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Essential functions of Pax-5 (BSAP) in pro-B cell development
S L Nutt1, C Thévenin, M Busslinger
1Research Institute of Molecular Pathology, Vienna, Austria.
Immunobiology
|January 27, 1998
Summary
Pax-5 is crucial for B cell development, acting as a transcription factor (BSAP). Its absence halts B cell maturation at an early pro-B cell stage in adult bone marrow, impacting differentiation and gene expression.
Area of Science:
- Immunology
- Developmental Biology
- Genetics
Background:
- Pax-5 encodes the transcription factor BSAP, essential for B-lymphoid lineage development.
- Pax-5 is expressed from early B cell progenitors to mature B cells.
Purpose of the Study:
- To investigate the role of Pax-5 in fetal and adult B-lymphopoiesis.
- To identify the B cell developmental stage affected by Pax-5 deficiency.
Main Methods:
- Germline gene targeting of the Pax-5 gene in mice.
- Analysis of B cell development in fetal liver and adult bone marrow.
- Assessment of gene expression (CD19, Ig alpha, N-myc) and immunoglobulin heavy-chain gene rearrangements.
Main Results:
- Pax-5 is essential for early B-lineage differentiation in fetal liver.
- In adult bone marrow, B cell development is arrested at the early pro-B cell stage without Pax-5.
- Reduced expression of CD19, Ig alpha, and N-myc, and significantly impaired VH-to-DHJH rearrangements in Pax-5-deficient pro-B cells.
- Pax-5-deficient pro-B cells do not progress to the pre-B cell stage even with functional mu heavy-chain transgenes.
Conclusions:
- B cell development in Pax-5-deficient mice is arrested at an early pro-B cell stage.
- This developmental block precedes responsiveness to pre-B cell receptor signaling.
- Pax-5 plays a critical, non-redundant role in B cell maturation.