Division of Neuroanatomy, Medical University of Innsbruck, 6020 Innsbruck, Austria.
Division of Histology and Embryology, Medical University of Innsbruck, 6020 Innsbruck, Austria.
Cells. 2019 Mar 14;8(3):243. doi: 10.3390/cells8030243.
The intracellular transport of receptor tyrosine kinases results in the differential activation of various signaling pathways. In this study, optogenetic stimulation of fibroblast growth factor receptor type 1 (FGFR1) was performed to study the effects of subcellular targeting of receptor kinases on signaling and neurite outgrowth. The catalytic domain of FGFR1 fused to the algal light-oxygen-voltage-sensing (LOV) domain was directed to different cellular compartments (plasma membrane, cytoplasm and nucleus) in human embryonic kidney (HEK293) and pheochromocytoma (PC12) cells. Blue light stimulation elevated the pERK and pPLCγ1 levels in membrane-opto-FGFR1-transfected cells similarly to ligand-induced receptor activation; however, no changes in pAKT levels were observed. PC12 cells transfected with membrane-opto-FGFR1 exhibited significantly longer neurites after light stimulation than after growth factor treatment, and significantly more neurites extended from their cell bodies. The activation of cytoplasmic FGFR1 kinase enhanced ERK signaling in HEK293 cells but not in PC12 cells and did not induce neuronal differentiation. The stimulation of FGFR1 kinase in the nucleus also did not result in signaling changes or neurite outgrowth. We conclude that FGFR1 kinase needs to be associated with membranes to induce the differentiation of PC12 cells mainly via ERK activation.
细胞内受体酪氨酸激酶的转运导致各种信号通路的差异激活。在这项研究中，采用光遗传学刺激成纤维细胞生长因子受体 1（FGFR1），研究受体激酶的亚细胞定位对信号转导和神经突生长的影响。FGFR1 的催化结构域与藻类光氧电压感应（LOV）结构域融合，定向到人胚肾（HEK293）和嗜铬细胞瘤（PC12）细胞的不同细胞区室（质膜、细胞质和细胞核）。蓝光刺激同样能像配体诱导受体激活一样，提高膜光控-FGFR1 转染细胞中的 pERK 和 pPLCγ1 水平；然而，pAKT 水平没有变化。与生长因子处理相比，转染膜光控-FGFR1 的 PC12 细胞在光刺激后表现出明显更长的神经突，并且从其细胞体延伸出更多的神经突。细胞质 FGFR1 激酶的激活增强了 HEK293 细胞中的 ERK 信号转导，但在 PC12 细胞中没有，并且没有诱导神经元分化。核内 FGFR1 激酶的刺激也没有导致信号变化或神经突生长。我们得出结论，FGFR1 激酶需要与膜结合才能主要通过 ERK 激活诱导 PC12 细胞的分化。
