ARHGAP32 as a novel RhoGAP interacting with desmoplakin is required for desmosomal organization and assembly.

Desmosomes play a critical role in maintaining tissue barrier integrity, particularly in mechanically stressed tissues. The assembly of desmosomes is regulated by the cytoskeleton and its regulators, while desmosomes also function as a central hub for regulating F-actin. However, the specific mechanisms underlying the crosstalk between desmosomes and F-actin remain unclear. Here, we identified that ARHGAP32, a Rho GTPase-activating protein, is located in desmosomes through its interaction with DSP via its GAB2-interacting domain (GAB2-ID). We confirmed that ARHGAP32 is required for desmosomal organization, maturation, and length regulation. Notably, loss of ARHGAP32 increased formation of F-actin stress fibers and phosphorylation of Myosin at T18/S19. Inhibition of ROCK1 activity in ARHGAP32 KO cells effectively restored desmosomal organization and the integrity of epithelial cell sheets. Moreover, loss of DSP impaired desmosomal ARHGAP32 while decreased actomyosin contractility. Deletion of the GAB2-ID of ARHGAP32 enhanced its association with RHOA in the cytosol and failed to rescue the desmosomal organization. Collectively, our study unveils ARHGAP32 associates with and regulates desmosomes by interacting with DSP. This interaction potentially facilitates the crosstalk between desmosomes and F-actin.