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In vivo system for characterizing clonal variation and tissue-specific gene regulatory factors based on function
E C Hardeman1, A Minty, P Benton-Vosman
1Department of Pharmacology, Stanford University School of Medicine, California 94305-5332.
The Journal of Cell Biology
|April 1, 1988
Summary
Muscle cells can induce alpha-cardiac actin gene expression in mouse fibroblast L cells. However, this inducibility varies among L cell clones, suggesting genomic integration site differences influence gene response.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Stable transfection of the human muscle alpha-cardiac actin gene promoter into mouse fibroblast L cells reveals low basal transcriptional activity.
- This activity is significantly lower (2-5%) compared to that observed in transfected muscle cells.
Purpose of the Study:
- To investigate the role of muscle-specific factors in inducing the expression of the human muscle alpha-cardiac actin gene promoter.
- To understand the variability in gene inducibility among different L cell clones.
Main Methods:
- Stable transfection of the human muscle alpha-cardiac actin gene promoter into mouse fibroblast L cells.
- Fusion of transfected L cells with muscle cells to form heterokaryons.
- Analysis of gene expression induction in heterokaryons.
Main Results:
- Fusion with muscle cells induced the transfected alpha-cardiac actin gene promoter in only 10% of L cell clones.
- The magnitude of induction varied widely (5- to 50-fold) among responsive clones.
- These responsive properties were stably inherited by the L cell clones.
Conclusions:
- Muscle cells possess factors that enhance the transcription of the transfected alpha-cardiac actin gene.
- Differences in L cell clones, potentially due to genomic integration sites, dictate the gene's responsiveness to these factors.
- Heterokaryon fusion is a valuable method for identifying responsive transfectants and studying tissue-specific transcription factors.