FERM domain containing protein 7 (FRMD7) upregulates the expression of neuronal cytoskeletal proteins and promotes neurite outgrowth in Neuro-2a cells

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.