About this seminarMost knowledge about membrane proteins has been obtained via biochemical methods but these analyze pooled material from many thousands of cells so that the information is based on population averages. Moreover, the proteins are extracted from their native environment of the cell membrane. Examining membrane protein function is now possible at the single molecule- and single cell level within intact mammalian cells using liquid-phase scanning transmission electron microscopy (STEM) [1, 2]. The key step is to specifically label the proteins of interest with small nanoparticles, for example, quantum dots. To maintain cells in liquid in the vacuum of the electron microscope, samples are covered with a protective sheet of graphene . Liquid-phase STEM was used to explore the formation of HER2 homodimers at the single-molecule level in whole SKBR3 breast cancer cells . HER2 is a receptor protein playing an important role in breast cancer aggressiveness and progression. Data analysis based on calculating the pair correlation function from individual HER2 positions revealed remarkable differences its functional state between rare- and bulk cancer cells with relevance for studying the role of cancer cell heterogeneity in drug response. Liquid STEM was then used to explore the effect of the antibody-based drug trastuzumab at the single cell and single molecule level, thereby unraveling the molecular mechanism of the drug binding . We have also examined HER2 in biopsy samples .
-  de Jonge, N., Ross, F.M., Electron microscopy of specimens in liquid, Nat. Nanotechnol. 6, 695-704, 2011.
-  de Jonge, N., Houben, L., Dunin-Borkowski, R.E., Ross, F.M., Resolution and aberration correction in liquid cell transmission electron microscopy, Nat. Rev. Mater. 4, 61-78, 2019.
-  Dahmke, I.N., Verch, A., Hermannsdorfer, J., Peckys, D.B., Weatherup, R.S., Hofmann, S., de Jonge, N., Graphene Liquid Enclosure for Single-Molecule Analysis of Membrane Proteins in Whole Cells Using Electron Microscopy, ACS Nano 11, 11108-11117, 2017.
-  Peckys, D.B., Korf, U., de Jonge, N., Local variations of HER2 dimerization in breast cancer cells discovered by correlative fluorescence and liquid electron microscopy, Sci. Adv. 1, e1500165, 2015.
-  Peckys, D.B., Korf, U., Wiemann, S., de Jonge, N., Liquid-phase electron microscopy of molecular drug response in breast cancer cells reveals irresponsive cell subpopulations related to lack of HER2 homodimers, Mol. Biol. Cell 28, 3193-3202, 2017.
-  Peckys, D.B., Hirsch, D., Gaiser, T., de Jonge, N., Visualisation of HER2 homodimers in single cells from HER2 overexpressing primary formalin fixed paraffin embedded tumour tissue, Mol. Med. in press, 2019.
Friday 20 September 2019, 10:00 - 11:00 hrs.
Figdor Lecture Theatre, route 289