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Updated: Jun 29, 2026
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Separation of Rat Epidermis and Dermis with Thermolysin to Detect Site-Specific Inflammatory mRNA and Protein
Published on: September 29, 2021
TNF-alpha production in the skin.
M M Bashir1, M R Sharma, V P Werth
1Department of Dermatology, University of Pennsylvania, 2, Rhodes Pavilion, 3600 Spruce Street, Philadelphia, PA, 19104, USA.
Archives of Dermatological Research
|October 1, 2008
Summary
Ultraviolet B (UVB) radiation upregulates tumor necrosis factor-alpha (TNF-alpha) in skin cells by activating the AP-1 transcription factor. This molecular mechanism is crucial for the early inflammatory response to UVB exposure.
Area of Science:
- Dermatology
- Molecular Biology
- Immunology
Background:
- Tumor necrosis factor-alpha (TNF-alpha) is a key mediator in skin's inflammatory response to ultraviolet B (UVB) radiation.
- UVB, but not UVA, specifically induces TNF-alpha expression in keratinocytes and dermal fibroblasts.
- Interleukin-1 alpha (IL-1alpha) synergistically enhances UVB-induced TNF-alpha, primarily through increased gene transcription.
Purpose of the Study:
- To elucidate the molecular mechanisms underlying UVB-induced TNF-alpha gene expression in keratinocytes.
- To identify specific cis-elements within the TNF-alpha promoter responsive to UVB.
- To investigate the role of transcription factors, particularly AP-1, in this process.
Main Methods:
- Utilized a series of TNF-alpha promoter-CAT reporter constructs to map UVB-responsive regions.
- Employed site-directed mutagenesis to assess the function of putative AP-1 and NFkB binding sites.
- Investigated the effect of AP-1 inhibition using SP600125 (JNK inhibitor) on TNF-alpha expression.
- Performed Electrophoretic Mobility Shift Assays (EMSA) to analyze transcription factor activation.
Main Results:
- A UVB-responsive element was localized to the -109 to +1 region of the TNF-alpha promoter.
- Mutation of the AP-1 binding site abolished UVB-induced promoter activity.
- Inhibition of AP-1 activity suppressed both reporter construct and endogenous TNF-alpha gene expression.
- EMSA confirmed increased phosphorylation and activity of the AP-1 transcription factor (c-Jun) upon UVB exposure.
Conclusions:
- UVB-induced TNF-alpha expression in keratinocytes is critically dependent on the activation of the AP-1 transcription factor.
- The AP-1 binding site within the proximal TNF-alpha promoter mediates the UVB response.
- This pathway highlights a key molecular event in the early inflammatory cascade initiated by UVB radiation in the skin.
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