The Drosophila Medea gene is required downstream of dpp and encodes a functional homolog of human Smad4

Development ◽  
1998 ◽  
Vol 125 (8) ◽  
pp. 1407-1420 ◽  
Author(s):  
J.B. Hudson ◽  
S.D. Podos ◽  
K. Keith ◽  
S.L. Simpson ◽  
E.L. Ferguson
Keyword(s):  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Sequence Similarity ◽  
Early Embryo ◽  
Drosophila Embryo ◽  
Phenotypic Analysis ◽  
Cell Fates ◽  
Functional Homolog ◽  
Phenotypic Rescue ◽  
Embryonic Ectoderm

The Transforming Growth Factor-beta superfamily member decapentaplegic (dpp) acts as an extracellular morphogen to pattern the embryonic ectoderm of the Drosophila embryo. To identify components of the dpp signaling pathway, we screened for mutations that act as dominant maternal enhancers of a weak allele of the dpp target gene zerknLllt. In this screen, we recovered new alleles of the Mothers against dpp (Mad) and Medea genes. Phenotypic analysis of the new Medea mutations indicates that Medea, like Mad, is required for both embryonic and imaginal disc patterning. Genetic analysis suggests that Medea may have two independently mutable functions in patterning the embryonic ectoderm. Complete elimination of maternal and zygotic Medea activity in the early embryo results in a ventralized phenotype identical to that of null dpp mutants, indicating that Medea is required for all dpp-dependent signaling in embryonic dorsal-ventral patterning. Injection of mRNAs encoding DPP or a constitutively activated form of the DPP receptor, Thick veins, into embryos lacking all Medea activity failed to induce formation of any dorsal cell fates, demonstrating that Medea acts downstream of the thick veins receptor. We cloned Medea and found that it encodes a protein with striking sequence similarity to human SMAD4. Moreover, injection of human SMAD4 mRNA into embryos lacking all Medea activity conferred phenotypic rescue of the dorsal-ventral pattern, demonstrating conservation of function between the two gene products.

An activity gradient of decapentaplegic is necessary for the specification of dorsal pattern elements in the Drosophila embryo

Development ◽  
1993 ◽  
Vol 117 (2) ◽  
pp. 807-822 ◽  
Author(s):  
K.A. Wharton ◽  
R.P. Ray ◽  
W.M. Gelbart
Keyword(s):  
Cell Fate ◽  
Gene Dosage ◽  
Early Embryo ◽  
Drosophila Embryo ◽  
Cell Fates ◽  
Gene Encoding ◽  
In The Wild ◽  
Intercellular Signalling ◽  
Overlapping Domains ◽  
Dorsal Pattern

decapentaplegic (dpp) is a zygotically expressed gene encoding a TGF-beta-related ligand that is necessary for dorsal-ventral patterning in the Drosophila embryo. We show here that dpp is an integral part of a gradient that specifies many different cell fates via intercellular signalling. There is a graded requirement for dpp activity in the early embryo: high levels of dpp activity specify the amnioserosa, while progressively lower levels specify dorsal and lateral ectoderm. This potential for dpp to specify cell fate is highly dosage sensitive. In the wild-type embryo, increasing the gene dosage of dpp can shift cell fates along the dorsal-ventral axis. Furthermore, in mutant embryos, in which only a subset of the dorsal-ventral pattern elements are represented, increasing the gene dosage of dpp can specifically transform those pattern elements into more dorsal ones. We present evidence that the zygotic dpp gradient and the maternal dorsal gradient specify distinct, non-overlapping domains of the dorsal-ventral pattern.

