scholarly journals eFGF and its mode of action in the community effect during Xenopus myogenesis

Development ◽  
2001 ◽  
Vol 128 (8) ◽  
pp. 1347-1357 ◽  
Author(s):  
H.J. Standley ◽  
A.M. Zorn ◽  
J.B. Gurdon
Keyword(s):  
Gene Expression ◽  
Precursor Cells ◽  
Specific Gene ◽  
Community Interactions ◽  
Community Factors ◽  
Community Effect ◽  
Muscle Precursor ◽  
Specific Gene Expression ◽  
The Right ◽  
Muscle Precursor Cells

The community effect is an interaction among a group of many nearby precursor cells, necessary for them to maintain tissue-specific gene expression and differentiate co-ordinately. During Xenopus myogenesis, the muscle precursor cells must be in group contact throughout gastrulation in order to develop into terminally differentiated muscle. The molecular basis of this community interaction has not to date been elucidated. We have developed an assay for testing potential community factors, in which isolated muscle precursor cells are treated with a candidate protein and cultured in dispersion. We have tested a number of candidate factors and we find that only eFGF protein is able to mediate a community effect, stimulating stable muscle-specific gene expression in demonstrably single muscle precursor cells. In contrast, Xwnt8, bFGF, BMP4 and TGF(β)2 do not show this capacity. We show that eFGF is expressed in the muscle precursor cells at the right time to mediate the community effect. Moreover, the time when the muscle precursor cells are sensitive to eFGF corresponds to the period of the endogenous community effect. Finally, we demonstrate that FGF signalling is essential for endogenous community interactions. We conclude that eFGF is likely to mediate the community effect in Xenopus myogenesis.

scholarly journals Phosphatidylinositol 3-Kinase Is a Negative Regulator of Cellular Differentiation

1997 ◽  
Vol 137 (5) ◽  
pp. 1127-1136 ◽  
Author(s):  
Andrzej Ptasznik ◽  
Gillian M. Beattie ◽  
Martin I. Mally ◽  
Vincenzo Cirulli ◽  
Ana Lopez ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cellular Differentiation ◽  
Precursor Cells ◽  
Negative Regulator ◽  
Specific Gene ◽  
Phosphatidylinositol 3 Kinase ◽  
Specific Gene Expression ◽  
Endocrine Differentiation ◽  
Pi3k Activity ◽  
Phosphatidylinositol 3

Phosphatidylinositol 3-kinase (PI3K) has been shown to be an important mediator of intracellular signal transduction in mammalian cells. We show here, for the first time, that the blockade of PI3K activity in human fetal undifferentiated cells induced morphological and functional endocrine differentiation. This was associated with an increase in mRNA levels of insulin, glucagon, and somatostatin, as well as an increase in the insulin protein content and secretion in response to secretagogues. Blockade of PI3K also increased the proportion of pluripotent precursor cells coexpressing multiple hormones and the total number of terminally differentiated cells originating from these precursor cells. We examined whether any of the recently described modulators of endocrine differentiation could participate in regulating PI3K activity in fetal islet cells. The activity of PI3K was inversely correlated with the hepatocyte growth factor/scatter factor–induced downregulation or nicotinamideinduced upregulation of islet-specific gene expression, giving support to the role of PI3K, as a negative regulator of endocrine differentiation. In conclusion, our results provide a mechanism for the regulation of hormone-specific gene expression during human fetal neogenesis. They also suggest a novel function for PI3K, as a negative regulator of cellular differentiation.

EphA4/ephrin-A5 interactions in muscle precursor cell migration in the avian forelimb

Development ◽  
2001 ◽  
Vol 128 (23) ◽  
pp. 4669-4680 ◽  
Author(s):  
Mary E. Swartz ◽  
Johann Eberhart ◽  
Elena B. Pasquale ◽  
Catherine E. Krull
Keyword(s):  
Cell Migration ◽  
Precursor Cells ◽  
Precursor Cell ◽  
Specific Gene ◽  
In Ovo ◽  
Muscle Precursor ◽  
In Ovo Electroporation ◽  
Lateral Portion ◽  
Muscle Precursor Cells ◽  
Muscle Precursor Cell

Limb muscles derive from muscle precursor cells that lie initially in the lateral portion of the somitic dermomyotome and subsequently migrate to their target limb regions, where muscle-specific gene transcription is initiated. Although several molecules that control the generation and delamination of muscle precursor cells have been identified, little is known about the mechanisms that guide muscle precursor cell migration in the limb. We have examined the distribution of members of the Eph family during muscle precursor cell development. The EphA4 receptor tyrosine kinase and its ligand, ephrin-A5, are expressed by muscle precursor cells and forelimb mesoderm in unique spatiotemporal patterns during the period when muscle precursors delaminate from the dermomyotome and migrate into the limb. To test the function of EphA4/ephrin-A5 interactions in muscle precursor migration, we used targeted in ovo electroporation to express ephrin-A5 ectopically specifically in the presumptive limb mesoderm. In the presence of ectopic ephrin-A5, Pax7-positive muscle precursor cells are significantly reduced in number in the proximal limb, compared with controls, and congregate abnormally near the lateral dermomyotome. In stripe assays, isolated muscle precursor cells avoid substrate-bound ephrin-A5 and this avoidance is abolished by addition of soluble ephrin-A5. These data suggest that ephrin-A5 normally restricts migrating, EphA4-positive muscle precursor cells to their appropriate territories in the forelimb, disallowing entry into abnormal embryonic regions.

scholarly journals Impaired viability of muscle precursor cells in muscular dystrophy with glycosylation defects and amelioration of its severe phenotype by limited gene expression

2013 ◽  
Vol 22 (15) ◽  
pp. 3003-3015 ◽  
Author(s):  
Motoi Kanagawa ◽  
Chih-Chieh Yu ◽  
Chiyomi Ito ◽  
So-ichiro Fukada ◽  
Masako Hozoji-Inada ◽  
...  
Keyword(s):  
Gene Expression ◽  
Muscular Dystrophy ◽  
Precursor Cells ◽  
Severe Phenotype ◽  
Muscle Precursor ◽  
Muscle Precursor Cells

scholarly journals Asymmetric division triggers cell-specific gene expression through coupled capture and stabilization of a phosphatase

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Niels Bradshaw ◽  
Richard Losick
Keyword(s):  
Gene Expression ◽  
Small Cell ◽  
Small Cells ◽  
Adjacent Cell ◽  
Specific Gene ◽  
Specific Gene Expression ◽  
Daughter Cells ◽  
Upstream Regulator ◽  
The Right ◽  
Stimulation Of

Formation of a division septum near a randomly chosen pole during sporulation in Bacillus subtilis creates unequal sized daughter cells with dissimilar programs of gene expression. An unanswered question is how polar septation activates a transcription factor (σF) selectively in the small cell. We present evidence that the upstream regulator of σF, the phosphatase SpoIIE, is compartmentalized in the small cell by transfer from the polar septum to the adjacent cell pole where SpoIIE is protected from proteolysis and activated. Polar recognition, protection from proteolysis, and stimulation of phosphatase activity are linked to oligomerization of SpoIIE. This mechanism for initiating cell-specific gene expression is independent of additional sporulation proteins; vegetative cells engineered to divide near a pole sequester SpoIIE and activate σF in small cells. Thus, a simple model explains how SpoIIE responds to a stochastically-generated cue to activate σF at the right time and in the right place.

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