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The transcription factors c-myb and C/EBP alpha regulate the monocytic/myeloic gene MRP14
M Klempt1, H Melkonyan, H A Hofmann
1Institute of Experimental Dermatology, University of Münster, Germany. klempt@uni-muenster.de
Abstract:
The entry of microorganisms into the body induces inflammatory processes. During this process a sequence of cellular, humoral, non-specific and specific actions are evoked to combat the infection. Macrophages and granulocytes, which are developed from a common progenitor cell, are the cellular components of the specific and non-specific immunoreaction. MRP14 (Macrophage migration inhibitory related protein) and MRP8, two S-100 proteins contained in high concentrations in these cells are obviously essential for adhesion and migration of monocytes and granulocytes. To investigate the transcriptional regulation of these genes we cotransfected constructs expressing CAT under control of the MRP14 promoter and expression constructs of C/EBP alpha and v-myb, two transcription factors involved in myeloid/monocytic differentiation. Transfection with C/EBP alpha revealed a massive enhancement of the MRP14 promoter in both, HL 60 cells (granulocytic differentiated) and L132 fibroblasts. In contrast, v-myb reduces MRP14 promoter activity. Northern blot analysis of L132 cells transfected with the C/EBP alpha expression vector demonstrate that C/EBP alpha is sufficient to enhance MRP14 expression in the context of the whole genome.
Insights
Transcription factors C/EBP alpha and v-myb regulate the MRP14 gene, crucial for immune cell function. C/EBP alpha enhances MRP14 promoter activity, while v-myb inhibits it, impacting monocyte and granulocyte behavior.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Inflammatory responses involve cellular and humoral actions to combat infections.
- Macrophages and granulocytes are key immune cells derived from a common progenitor.
- MRP14 and MRP8 (S-100 proteins) are vital for monocyte and granulocyte adhesion and migration.
Purpose of the Study:
- To investigate the transcriptional regulation of the MRP14 gene.
- To determine the role of transcription factors C/EBP alpha and v-myb in MRP14 gene expression.
Main Methods:
- Cotransfection of constructs with the MRP14 promoter and expression vectors for C/EBP alpha and v-myb.
- Analysis of promoter activity using CAT reporter assays.
- Northern blot analysis to assess gene expression in whole genome context.
Main Results:
- C/EBP alpha significantly enhanced MRP14 promoter activity in HL 60 and L132 cells.
- v-myb reduced MRP14 promoter activity.
- C/EBP alpha was sufficient to enhance MRP14 expression in L132 cells.
Conclusions:
- C/EBP alpha acts as a positive regulator of MRP14 transcription.
- v-myb functions as a negative regulator of MRP14 transcription.
- These findings elucidate key regulatory mechanisms of MRP14, important for immune cell function.