What is the key significance of the regulation of NF-κB p65 (Ser529) phosphorylation in inflammation and disease research?

1. What is the core role of NF-κB p65 in cellular signal transduction?

Nuclear factor-κB (NF-κB) is a family of key transcription factors widely present in eukaryotic cells, playing a central role in regulating immune responses, inflammatory reactions, cell proliferation and apoptosis, as well as stress responses. The mammalian NF-κB family consists of five members: RelA (p65), RelB, c-Rel, NF-κB1 (p50 and its precursor p105), and NF-κB2 (p52 and its precursor p100). They function by forming homodimers or heterodimers, with the heterodimer composed of p65 and p50 being the most common and extensively studied classical NF-κB complex.

The p65 subunit (RelA) is the primary carrier of NF-κB's transcriptional activation function. In resting cells, the classical p50/p65 heterodimer is typically bound to its inhibitory protein IκBα, anchored in the cytoplasm in an inactive state. When cells are exposed to external stimuli such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), bacterial lipopolysaccharide (LPS), or oxidative stress, specific IκB kinase (IKK) complexes are activated. The activated IKK complex phosphorylates IκBα, leading to its ubiquitination and degradation via the proteasome pathway. The degradation of IκBα releases the NF-κB dimer from its constraints, allowing the p50/p65 dimer to rapidly translocate into the nucleus. In the nucleus, the p65 subunit binds to specific κB sequences in the promoter or enhancer regions of target genes and recruits coactivator complexes, thereby initiating the transcription of a series of downstream genes (including pro-inflammatory cytokines, chemokines, adhesion molecules, and anti-apoptotic proteins) and driving complex biological responses.

2. Why are post-translational modifications of p65 critical for regulating its function?

The activity of NF-κB p65 is finely and multi-layered regulated, with post-translational modifications (PTMs) being the core mechanism determining its transcriptional activity, subcellular localization, protein stability, and interactions with other factors. Phosphorylation and acetylation are the two most extensively studied modification types of p65.

1. Phosphorylation regulation: The C-terminal transcriptional activation domain (TAD) and nuclear localization signal (NLS) of the p65 subunit contain multiple conserved serine (Ser) and threonine (Thr) phosphorylation sites. Different kinases (such as IKK, MSK1, CK2, PKCζ, etc.) respond to various upstream signals and specifically phosphorylate these sites. These phosphorylation events have diverse functions: some (e.g., Ser536) are widely recognized as markers of full p65 activation in the classical pathway, enhancing its transcriptional activity; others (e.g., Ser276) promote p65's binding to the coactivator CBP/p300 to enhance transcription; while some phosphorylations may affect p65's protein stability or nucleocytoplasmic shuttling.

2. Acetylation regulation: Multiple lysine (Lys) residues of p65 can be acetylated by histone acetyltransferases (e.g., CBP/p300). Acetylation modifications can alter p65's charge and conformation, affecting its DNA-binding ability, interaction with IκBα, and nuclear export process. For example, acetylation at certain sites may enhance p65's transcriptional activity, while acetylation at other sites may promote its binding to nuclear export proteins, leading to its transport back to the cytoplasm and thereby terminating transcriptional signals. Deacetylases (HDACs) can reverse this process.

These dynamic and reversible modifications collectively form a complex "modification code," enabling cells to precisely regulate NF-κB-mediated gene expression programs in time and space according to different stimulus types and intensities. Therefore, when studying the NF-κB pathway, detecting total p65 protein levels is often insufficient to reflect its functional state; analysis of its key modification sites must be combined.

3. What is the biological function and research value of p65 Ser529 phosphorylation?

Among the numerous phosphorylation sites of p65, Ser529 phosphorylation has garnered increasing attention. Although its upstream kinases and precise regulatory networks are still under exploration, existing research indicates that Ser529 phosphorylation plays an important role in specific physiological and pathological contexts. Some studies suggest that Casein Kinase II (CK2) may be one of the kinases catalyzing p65 Ser529 phosphorylation. Phosphorylation at this site has been found to be associated with the regulation of p65's transcriptional activity, possibly by affecting its binding efficiency to DNA or other transcriptional cofactors.

