Zhan X, Hu X, Friedman S, Maciag T
Department of Molecular Biology, Holland Laboratory, American Red Cross, Rockville, MD 20855.
Biochem Biophys Res Commun. 1992 Nov 16;188(3):982-91. doi: 10.1016/0006-291x(92)91328-n.
Nuclear localization of fibroblast growth factors (FGF) have been reported by many laboratories. We demonstrate here that FGF-1, the precursor for acidic FGF contains a putative nuclear translocation sequence (NTS) NYKKPKL, which is able to direct the expression of the bacterial beta galactosidase (beta gal) gene to the nucleus of transfected NIH 3T3 cells. However, this NTS is unable to target either FGF-1 itself or a FGF-1-beta gal fusion protein into the nucleus, suggesting that FGF-1 may contain an additional sequence which prevents endogenously expressed FGF-1 from being translocated into the nucleus. Indeed, when FGF-1 was fused to the NTS derived from the yeast histone 2B gene, the chimeric construct also failed to be transported into the nucleus either by itself or as a beta gal fusion protein. Interestingly, when 125I-FGF-1 was used to stimulate quiescent NIH 3T3 cells, a significant amount of internalized 125I-FGF-1 (approximately 10%) was found within the nucleus and the nuclear localization of FGF-1 through the exogenous pathway could be significantly reduced by suramin, an inhibitor of the interaction of FGF-1 with its receptor. These data suggest that while FGF-1 contains a NTS, nuclear translocation requires an exogenous and not an endogenous pathway.
许多实验室都报道过成纤维细胞生长因子（FGF）的核定位现象。我们在此证明，酸性FGF的前体FGF-1含有一个假定的核转运序列（NTS）NYKKPKL，该序列能够将细菌β-半乳糖苷酶（β-gal）基因的表达导向转染的NIH 3T3细胞的细胞核。然而，这个NTS无法将FGF-1自身或FGF-1-β-gal融合蛋白靶向转运到细胞核中，这表明FGF-1可能还含有一个额外的序列，该序列阻止内源性表达的FGF-1转运到细胞核中。事实上，当FGF-1与源自酵母组蛋白2B基因的NTS融合时，该嵌合构建体自身或作为β-gal融合蛋白时也都无法转运到细胞核中。有趣的是，当使用125I-FGF-1刺激静止的NIH 3T3细胞时，在细胞核内发现了大量内化的125I-FGF-1（约10%），并且苏拉明（一种FGF-1与其受体相互作用的抑制剂）可以显著降低通过外源性途径实现的FGF-1的核定位。这些数据表明，虽然FGF-1含有一个NTS，但核转运需要外源性而非内源性途径。
