DCM associated LMNA mutations cause distortions in lamina structure and assembly
DCM associated LMNA mutations cause distortions in lamina structure and assembly
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DOI：
10.1016/j.bbagen.2017.08.016
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发表时间：
2017-11-01
影响因子：
3
通讯作者：
Sengupta, Kaushik
中科院分区：
文献类型：
--
作者：
Bhattacharjee, Pritha;Dasgupta, Dipak;Sengupta, Kaushik
背景：A 型和 B 型核纤层蛋白是核纤层的整体支架组件，赋予所有后生动物细胞核刚性和形状。 A 型核纤层蛋白中超过 450 个突变与 16 种人类疾病相关，其中包括扩张型心肌病 (DCM)。在这里，我们发现 DCM 突变体扰乱核纤层蛋白 A (LA) 的自缔合及其与核纤层蛋白 B1 (LB1) 的结合。方法：我们使用共聚焦和超分辨率显微镜 (NSIM) 研究 LA 突变体对核纤层的影响。我们进一步使用圆二色性、荧光光谱和等温滴定量热法（ITC）来探讨突变体LA的结构调制、自缔合和异聚缔合。结果：在培养细胞系中转染突变体导致形成不同大小和分布的核聚集体。内源性 LB1 被隔离在这些聚集体中。这与突变蛋白的关联常数比野生型蛋白增加十倍是一致的。这些突变体表现出与 LB1 的不同异型相互作用，以及相互作用蛋白的显着二级和三级结构改变。热力学研究表明，突变体以不同的化学计量、亲和力和能量与 LB1 结合。结论：在本报告中，我们表明突变体 LA 自缔合倾向的增加调节了 LA-LB1 相互作用，并阻止了均匀层状网络的形成。
Background: A and B-type lamins are integral scaffolding components of the nuclear lamina which impart rigidity and shape to all metazoan nuclei. Over 450 mutations in A-type lamins are associated with 16 human diseases including dilated cardiomyopathy (DCM). Here, we show that DCM mutants perturb the self-association of lamin A (LA) and it's binding with lamin B1 (LB1).Methods: We used confocal and superresolution microscopy (NSIM) to study the effect of LA mutants on the nuclear lamina. We further used circular dichroism, fluorescence spectroscopy and isothermal titration calorimetry (ITC) to probe the structural modulations, self-association and heteropolymeric association of mutant LA.Results: Transfection of mutants in cultured cell lines result in the formation of nuclear aggregates of varied size and distribution. Endogenous LB1 is sequestered into these aggregates. This is consistent with the ten-fold increase in association constant of the mutant proteins compared to the wild type. These mutants exhibit differential heterotypic interaction with LB1, along with significant secondary and tertiary structural alterations of the interacting proteins. Thermodynamic studies demonstrate that the mutants bind to LB1 with different stoichiometry, affinity and energetics.Conclusions: In this report we show that increased self-association propensity of mutant LA modulates the LA-LB1 interaction and precludes the formation of an otherwise uniform laminar network.