In vivo analysis using variants of zebrafish BMPR-IA: range of action and involvement of BMP in ectoderm patterning

Development ◽  
1999 ◽  
Vol 126 (1) ◽  
pp. 181-190 ◽  
Author(s):  
M. Nikaido ◽  
M. Tada ◽  
H. Takeda ◽  
A. Kuroiwa ◽  
N. Ueno
Keyword(s):  
Cell Fate ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Active Form ◽  
Ectopic Expression ◽  
Signal Propagation ◽  
Early Embryo ◽  
Type I ◽  
Cell Fate Conversion

It has been an intriguing problem whether the polypeptide growth factors belonging to the transforming growth factor-beta (TGF-beta) superfamily function as direct and long-range signaling molecules in pattern formation of the early embryo. In this study, we examined the mechanism of signal propagation of bone morphogenetic protein (BMP) in the ectodermal patterning of zebrafish embryos, in which BMP functions as an epidermal inducer and a neural inhibitor. To estimate the effective range of zbmp-2, we first performed whole-mount in situ hybridization analysis. The zbmp-2-expressing domain and the neuroectoderm, marked by otx-2 expression, were complementary, suggesting that BMP has a short-range effect in vivo. Moreover, mosaic experiments using a constitutively active form of a zebrafish BMP type I receptor (CA-BRIA) demonstrated that the cell-fate conversion, revealed by ectopic expression of gata-3 and repression of otx-2, occurred in a cell-autonomous manner, denying the involvement of the relay mechanism. We also found that zbmp-2 was induced cell autonomously within the transplanted cells in the host ectoderm, suggesting that BMP cannot influence even the neighboring cells. This result is consistent with the observation that there is no gap between the expression domains of zbmp-2 and otx-2. Taken together, we propose that, in ectodermal patterning, BMP exerts a direct and cell-autonomous effect to fate uncommitted ectodermal cells to become epidermis.

scholarly journals Natural and environmental oestrogens induce TGFB1 synthesis in oviduct cells

Reproduction ◽  
2018 ◽  
Vol 155 (3) ◽  
pp. 233-244 ◽  
Author(s):  
Barbara P S Cometti ◽  
Raghvendra K Dubey ◽  
Bruno Imthurn ◽  
Marinella Rosselli
Keyword(s):  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
De Novo ◽  
Embryo Implantation ◽  
Early Embryo ◽  
Biochanin A ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Paracrine Factors ◽  
Aryl Hydrocarbon

Autocrine/paracrine factors generated in response to 17β-oestradiol (E2), within the oviduct, facilitate early embryo development for implantation. Since transforming growth factor beta 1 (TGFB1) plays a key role in embryo implantation, regulation of its synthesis by E2 may be of biological/pathophysiological relevance. Here, we investigated whether oviduct cells synthesize TGFB1 and whether E2 and environmental oestrogens (EOEs; xenoestrogens and phytoestrogens) modulate its synthesis. Under basal conditions, bovine oviduct cells (OCs; oviduct epithelial cells and oviduct fibroblasts; 1:1 ratio) synthesized TGFB1. E2 concentration-dependent induced TGFB1 levels in OCs and these effects were mimicked by some, but not all EOEs (genistein, biochanin A and 4-hydroxy-2′,4′,6′-trichlorobiphenyl, 4-hydroxy-2′,4′,6′-dichlorobiphenyl); moreover, EOEs enhanced (P < 0.05) the stimulatory effects of E2 on TGFB1 synthesis. The OCs expressed oestrogen receptors alpha and beta and aryl hydrocarbon; moreover, co-treatment with ER antagonist ICI182780 blocked the stimulatory effects of E2 and EOEs on TGFB1 synthesis. Treatment with non-permeable E2-BSA failed to induce TGFB1, thereby ruling out the involvement of membrane ERs. Cycloheximide (protein synthesis inhibitor) blocked E2-induced TGFB1 synthesis providing evidence forde novosynthesis. The stimulatory effects of E2 and EOEs, were inhibited (P < 0.05) by MAPK inhibitor (PD98059), whereas intracellular-Ca2+chelator (BAPTA-AM) and adenylyl cyclase inhibitor (SQ22536) abrogated the effects of E2, but not EOEs, suggesting that post-ER effects of E2 and EOEs involve different pathways. Our results provide the first evidence that in OCs, E2 and EOEs stimulate TGFB1 synthesis via an ER-dependent pathway. Exposure of the oviduct to EOEs may result in continuous/sustained induction of TGFB1 levels in a non-cyclic fashion and may induce deleterious effects on reproduction.

scholarly journals Genetic characterization and cloning of mothers against dpp, a gene required for decapentaplegic function in Drosophila melanogaster.

