Nuclear fibroblast growth factor-2 interacts specifically with splicing factor SF3a66.
Fibroblast growth factor 2 (FGF-2) has a dual role as a classical extracellular signaling protein and as an intracellular factor. Isoforms of FGF-2, resulting from alternatively used start codons on one mRNA species, locate differentially to nuclear compartments. In this study we aimed to analyze functions of intracellular FGF-2 by identification of interacting proteins. We identified the 66-kDa subunit of splicing factor 3a (SF3a66) as a binding partner in a yeast two-hybrid screen and confirmed this interaction by pull-down assays. The splicing factor interacted with the 18-kDa (FGF-2(18)) and with the 23-kDa (FGF-2(23)) isoforms, indicating an interaction with a domain common to both isoforms. Moreover, FGF-2 interacted with the C-terminus of SF3a66, a sequence that has not previously been assigned a functional role. In a functional neurite outgrowth assay, SF3a66 enhanced neurite lengths similar to FGF-2(18). We have previously identified the spliceosomal assembly factor survival of motoneuron (SMN) protein as a protein interacting specifically with the FGF-2(23) isoform [Claus et al., J. Biol. Chem. 278 (2003), 479-485]. The identification of two FGF-2 interacting proteins from the same biochemical pathway suggests a novel intranuclear role of FGF-2.
Gringel
Susanne
S
Department of Neuroanatomy, Hannover Medical School, D-30625 Hannover, Germany.
van Bergeijk
Jeroen
J
Haastert
Kirsten
K
Grothe
Claudia
C
Claus
Peter
P
D000818:Animals; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D003001:Cloning, Molecular; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005456:Fluorescent Dyes; D005690:Galactose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007536:Isomerism; D009414:Nerve Growth Factors / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D016501:Neurites / Q000187:drug effects; D016716:PC12 Cells; D010957:Plasmids / Q000235:genetics; D016601:RNA-Binding Proteins; D051381:Rats; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000378:metabolism
D005456:Fluorescent Dyes; C108381:GEMIN2 protein, human; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D017413:Ribonucleoprotein, U2 Small Nuclear; C088049:splicing factor 3a; D016222:Fibroblast Growth Factor 2; D049452:Green Fluorescent Proteins; D005947:Glucose; D005690:Galactose