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Activation of immunoglobulin control elements in transgenic mice
A E Miller1, D L Ennist, K Ozato
1Laboratory of Mammalian Genes and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
Immunogenetics
|January 1, 1992
Summary
Interleukins and mitogens regulate immunoglobulin gene expression through the Ig enhancer (Emu) and kappa promoter. This study used transgenic mice to show Emu is essential for stimulating gene expression by these factors in B cells.
Area of Science:
- Immunology
- Molecular Biology
- Genetics
Background:
- Immunoglobulin (Ig) gene expression is tightly regulated.
- Interleukins and mitogens are key signaling molecules in immune responses.
- The role of Ig enhancers and promoters in mediating these regulatory effects requires further elucidation.
Purpose of the Study:
- To investigate the role of interleukins and mitogens in regulating Ig gene expression.
- To assess the contribution of the Ig heavy chain enhancer (Emu) and kappa light chain promoter in this regulation.
- To establish a transgenic mouse model for studying Ig gene regulatory elements.
Main Methods:
- Generation of transgenic mice with two distinct Ig gene regulatory constructs: EmukCAT (Emu enhancer + kappa promoter) and delta EmukCAT (kappa promoter alone).
- Assessment of chloramphenicol acetyltransferase (CAT) gene expression as a reporter for regulatory activity.
- Treatment of spleen cell cultures with various lymphokines and mitogens, including lipopolysaccharide (LPS), concanavilin A (Con A), interleukin 6 (IL-6), and interferon-gamma (IFN-gamma).
- Separation of B cells into small and large populations based on density.
Main Results:
- EmukCAT mice showed CAT expression in lymphoid tissues, while delta EmukCAT mice exhibited minimal expression, indicating enhancer-dependent tissue specificity.
- LPS, Con A, IL-6, and IFN-gamma significantly increased CAT expression in EmukCAT cells but not in delta EmukCAT cells.
- Small B cells required LPS for increased CAT expression, whereas large B cells showed basal expression and further induction upon stimulation.
- The Emu enhancer, in conjunction with the kappa promoter, is crucial for mediating the stimulatory effects of these factors.
Conclusions:
- The Ig heavy chain enhancer (Emu) is essential for the induction of immunoglobulin gene expression by interleukins and mitogens.
- This transgenic system effectively identifies exogenous factors that activate Ig enhancers and promoters.
- The findings provide insights into the molecular mechanisms controlling B cell activation and immunoglobulin production.