Light-induced, spatiotemporal control of protein in the developing embryo of the sea urchin

Differential protein regulation is a critical biological process that regulates cellular activity and controls cell fate determination. It is especially important during early embryogenesis when post-transcriptional events predominate differential fate specification in many organisms. Light-induced approaches have been a powerful technology to interrogate protein functions with temporal and spatial precision, even at subcellular levels within a cell by controlling laser irradiation on the confocal microscope. However, application and efficacy of these tools need to be tested for each model system or for the cell type of interest because of the complex nature of each system. Here, we introduce two types of light-induced approaches to track and control proteins at a subcellular level in the developing embryo of the sea urchin. We found that the photoconvertible fluorescent protein, Kaede, is highly efficient to distinguish pre-existing and newly synthesized proteins with no apparent phototoxicity, even with interrogating proteins associated with mitotic spindle. Further, chromophore-assisted light inactivation (CALI) using miniSOG successfully inactivated proteins of interest at the vegetal cortex and selectively delayed or inhibited asymmetric cell division. Overall, these light-induced approaches serve as additional molecular tools to identify protein activity, not only in each cell lineage but also at a subcellular level in developing embryos.