(391f) Nucleocytoplasmic Trafficking of NF-κB Studied by Microfluidic Electroporative Flow Cytometry

As a central mediator of the human immune response, nuclear factor NF-κB is involved in a range of cell activities including inflammatory response and apoptosis regulation. The transduction of signal often requires NF-κB to translocate into nucleus from cytoplasm when the cell is under stress. The translocation of NF-κB was investigated either by imaging few cells, or western blotting and electrophoretic mobility shift essay (EMSA) that reflect only the average information of the cell population. However high throughput studies of NF-κB translocation at the single cell level are desired since the translocation event was found asynchronous from cell to cell. Here we demonstrate the application of microfluidic electroporative flow cytometry (EFC) to sensitively detect NF-κB translocation events with a throughput of 250 - 300 cells/s. CHO cells expressing NF-κB tagged by EGFP were used as a model and the translocation was induced by applying IL-1β. We found that cells with NFκB translocation to the nucleus could retain more protein than the cells without it during flow-through electroporation process. We used microfluidic EFC to follow the progress of the translocation in real time. The temperature for the stimulation had a strong effect on the kinetics of the translocation. Quantitative information about the process at the population level can be generated from the data. We envision that microfluidic EFC will find applications for studying biological processes involving nucleocytoplasmic trafficking in general.