Quantitative bioimaging in single cell signaling

Imaging of cellular samples has for several hundred years been a way for scientists to investigate biological systems. With the discovery of immunofluorescence labeling in the 1940’s and later genetic fluorescent protein labeling in the 1980’s the most important part in imaging, contrast and specificity, was drastically improved. Ever since, we have seen a increased use of fluorescence imaging in biological research, and the application and tools are constantly being developed further. Specific ion imaging has long been a way to discern signaling events in cell systems. Through use of fluorescent ion reporters, ionic concentrations can be measured in living cells as result of applied stimuli. Using Ca2+ imaging we have demonstrated that there is a inverse influence by plasma membrane voltage gated calcium channels on angiotensin II type 1 receptor (a protein involved in blood pressure regulation). This has direct implications in treatment of hypertension (high blood pressure), one of the most common serious diseases in the western civilization today with approximately one billion afflicted adults world wide in 2016. Extending from this more lower resolution live cell bioimaging I have moved into super resolution imaging. This thesis includes works on the interpretation of super resolution imaging data of the neuronal Na+, K+ ATPase α3, a receptor responsible for maintaining cell homeostasis during brain activity. The imaging data is correlated with electrophyiological measurments and computer models to point towards possible artefacts in super-resolution imaging that needs to be taken into account when interpreting imaging data. Moreover, I proceeded to develop a software for single-molecule localization microscopy analysis aimed for the wider research community and employ this software to identify expression artifacts in transiently transfected cell systems. In the concluding work super-resultion imaging was used to map out the early steps of the intrinsic apoptotic signaling cascade in space and time. Using super resoultion imaging, I mapped out in intact cells at which time points and at which locations the various proteins involved in apoptotic regulation are activated and interact.