Ann Wehman's lab from the Virchow Center of the University of Würzburg developed a wonderful degron-based approach to probe membrane topology by light microscopy in C. elegans. Kristyna from our lab showed that this approach can also be applied to human cells and to auxin-mediated degradation by monitoring the stability of mAID-tagged lamin A, a component of the nuclear lamina. In the movie below you can see that nuclear mAID-tagged lamin A is only degraded during mitosis after nuclear envelope breakdown in cells where TIR1- the ubiquitin ligase adapter responsible for mAID-dependent degradation is otherwise sequestered to the cytoplasm. Hence, only when the nuclear and cytoplasmic compartments mix in mitosis can mAID-lamin A be degraded and thus precisely marks the loss of nuclear envelope permeability. Have a look to see how this approach works in detail and how it can help studying your preferred organelle.