Genetics ◽  
1995 ◽  
Vol 139 (3) ◽  
pp. 1347-1358 ◽  
Author(s):  
J J Sekelsky ◽  
S J Newfeld ◽  
L A Raftery ◽  
E H Chartoff ◽  
W M Gelbart
Keyword(s):  
Drosophila Melanogaster ◽  
Growth Factor ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Genetic Characterization ◽  
Genomic Sequence ◽  
Sequence Similarity ◽  
Transcription Unit ◽  
Loss Of Function ◽  
Protein Motifs

Abstract The decapentaplegic (dpp) gene of Drosophila melanogaster encodes a growth factor that belongs to the transforming growth factor-beta (TGF-beta) superfamily and that plays a central role in multiple cell-cell signaling events throughout development. Through genetic screens we are seeking to identify other functions that act upstream, downstream or in concert with dpp to mediate its signaling role. We report here the genetic characterization and cloning of Mothers against dpp (Mad), a gene identified in two such screens. Mad loss-of-function mutations interact with dpp alleles to enhance embryonic dorsal-ventral patterning defects, as well as adult appendage defects, suggesting a role for Mad in mediating some aspect of dpp function. In support of this, homozygous Mad mutant animals exhibit defects in midgut morphogenesis, imaginal disk development and embryonic dorsal-ventral patterning that are very reminiscent of dpp mutant phenotypes. We cloned the Mad region and identified the Mad transcription unit through germline transformation rescue. We sequenced a Mad cDNA and identified three Mad point mutations that alter the coding information. The predicted MAD polypeptide lacks known protein motifs, but has strong sequence similarity to three polypeptides predicted from genomic sequence from the nematode Caenorhabditis elegans. Hence, MAD is a member of a novel, highly conserved protein family.

scholarly journals Genetic screens to identify elements of the decapentaplegic signaling pathway in Drosophila.

Genetics ◽  
1995 ◽  
Vol 139 (1) ◽  
pp. 241-254 ◽  
Author(s):  
L A Raftery ◽  
V Twombly ◽  
K Wharton ◽  
W M Gelbart
Keyword(s):  
Signaling Pathway ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Genetic Interaction ◽  
Early Embryo ◽  
Loss Of Function ◽  
Morphogenetic Protein ◽  
Imaginal Disks ◽  
Novel Alleles ◽  
Mutant Phenotypes

Abstract Pathways for regulation of signaling by transforming growth factor-beta family members are poorly understood at present. The best genetically characterized member of this family is encoded by the Drosophila gene decapentaplegic (dpp), which is required for multiple events during fly development. We describe here the results of screens for genes required to maximize dpp signaling during embryonic dorsal-ventral patterning. Screens for genetic interactions in the zygote have identified an allele of tolloid, as well as two novel alleles of screw, a gene recently shown to encode another bone morphogenetic protein-like polypeptide. Both genes are required for patterning the dorsalmost tissues of the embryo. Screens for dpp interactions with maternally expressed genes have identified loss of function mutations in Mothers against dpp and Medea. These mutations are homozygous pupal lethal, engendering gut defects and severely reduced imaginal disks, reminiscent of dpp mutant phenotypes arising during other dpp-dependent developmental events. Genetic interaction phenotypes are consistent with reduction of dpp activity in the early embryo and in the imaginal disks. We propose that the novel screw mutations identified here titrate out some component(s) of the dpp signaling pathway. We propose that Mad and Medea encode rate-limiting components integral to dpp pathways throughout development.

scholarly journals The transcription factor Pitx2 positions the embryonic axis and regulates twinning

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Angela Torlopp ◽  
Mohsin A F Khan ◽  
Nidia M M Oliveira ◽  
Ingrid Lekk ◽  
Luz Mayela Soto-Jiménez ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Axis Formation ◽  
Cell Fates ◽  
Embryonic Polarity ◽  
Polarity Determination ◽  
Maternal Determinants ◽  
Left Right Asymmetry ◽  
Determination Mechanism

