## Abstract **BACKGROUND:** We observed previously that tumor necrosis factor α (TNFα)–knockout embryos are more sensitive to a cyclophosphamide (CP)–induced teratogenic insult than their TNFα‐positive counterparts, implicating molecules acting in TNFα‐activated antiapoptotic pathways in the mechan
Role of phosphorylated p50-NF-κB in the ultraviolet response of mouse skin
✍ Scribed by Paloma Pérez; Angustias Page; José L. Jorcano
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 158 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0899-1987
No coin nor oath required. For personal study only.
✦ Synopsis
The skin constitutes a primary target for stimuli such as ultraviolet (UV) radiation and tumor promoters, leading to both inflammatory and altered proliferative responses. Since the nuclear factor kB (NF-kB) family of transcription factors plays a major role in these biological processes, we sought to elucidate its expression in newborn mouse skin upon UV and 12-O-tetradecanoylphorbol-13-acetate (TPA) exposures. We have identified the nuclear NF-kB binding activity in mouse skin as composed of p50/p65 heterodimers and p50 homodimers by supershift assays using different NF-kB±containing sequences. After UV exposure, but not TPA treatment, we detected increased NF-kB binding activity that correlated with a decrease of IkBa protein levels, although it was not accompanied by p50 or p65 translocation. Immunostaining of newborn mouse sections confirmed that p50 was predominantly localized in the cytoplasm of epidermal basal cells before and after UV treatment. By immunoblotting, we found distinct phosphorylated forms of p50 in cytoplasmic extracts, while only a hyperphosphorylated form was detected in nuclear extracts. In vitro dephosphorylation of skin extracts dramatically reduced the affinity of p50-containing dimers for DNA. Our data suggest that the NF-kB response of mouse skin to UV exposure, contrary to most stimuli in other tissues, implies additional mechanisms other than translocation, such as p50 phosphorylation. Mol.
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