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Abstract：
Imaging mass spectrometry (IMS) enables targeted and untargeted visualization of the spatial localization of molecules in tissues with great specificity. The lens is a unique tissue that contains fiber cells corresponding to various stages of differentiation that are packed in a highly spatial order. The application of IMS to lens tissue localizes molecular features that are spatially related to the fiber cell organization. Such spatially resolved molecular information assists our understanding of lens structure and physiology; however, protein IMS studies are typically limited to abundant, soluble, low molecular weight proteins. In this study, a method was developed for imaging low solubility cytoskeletal proteins in the lens; a tissue that is filled with high concentrations of soluble crystallins. Optimized tissue washes combined with on-tissue enzymatic digestion allowed successful imaging of peptides corresponding to known lens cytoskeletal proteins. The resulting peptide signals facilitated segmentation of the bovine lens into molecularly distinct regions. A sharp intermediate filament transition from vimentin to lens-specific beaded filament proteins was detected in the lens cortex. MALDI IMS also revealed the region where posttranslational myristoylation of filensin occurs and the results indicate that truncation and myristoylation of filensin starts soon after filensin expression increased in the inner cortex. From intermediate filament switch to filensin truncation and myristoylation, multiple remarkable changes occur in the narrow region of lens cortex. MALDI images delineated the boundaries of distinct lens regions that will guide further proteomic and interactomic studies.
摘要：
成像质谱(IMS)能够以极大的特异性实现组织中分子的空间定位的靶向和非靶向可视化。晶状体是一种独特的组织,其包含对应于以高度空间顺序包装的各个分化阶段的纤维细胞。IMS在晶状体组织中的应用使与纤维细胞组织在空间上相关的分子特征局部化。这种空间分辨的分子信息有助于我们对晶状体结构和生理学的理解；然而，蛋白质IMS研究通常限于丰富，可溶性，低分子量蛋白质。在这项研究中,开发了一种用于成像晶状体中低溶解度细胞骨架蛋白的方法;一种充满高浓度可溶性晶状体蛋白的组织。优化的组织洗液与组织上的酶消化相结合，可以成功成像对应于已知晶状体细胞骨架蛋白的肽。所产生的肽信号有助于将牛晶状体分割成分子上不同的区域。在晶状体皮层中检测到从波形蛋白到晶状体特异性珠丝蛋白的急剧中间丝转变。MALDIIMS还揭示了丝素的翻译后肉豆蔻化发生的区域，结果表明，丝素的截断和肉豆蔻化在内皮质中丝素表达增加后不久就开始。从中间细丝转换到丝状蛋白截短和肉豆蔻酰化，晶状体皮质狭窄区域发生多种显著变化。MALDI图像描绘了不同晶状体区域的边界，这将指导进一步的蛋白质组学和相互作用组学研究。
