Animal and vegetal pole cells of early Xenopus embryos respond differently to maternal dorsal determinants: implications for the patterning of the organiser

Development ◽  
1997 ◽  
Vol 124 (21) ◽  
pp. 4275-4286 ◽  
Author(s):  
S. Darras ◽  
Y. Marikawa ◽  
R.P. Elinson ◽  
P. Lemaire
Keyword(s):  
Signal Transduction ◽  
Signal Transduction Pathways ◽  
Beta Catenin ◽  
Embryonic Cells ◽  
Dorsal Region ◽  
Animal Cells ◽  
Molecular Identity ◽  
Vegetal Pole ◽  
Pole Cells ◽  
Different Levels

The maternal dorsal determinants required for the specification of the dorsal territories of Xenopus early gastrulae are located at the vegetal pole of unfertilised eggs and are moved towards the prospective dorsal region of the fertilised egg during cortical rotation. While the molecular identity of the determinants is unknown, there are dorsal factors in the vegetal cortical cytoplasm (VCC). Here, we show that the VCC factors, when injected into animal cells activate the zygotic genes Siamois and Xnr3, suggesting that they act along the Wnt/beta-catenin pathway. In addition, Siamois and Xnr3 are activated at the vegetal pole of UV-irradiated embryos, indicating that these two genes are targets of the VCC factors in all embryonic cells. However, the consequences of their activation in cells that occupy different positions along the animal-vegetal axis differ. Dorsal vegetal cells of normal embryos or VCC-treated injected animal cells are able to dorsalise ventral mesoderm in conjugate experiments but UV-treated vegetal caps do not have this property. This difference is unlikely to reflect different levels of activation of FGF or activin-like signal transduction pathways but may reflect the activation of different targets of Siamois. Chordin, a marker of the head and axial mesoderm, is activated by the VCC/Siamois pathway in animal cells but not in vegetal cells whereas cerberus, a marker of the anterior mesendoderm which lacks dorsalising activity, can only be activated by the VCC/Siamois pathway in vegetal cells. We propose that the regionalisation of the organiser during gastrulation proceeds from the differential interpretation along the animal-vegetal axis of the activation of the VCC/beta-catenin/Siamois pathway.

The development of animal cap cells in Xenopus: the effects of environment on the differentiation and the migration of grafted ectodermal cells

Development ◽  
1987 ◽  
Vol 101 (1) ◽  
pp. 23-32 ◽  
Author(s):  
E.A. Jones ◽  
H.R. Woodland
Keyword(s):  
Striated Muscle ◽  
Animal Cells ◽  
Animal Pole ◽  
Mesoderm Development ◽  
Dorsal Axis ◽  
Dorsal Mesoderm ◽  
Vegetal Pole ◽  
Pole Cells ◽  
Inductive Signal ◽  
Host Tissues

We have used blastocoel and vegetal pole grafts to investigate the effect of environment on differentiation and movement of animal pole cells of Xenopus. In the blastocoel of embryos earlier than stage 10, fragments of animal pole primarily form mesoderm. The cells are either integrated into normal host tissues or they organize a secondary posterior dorsal axis. If either host or graft is later than stage 9 the graft forms ectoderm and its cells all migrate into the host ectoderm. Inner layer animal cells form sensorial layer; outer cells move to the epidermis. Thus considerable powers of appropriate movement are seen. In the vegetal pole no movement occurs. If the graft is stage 9 or earlier, or the host is stage 101/2 or earlier, the graft forms mesoderm, including striated muscle in the gut. This shows that muscle can develop in wholly the wrong environment, it suggests that the dorsal inductive signal from mesoderm is rather general in the vegetal mass and suggests that dorsal mesoderm development involves little subsequent adjustability. If the host is stage 11 or later, or the graft later than stage 9, the graft forms epidermis in the gut. This shows that the epidermal pathway of development is also insensitive to environment.

Signal-regulated oxidation of proteins via MICAL

2020 ◽  
Vol 48 (2) ◽  
pp. 613-620
Author(s):  
Clara Ortegón Salas ◽  
Katharina Schneider ◽  
Christopher Horst Lillig ◽  
Manuela Gellert
Keyword(s):  
Signal Transduction ◽  
Hydrogen Peroxide ◽  
Cell Death ◽  
Redox Regulation ◽  
Signal Transduction Pathways ◽  
Cellular Functions ◽  
Intracellular Signals ◽  
Amino Acid Side Chains ◽  
Specific Receptors ◽  
Sulfur Containing

Processing of and responding to various signals is an essential cellular function that influences survival, homeostasis, development, and cell death. Extra- or intracellular signals are perceived via specific receptors and transduced in a particular signalling pathway that results in a precise response. Reversible post-translational redox modifications of cysteinyl and methionyl residues have been characterised in countless signal transduction pathways. Due to the low reactivity of most sulfur-containing amino acid side chains with hydrogen peroxide, for instance, and also to ensure specificity, redox signalling requires catalysis, just like phosphorylation signalling requires kinases and phosphatases. While reducing enzymes of both cysteinyl- and methionyl-derivates have been characterised in great detail before, the discovery and characterisation of MICAL proteins evinced the first examples of specific oxidases in signal transduction. This article provides an overview of the functions of MICAL proteins in the redox regulation of cellular functions.

Control of Mammary Differentiation by Ras-Dependent Signal Transduction Pathways

2002 ◽  
Author(s):  
Mary L. Cutler ◽  
Mari G. Cerrito ◽  
Treas Chopp ◽  
Weihan Wang
Keyword(s):  
Signal Transduction ◽  
Signal Transduction Pathways ◽  
Dependent Signal
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