The Drosophila saxophone gene: a serine-threonine kinase receptor of the TGF-beta superfamily

Science ◽  
1994 ◽  
Vol 263 (5154) ◽  
pp. 1756-1759 ◽  
Author(s):  
T Xie ◽  
A. Finelli ◽  
R. Padgett
Development ◽  
1997 ◽  
Vol 124 (16) ◽  
pp. 3167-3176 ◽  
Author(s):  
S.J. Newfeld ◽  
A. Mehra ◽  
M.A. Singer ◽  
J.L. Wrana ◽  
L. Attisano ◽  
...  

Mothers against dpp (Mad) is the prototype of a family of genes required for signaling by TGF-beta related ligands. In Drosophila, Mad is specifically required in cells responding to Decapentaplegic (DPP) signals. We further specify the role of Mad in DPP-mediated signaling by utilizing tkvQ199D, an activated form of the DPP type I receptor serine-threonine kinase thick veins (tkv). In the embryonic midgut, tkvQ199D mimics DPP-mediated inductive interactions. Homozygous Mad mutations block signaling by tkvQ199D. Appropriate responses to signaling by tkvQ199D are restored by expression of MAD protein in DPP-target cells. Endogenous MAD is phosphorylated in a ligand-dependent manner in Drosophila cell culture. DPP overexpression in the embryonic midgut induces MAD nuclear accumulation; after withdrawal of the overexpressed DPP signal, MAD is detected only in the cytoplasm. However, in three different tissues and developmental stages actively responding to endogenous DPP, MAD protein is detected in the cytoplasm but not in the nucleus. From these observations, we discuss possible roles for MAD in a DPP-dependent serine-threonine kinase signal transduction cascade integral to the proper interpretation of DPP signals.


Development ◽  
1996 ◽  
Vol 122 (12) ◽  
pp. 3735-3743 ◽  
Author(s):  
A. Renucci ◽  
V. Lemarchandel ◽  
F. Rosa

The role of Transforming Growth Factor beta (TGF-beta)-related molecules in axis formation and mesoderm patterning in vertebrates has been extensively documented, but the identity and mechanisms of action of the endogenous molecules remained uncertain. In this study, we isolate a novel serine/threonine kinase type I receptor, TARAM-A, expressed during early zebrafish embryogenesis first ubiquitously and then restricted to dorsal mesoderm during gastrulation. A constitutive form of the receptor is able to induce the most anterior dorsal mesoderm rapidly and to confer an anterior organizing activity. By contrast, the wild-type form is only able to induce a local expansion of the dorsal mesoderm. Thus an activated form of TARAM-A is sufficient to induce dorsoanterior structures and TARAM-A may be activated by dorsally localized signals. Our data suggest the existence in fish of a specific TGF-beta-related pathway for anterior dorsal mesoderm induction, possibly mediated by TARAM-A and activated at the late blastula stage by localized dorsal determinant.


Development ◽  
1994 ◽  
Vol 120 (1) ◽  
pp. 189-197 ◽  
Author(s):  
W.M. Baarends ◽  
M.J. van Helmond ◽  
M. Post ◽  
P.J. van der Schoot ◽  
J.W. Hoogerbrugge ◽  
...  

The activin and TGF-beta type II receptors are members of a separate subfamily of transmembrane receptors with intrinsic protein kinase activity, which also includes the recently cloned TGF-beta type I receptor. We have isolated and characterized a cDNA clone (C14) encoding a new member of this subfamily. The domain structure of the C14-encoded protein corresponds with the structure of the other known transmembrane serine/threonine kinase receptors. It also contains the two inserts in the kinase domain that are characteristic for this subfamily. Using in situ hybridization, C14 mRNA was detected in the mesenchymal cells located adjacent to the mullerian ducts of males and females at day 15 (E15) of embryonic development. Marked C14 mRNA expression was also detected in the female gonads. In female E16 embryos, the C14 mRNA expression pattern remained similar to that in E15 embryos. However, in male E16 embryos C14 mRNA was detected in a circular area that includes the degenerating mullerian duct. The expression of C14 mRNA was also studied using RNase protection assays. At E15 and E16, C14 mRNA is expressed in the female as well as in the male urogenital ridge. However, at E19, a high C14 mRNA level in the female urogenital ridge contrasts with a lack of C14 mRNA in the male urogenital ridge. This correlates with the almost complete degeneration of the mullerian ducts in male embryos at E19. C14 mRNA expression was also detected in embryonic testes at E15, E16 and E19 using RNase protection assays, but at much lower levels than those found in the developing ovaries.(ABSTRACT TRUNCATED AT 250 WORDS)


