Pannexin1 and Pannexin3 exhibit distinct localization patterns in human skin appendages and are regulated during keratinocyte differentiation and carcinogenesis.

Having shown that Panx1 and Panx3 are expressed in the epidermis, we investigated their distribution in human skin adnexal structures and skin cancer. Both proteins were found in hair follicles, sebaceous and eccrine glands, as well as blood vessels. Panx1 was detected as punctate or diffuse intracellular labeling, while Panx3 was only observed as diffuse intracellular staining, suggesting different functions. We also identified the Panx3 immunoreactive ~70 kD species modulated during keratinocyte differentiation as Panx3. Since our data indicate that pannexins are regulated during keratinocyte differentiation, we assessed whether their levels are altered under circumstances in which keratinocyte differentiation is compromised. We found that Panx1 and Panx3 levels are highly reduced in human keratinocyte tumors, thus showing for the first time that both pannexins are dysregulated in human cancers. Altogether, these data suggest that Panx1 and Panx3 have distinct and unique functions within the skin in health and disease.