Lamins are intermediate filament proteins that form a fibrous meshwork, called the nuclear lamina, between the inner nuclear membrane and peripheral heterochromatin of metazoan cells. The assembly and incorporation of lamin A/C into the lamina, as well as their various functions, are still not well understood. Here, we employed designed ankyrin repeat proteins (DARPins) as new experimental tools for lamin research. We screened for DARPins that specifically bound to lamin A/C, and interfered with lamin assembly in vitro and with incorporation of lamin A/C into the native lamina in living cells. The selected DARPins inhibited lamin assembly and delocalized A-type lamins to the nucleoplasm without modifying lamin expression levels or the amino acid sequence. Using these lamin binders, we demonstrate the importance of proper integration of lamin A/C into the lamina for nuclear mechanical properties and nuclear envelope integrity. Finally, our study provides evidence for cell-type-specific differences in lamin functions.
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机译：核纤层蛋白是中间的细丝蛋白，在后生子细胞的内核膜和外周异染色质之间形成称为核层的纤维网。层粘连蛋白A / C在薄片中的组装和结合，以及它们的各种功能，仍未得到很好的理解。在这里，我们采用了设计的锚蛋白重复蛋白（DARPins）作为层蛋白研究的新实验工具。我们筛选了DARPins，这些DARPins特异性结合了lamin A / C，并在体外干扰了lamin的组装，并干扰了lamin A / C进入活细胞中的天然层板。所选的DARPins抑制了lamin的组装并将A型lamins分散到核质上，而没有改变lamin的表达水平或氨基酸序列。使用这些层状粘合剂，我们证明了将层状A / C正确整合到层中对于核力学性能和核包膜完整性的重要性。最后，我们的研究为层粘连蛋白功能中特定于细胞类型的差异提供了证据。
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