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Structure and expression of the mb-1 transcript in human lymphoid cells
I Leduc1, J L Preud'homme, M Cogné
1CNRS URA 1172, Laboratory of Molecular Immunology, Faculté des Sciences, Poitiers, France.
Clinical and Experimental Immunology
|October 1, 1992
Summary
The mb-1 gene is crucial for B cell function, with its mRNA found in B cells and pre-B cells but not in plasma cells. This indicates mb-1 gene expression is specific to B lymphocyte maturation stages.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- The mb-1 gene encodes a protein linked to membrane-bound immunoglobulins (mIg).
- mb-1 is hypothesized to be involved in signal transduction pathways.
- Previous studies reported conflicting human cDNA sequences for mb-1.
Purpose of the Study:
- To clone and characterize the human mb-1 complementary DNA (cDNA).
- To investigate the expression pattern of the mb-1 gene in human cells during different maturation stages.
Main Methods:
- Cloning of human mb-1 cDNA using a murine probe.
- Analysis of mb-1 gene expression via mRNA detection in various human cell types.
- Comparison of newly sequenced human mb-1 cDNA with previously reported sequences.
Main Results:
- A complete human mb-1 cDNA sequence was obtained, consistent with recent reports.
- mb-1 mRNA was highly expressed in B cell lines with various membrane-bound immunoglobulin isotypes (mu, gamma, alpha 1, alpha 2).
- mb-1 mRNA was also detected in pre-B cells and cells with truncated mu chains, but significantly reduced or absent in plasma cells and plasmacytoma cell lines.
Conclusions:
- The human mb-1 gene is expressed in pre-B cells and B lymphocytes.
- mb-1 gene expression is independent of the membrane-bound immunoglobulin heavy chain isotype.
- mb-1 gene expression is downregulated or silenced in plasma cells.