eFGF and its mode of action in the community effect during Xenopus myogenesis.
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(&bgr;)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.
Wellcome/CRC Institute, Tennis Court Road, Cambridge, CB2 1QR and Department of Zoology, University of Cambridge, UK.
H J
HJ
Standley
A M
AM
Zorn
J B
JB
Gurdon
D000818:Animals; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D004268:DNA-Binding Proteins; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D015870:Gene Expression; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009132:Muscles / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism*; D051787:Myogenic Regulatory Factor 5; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013234:Stem Cells / Q000378:metabolism; D013997:Time Factors; D015534:Trans-Activators; D016212:Transforming Growth Factor beta / Q000378:metabolism; D053781:Transforming Growth Factor beta2; D051153:Wnt Proteins; D014981:Xenopus / Q000196:embryology; D029867:Xenopus Proteins; D029961:Zebrafish Proteins
D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D006023:Glycoproteins; D009124:Muscle Proteins; C497419:Myf5 protein, Xenopus; D017570:MyoD Protein; D051787:Myogenic Regulatory Factor 5; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053781:Transforming Growth Factor beta2; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C525812:bmp4 protein, Xenopus; C525813:bmp4 protein, zebrafish; D005346:Fibroblast Growth Factors