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p53 is a regulator of macrophage differentiation
D Matas1, M Milyavsky, I Shats
1Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel.
Abstract:
While it is well accepted that p53 plays a role in apoptosis, less is known as to its involvement in cell differentiation. Here we show that wild-type p53 facilitates IL-6-dependent macrophage differentiation. Treatment of M1/2 cells expressing the temperature-sensitive p53 143 (Val to Ala) mutant, at the wild-type conformation, facilitated the appearance of mature macrophages that exhibited phagocytic activity. Enhancement of differentiation by the p53 143 (Val to Ala) in the wild-type conformation was coupled with the inhibition of apoptosis induction by this protein. In agreement with previous studies, we found that p53 levels were reduced during p53-dependent macrophage differentiation. This occurred when p53 levels before IL-6 stimuli were high. Interestingly, the p53 143 (Val to Ala) protein, at the mutant conformation, enhanced macrophage differentiation, as did the wild-type conformation, whereas the p53 273 (Arg to His) core mutant exerted an inhibitory effect on this pathway. The transcription-deficient p53 molecules, p53 (22-23) and p53 22,23,143, could not induce p53-dependent differentiation. Moreover, the p53 (22-23) protein inhibited the p53-independent differentiation pathway. Interestingly, the p53 (22-23) protein not only blocked IL-6-mediated differentiation, but also induced significant apoptotic cell death, upon IL-6 stimulation. Taken together, our data show that wild-type p53 enhances macrophage differentiation, while various p53 mutant types exert different effects on this differentiation pathway.
Insights
Wild-type p53 promotes macrophage differentiation, while specific p53 mutants have varied effects on this process and apoptosis. Understanding p53
Area of Science:
- Molecular Biology
- Cell Biology
- Immunology
Background:
- The tumor suppressor protein p53 is primarily known for its role in apoptosis.
- Its involvement in cell differentiation, particularly macrophage differentiation, is less understood.
- Interleukin-6 (IL-6) is a key cytokine in macrophage differentiation.
Purpose of the Study:
- To investigate the role of wild-type and mutant p53 in IL-6-dependent macrophage differentiation.
- To elucidate how different p53 conformations and mutations affect macrophage differentiation and apoptosis.
Main Methods:
- Utilized M1/2 cells expressing temperature-sensitive p53 mutants (p53 143 Val to Ala, p53 273 Arg to His).
- Examined the effects of wild-type and mutant p53 conformations on macrophage differentiation and phagocytic activity.
- Assessed p53 levels during differentiation and analyzed the impact of transcription-deficient p53 mutants (p53 22-23, p53 22,23,143).
Main Results:
- Wild-type p53, and the p53 143 (Val to Ala) mutant in its wild-type conformation, enhanced IL-6-dependent macrophage differentiation.
- The p53 143 (Val to Ala) mutant also inhibited apoptosis induction, while the p53 273 (Arg to His) mutant inhibited differentiation.
- Transcription-deficient p53 mutants (p53 22-23, p53 22,23,143) failed to induce differentiation and inhibited IL-6-mediated pathways, with p53 (22-23) inducing apoptosis.
Conclusions:
- Wild-type p53 plays a crucial role in facilitating IL-6-dependent macrophage differentiation.
- Specific p53 mutations and conformations differentially regulate macrophage differentiation and apoptosis.
- The transcriptional activity of p53 is essential for its role in promoting macrophage differentiation.