cells predominantly secrete dopamine, whereas noradrenaline and adrenaline production is negligible. BMP-2, -4, -6, and -7 and activin A each suppressed dopamine and cAMP synthesis in a dose-dependent fashion. The BMP ligands also decreased 3,4-dihydroxyphenylalanine decarboxylase mRNA expression, whereas activin suppressed tyrosine hydroxylase expression. BMPs induced both Smad1/5/8 phosphorylation and Tlx2-Luc activation, whereas activin stimulated 3TP-Luc activity and p38 MAPK phosphorylation. ERK signaling was not affected by BMPs or activin. Dexamethasone enhanced catecholamine synthesis, accompanying increases in tyrosine hydroxylase and 3,4-dihydroxyphenylalanine decarboxylase transcription without cAMP accumulation. In the presence of dexamethasone, BMPs and activin failed to reduce dopamine as well as cAMP production. In addition, dexamethasone modulated mitotic suppression of PC12 induced by BMPs in a ligand-dependent manner. Furthermore, intracellular BMP signaling was markedly suppressed by dexamethasone treatment and the expression of ALK-2, ALK-3, and BMPRII was significantly inhibited by dexamethasone. Collectively, the endogenous BMP/activin system plays a key role in the regulation of catecholamine production. Controlling activity of the BMP system may be critical for glucocorticoid-induced catecholamine synthesis by adrenomedullar cells.

scholarly journals Cooperative Inhibition of Bone Morphogenetic Protein Signaling by Smurf1 and Inhibitory Smads

2003 ◽  
Vol 14 (7) ◽  
pp. 2809-2817 ◽  
Author(s):  
Gyo Murakami ◽  
Tetsuro Watabe ◽  
Kunio Takaoka ◽  
Kohei Miyazono ◽  
Takeshi Imamura
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Mammalian Cells ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Bmp Signaling ◽  
Type I ◽  
Protein Signaling ◽  
Reporter Construct ◽  
Bone Morphogenetic Protein Signaling ◽  
Morphogenetic Protein

Smad ubiquitin regulatory factor (Smurf) 1 binds to receptor-regulated Smads for bone morphogenetic proteins (BMPs) Smad1/5 and promotes their degradation. In addition, Smurf1 associates with transforming growth factor-β type I receptor through the inhibitory Smad (I-Smad) Smad7 and induces their degradation. Herein, we examined whether Smurf1 negatively regulates BMP signaling together with the I-Smads Smad6/7. Smurf1 and Smad6 cooperatively induced secondary axes in Xenopus embryos. Using a BMP-responsive promoter-reporter construct in mammalian cells, we found that Smurf1 cooperated with I-Smad in inhibiting BMP signaling and that the inhibitory activity of Smurf1 was not necessarily correlated with its ability to bind to Smad1/5 directly. Smurf1 bound to BMP type I receptors via I-Smads and induced ubiquitination and degradation of these receptors. Moreover, Smurf1 associated with Smad1/5 indirectly through I-Smads and induced their ubiquitination and degradation. Smurf1 thus controls BMP signaling with and without I-Smads through multiple mechanisms.

scholarly journals Drosophila Dullard functions as a Mad phosphatase to terminate BMP signaling

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Hugo Urrutia ◽  
Abigail Aleman ◽  
Edward Eivers
Keyword(s):  
Growth Factors ◽  
Bone Morphogenetic Proteins ◽  
Bmp Signaling ◽  
Tissue Homeostasis ◽  
Type I ◽  
Binding Assays ◽  
Adult Tissue ◽  
Phosphatase Domain ◽  
Receptor Kinases ◽  
Normal Embryonic Development

Abstract Bone morphogenetic proteins (BMPs) are growth factors that provide essential signals for normal embryonic development and adult tissue homeostasis. A key step in initiating BMP signaling is ligand induced phosphorylation of receptor Smads (R-Smads) by type I receptor kinases, while linker phosphorylation of R-Smads has been shown to cause BMP signal termination. Here we present data demonstrating that the phosphatase Dullard is involved in dephosphorylating the Drosophila R-Smad, Mad and is integral in controlling BMP signal duration. We show that a hypomorphic Dullard allele or Dullard knockdown leads to increased Mad phosphorylation levels, while Dullard overexpression resulted in reduced Mad phosphorylations. Co-immunoprecipitation binding assays demonstrate phosphorylated Mad and Dullard physically interact, while mutation of Dullard’s phosphatase domain still allowed Mad-Dullard interactions but abolished its ability to regulate Mad phosphorylations. Finally, we demonstrate that linker and C-terminally phosphorylated Mad can be regulated by one of two terminating mechanisms, degradation by proteasomes or dephosphorylation by the phosphatase Dullard.

