Kulczyk Arkadiusz W, McKee Karen K, Yurchenco Peter D
Institute for Quantitative Biomedicine, Department of Biochemistry and Microbiology, Rutgers University, Piscataway, NJ, USA.
Cryo-EMcorp, Bridgewater, NJ, USA.
Nat Commun. 2025 Aug 6;16(1):7256. doi: 10.1038/s41467-025-62814-7.
Netrin-4 is a tumor suppressor that interferes with formation of the laminin lattice. We employed cryo-electron microscopy to determine a structure of the protein complex consisting of the N-terminal fragments from netrin-4 and laminin γ1. The structure reveals that netrin-4 binds laminin γ1 at the molecular interface where laminin β1 would have bound, thus inhibiting the assembly of the heterotrimeric laminin polymer nodes consisting of α1, β1, and γ1 subunits, and their polymerization into the extracellular lattice. The four orders of magnitude higher affinity of the netrin-4-laminin γ1 interaction results from the larger buried surface area than the one formed by β1 and γ1 laminins and greater electrostatic surface complementarity. Our findings, supported by site-directed mutagenesis, solid-phase binding analysis, laminin polymerization, and Schwann cell assays, collectively demonstrate that, in addition to inhibiting laminin polymerization, netrin-4 disassembles the pre-existing laminin lattice. The structure has the potential to facilitate the development of novel therapies for cancer treatment.
Netrin-4是一种肿瘤抑制因子，可干扰层粘连蛋白晶格的形成。我们采用冷冻电子显微镜来确定由Netrin-4和层粘连蛋白γ1的N端片段组成的蛋白质复合物的结构。该结构表明，Netrin-4在层粘连蛋白β1原本会结合的分子界面处与层粘连蛋白γ1结合，从而抑制由α1、β1和γ1亚基组成的异三聚体层粘连蛋白聚合物节点的组装及其聚合成细胞外晶格。Netrin-4与层粘连蛋白γ1相互作用的亲和力比层粘连蛋白β1和γ1形成的亲和力高四个数量级，这是由于其掩埋表面积更大以及静电表面互补性更强。我们的研究结果得到定点诱变、固相结合分析、层粘连蛋白聚合和雪旺细胞检测的支持，共同表明，除了抑制层粘连蛋白聚合外，Netrin-4还能分解预先存在的层粘连蛋白晶格。该结构有可能促进癌症治疗新疗法的开发。
