Inhibition of Transcription by B Cell Leukemia 3 (Bcl-3) Protein Requires Interaction with Nuclear Factor κB (NF-κB) p50
Inhibition of Transcription by B Cell Leukemia 3 (Bcl-3) Protein Requires Interaction with Nuclear Factor κB (NF-κB) p50
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DOI：
10.1074/jbc.m114.551986
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发表时间：
2014-03-07
影响因子：
4.8
通讯作者：
Carmody, Ruaidhri J.
中科院分区：
文献类型：
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作者：
Collins, Patricia E.;Kiely, Patrick A.;Carmody, Ruaidhri J.
背景：Bcl-3是细胞因子表达的重要负调控因子。结果：NF-B p50的突变阻止了与Bcl-3的相互作用，从而消除了Bcl-3对基因表达的抑制作用。结论：Bcl-3抑制细胞因子表达需要与nf - bp50相互作用。意义：nf - bp50是Bcl-3抗炎活性的关键靶点。B细胞白血病3 （Bcl-3）是toll样受体和TNF受体信号传导过程中NF-B的重要负调节因子。Bcl-3还与许多转录调节因子相互作用，包括NF-B p50亚基的同型二聚体。Bcl-3的缺失导致NF-B p50泛素化和蛋白酶体降解增加，炎症基因表达增加。我们采用固定化肽阵列技术确定了形成Bcl-3p50同源二聚体免疫抑制复合物所需的p50区域。我们的数据表明，p50的359-361和363氨基酸对于与Bcl-3的相互作用至关重要，并且对于Bcl-3介导的炎症基因表达抑制至关重要。当这些氨基酸发生突变时，Bcl-3无法与p50相互作用，因此无法抑制NF-B的转录活性。Bcl-3相互作用缺陷的p50是高泛素化的，与野生型p50相比，其半衰期明显缩短。通过炎症基因表达测量，与野生型p105相比，用突变p50前体p105重组的Nfkb1（-/-）细胞对TNF刺激的反应更高。突变体p105再现了Bcl3（-/-）表型。本研究表明，与p50的相互作用对于Bcl-3的抗炎特性是必要和充分的，并进一步强调了p50同型二聚体的稳定性在控制NF-B靶基因表达中的重要性。
Background: Bcl-3 is an essential negative regulator of cytokine expression. Results: A mutation in NF-B p50 that prevents interaction with Bcl-3 abrogates Bcl-3 inhibition of gene expression. Conclusion: The inhibition of cytokine expression by Bcl-3 requires interaction with NF-B p50. Significance: NF-B p50 is the key target of Bcl-3 anti-inflammatory activity.B cell leukemia 3 (Bcl-3) is an essential negative regulator of NF-B during Toll-like receptor and TNF receptor signaling. Bcl-3 also interacts with a number of transcriptional regulators, including homodimers of the NF-B p50 subunit. Deletion of Bcl-3 results in increased NF-B p50 ubiquitination and proteasomal degradation and increased inflammatory gene expression. We employed immobilized peptide array technology to define a region of p50 required for the formation of a Bcl-3p50 homodimer immunosuppressor complex. Our data demonstrate that amino acids 359-361 and 363 of p50 are critical for interaction with Bcl-3 and essential for Bcl-3-mediated inhibition of inflammatory gene expression. Bcl-3 is unable to interact with p50 when these amino acids are mutated, rendering it incapable of inhibiting the transcriptional activity of NF-B. Bcl-3 interaction-defective p50 is hyperubiquitinated and has a significantly reduced half-life relative to wild-type p50. Nfkb1(-/-) cells reconstituted with mutated p50 precursor p105 are hyperresponsive to TNF stimulation relative to wild-type p105, as measured by inflammatory gene expression. Mutant p105 recapitulates a Bcl3(-/-) phenotype. This study demonstrates that interaction with p50 is necessary and sufficient for the anti-inflammatory properties of Bcl-3 and further highlights the importance of p50 homodimer stability in the control of NF-B target gene expression.