Su Pei, McGee John P, Durbin Kenneth R, Hollas Michael A R, Yang Manxi, Neumann Elizabeth K, Allen Jamie L, Drown Bryon S, Butun Fatma Ayaloglu, Greer Joseph B, Early Bryan P, Fellers Ryan T, Spraggins Jeffrey M, Laskin Julia, Camarillo Jeannie M, Kafader Jared O, Kelleher Neil L
Departments of Molecular Biosciences, Chemistry, and Chemical and Biological Engineering and the Feinberg School of Medicine, Northwestern University, Evanston, IL, USA.
Department of Chemistry, Purdue University, West Lafayette, IN, USA.
Sci Adv. 2022 Aug 12;8(32):eabp9929. doi: 10.1126/sciadv.abp9929. Epub 2022 Aug 10.
Imaging of proteoforms in human tissues is hindered by low molecular specificity and limited proteome coverage. Here, we introduce proteoform imaging mass spectrometry (PiMS), which increases the size limit for proteoform detection and identification by fourfold compared to reported methods and reveals tissue localization of proteoforms at <80-μm spatial resolution. PiMS advances proteoform imaging by combining ambient nanospray desorption electrospray ionization with ion detection using individual ion mass spectrometry. We demonstrate highly multiplexed proteoform imaging of human kidney, annotating 169 of 400 proteoforms of <70 kDa using top-down MS and a database lookup of ~1000 kidney candidate proteoforms, including dozens of key enzymes in primary metabolism. PiMS images reveal distinct spatial localizations of proteoforms to both anatomical structures and cellular neighborhoods in the vasculature, medulla, and cortex regions of the human kidney. The benefits of PiMS are poised to increase proteome coverage for label-free protein imaging of tissues.
蛋白质异构体在人体组织中的成像受到低分子特异性和有限蛋白质组覆盖范围的阻碍。在此，我们引入了蛋白质异构体成像质谱法（PiMS），与已报道的方法相比，该方法将蛋白质异构体检测和鉴定的分子量上限提高了四倍，并在小于80微米的空间分辨率下揭示了蛋白质异构体的组织定位。PiMS通过将常压纳米喷雾解吸电喷雾电离与使用单离子质谱的离子检测相结合，推动了蛋白质异构体成像技术的发展。我们展示了对人类肾脏的高度多重蛋白质异构体成像，使用自上而下的质谱法和对约1000种肾脏候选蛋白质异构体的数据库查询，对400种分子量小于70 kDa的蛋白质异构体中的169种进行了注释，其中包括初级代谢中的数十种关键酶。PiMS图像揭示了蛋白质异构体在人类肾脏的血管、髓质和皮质区域的解剖结构和细胞邻域中的不同空间定位。PiMS的优势有望增加用于组织无标记蛋白质成像的蛋白质组覆盖范围。