scholarly journals Specification of BMP Signaling

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1579 ◽  
Author(s):  
Joachim Nickel ◽  
Thomas D. Mueller
Keyword(s):  
Growth Factors ◽  
Transforming Growth Factor ◽  
Bmp Signaling ◽  
Current View ◽  
Receptor Subtypes ◽  
Type I ◽  
Dependent Manner ◽  
Type Ii ◽  
Tgfβ Signaling ◽  
Receptor Complexes

Bone Morphogenetic Proteins (BMPs) together with the Growth and Differentiation Factors (GDFs) form the largest subgroup of the Transforming Growth Factor (TGF)β family and represent secreted growth factors, which play an essential role in many aspects of cell communication in higher organisms. As morphogens they exert crucial functions during embryonal development, but are also involved in tissue homeostasis and regeneration in the adult organism. Their involvement in maintenance and repair processes of various tissues and organs made these growth factors highly interesting targets for novel pharmaceutical applications in regenerative medicine. A hallmark of the TGFβ protein family is that all of the more than 30 growth factors identified to date signal by binding and hetero-oligomerization of a very limited set of transmembrane serine-threonine kinase receptors, which can be classified into two subgroups termed type I and type II. Only seven type I and five type II receptors exist for all 30plus TGFβ members suggesting a pronounced ligand-receptor promiscuity. Indeed, many TGFβ ligands can bind the same type I or type II receptor and a particular receptor of either subtype can usually interact with and bind various TGFβ ligands. The possible consequence of this ligand-receptor promiscuity is further aggravated by the finding that canonical TGFβ signaling of all family members seemingly results in the activation of just two distinct signaling pathways, that is either SMAD2/3 or SMAD1/5/8 activation. While this would implicate that different ligands can assemble seemingly identical receptor complexes that activate just either one of two distinct pathways, in vitro and in vivo analyses show that the different TGFβ members exert quite distinct biological functions with high specificity. This discrepancy indicates that our current view of TGFβ signaling initiation just by hetero-oligomerization of two receptor subtypes and transduction via two main pathways in an on-off switch manner is too simplified. Hence, the signals generated by the various TGFβ members are either quantitatively interpreted using the subtle differences in their receptor-binding properties leading to ligand-specific modulation of the downstream signaling cascade or additional components participating in the signaling activation complex allow diversification of the encoded signal in a ligand-dependent manner at all cellular levels. In this review we focus on signal specification of TGFβ members, particularly of BMPs and GDFs addressing the role of binding affinities, specificities, and kinetics of individual ligand-receptor interactions for the assembly of specific receptor complexes with potentially distinct signaling properties.

scholarly journals Heparan Sulfate Acts as a Bone Morphogenetic Protein Coreceptor by Facilitating Ligand-induced Receptor Hetero-oligomerization

2010 ◽  
Vol 21 (22) ◽  
pp. 4028-4041 ◽  
Author(s):  
Wan-Jong Kuo ◽  
Michelle A. Digman ◽  
Arthur D. Lander
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Cell Surface ◽  
Heparan Sulfate ◽  
Bone Morphogenetic Proteins ◽  
Growth Factor Receptor ◽  
In Vivo Studies ◽  
Type I ◽  
Receptor Complexes

Cell surface heparan sulfate (HS) not only binds several major classes of growth factors but also sometimes potentiates their activities—an effect usually termed “coreception.” A view that coreception is due to the stabilization of growth factor–receptor interactions has emerged primarily from studies of the fibroblast growth factors (FGFs). Recent in vivo studies have strongly suggested that HS also plays an important role in regulating signaling by the bone morphogenetic proteins (BMPs). Here, we provide evidence that the mechanism of coreception for BMPs is markedly different from that established for FGFs. First, we demonstrate a direct, stimulatory role for cell surface HS in the immediate signaling activities of BMP2 and BMP4, and we provide evidence that HS–BMP interactions are required for this effect. Next, using several independent assays of ligand binding and receptor assembly, including coimmunoprecipitation, cross-linking, and fluorescence fluctuation microscopy, we show that HS does not affect BMP binding to type I receptor subunits but instead enhances the subsequent recruitment of type II receptor subunits to BMP-type I receptor complexes. This suggests a view of HS as a catalyst of the formation of signaling complexes, rather than as a stabilizer of growth factor binding.

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