1994 ◽  
Vol 124 (4) ◽  
pp. 557-568 ◽  
Author(s):  
F López-Casillas ◽  
HM Payne ◽  
JL Andres ◽  
J Massagué

Betaglycan, also known as the TGF-beta type III receptor, is a membrane-anchored proteoglycan that presents TGF-beta to the type II signaling receptor, a transmembrane serine/threonine kinase. The betaglycan extracellular region, which can be shed by cells into the medium, contains a NH2-terminal domain related to endoglin and a COOH-terminal domain related to uromodulin, sperm receptors Zp2 and 3, and pancreatic secretory granule GP-2 protein. We identified residues Ser535 and Ser546 in the uromodulin-related region as the glycosaminoglycan (GAG) attachment sites. Their mutation to alanine prevents GAG attachment but does not interfere with betaglycan stability or ability to bind and present TGF-beta to receptor II. Using a panel of deletion mutants, we found that TGF-beta binds to the NH2-terminal endoglin-related region of betaglycan. The remainder of the extracellular domain and the cytoplasmic domain are not required for presentation of TGF-beta to receptor II; however, membrane anchorage is required. Soluble betaglycan can bind TGF-beta but does not enhance binding to membrane receptors. In fact, recombinant soluble betaglycan acts as potent inhibitor of TGF-beta binding to membrane receptors and blocks TGF-beta action, this effect being particularly pronounced with the TGF-beta 2 isoform. The results suggest that release of betaglycan into the medium converts this enhancer of TGF-beta action into a TGF-beta antagonist.


Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Dauren Biyashev ◽  
Chan Boriboun ◽  
Junlan Zhou ◽  
Gangjian Qin

Background: E2F1 is best studied in cell-cycle control and cancer biology. Recently, we have disclosed a novel function of E2F1 that suppresses TGF-beta signaling pathway; however the underlying molecular mechanisms and physiological significance of this regulation remains unknown. Methods and Results: In a proteomics approach, Flag-tagged Smad3 protein was overexpressed in the embryonic fibroblasts (MEF) isolated from wild-type (WT) and E2F1-null (E2F1-KO) mice, and the Smad3-interacting proteins were isolated by co-immunoprecipitation and identified by mass spectrometry. Notably, the serine-threonine kinase receptor-associated protein (Strap) was found associated with Smad3 in WT MEFs, but not in E2F1-KO MEFs. This is important because Strap has been shown as inhibitor of canonical TGF-beta signaling pathway by interacting with both TGF-beta receptor I and Smad7 to interfere with Smad2/3 activation. When analyzed by Western blotting, we found that the expression of Strap was significantly higher in WT MEFs than in E2F1-KO MEFs, and similar results were obtained in the cardiac and lung tissues of WT and E2F1-KO mice. Remarkably, both bleomycin and Ang II treatments resulted in a significantly greater degree of lung fibrosis in E2F1-KO mice than in WT mice. Conclusion: Our results suggest that E2F1 suppresses tissue fibrosis through Strap expression and Strap-mediated repression of canonical TGF-beta signaling pathway.


2008 ◽  
Vol 415 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Meghna Thakur ◽  
Pradip K. Chakraborti

Eukaryotic-type serine/threonine protein kinases in bacteria have been implicated in controlling a host of cellular activities. PknA is one of eleven such protein kinases from Mycobacterium tuberculosis which regulates morphological changes associated with cell division. In the present study we provide the evidence for the ability of PknA to transphosphorylate mMurD (mycobacterial UDP-N-acetylmuramoyl-L-alanine:D-glutamate-ligase), the enzyme involved in peptidoglycan biosynthesis. Its co-expression in Escherichia coli along with PknA resulted in phosphorylation of mMurD. Consistent with these observations, results of the solid-phase binding assays revealed a high-affinity in vitro binding between the two proteins. Furthermore, overexpression of m-murD in Mycobacterium smegmatis yielded a phosphorylated protein. The results of the present study therefore point towards the possibility of mMurD being a substrate of PknA.


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