ADP-Ribosylation: Role and Research

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What Is Adenosine Diphosphate-Ribosylation?  

Adenosine diphosphate-ribosylation (ADPr) is a reversible form of posttranslational modification (PTM) and involves the addition of ADP-ribose to specific amino acids on target proteins. This process is controlled by transferases, including poly (ADP-ribose) polymerases (PARPs), which add either a single ADP-ribose to their targets (mono-ADPr) or create branching ADPr chains (poly-ADPr) (Qi et al. 2020). PARP1 is an example of a transferase which is able to create branching ADPr chains and is important within the DNA damage response, rapidly producing ADPr chains on damaged chromatin.

ADPr Function and Therapeutic Potential

In addition to the DNA damage response, ADPr controls multiple fundamental biological processes including cell proliferation and differentiation, metabolism, stress, and the immune response (Palazzo et al. 2019).

As a dynamic regulator of cell signaling, ADPr modifies key signaling proteins through the reversible addition of ADP‑ribose units. This posttranslational modification alters protein activity, stability, localization, and protein–protein interactions, enabling rapid and context‑dependent signal transduction. ADPr modulates multiple intracellular signaling pathways by acting as a molecular switch or scaffold, coordinating signal amplification and termination in response to cellular stress, growth cues, and immune stimuli. Through these mechanisms, ADPr integrates environmental and intracellular signals to fine‑tune cellular responses and maintain homeostasis.

Dysregulation of ADPr disrupts the precise control of cellular signaling, gene regulation, and stress responses, and has been strongly linked to a range of human diseases. Aberrant ADPr activity—arising from altered expression or function of ADP-ribosyltransferases or ADPr-removing enzymes—can lead to persistent or inappropriate modification of key regulatory proteins (Suskiewicz et al. 2023). This imbalance affects DNA damage repair, immune and inflammatory signaling, and cell survival pathways, directly contributing to the development and progression of specific conditions such as breast and ovarian cancers, neurodegenerative diseases like Parkinson’s and Alzheimer’s, and autoimmune disorders, including systemic lupus erythematosus and rheumatoid arthritis.

In cancer, for example, defective ADPr can result in the accumulation of DNA damage, driving tumor growth and resistance to therapy. In neurological diseases, abnormal ADPr impairs neuronal survival and function, while in autoimmune conditions, it can promote chronic inflammation and tissue damage. Consequently, restoring proper ADPr regulation has emerged as an important therapeutic strategy, exemplified by the clinical use of PARP inhibitors in oncology to target DNA repair defects in cancers such as BRCA-mutated breast and ovarian tumors.

Emerging evidence suggests that modulating ADPr may also be beneficial in inflammatory, immune‑mediated, neurological, and infectious diseases, highlighting ADPr as a clinically actionable pathway beyond cancer (Bondar and Karpichev 2024, Kassab et al. 2020, Wang et al. 2025).

ADPr Research

ADPr is understudied relative to other forms of PTM such as phosphorylation and methylation. This is partly explained by the lack of robust tools for studying this process; it has remained a challenge to generate antibodies that specifically recognize ADPr events. However, novel methods for the generation of ADP-ribosylated peptides using recombinant antibody technology have recently resulted in the successful generation of 14 antibodies. The recombinant antibodies were generated using the Human Combinatorial Antibody Library (HuCAL®), a proprietary method of phage display.

Bio-Rad has obtained the right for the manufacture and commercialization of these antibodies from Max-Planck-Innovation GmbH, the technology transfer office of the Max Planck Institute for Biology of Ageing. Further information on the Serine ADP-ribosylation technology used to generate and characterize the antibodies can be found here: Patent WO2020058277A1 and Papers: Suskiewicz et al. 2023, Bonfiglio et al. 2020.

HuCAL technology is proven and well published and has been used by the custom antibody team at Bio-Rad, to generate antibodies for research and diagnostic applications since 2004. Read HuCAL explained to discover more about this recombinant technology and watch our “Designed Just for You” video to see inside Bio-Rad’s custom antibody facility, and learn how your requirements for specialized custom antibodies can become a reality through the use of HuCAL technology.

