Regulation of MYC by CARD14 in human epithelium is a determinant of epidermal homeostasis and disease.

Caspase recruitment domain family member 14 (CARD14) and its variants are associated with both atopic dermatitis (AD) and psoriasis, but their mechanistic impact on skin barrier homeostasis is largely unknown. CARD14 is known to signal via NF-κB; however, CARD14-NF-κB signaling does not fully explain the heterogeneity of CARD14-driven disease. Here, we describe a direct interaction between CARD14 and MYC and show that CARD14 signals through MYC in keratinocytes to coordinate skin barrier homeostasis. CARD14 directly binds MYC and influences barrier formation in an MYC-dependent fashion, and this mechanism is undermined by disease-associated CARD14 variants. These studies establish a paradigm that CARD14 activation regulates skin barrier function by two distinct mechanisms, including activating NF-κB to bolster the antimicrobial (chemical) barrier and stimulating MYC to bolster the physical barrier. Finally, we show that CARD14-dependent MYC signaling occurs in other epithelia, expanding the impact of our findings beyond the skin. [Display omitted] • CARD14 signaling directly regulates MYC in keratinocytes to promote barrier homeostasis • Pathogenic genetic variants dysregulate CARD14-MYC signaling, promoting barrier dysfunction • Skin barrier function remains intact in the context of complete CARD14 deficiency • The CARD14-MYC mechanism may contribute to diseases beyond the epidermis The epithelial protein CARD14 canonically regulates NF-κB and is associated with atopic dermatitis and psoriasis. DeVore et al. report that CARD14 also regulates MYC signaling to influence barrier homeostasis—a mechanism altered by disease-associated genetic variants. This pathway may represent a potential therapeutic target in diseases of dysregulated barrier function. [ABSTRACT FROM AUTHOR]