Related Experiment Videos
Expression and modulation of CD44 variant isoforms in humans
C R Mackay1, H J Terpe, R Stauder
1Basel Institute for Immunology, Switzerland.
Abstract:
CD44 is a ubiquitous surface molecule that exists as a number of isoforms, generated by alternative splicing of 10 "variant" exons. Little is known about the expression and function of the variant isoforms, except that certain isoforms may play a role in cancer metastasis. We produced mAbs against CD44 variant regions encoded by exons 4v, 6v, and 9v, by immunizing mice with a fusion protein spanning variant exons 3v to 10v. A comprehensive analysis of human tissues revealed that CD44 variant isoforms were expressed widely throughout the body, principally by epithelial cells. However there was differential expression of CD44 variant exons by different epithelia. Most epithelia expressed exon 9v, but much fewer expressed 6v or 4v. The regions of epithelia that expressed the highest levels of the variant isoforms were the generative cells, particularly the basal cells of stratified squamous epithelium, and of glandular epithelium. CD44 variant isoforms were also expressed differentially by leukocytes, with CD44-9v expressed at very low levels and CD44-6v and 4v virtually absent. However, CD44-9v and CD44-6v were the main variants that were transiently upregulated on T cells after mitogenic stimulation and on myelomonocytic cell lines by TNF alpha and IFN gamma treatment. Some epithelial cell lines could preferentially upregulate CD44-6v upon IFN gamma incubation. These results show that CD44 variant isoforms are expressed much more widely than first appreciated, and that expression of the variant isoforms on some cell types can be modulated by particular cytokines.
Insights
CD44 variant isoforms are widely expressed in human tissues, particularly by epithelial cells. Their expression can be modulated by cytokines, suggesting broader roles beyond cancer metastasis.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- CD44 is a cell surface molecule with multiple isoforms generated by alternative splicing of variant exons.
- The expression and function of CD44 variant isoforms are largely unknown, with some implicated in cancer metastasis.
Purpose of the Study:
- To produce monoclonal antibodies (mAbs) against CD44 variant regions (exons 4v, 6v, 9v).
- To comprehensively analyze the expression patterns of CD44 variant isoforms in human tissues and cell types.
- To investigate the modulation of CD44 variant isoform expression by cytokines.
Main Methods:
- Immunization of mice with a fusion protein spanning CD44 variant exons 3v to 10v to generate mAbs.
- Comprehensive analysis of human tissues to determine CD44 variant isoform expression.
- Treatment of cell lines (leukocytes, myelomonocytic, epithelial) with cytokines (TNF alpha, IFN gamma) to assess expression changes.
Main Results:
- CD44 variant isoforms are widely expressed in human tissues, primarily by epithelial cells, with differential expression of exons 4v, 6v, and 9v.
- Generative cells, especially basal cells of epithelia, showed the highest variant isoform levels.
- Variant isoforms were differentially expressed on leukocytes and could be upregulated on T cells and myelomonocytic cell lines by cytokines; some epithelial cells upregulated CD44-6v upon IFN gamma treatment.
Conclusions:
- CD44 variant isoforms are expressed more broadly than previously understood.
- Expression of CD44 variant isoforms is differential across various cell types and can be modulated by specific cytokines, indicating diverse functional roles.