Given the potential importance of Ser529 phosphorylation in NF-κB signal transduction, antibodies that can specifically recognize this modification event have become key tools for in-depth research. The NF-κB p65 (Ser529) recombinant rabbit monoclonal antibody is such a highly specific research tool. Its application value is reflected at multiple levels:

1. Precise pathway analysis: When investigating the effects of specific stimuli (e.g., specific cytokines, microbial infections, or oxidative stress) on the NF-κB pathway, using this antibody can determine whether the stimulus specifically regulates p65 Ser529 phosphorylation, thereby refining the understanding of the upstream kinase network of this pathway.

2. Distinguishing different activation modes: Different stimuli may induce distinct combinations of p65 phosphorylation patterns. By simultaneously detecting p-p65 (Ser529), p-p65 (Ser536), and other sites, the "activation fingerprint" of NF-κB can be distinguished and defined, correlating specific modification patterns with specific biological outputs (e.g., expression of particular gene sets).

3. Disease mechanism research: In pathological models closely related to abnormal NF-κB activation, such as cancer, autoimmune diseases, and chronic inflammation, using this antibody to detect p65 Ser529 phosphorylation status in diseased tissues can help reveal disease-specific NF-κB regulatory abnormalities, potentially identifying new disease markers or therapeutic targets.

4. Drug mechanism evaluation: When screening or evaluating candidate drugs targeting the NF-κB pathway, monitoring changes in p65 Ser529 phosphorylation levels can serve as an important pharmacodynamic indicator to assess the drug's inhibitory effects on specific branches or nodes of the pathway.

4. Summary and Outlook

NF-κB p65, as a central hub connecting extracellular stimuli and nuclear gene expression programs, achieves precise regulation through a complex network of post-translational modifications. A deep understanding of the biological significance of different modification sites (e.g., Ser529) holds significant value for uncovering the molecular mechanisms of inflammation, immunity, and cancer. With the emergence and application of highly specific tools like the NF-κB p65 (Ser529) recombinant rabbit monoclonal antibody, researchers can now dissect the spatiotemporal dynamics and functional diversity of the NF-κB pathway with unprecedented precision. In the future, by integrating multidisciplinary technologies such as proteomics, genome editing, and live-cell imaging, we aim to map a more complete "modification map" and "functional map" of NF-κB, and on this basis, develop new-generation therapeutic strategies to more precisely intervene in this pathway.

5. Which manufacturers provide NF-κB p65 (S529) recombinant rabbit monoclonal antibodies?

Hangzhou Starter Biotechnology Co., Ltd. has independently developed the "Phospho-NF-κB p65 (S529) Recombinant Rabbit mAb" (product name: Phospho-NF-κB p65 (S529) Recombinant Rabbit mAb (S-1125-59), catalog number: S0B1210), a high-phosphorylation-site-specific, highly sensitive, and exceptionally stable detection tool for key regulatory sites in the NF-κB signaling pathway. This product was developed using recombinant rabbit monoclonal antibody technology and has been rigorously validated across multiple platforms, including Western Blot (WB) and immunofluorescence (IF). It holds significant value in research areas such as NF-κB transcriptional activity regulation, cellular stress responses, and disease mechanisms.

Professional technical support: We provide detailed product technical materials, including examples of phosphorylation changes under relevant signaling stimuli, comparative study recommendations with other p65 phosphorylation sites (e.g., S536, S468), and specialized technical consultations, fully assisting customers in achieving in-depth and reliable discoveries in the complex regulatory research of the NF-κB signaling network.

Hangzhou Starter Biotechnology Co., Ltd. is committed to providing high-quality, high-value biological reagents and solutions to global innovative pharmaceutical companies and research institutions. For more information about the "Phospho-NF-κB p65 (S529) Recombinant Rabbit mAb" (catalog number S0B1210) or to request a sample test, please feel free to contact us.

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