Cellular interpretation of multiple TGF-beta signals: intracellular antagonism between activin/BVg1 and BMP-2/4 signaling mediated by Smads

Development ◽  
1997 ◽  
Vol 124 (22) ◽  
pp. 4467-4480 ◽  
Author(s):  
A.F. Candia ◽  
T. Watabe ◽  
S.H. Hawley ◽  
D. Onichtchouk ◽  
Y. Zhang ◽  
...  
Keyword(s):  
Cell Fate ◽  
Bone Morphogenetic Proteins ◽  
Dominant Negative ◽  
Signaling Cascades ◽  
Mesoderm Induction ◽  
Tgf Beta ◽  
Functional Involvement ◽  
Dominant Negative Variant ◽  
Transcriptional Complex ◽  
Mesoderm Patterning

During early embryogenesis of Xenopus, dorsoventral polarity of the mesoderm is established by dorsalizing and ventralizing agents, which are presumably mediated by the activity of an activin/BVg1-like protein and Bone Morphogenetic Proteins (BMP), respectively. Interestingly, these two TGF-beta subfamilies are found in overlapping regions during mesoderm patterning. This raises the question of how the presumptive mesodermal cells recognize the multiple TGF-beta signals and differentially interpret this information to assign a particular cell fate. In this study, we have exploited the well characterized model of Xenopus mesoderm induction to determine the intracellular interactions between BMP-2/4 and activin/BVg1 signaling cascades. Using a constitutively active BMP-2/4 receptor that transduces BMP-2/4 signals in a ligand-independent fashion, we demonstrate that signals provided by activin/BVg1 and BMP modulate each other's activity and that this crosstalk occurs through intracellular mechanisms. In assays using BMP-2/4 and activin/BVg1-specific reporters, we determined that the specificity of BMP-2/4 and activin/BVg1 signaling is mediated by Smad1 and Smad2, respectively. These Smads should be considered as the mediators of the intracellular antagonism between BMP-2/4 and activin/BVg1 signaling possibly through sequestration of a limited pool of Smad4. Consistent with such a mechanism, Smad4 interacts functionally with both Smad1 and −2 to potentiate their signaling activities, and a dominant negative variant of Smad4 can inhibit both activin/BVg1 and BMP-2/4 mediated signaling Finally, we demonstrate that an activin/BVg1-dependent transcriptional complex contains both Smad2 and Smad4 and thereby provides a physical basis for the functional involvement of both Smads in TGF-beta-dependent transcriptional regulation. Thus, Smad4 plays a central role in synergistically activating activin/BVg1 and BMP-dependent transcription and functions as an intracellular sensor for TGF-beta-related signals.

scholarly journals Activin-mediated mesoderm induction requires FGF

Development ◽  
1994 ◽  
Vol 120 (2) ◽  
pp. 453-462 ◽  
Author(s):  
R.A. Cornell ◽  
D. Kimelman
Keyword(s):  
Dominant Negative ◽  
Mesoderm Induction ◽  
Fibroblast Growth ◽  
Fgf Signaling ◽  
Tgf Beta ◽  
Fgf Receptor ◽  
Basic Fgf ◽  
Dominant Negative Form ◽  
Negative Form

The early patterning of mesoderm in the Xenopus embryo requires signals from several intercellular factors, including mesoderm-inducing agents that belong to the fibroblast growth factor (FGF) and TGF-beta families. In animal hemisphere explants (animal caps), basic FGF and the TGF-beta family member activin are capable of converting pre-ectodermal cells to a mesodermal fate, although activin is much more effective at inducing dorsal and anterior mesoderm than is basic FGF. Using a dominant-negative form of the Xenopus type 1 FGF receptor, we show that an FGF signal is required for the full induction of mesoderm by activin. Animal caps isolated from embryos that have been injected with the truncated FGF receptor and cultured with activin do not extend and the induction of some genes, including cardiac actin and Xbra, is greatly diminished, while the induction of other genes, including the head organizer-specific genes gsc and Xlim-1, is less sensitive. These results are consistent with the phenotype of the truncated FGF receptor-injected embryo and imply that the activin induction of mesoderm depends on FGF, with some genes requiring a higher level of FGF signaling than others.

