Proximity Mapping of Desmosomes Reveals a Striking Shift in Their Molecular Neighborhood Associated With Maturation.

Desmosomes are multiprotein adhesion complexes that link intermediate filaments to the plasma membrane, ensuring the mechanical integrity of cells across tissues, but how they participate in the wider signaling network to exert their full function is unclear. To investigate this, we carried out protein proximity mapping using biotinylation (BioID). The combined interactomes of the essential desmosomal proteins desmocollin 2a, plakoglobin, and plakophilin 2a (Pkp2a) in Madin-Darby canine kidney epithelial cells were mapped and their differences and commonalities characterized as desmosome matured from Ca2+ dependence to the mature, Ca2+-independent, hyper-adhesive state, which predominates in tissues. Results suggest that individual desmosomal proteins have distinct roles in connecting to cellular signaling pathways and that these roles alter substantially when cells change their adhesion state. The data provide further support for a dualistic concept of desmosomes in which the properties of Pkp2a differ from those of the other, more stable proteins. This body of data provides an invaluable resource for the analysis of desmosome function.

Duox is the primary NADPH oxidase responsible for ROS production during adult caudal fin regeneration in zebrafish.

Sustained elevated levels of reactive oxygen species (ROS) have been shown to be essential for regeneration in many organisms. This has been shown primarily via the use of pharmacological inhibitors targeting the family of NADPH oxidases (NOXes). To identify the specific NOXes involved in ROS production during adult caudal fin regeneration in zebrafish, we generated nox mutants for duox, nox5 and cyba (a key subunit of NOXes 1-4) and crossed these lines with a transgenic line ubiquitously expressing HyPer, which permits the measurement of ROS levels. Homozygous duox mutants had the greatest effect on ROS levels and rate of fin regeneration among the single mutants. However, duox:cyba double mutants showed a greater effect on fin regeneration than the single duox mutants, suggesting that Nox1-4 also play a role during regeneration. This work also serendipitously found that ROS levels in amputated adult zebrafish fins oscillate with a circadian rhythm.