Regulation of myogenic differentiation in the developing limb bud

Abstract

The limb myogenic precursors arise by delamination from the lateral dermomyotome in response to signals from the lateral plate mesoderm. They subsequently migrate into the developing limb bud where they switch on the expression of the myogenic regulatory factors, MyoD and Myf5 , and coalese to form the dorsal and ventral muscle masses. The myogenic cells subsequently undergo terminal differentiation into slow or fast fibres which have distinct contractile properties determining how a muscle will function. In general, fast fibres contract rapidly with high force and are characterized by the expression of fast myosin heavy chains (MyHC). These fibres are needed for movement. In contrast, slow fibres express slow MyHC, contract slowly and are required for maintenance of posture. This review focuses on the molecular signals that control limb myogenic development from the initial delamination and migration of the premyogenic cells to the ultimate formation of the complex muscle pattern and differentiation of slow and fast fibres.

Muscle formation in regenerating Xenopus froglet limb

“…Overexpression of fibroblast growth factor (FGF) 4, which has its expression domain in the apical ectodermal ridge (AER) in the limb bud, results in a reduction in the number of terminally differentiated myogenic cells both in vivo (Edom-Vovard et al, 2001) and in vitro (Robson and Hughes, 1996). These studies suggest that the distal mesenchyme and the AER in the developing limb bud have inhibitory effects on muscle differentiation, and several molecules expressed in these regions, such as FGFs and bone morphogenetic proteins, are thought to play roles in the repression of muscle differentiation (reviewed by Francis-West et al, 2003). Considering the evidence of a negative environment in the developing limb bud for muscle differentiation, the blastema environment in the amputated Xenopus froglet limb might be suppressive for muscle redifferentiation.…”

The chemokine SDF1 controls multiple steps of myogenesis through atypical PKCζ

“…The expression of MyoD and Myf5 mark the onset of the myogenic commitment and is succeeded by myogenin and MRF4 (Pownall et al, 2002). Myogenic commitment and progression along the myogenic differentiation cascade is again tightly controlled by a multitude of gene products, including the homeobox factors Mox2 and Msx1, FGF and TGF␤ family members, IGF1, sonic hedgehog as well as by Notch and Wnt signaling (Francis-West et al, 2003). Committed myoblasts finally fuse to form muscle fibers.…”

Ultrastructural analysis of the smooth‐to‐striated transition zone in the developing mouse esophagus: Emphasis on apoptosis of smooth and origin and differentiation of striated muscle cells

“…Developing striated muscle cells occur first in the most rostral part of the esophagus at approximately embryonic day (E) 14 and replace the smooth muscle fibers in a caudal direction during the following developmental stages, until the complete tunica muscularis is striated at postnatal day (P) 14 (Patapoutian et al, 1995;Sang and Young, 1997;Kablar et al, 2000;Wörl and Neuhuber, 2000;Zhao and Dhoot, 2000a). Although it is well established that skeletal muscles of the limb, trunk, and head develop from myogenic precursors cells originating in the somites, paraxial head mesoderm, or prechordal mesoderm and migrate to their target sites (for review, see Brand-Saberi and Christ, 1999;Christ and Brand-Saberi, 2002;Buckingham et al, 2003;Francis-West et al, 2003), the origin of striated muscle fibers in the esophagus is controversial.…”