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 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 The TOR–Auxin Connection Upstream of Root Hair Growth

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 150 ◽  
Author(s):  
Katarzyna Retzer ◽  
Wolfram Weckwerth
Keyword(s):  
Cell Fate ◽  
Root Hair ◽  
Hair Growth ◽  
Environmental Changes ◽  
Growth Control ◽  
Root Hairs ◽  
Signaling Cascades ◽  
Continuous Growth ◽  
Root Hair Cell ◽  
Root Hair Growth

Plant growth and productivity are orchestrated by a network of signaling cascades involved in balancing responses to perceived environmental changes with resource availability. Vascular plants are divided into the shoot, an aboveground organ where sugar is synthesized, and the underground located root. Continuous growth requires the generation of energy in the form of carbohydrates in the leaves upon photosynthesis and uptake of nutrients and water through root hairs. Root hair outgrowth depends on the overall condition of the plant and its energy level must be high enough to maintain root growth. TARGET OF RAPAMYCIN (TOR)-mediated signaling cascades serve as a hub to evaluate which resources are needed to respond to external stimuli and which are available to maintain proper plant adaptation. Root hair growth further requires appropriate distribution of the phytohormone auxin, which primes root hair cell fate and triggers root hair elongation. Auxin is transported in an active, directed manner by a plasma membrane located carrier. The auxin efflux carrier PIN-FORMED 2 is necessary to transport auxin to root hair cells, followed by subcellular rearrangements involved in root hair outgrowth. This review presents an overview of events upstream and downstream of PIN2 action, which are involved in root hair growth control.

scholarly journals Protein kinase C-theta isoenzyme selective stimulation of the transcription factor complex AP-1 in T lymphocytes.

1996 ◽  
Vol 16 (4) ◽  
pp. 1842-1850 ◽  
Author(s):  
G Baier-Bitterlich ◽  
F Uberall ◽  
B Bauer ◽  
F Fresser ◽  
H Wachter ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transcriptional Activation ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Pkc Alpha ◽  
Transcriptional Complex ◽  
Induced Signal ◽  
Transcription Factor Complex

T-lymphocyte stimulation requires activation of several protein kinases, including the major phorbol ester receptor protein kinase C (PKC), ultimately leading to induction of lymphokines, such as interleukin-2 (IL-2). The revelant PKC isoforms which are involved in the activation cascades of nuclear transcription factors involved in IL-2 production have not yet been clearly defined. We have examined the potential role of two representative PKC isoforms in the induction of the IL-2 gene, i.e., PKC-alpha and PKC-theta, the latter being expressed predominantly in hematopoietic cell lines, particularly T cells. Similar to that of PKC-alpha, PKC-theta overexpression in murine EL4 thymoma cells caused a significant increase in phorbol 12-myristate 13-acetate (PMA)-induced transcriptional activation of full-length IL-2-chloramphenicol acetyltransferase (CAT) and NF-AT-CAT but not of NF-IL2A-CAT or NF-kappaB promoter-CAT reporter gene constructs. Importantly, the critical AP-1 enhancer element was differentially modulated by these two distinct PKC isoenzymes, since only PKC-theta but not PKC-alpha overexpression resulted in an approximately 2.8-fold increase in AP-1-collagenase promoter CAT expression in comparison with the vector control. Deletion of the AP-1 enhancer site in the collagenase promoter rendered it unresponsive to PKC-theta. Expression of a constitutively active mutant PKC-theta A148E (but not PKC-alpha A25E) was sufficient to induce activation of AP-1 transcription factor complex in the absence of PMA stimulation. Conversely, a catalytically inactive PKC-theta K409R (but not PKC-alpha K368R) mutant abrogated endogenous PMA-mediated activation of AP-1 transcriptional complex. Dominant negative mutant Ha-RasS17N completely inhibited the PKC-O A148E-induced signal, PKC-O. Expression of a constitutively active mutant PKC-O A148E (but not PKC-alpha A25E) was sufficient to induce activation of AP-1 transcription factor complex in the absence of PMA stimulation. Conversely, a catalytically inactive PKC-O K409R (but not PKC-alpha K368R) mutant abrogated endogenous PMA-mediated activation of AP-1 transcriptional complex. Dominant negative mutant Ha-enRasS17N completely inhibited in the PKC-O A148E-induced signal, identifying PKC-theta as a specific constituent upstream of or parallel to Ras in the signaling cascade leading to AP transcriptional activation.

