真核细胞通过保守的分子桥将核骨架连接到细胞骨架上,称为LINC复合体。LINC复合物的核心包含SUN结构域和KASH结构域蛋白,其在核包膜腔内直接缔合。链内和链间二硫键,随着KASH域蛋白质相互作用,两者都有助于脊椎动物SUN结构域蛋白的三级和四级结构。这些键的重要性以及PDIs(蛋白质二硫键异构酶)在LINC复合物生物学中的作用尚不清楚。还原性和非还原性SDS-PAGE分析显示SUN2同二聚体在非致瘤性乳腺上皮MCF10A细胞中普遍存在,但不在浸润性三阴性乳腺癌MDA-MB-231细胞系中。此外,超分辨率显微镜显示MCF10A的SUN2染色改变,但不是在MDA-MB-231细胞核中,在还原剂暴露时。虽然PDIA1水平在两种细胞系中相似,MDA-MB-231细胞PDI活性的药理学抑制导致SUN结构域蛋白下调,以及Nesprin-2从细胞核的位移。这种抑制也引起核周细胞骨架结构和层板蛋白下调的变化,并在空间限制性的体外环境中增加了PDI抑制的MDA-MB-231细胞的侵袭力,与未处理的细胞相比。这些结果强调了PDIs在调节LINC复杂生物学中的关键作用,蜂窝架构,生物力学,和入侵。
Eukaryotic cells tether the nucleoskeleton to the cytoskeleton via a conserved molecular bridge, called the LINC complex. The core of the LINC complex comprises SUN-domain and KASH-domain proteins that directly associate within the nuclear envelope lumen. Intra- and inter-chain disulphide bonds, along with KASH-domain protein interactions, both contribute to the tertiary and quaternary structure of vertebrate SUN-domain proteins. The significance of these bonds and the role of PDIs (protein disulphide isomerases) in LINC complex biology remains unclear. Reducing and non-reducing SDS-PAGE analyses revealed a prevalence of SUN2 homodimers in non-tumorigenic breast epithelia MCF10A cells, but not in the invasive triple-negative breast cancer MDA-MB-231 cell line. Furthermore, super-resolution microscopy revealed SUN2 staining alterations in MCF10A, but not in MDA-MB-231 nuclei, upon reducing agent exposure. While PDIA1 levels were similar in both cell lines, pharmacological inhibition of PDI activity in MDA-MB-231 cells led to SUN-domain protein down-regulation, as well as Nesprin-2 displacement from the nucleus. This inhibition also caused changes in perinuclear cytoskeletal architecture and lamin downregulation, and increased the invasiveness of PDI-inhibited MDA-MB-231 cells in space-restrictive in vitro environments, compared to untreated cells. These results emphasise the key roles of PDIs in regulating LINC complex biology, cellular architecture, biomechanics, and invasion.