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The regulation of membrane cofactor protein (CD46) expression by the 3' untranslated region in transgenic mice
S Miyagawa1, S Mikata, H Tanaka
1Division of Organ Transplantation, Osaka University Medical School, Japan. miyagawa@orgtrp.med.osaka-u.ac.jp
Abstract:
Regulation of the membrane cofactor protein (MCP: CD46) was examined. While the expression of MCP in mice carrying MCP(BC2) cDNA with 125 bp of 3' untranslated region (3'UT) was minimal, that in mice carrying MCP cDNA without total 3' UT was evident in many organs. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis clearly showed the presence of mRNA even in transgenic mice with 3' UT, suggesting that the expression was regulated at the post-transcriptional stage. The in vitro expression data of MCP molecules on the stable Chinese hamster ovary (CHO) cell clone corresponded to that in transgenic mice. The first 125 bp downregulated the expression of MCP molecules in combination with not only beta-actin, but also SR alpha, promoter. Also, this region inhibited expression of decay accelerating factor (DAF: CD55) molecules when it was inserted into cDNA of DAF. Furthermore, the first 32 bp of the 3' UT revealed the same downregulation effect as 125 bp on MCP molecules. These findings indicated that the first 125 bp (and the first 32 bp in particular) of 3' UT regulate the expression of MCP molecules in transgenic mice.
Insights
The 3' untranslated region (3'UT) of membrane cofactor protein (MCP: CD46) regulates its expression. Specifically, the first 125 bp, and particularly the first 32 bp, of the 3'UT significantly downregulate MCP expression in transgenic mice.
Area of Science:
- Molecular Biology
- Immunology
- Genetics
Background:
- Membrane cofactor protein (MCP), also known as CD46, is a key regulator of the complement system.
- Understanding the post-transcriptional regulation of MCP is crucial for its role in immune responses and disease.
Purpose of the Study:
- To investigate the role of the 3' untranslated region (3'UT) in regulating membrane cofactor protein (MCP: CD46) expression.
- To identify specific sequences within the 3'UT responsible for MCP expression control.
Main Methods:
- Generation of transgenic mice carrying MCP cDNA with varying lengths of 3'UT.
- Reverse transcriptase polymerase chain reaction (RT-PCR) to analyze mRNA expression.
- In vitro expression studies using Chinese hamster ovary (CHO) cells.
Main Results:
- Transgenic mice with a full 3'UT showed minimal MCP expression, while those with truncated 3'UT had higher expression.
- RT-PCR confirmed mRNA presence, indicating post-transcriptional regulation.
- The first 125 bp of the 3'UT, particularly the first 32 bp, significantly downregulated MCP expression.
Conclusions:
- The 3'UT of MCP plays a critical role in regulating its expression at the post-transcriptional level.
- Specific sequences within the 5' portion of the 3'UT are potent negative regulators of MCP expression.
- These findings provide insights into the complex regulatory mechanisms governing MCP function.