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p53 regulates Btk-dependent B cell proliferation but not differentiation
Nathan W Schmidt1, Lindsey D Mayo, David B Donner
1Department of Pediatrics and Microbiology and Immunology and Walther Oncology Center, Indiana University School of Medicine, and Walther Cancer Institute, RI 2600, Indianapolis, IN 46202, USA.
Journal of Leukocyte Biology
|February 8, 2006
Summary
The tumor suppressor p53 promotes B cell expansion. However, p53 deficiency cannot overcome Btk deficiency in B cell subset development, despite partial recovery in proliferation.
Area of Science:
- Immunology
- Cell Biology
- Genetics
Background:
- Bruton's tyrosine kinase (Btk) is essential for B cell development and proliferation.
- Mice lacking Btk exhibit defective B cell development and reduced proliferative responses.
- Mice deficient in the tumor suppressor p53 show increased developing B cell populations.
Purpose of the Study:
- To investigate the role of p53 in Btk-dependent B cell development and function.
- To analyze B cell development and proliferation in mice lacking both p53 and Btk.
Main Methods:
- Generation of double-deficient mice lacking both p53 and Btk.
- Flow cytometry analysis of splenic B cell populations (B220+).
- Assessment of B cell proliferation in response to various stimuli (lipopolysaccharide, anti-IgM, IL-4).
Main Results:
- Btk/p53-deficient mice had increased splenic B220+ cell numbers compared to Btk-deficient mice.
- No recovery in B cell subset differentiation was observed in double-deficient mice.
- Partial recovery of proliferation was seen in response to lipopolysaccharide and anti-IgM plus IL-4, but not anti-IgM alone.
Conclusions:
- p53 plays a role in promoting B cell expansion and proliferation.
- p53 deficiency does not rescue the B cell development defects caused by Btk deficiency.
- Btk is indispensable for proper B cell subset differentiation, a function not compensated by p53.