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Developmentally programmed expression of AID in chicken B cells.
David R Withers1, T Fred Davison, John R Young
1Immunology and Pathology Division, Institute for Animal Health, Compton, Newbury, Berkshire RG20 7NN, UK.
Developmental and Comparative Immunology
|March 24, 2005
Summary
Activation induced deaminase (AID) expression in chickens increases with immunoglobulin gene conversion in the bursa. This suggests developmental regulation of AID, crucial for immune diversity.
Area of Science:
- Immunology
- Molecular Biology
- Developmental Biology
Background:
- Immunoglobulin gene rearrangement in chickens and mammals creates limited diversity.
- Somatic hypermutation and gene conversion are key processes for expanding immunoglobulin diversity.
- Chicken immunoglobulin gene conversion initiates in the embryonic bursa prior to antigen exposure.
Purpose of the Study:
- To investigate the developmental regulation of Activation Induced Deaminase (AID) expression in chickens.
- To correlate AID mRNA expression with the onset of immunoglobulin gene conversion in the bursa.
Main Methods:
- Quantitative analysis of AID mRNA expression.
- Examination of AID mRNA localization during embryonic development.
- Correlation of AID expression timing with immunoglobulin gene conversion activity.
Main Results:
- A significant increase in AID mRNA levels was observed coinciding with the initiation of extensive immunoglobulin gene conversion in the bursa.
- AID mRNA expression was also detected at earlier developmental stages, preceding extensive gene conversion.
Conclusions:
- AID expression is developmentally regulated and closely linked to the onset of immunoglobulin gene conversion in the chicken bursa.
- The presence of AID mRNA before extensive gene conversion suggests other regulatory factors may be involved or that gene conversion can occur before bursal follicle formation.