scholarly journals The dynamic role of bone morphogenetic proteins in neural stem cell fate and maturation

2012 ◽  
Vol 72 (7) ◽  
pp. 1068-1084 ◽  
Author(s):  
Allison M. Bond ◽  
Oneil G. Bhalala ◽  
John A. Kessler
Keyword(s):  
Stem Cell ◽  
Cell Fate ◽  
Neural Stem Cell ◽  
Bone Morphogenetic Proteins ◽  
Stem Cell Fate

scholarly journals Alpha/Beta Interferons Potentiate Virus-Induced Apoptosis through Activation of the FADD/Caspase-8 Death Signaling Pathway

2000 ◽  
Vol 74 (3) ◽  
pp. 1513-1523 ◽  
Author(s):  
Siddharth Balachandran ◽  
P. Christopher Roberts ◽  
Todd Kipperman ◽  
Kapil N. Bhalla ◽  
Richard W. Compans ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Sindbis Virus ◽  
Influenza Virus Infection ◽  
Dominant Negative ◽  
Caspase 8 ◽  
Signaling Complex ◽  
Dependent Protein ◽  
Induced Apoptosis ◽  
Dominant Negative Variant

ABSTRACT Interferon (IFN) mediates its antiviral effects by inducing a number of responsive genes, including the double-stranded RNA (dsRNA)-dependent protein kinase, PKR. Here we report that inducible overexpression of functional PKR in murine fibroblasts sensitized cells to apoptosis induced by influenza virus, while in contrast, cells expressing a dominant-negative variant of PKR were completely resistant. We determined that the mechanism of influenza virus-induced apoptosis involved death signaling through FADD/caspase-8 activation, while other viruses such as vesicular stomatitis virus (VSV) and Sindbis virus (SNV) did not significantly provoke PKR-mediated apoptosis but did induce cytolysis of fibroblasts via activation of caspase-9. Significantly, treatment with IFN-α/β greatly sensitized the fibroblasts to FADD-dependent apoptosis in response to dsRNA treatment or influenza virus infection but completely protected the cells against VSV and SNV replication in the absence of any cellular destruction. The mechanism by which IFN increases the cells' susceptibility to lysis by dsRNA or certain virus infection is by priming cells to FADD-dependent apoptosis, possibly by regulating the activity of the death-induced signaling complex (DISC). Conversely, IFN is also able to prevent the replication of viruses such as VSV that avoid triggering FADD-mediated DISC activity, by noncytopathic mechanisms, thus preventing destruction of the cell.

Regulation of CCK-induced amylase release by PKC-δ in rat pancreatic acinar cells

2004 ◽  
Vol 287 (4) ◽  
pp. G764-G771 ◽  
Author(s):  
Chenwei Li ◽  
Xuequn Chen ◽  
John A. Williams
Keyword(s):  
Acinar Cells ◽  
Adenoviral Vectors ◽  
Dominant Negative ◽  
Pancreatic Acinar Cells ◽  
Amylase Secretion ◽  
Wild Type ◽  
Amylase Release ◽  
Pkc Isoforms ◽  
Chemical Inhibitors ◽  
Dominant Negative Variant

