The effects of FGF ectopic expression on avian skeletal muscle development
Abstract
The eighteen members of the FGF family are expressed in a specific spatiotemporal pattern during development and yet their functions are still not clear. The role of altFGF2, FGF5, FGF8 and FGF10 in primary skeletal muscle cell development was examined. Serum and media conditions were developed for the optimal growth of primary skeletal muscle cells in vitro. Subsequently, the proliferation and differentiation of primary skeletal muscle cells were examined in vitro with immunospecific fluorescent stains. Retroviral expression vectors were used to infect embryonic day 5 and embryonic day 12 primary skeletal muscle cells with specific members of the FGF family to analyze their effects on the growth of skeletal muscle in vitro . AltFGF2, FGF5, FGF8 and FGF10 had contrasting effects on the proliferation and differentiation of skeletal muscle primary cells in vitro. AltFGF2, FGF8 and FGF10 all stimulated proliferation and repressed differentiation. In contrast, FGF5 appeared to promote differentiation with little effect on proliferation. In support of a role for FGF5 in skeletal muscle differentiation, previously reported data demonstrate that the expression of FGF5 is up regulated during muscle differentiation in vitro. In order to further explore the unique effect that FGF5 had during avian skeletal muscle development, FGF5 function during limb bud development in vivo was examined. A FGF5 retroviral expression vector was used to infect the hind limb of embryonic day 4 avian embryos. Embryos were harvested at 3, 5, and 7 days post-injection, sectioned and analyzed by immunohistochemistry and antibody-specific fluorescent staining. Ectopic expression of FGF5 resulted in a dramatic decrease in muscle development within infected limbs. In addition, the development of skeletal elements also was severely affected. Preliminary studies to examine the mechanism suggest that FGF5 promotes quiescence and inhibits the migration and expansion of myogenic precursor cells that results in an inhibition of further skeletal muscle development.
Degree
Ph.D.
Advisors
Hannon, Purdue University.
Subject Area
Molecular biology|Physiology
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