Circadian protection against bacterial skin infection by epidermal CXCL14-mediated innate immunity.

The epidermis is the outermost layer of the skin and the body's primary barrier to external pathogens; however, the early epidermal immune response remains to be mechanistically understood. We show that the chemokine CXCL14, produced by epidermal keratinocytes, exhibits robust circadian fluctuations and initiates innate immunity. Clearance of the skin pathogen in nocturnal mice was associated with CXCL14 expression, which was high during subjective daytime and low at night.

Circadian coordination of ATP release in the urothelium via connexin43 hemichannels.

Day-night changes in the storage capacity of the urinary bladder are indispensable for sound sleep. Connexin 43 (Cx43), a major gap junction protein, forms hemichannels as a pathway of ATP in other cell types, and the urinary bladder utilizes ATP as a mechanotransduction signals to modulate its capacity. Here, we demonstrate that the circadian clock of the urothelium regulates diurnal ATP release through Cx43 hemichannels.