Fibroblast growth factors (FGFs) are believed to play a key role in tissue differentiation and maturation. Thus, the expression of the four members of the high-affinity @entity669 kinase FGF receptor family (FGFRs) and of the low-affinity heparan @entity597 proteoglycan binding sites, @entity13221 , was studied in the @entity1 skeletal muscle during development. Northern blot analysis demonstrated a developmentally regulated expression of the mRNAs for @entity7167 , @entity2557 , @entity16756 , whereas only traces of @entity7991 mRNA were found. Each receptor type had a different developmental pattern, suggesting an independent regulation. Signal for @entity2557 was retained only in the adult muscle. Among the low-affinity FGF binding sites, perlecan was absent, whereas RNA transcript for @entity13221 peaked at week 13 of gestation, after which a significant decrease was observed. Immunohistochemistry for FGFRs revealed that their localization changed with muscle maturation. At early embryonic stages, @entity2557 and @entity16756 had a scattered distribution in the tissue, and @entity7167 was found on myotube and myofiber plasma membranes. At later stages, @entity7167 positivity decreased and was found in a few areas of the muscle, @entity2557 was concentrated in the nuclei of some, but not all, muscle fibers, and @entity16756 maintained an association with plasma membrane. In adult tissue, weak positivity for @entity2557 and @entity16756 was observed in the connective tissue only. When immunocytochemistry was performed on @entity1 fetal myoblasts in culture, confocal microscope analysis revealed a nonhomogeneous cell membrane distribution of FGFRs. Taken together, the data strongly suggest that developmentally regulated expression and cell distribution of FGFRs play a role during muscle maturation.

Developmentally regulated expression and localization of fibroblast growth factor receptors in the XXXX muscle.

@entity1 :: ('9606', 'Species') :: ['human'] @entity2557 :: ('2261', 'Gene') :: ['FGFR-3'] @entity16756 :: ('2264', 'Gene') :: ['FGFR-4'] @entity7991 :: ('2263', 'Gene') :: ['FGFR-2'] @entity13221 :: ('6382', 'Gene') :: ['syndecan-1 and perlecan', 'syndecan-1'] @entity669 :: ('CHEBI:18186', 'Chemical') :: ['tyrosine'] @entity7167 :: ('2260', 'Gene') :: ['FGFR-1'] @entity597 :: ('CHEBI:16189', 'Chemical') :: ['sulphate']
@entity1 :: (9606,Species) :: ['human']
