Disruption of the actin network enhances MAP-2c and Fyn-induced process outgrowth

Mouse Fyn induces pseudopodium formation in Chinese hamster ovary cells

Molecular mechanisms underlying the effects of Fyn on cell morphology, pseudopodium movement, and cell migration were investigated. The Fyn gene was subcloned into pEGFP-N1 to produce pEGFP-N1-Fyn. Chinese hamster ovary (CHO) cells were transfected with pEGFP-N1-Fyn. The expression of Fyn mRNA and proteins was monitored by reverse transcription-PCR and Western blotting. Additionally, transfected cells were stained with 4',6-diamidino-2-phenylindole and a series of time-lapse images was taken. Sequences of the recombinant plasmids pMD18-T-Fyn and pEGFP-N1-Fyn were confirmed by sequence identification using National Center for Biotechnology Information in USA, and Fyn expression was detected by RT-PCR and Western blotting. The morphology of CHO cells transfected with the recombinant vector was significantly altered. Fyn expression induced filopodia and lamellipodia formation. Based on these results, we concluded that overexpression of mouse Fyn induces the formation of filopodia and lamellipodia in CHO cells, and promotes cell movement.

Involvement of α2-antiplasmin in dendritic growth of hippocampal neurons

The α2-Antiplasmin (α2AP) protein is known as a principal physiological inhibitor of plasmin, but we previously demonstrated that it acts as a regulatory factor for cellular functions independent of plasmin. α2AP is highly expressed in the hippocampus, suggesting a potential role for α2AP in hippocampal neuronal functions. However, the role for α2AP was unclear. This study is the first to investigate the involvement of α2AP in the dendritic growth of hippocampal neurons. The expression of microtubule-associated protein 2, which contributes to neurite initiation and neuronal growth, was lower in the neurons from α2AP⁻/⁻ mice than in the neurons from α2AP⁺/⁺ mice. Exogenous treatment with α2AP enhanced the microtubule-associated protein 2 expression, dendritic growth and filopodia formation in the neurons. This study also elucidated the mechanism underlying the α2AP-induced dendritic growth. Aprotinin, another plasmin inhibitor, had little effect on the dendritic growth of neurons, and α2AP induced its expression in the neurons from plaminogen⁻/⁻ mice. The activation of p38 MAPK was involved in the α2AP-induced dendritic growth. Therefore, our findings suggest that α2AP induces dendritic growth in hippocampal neurons through p38 MAPK activation, independent of plasmin, providing new insights into the role of α2AP in the CNS.