Myogenesis
Encyclopedia
Myogenesis is the formation of muscular tissue, in particular during embryonic development.
Muscle fibers form from the fusion of myoblasts into multi-nucleated fibers (called myotubes). In the early development of an embryo
these myoblasts will proliferate if enough fibroblast growth factor
is present. When the FGF runs out, the myoblasts cease division and secrete fibronectin
onto their extracellular matrix
.
The second stage involves the alignment of the myoblasts into the myotubes. The identity of the myoblasts in this stage is not crucial. Studies have shown that even rat and chick myoblasts have aligned.
The third stage is the actual cell fusion itself. In this stage, calcium
ions are critical for development. Fusion is mediated by a set of metalloproteinases called meltrins.
Myocyte Enhance Factors (MEFs) promote myogenesis. Serum response factor (SRF) plays a central role during myogenesis, being required for the expression of striated alpha-actin genes. Expression of skeletal alpha-actin is also regulated by the Androgen Receptor; steroids can thereby regulate myogenesis .
Muscle fibers form from the fusion of myoblasts into multi-nucleated fibers (called myotubes). In the early development of an embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
these myoblasts will proliferate if enough fibroblast growth factor
Fibroblast growth factor
Fibroblast growth factors, or FGFs, are a family of growth factors involved in angiogenesis, wound healing, and embryonic development. The FGFs are heparin-binding proteins and interactions with cell-surface associated heparan sulfate proteoglycans have been shown to be essential for FGF signal...
is present. When the FGF runs out, the myoblasts cease division and secrete fibronectin
Fibronectin
Fibronectin is a high-molecular weight glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. In addition to integrins, fibronectin also binds extracellular matrix components such as collagen, fibrin and heparan sulfate proteoglycans...
onto their extracellular matrix
Extracellular matrix
In biology, the extracellular matrix is the extracellular part of animal tissue that usually provides structural support to the animal cells in addition to performing various other important functions. The extracellular matrix is the defining feature of connective tissue in animals.Extracellular...
.
The second stage involves the alignment of the myoblasts into the myotubes. The identity of the myoblasts in this stage is not crucial. Studies have shown that even rat and chick myoblasts have aligned.
The third stage is the actual cell fusion itself. In this stage, calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
ions are critical for development. Fusion is mediated by a set of metalloproteinases called meltrins.
Myocyte Enhance Factors (MEFs) promote myogenesis. Serum response factor (SRF) plays a central role during myogenesis, being required for the expression of striated alpha-actin genes. Expression of skeletal alpha-actin is also regulated by the Androgen Receptor; steroids can thereby regulate myogenesis .