PKC is known to be activated by pancreatic secretagogues such as CCK and carbachol and to participate along with calcium in amylase release. Four PKC isoforms, α, δ, ε, and ζ, have been identified in acinar cells, but which isoforms participate in amylase release are unknown. To identify the responsible isoforms, we used translocation assays, chemical inhibitors, and overexpression of individual isoforms and their dominant-negative variants by means of adenoviral vectors. CCK stimulation caused translocation of PKC-α, -δ, and -ε, but not -ζ from soluble to membrane fraction. CCK-induced amylase release was inhibited ∼30% by GF109203X, a broad spectrum PKC inhibitor, and by rottlerin, a PKC-δ inhibitor, but not by Gö6976, a PKC-α inhibitor, at concentrations from 1 to 5 μM. Neither overexpression of wild-type or dominant-negative PKC-α affected CCK-induced amylase release. Overexpression of PKC-δ and -ε enhanced amylase release, whereas only dominant-negative PKC-δ inhibited amylase release by 25%. PKC-δ overexpression increased amylase release at all concentrations of CCK, but dominant-negative PKC-δ only inhibited the maximal concentration; both similarly affected carbachol and JMV-180-induced amylase release. Overexpression of both PKC-δ and its dominant-negative variant affected the late but not the early phase of amylase release. GF109203X totally blocked the enhancement of amylase release by PKC-δ but had no further effect in the presence of dominant-negative PKC-δ. These results indicate that PKC-δ is the PKC isoform involved with amylase secretion.

scholarly journals The Yeast AAA+ Chaperone Hsp104 Is Part of a Network That Links the Actin Cytoskeleton with the Inheritance of Damaged Proteins

2009 ◽  
Vol 29 (13) ◽  
pp. 3738-3745 ◽  
Author(s):  
Peter Tessarz ◽  
Michael Schwarz ◽  
Axel Mogk ◽  
Bernd Bukau
Keyword(s):  
Actin Cytoskeleton ◽  
Dominant Negative ◽  
Genetic Evidence ◽  
Asymmetric Distribution ◽  
Dominant Negative Variant ◽  
Substrate Proteins

ABSTRACT The yeast AAA+ chaperone Hsp104 is essential for the development of thermotolerance and for the inheritance of prions. Recently, Hsp104, together with the actin cytoskeleton, has been implicated in the asymmetric distribution of carbonylated proteins. Here, we investigated the interplay between Hsp104 and actin by using a dominant-negative variant of Hsp104 (HAP/ClpP) that degrades substrate proteins instead of remodeling them. Coexpression of HAP/ClpP causes defects in morphology and the actin cytoskeleton. Taking a candidate approach, we identified Spa2, a member of the polarisome complex, as an Hsp104 substrate. Furthermore, we provided genetic evidence that links Spa2 and Hsp104 to Hof1, a member of the cytokinesis machinery. Spa2 and Hof1 knockout cells are affected in the asymmetric distribution of damaged proteins, suggesting that Hsp104, Spa2, and Hof1 are members of a network controlling the inheritance of carbonylated proteins.

scholarly journals Brassinosteroids control root epidermal cell fate via direct regulation of a MYB-bHLH-WD40 complex by GSK3-like kinases

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Yinwei Cheng ◽  
Wenjiao Zhu ◽  
Yuxiao Chen ◽  
Shinsaku Ito ◽  
Tadao Asami ◽  
...  
Keyword(s):  
Hair Cell ◽  
Cell Fate ◽  
Epidermal Cell ◽  
Hair Cells ◽  
Root Hair ◽  
Cell Nuclei ◽  
Brassinosteroid Signaling ◽  
Root Hair Formation ◽  
A Cell ◽  
Transcriptional Complex

In Arabidopsis, root hair and non-hair cell fates are determined by a MYB-bHLH-WD40 transcriptional complex and are regulated by many internal and environmental cues. Brassinosteroids play important roles in regulating root hair specification by unknown mechanisms. Here, we systematically examined root hair phenotypes in brassinosteroid-related mutants, and found that brassinosteroid signaling inhibits root hair formation through GSK3-like kinases or upstream components. We found that with enhanced brassinosteroid signaling, GL2, a cell fate marker for non-hair cells, is ectopically expressed in hair cells, while its expression in non-hair cells is suppressed when brassinosteroid signaling is reduced. Genetic analysis demonstrated that brassinosteroid-regulated root epidermal cell patterning is dependent on the WER-GL3/EGL3-TTG1 transcriptional complex. One of the GSK3-like kinases, BIN2, interacted with and phosphorylated EGL3, and EGL3s mutated at phosphorylation sites were retained in hair cell nuclei. BIN2 phosphorylated TTG1 to inhibit the activity of the WER-GL3/EGL3-TTG1 complex. Thus, our study provides insights into the mechanism of brassinosteroid regulation of root hair patterning.

Sign in / Sign up

Export Citation Format

Share Document