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Isolation of early immunoglobulin lambda-like gene transcripts in human fetal liver
C Schiff1, M Milili, M Fougereau
1Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, Marseille, France.
European Journal of Immunology
|October 1, 1989
Summary
Researchers identified novel human immunoglobulin lambda-like genes (F lambda 1 and F lambda 8) in fetal liver, potentially representing early B-cell expression and offering insights into gene regulation.
Area of Science:
- Immunogenetics
- Molecular Biology
- Human Gene Expression
Background:
- Investigating early events in human immunoglobulin (Ig) gene expression is crucial for understanding B-cell development.
- Previous studies focused on identifying functional Ig light chain genes, leaving potential pseudogenes and regulatory elements less explored.
Purpose of the Study:
- To identify and characterize novel human immunoglobulin lambda (Ig lambda) gene sequences expressed during early fetal development.
- To investigate the potential role of these novel genes in early B-cell differentiation and Ig gene expression.
Main Methods:
- Screening of a human fetal liver cDNA library using specific probes for constant mu (C mu), gamma (C gamma), kappa (C kappa), and lambda (C lambda) genes.
- Characterization of positive clones (F lambda 1 and F lambda 8) through sequence homology analysis and pulsed field gel electrophoresis.
- Comparative analysis with mouse lambda 5 gene and assessment of transcript presence in fetal liver samples.
Main Results:
- Two novel clones, F lambda 1 and F lambda 8, were identified, showing homology to human C lambda genes but distinct from functional alleles.
- These clones represent nonallelic members of the 14.1/16.1 C lambda-like gene family, clustered separately from functional C lambda genes.
- F lambda 1 exhibits characteristics of a pseudogene due to a nucleotide deletion, while its homology to mouse lambda 5 suggests a potential role in early B-cell development.
Conclusions:
- The identified human C lambda-like genes (F lambda 1 and F lambda 8) may represent early expressed Ig lambda elements, potentially analogous to the mouse lambda 5 gene.
- Their expression in fetal liver, alongside mu and gamma transcripts and absence of functional light chains, supports a role in pre-B cell stages.
- Further investigation is needed to determine the precise function and allelic status of the 14.1/16.1 C lambda-like gene family in human B-cell ontogeny.