High impact information on XMyf-5

• These fibres probably derive from an outer cell layer expressing the myogenic determination genes XMyf5, XMyoD and Pax3 in a pattern reminiscent of amniote dermomyotome [1].
• As in zebrafish, Hh signalling is required for XMyf5 expression and generation of a first wave of early superficial slow muscle fibres in tail somites [1].
• Although notochord is required for early medial XMyf5 expression, Hh signalling fails to drive these cells to slow myogenesis [1].
• Transient ectopic expression of XMyf5 activates cardiac actin and XMyoD genes in animal cap cells, but does not cause full myogenesis, even in combination with XMyoD [2].
• In the present study, we used the Xenopus model to examine the role of XMyoD, XMyf5, and XMRF4 for the transactivation of the (nicotinic acetylcholine receptor) nAChR genes in vivo [3].

Biological context of XMyf-5

• During early embryogenesis, after the initial molecular signals inducing mesoderm, the myogenic determination factors XMyoD and XMyf-5 are activated in presomitic mesoderm in response to mesoderm-inducing factors [4].
• In embryos, overexpression of a dominant-negative XMyf5 variant led to the repression of delta-but not gamma-subunit gene expression [3].
• Overexpression of XMyoD and XMyf5 also affected the morphogenesis of the skin and the nervous system [5].

Anatomical context of XMyf-5

• Xenopus Myf-5 (XMyf5) transcripts first accumulate in the prospective somite region of early gastrulae [2].
• XMRF4 mRNA accumulation later extended posteriorly but was never detected in the posterior unsegmented mesoderm, in contrast to XMyoD and XMyf-5 [6].
• We show that XMyf5 specifically induced the expression of the delta-subunit gene in cap animal assays and in endoderm cells of Xenopus embryos but was unable to activate the expression of the gamma-subunit gene [3].
• We show that activation of Wnt/beta-catenin signaling at the early gastrula stage rapidly induces ectopic expression of XMyf5 in both the dorsal and ventral mesoderm [7].
• To understand how tenascin expression in somitic mesoderm is controlled, we have expressed Xbra and the myogenic factors XMyoD and XMyf5 in blastula animal cap tissue [8].

Associations of XMyf-5 with chemical compounds

• In situ hybridization analysis reveals that the induction of ectopic XMyf5 expression in the dorsal mesoderm occurs within 45 min and is not blocked by the protein synthesis inhibitor cycloheximide [7].
• Analysis by RT-PCR of ectodermal explants isolated soon after midblastula transition indicates that lithium also specifically induces XMyf5 expression, which takes place 30 min following lithium treatment and is not blocked by cycloheximide, arguing strongly for an immediate-early response [7].

Regulatory relationships of XMyf-5

• We further show that zygotic Wnt/beta-catenin signaling interacts specifically with bFGF and eFGF to promote XMyf5 expression in ectodermal cells [7].

Other interactions of XMyf-5

• Interestingly, Xhairy-1/VP16 does not induce the expression of Xbra and XMyf5 in the same condition [9].

References