I. Munoz-sanjuan et al., Expression and regulation of chicken fibroblast growth factor homologous factor (FHF)-4 at the base of the developing limbs, MECH DEVEL, 95(1-2), 2000, pp. 101-112
Fibroblast growth factor homologous factors (FHFs) have been implicated in
limb and nervous system development. In this paper we describe the expressi
on of the cFHF-4 gene during early chicken development, cFHF-4 is expressed
in the paraxial mesoderm, lateral ridge, and, most prominently, in the pos
terior-dorsal side of the base of each limb bud. The expression pattern of
cFHF-4 at the base of the limbs is not altered by tissue grafts containing
the zone of polarizing activity (ZPA), by implants of Shh-expressing cells,
or by implants of beads containing retinoic acid, nor does it depend on th
e distal growth of the limb as it is not altered in limb buds that are surg
ically truncated. In three chicken mutants affecting limb patterning - talp
id(2), limbless, and wingless - altered patterns of cFHF-4 expression are c
orrelated with abnormal nerve plexus formation and altered patterns of limb
bud innervation. Similarly, ectopic expression of cFHF-4 is correlated wit
h a local induction of limb-like innervation patterns when beads containing
FGF-2 are implanted in the flank. In these experiments, both ectopic inner
vation and ectopic expression of cFHF-4 in the flank were observed regardle
ss of the size of the FGF-2-induced outgrowths. By contrast, ectopic expres
sion of Shh and HoxD13 are seen only in the larger FGF-2-induced outgrowths
. Taken together, these data suggest that cFHF-4 regulates or is coregulate
d with early events related to innervation at the base of the limbs. (C) 20
00 Elsevier Science Ireland Ltd. All rights reserved.