Pu Jiali, Lu Xiaoxiong, Zhao Guohua, Yan Yaping, Tian Jun, Zhang Baorong
Department of Neurology, second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Mol Vis. 2012;18:1428-35. Epub 2012 Jun 1.
Mutations of the FERM domain containing protein 7 gene (FRMD7) are associated with X-linked idiopathic congenital nystagmus. Previous studies have shown that FRMD7 plays an important role in neuronal development and is involved in the regulation of F-actin. However, its specific mechanism of action remains undetermined.
Our study used quantitative real-time PCR to assess the levels of neuron-specific genes in a mouse neuroblastoma cell line (Neuro-2a) after transfection with a full-length coding transcript of FRMD7 or a blank control vector. F-actin was detected by rhodamine-phalloidin staining. Neurite number and length were assessed by a confocal laser scanning microscope.
We demonstrated that FRMD7 can promote neurite outgrowth following retinoic acid-induced differentiation in Neuro-2a cells. Neurites were significantly longer in cells transfected with FRMD7, but there was no difference in cell numbers. The mRNA expression of neuron cytoskeletal-related genes (microtubule-associated protein 2 [Mtap2], neurofilament-L and M [NF-L and NF-M] and the microtubule-associated protein tau [MAPT]) were significantly increased compared to controls. Other genes (NF-H, MAPT, neuron-specific class III beta-tubulin (Tuj-1), nestin, and growth-associated protein-43 [GAP-43]) were not obviously altered by FRMD7 overexpression.
Taken together, our data suggest that FRMD7 promotes the extension of neurites and may be involved in regulating the movement of cytoskeletal proteins, which influences not only F-actin, but also NF and microtubule dynamics.
含FERM结构域蛋白7基因（FRMD7）的突变与X连锁特发性先天性眼球震颤相关。先前的研究表明，FRMD7在神经元发育中起重要作用，并参与F-肌动蛋白的调节。然而，其具体作用机制仍未确定。
我们的研究使用定量实时PCR来评估在用FRMD7全长编码转录本或空白对照载体转染后，小鼠神经母细胞瘤细胞系（Neuro-2a）中神经元特异性基因的水平。通过罗丹明-鬼笔环肽染色检测F-肌动蛋白。通过共聚焦激光扫描显微镜评估神经突的数量和长度。
我们证明，在视黄酸诱导Neuro-2a细胞分化后，FRMD7可促进神经突生长。转染FRMD7的细胞中神经突明显更长，但细胞数量没有差异。与对照组相比，神经元细胞骨架相关基因（微管相关蛋白2 [Mtap2]、神经丝-L和M [NF-L和NF-M]以及微管相关蛋白tau [MAPT]）的mRNA表达显著增加。其他基因（NF-H、MAPT、神经元特异性III类β-微管蛋白（Tuj-1）、巢蛋白和生长相关蛋白43 [GAP-43]）未因FRMD7过表达而明显改变。
综上所述，我们的数据表明，FRMD7促进神经突的延伸，并可能参与调节细胞骨架蛋白的运动，这不仅影响F-肌动蛋白，还影响神经丝和微管动力学。
