Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, van der Maasweg 9, Delft, the Netherlands.
Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, Utrecht, the Netherlands.
Nat Commun. 2024 Apr 29;15(1):3648. doi: 10.1038/s41467-024-47763-x.
Neuronal network formation is facilitated by recognition between synaptic cell adhesion molecules at the cell surface. Alternative splicing of cell adhesion molecules provides additional specificity in forming neuronal connections. For the teneurin family of cell adhesion molecules, alternative splicing of the EGF-repeats and NHL domain controls synaptic protein-protein interactions. Here we present cryo-EM structures of the compact dimeric ectodomain of two teneurin-3 isoforms that harbour the splice insert in the EGF-repeats. This dimer is stabilised by an EGF8-ABD contact between subunits. Cryo-EM reconstructions of all four splice variants, together with SAXS and negative stain EM, reveal compacted dimers for each, with variant-specific dimeric arrangements. This results in specific trans-cellular interactions, as tested in cell clustering and stripe assays. The compact conformations provide a structural basis for teneurin homo- and heterophilic interactions. Altogether, our findings demonstrate how alternative splicing results in rearrangements of the dimeric subunits, influencing neuronal recognition and likely circuit wiring.
神经元网络的形成是通过细胞表面的突触细胞粘附分子之间的识别来促进的。细胞粘附分子的选择性剪接为形成神经元连接提供了额外的特异性。对于神经钙黏蛋白家族的细胞粘附分子，EGF 重复和 NHL 结构域的选择性剪接控制着突触蛋白-蛋白相互作用。在这里，我们展示了两个携带有 EGF 重复插入片段的神经钙黏蛋白-3 异构体的紧凑二聚体胞外结构域的冷冻电镜结构。这种二聚体通过亚基之间的 EGF8-ABD 接触得到稳定。所有四种剪接变体的冷冻电镜重建，以及 SAXS 和负染电镜，揭示了每个变体的紧凑二聚体，具有变体特异性的二聚体排列。这导致了特定的细胞间相互作用，如在细胞聚类和条纹测定中所测试的那样。这种紧凑的构象为神经钙黏蛋白同亲和异亲和相互作用提供了结构基础。总之，我们的发现表明了选择性剪接如何导致二聚体亚基的重排，从而影响神经元的识别，并可能影响电路布线。
