Chauhan Anil Kumar, Moretti Federico Andrea, Iaconcig Alessandra, Baralle Francisco Ernesto, Muro Andrés Fernando
International Centre for Genetic Engineering and Biotechnology, Mouse Molecular Genetics Group, Padriciano 99, 34012 Trieste, Italy.
Behav Brain Res. 2005 Jun 3;161(1):31-8. doi: 10.1016/j.bbr.2005.02.020. Epub 2005 Apr 12.
The extracellular matrix (ECM) plays an important role in the central nervous system (CNS) by modulating the migration of cells, axons and dendrites of neurons. Fibronectin (FN) is a major component of the ECM in the CNS and plays essential roles in development, cell adhesion and cell migration. Specific FN-isoforms, generated by alternative splicing at three conserved regions, the extra domain B (EDB), extra domain A (EDA) and type III homologies connecting segment (IIICS), have been shown to modulate these processes in vitro and in vivo. The inclusion of the EDA exon in the brain is highly regulated during development and aging, suggesting an important role of this exon in brain function. However, the direct role of FN-isoforms in brain function and behaviour is still obscure. Therefore, to directly assess the role of the FN-EDA exon in vivo, we have generated two mouse strains devoid of EDA exon regulated splicing in the FN gene that constitutively include (EDA(+/+)) or exclude (EDA(-/-)) the EDA exon in all tissues. Here, we show the behavioural consequences of the absence of regulated splicing of the EDA exon in the FN gene. Deletion of the EDA domain in the FN protein results in reduced motor-coordination abilities and vertical exploratory capacity, whereas mice that constitutively include the EDA domain displayed a decrease in locomotory activity in the open field (OF) test. These results strongly suggest that regulated splicing of the EDA exon is necessary for a normal function of the brain.
细胞外基质（ECM）通过调节神经元的细胞、轴突和树突的迁移，在中枢神经系统（CNS）中发挥重要作用。纤连蛋白（FN）是中枢神经系统中细胞外基质的主要成分，在发育、细胞黏附和细胞迁移中起重要作用。由三个保守区域（额外结构域B（EDB）、额外结构域A（EDA）和III型同源连接段（IIICS））的可变剪接产生的特定FN异构体，已被证明在体外和体内调节这些过程。在发育和衰老过程中，大脑中EDA外显子的包含受到高度调控，这表明该外显子在脑功能中起重要作用。然而，FN异构体在脑功能和行为中的直接作用仍然不清楚。因此，为了直接评估FN-EDA外显子在体内的作用，我们构建了两种小鼠品系，它们在FN基因中缺乏受调控的EDA外显子剪接，在所有组织中组成性地包含（EDA(+/+)）或排除（EDA(-/-)）EDA外显子。在这里，我们展示了FN基因中EDA外显子缺乏受调控剪接的行为后果。FN蛋白中EDA结构域的缺失导致运动协调能力和垂直探索能力下降，而组成性包含EDA结构域的小鼠在旷场（OF）试验中的运动活动减少。这些结果强烈表明，EDA外显子的受调控剪接对于大脑的正常功能是必要的。