Tools for Detecting ADPr

The ADPr antibodies, shown in Table 1, provide different options for the detection of ADPr, including antibodies that are pan and site-specific. The site-specific antibodies are particularly important for the unambiguous detection of cellular ADPr by PARP1 when its active site is completed by HPF1. The mono-specific antibodies have enabled specific immunoaffinity purification of mono-ADP-ribosylated substrates, with the identification of 272 mono-ADP-ribosylated sites on 151 primary PARP1 targets. There are also five Fab formats of these full-length antibodies and three further Fab antibodies for the detection of ADPr. Tagged with a SpyTag at the C-terminus of the Fab heavy chain, it enables the user to couple these antibodies to a SpyCatcher reagent for conversion to alternative formats in less than an hour.

Alternatively, if a fluorescent format is required, the SpyTag allows for easy, rapid conjugation to any of our 32 StarBright™ Dyes using the TrailBlazer™ StarBright Dye Label Kits, giving you more flexibility in panel design. A spontaneous reaction between the SpyTag and the SpyCatcher-StarBright Dye in the labeling kit forms an irreversible covalent isopeptide bond, resulting in highly stable, labeled antibodies.

The antibodies have been characterized by ELISA, immunofluorescence, and western blotting. They are valuable tools for further investigation of ADP-ribosylation in a variety of biological processes, opening previously inaccessible avenues of research. Figures 1 and 2 illustrate the quality of data that can be obtained using these antibodies in western blotting and immunofluorescence.

Fig. 1. Western blot analysis of cell extracts using Fab mono-ADP-ribose antibodies. Cell extracts were prepared from 2 mM H₂O₂-treated U2OS wild-type (WT) and HPF1 knockout (HPF1KO) cells, probed with Anti-Mono-ADP-Ribose Antibody, clone AbD41122 (TZA0118), or the Anti-Mono-ADP-Ribose Antibody, clones AbD33205 (TZA021) and AbD43647 (TZA020). Antibodies were conjugated to HRP using BiSpyCatcher2:HRP (TZC002P). Image courtesy of the Matić research group (Max Planck Institute for Biology of Ageing).

Fig. 2. Immunofluorescence detection of mono-ADP-ribose. U2OS WT or HPF1 knockout (HPF1KO) cells treated with 2 mM H₂O₂ and stained with Anti-Mono-ADP-Ribose Antibody, clone AbD41122 (TZA0118), or the Anti-Mono-ADP-Ribose Antibody, clone AbD33205 (TZA021). Antibodies were converted to synthetic IgG format using Rabbit IgG-FcSpyCatcher3 (TZC013). Scale bar, 10 μM. Image courtesy of the Matić research group (Max Planck Institute for Biology of Ageing).

Table 1. HuCAL generated antibodies for the detection of ADPr.

Abbreviations: IF, immunofluorescence; WB, western blotting.
*TZA0117P is in a HRP format

Additional Antibodies

To further facilitate research into ADPr and PARPs, Bio-Rad also offers:

Table 2. Antibodies for the detection of ADPr.

Abbreviations: IF, immunofluorescence; IHC-F, immunohistology – frozen sections; IHC-P, immunohistology – paraffin sections; IP, immunoprecipitation; WB, western blotting.

*A PrecisionAb Antibody that has enhanced western blotting validation.
 

References

• Bondar D and Karpichev Y (2024). Poly(ADP-ribose) polymerase (PARP) inhibitors for cancer therapy: advances, challenges, and future directions. Biomolecules 14, 1269
• Bonfiglio J et al. (2020). An HPF1/PARP1-based chemical biology strategy for exploring ADP-ribosylation. Cell 183, 1086–1102
• Kassab MA et al. (2020). Targeting dePARylation for cancer therapy. Cell Biosci 10. Accessed September 16, 2021
• Palazzo L et al. (2019). ADP-ribosylation signalling and human disease. Open Biol 9; 190041
• Qi H et al. (2020). Multiple roles for mono- and poly(ADP-ribose) in regulating stress responses. Trends Genet 35, 159–172
• Suskiewicz MJ et al. (2023). ADP-ribosylation from molecular mechanisms to therapeutic implications. Cell 186, 21
• Wang F et al. (2025). PARPs and PARP inhibitors: molecular mechanisms and clinical applications. Mol Biomed 6, 152

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