Effect of cytokines and ultraviolet B radiation on the promoter activity of the metallothionein gene in keratinocytes

Metallothionein (MT) has many functions that are modulated by several factors, including ultraviolet (UV) radiation and cytokines. We thought that these diverse functions of MT might reflect the specific regulatory mechanisms of its expression. To understand some of the molecular mechanisms underlying MT expression, we examined the effects of several cytokines and UVB on the promoter activity of the MT gene. First, we introduced the MT promoter construct into the HaCaT keratinocytes and treated them with various concentrations of interleukin-1α (IL-1α) and IL-6. The addition of IL-1α and IL-6 led to an increase in the promoter activity of the MT gene. UVB is known to induce MT expression in epidermal keratinocytes, and IL-6 is a possible mediator of MT induction by UV radiation. Therefore, we investigated whether UVB could induce MT promoter activity. Our results showed, interestingly, that UVB radiation has no or little effect on the promoter activity. This suggested a complex molecular regulation of the MT gene.