Fibin, a novel secreted lateral plate mesoderm signal, is essential for pectoral fin bud initiation in zebrafish.
We identified a novel secreted protein, fibin, in zebrafish, mice and humans. We inhibited its function in zebrafish embryos by injecting antisense fibin morpholino oligonucleotides. A knockdown of fibin function in zebrafish resulted in no pectoral fin bud initiation and abolished the expression of tbx5, which is involved in the specification of pectoral fin identification. The lack of pectoral fins in fibin-knockdown embryos was partially rescued by injection of fibin RNA. fibin was expressed in the lateral plate mesoderm of the presumptive pectoral fin bud regions. Its expression region was adjacent to that of tbx5. fibin expression temporally preceded tbx5 expression in presumptive pectoral fin bud regions, and not abolished in tbx5-knockdown presumptive fin bud regions. In contrast, fibin expression was abolished in retinoic acid signaling-inhibited or wnt2b-knockdown presumptive fin bud regions. These results indicate that fibin is a secreted signal essential for pectoral fin bud initiation in that it potentially acts downstream of retinoic acid and wnt signaling and is essential for tbx5 expression. The present findings have revealed a novel secreted lateral plate mesoderm signal essential for fin initiation in the lateral plate mesoderm.
Wakahara
Takashi
T
Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto 606-8501, Japan.
Kusu
Naoki
N
Yamauchi
Hajime
H
Kimura
Ikuo
I
Konishi
Morichika
M
Miyake
Ayumi
A
Itoh
Nobuyuki
N
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018507:Gene Expression Regulation, Developmental; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D020319:Oligodeoxyribonucleotides, Antisense / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
D006023:Glycoproteins; D047908:Intracellular Signaling Peptides and Proteins; D020319:Oligodeoxyribonucleotides, Antisense; D011994:Recombinant Proteins; D020825:T-Box Domain Proteins; C103172:T-box transcription factor 5; D051153:Wnt Proteins; D029961:Zebrafish Proteins; C519055:fibinb protein, zebrafish; C492033:wnt2ba protein, zebrafish