Embryonic polarity of invertebrates, amphibians and fish is specified largely by maternal determinants, which fixes cell fates early in development. In contrast, amniote embryos remain plastic and can form multiple individuals until gastrulation. How is their polarity determined? In the chick embryo, the earliest known factor is cVg1 (homologous to mammalian growth differentiation factor 1, GDF1), a transforming growth factor beta (TGFβ) signal expressed posteriorly before gastrulation. A molecular screen to find upstream regulators of cVg1 in normal embryos and in embryos manipulated to form twins now uncovers the transcription factor Pitx2 as a candidate. We show that Pitx2 is essential for axis formation, and that it acts as a direct regulator of cVg1 expression by binding to enhancers within neighbouring genes. Pitx2, Vg1/GDF1 and Nodal are also key actors in left–right asymmetry, suggesting that the same ancient polarity determination mechanism has been co-opted to different functions during evolution.

Positive and negative regulation of Easter, a member of the serine protease family that controls dorsal-ventral patterning in the Drosophila embryo

Development ◽  
1998 ◽  
Vol 125 (7) ◽  
pp. 1261-1267 ◽  
Author(s):  
S. Misra ◽  
P. Hecht ◽  
R. Maeda ◽  
K.V. Anderson
Keyword(s):  
Serine Proteases ◽  
Feedback Loop ◽  
Early Embryo ◽  
High Molecular Mass ◽  
Drosophila Embryo ◽  
Zymogen Activation ◽  
Cell Fates ◽  
Biochemical Processes ◽  
Serine Protease Family

The sequential activities of four members of the trypsin family of extracellular serine proteases are required for the production of the ventrally localized ligand that organizes the dorsal-ventral pattern of the Drosophila embryo. The last protease in this sequence is encoded by easter, which is a candidate to activate proteolytically the ligand encoded by spatzle. Here, we demonstrate biochemically that the zymogen form of Easter is processed in vivo by a proteolytic cleavage event that requires the three upstream proteases. Processed Easter is present in extremely low amounts in the early embryo because it is rapidly converted into a high molecular mass complex, which may contain a protease inhibitor. Easter zymogen activation is also controlled by a negative feedback loop from Dorsal, the transcription factor at the end of the signaling pathway. Each of these regulated biochemical processes is likely to be important in generating the ventral-to-dorsal gradient of Dorsal protein that organizes cell fates in the early embryo.

Laser scanning confocal microscopic analysis of cytoskeletal and nuclear reorganization in live Drosophila embryos

1993 ◽  
Vol 51 ◽  
pp. 174-175
Author(s):  
William Theurkauf
Keyword(s):  
Laser Scanning ◽  
Microscopic Analysis ◽  
Large Cell ◽  
Early Embryo ◽  
Drosophila Embryo ◽  
Cortical Actin ◽  
Nuclear Reorganization ◽  
Cytoskeletal Elements ◽  
Microtubule Structure ◽  
Drosophila Embryos

Cell division in eucaryotes depends on coordinated changes in nuclear and cytoskeletal components. In Drosophila melanogaster embryos, the first 13 nuclear divisions occur without cytokinesis. During the final four divisions, nuclei divide in a uniform monolayer at the surface of the embryo. These surface divisions are accompanied by dramatic changes in cortical actin and microtubule structure (Karr and Alberts, 1986), and inhibitor studies indicate that these changes are essential to orderly mitosis (Zalokar and Erk, 1976). Because the early embryo is syncytial, fluorescent probes introduced by microinjection are incorporated in structures associated with all of the nuclei in the blastoderm. In addition, the nuclei divide synchronously every 10 to 20 min. These characteristics make the syncytial blastoderm embryo an excellent system for the analysis of mitotic reorganization of both nuclear and cytoskeletal elements. However, the Drosophila embryo is a large cell, and resolution of cytoskeletal filaments and nuclear structure is hampered by out-of focus signal.

Sign in / Sign up

Export Citation Format

Share Document