# Ivan Ahel
**Ivan Ahel** is a biochemist who studied at the [University of Zagreb](https://www.edgepedia.org/university-of-zagreb) in Croatia and works on [DNA repair](https://www.edgepedia.org/dna-repair) and ADP-ribosylation, the attachment of [ADP-ribose](https://www.edgepedia.org/adp-ribose) units to proteins. He holds the E.P. Abraham Chair of Chemical Pathology, in association with Lincoln College, and became an EMBO Member in 2022.[2](https://www.path.ox.ac.uk/news-article/ivan-ahel-appointed-professor-of-chemical-pathology/) • [3](https://people.embo.org/profile/ivan-ahel) His work has defined how the PARP enzymes and the accessory factor HPF1 together build serine-linked ADP-ribosylation at DNA breaks.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC7104379/)
| Key fact | Detail |
|---|---|
| Field | DNA repair and ADP-ribosylation signaling in genome stability[3](https://people.embo.org/profile/ivan-ahel) |
| Chair | E.P. Abraham Professor of Chemical Pathology, with Lincoln College[2](https://www.path.ox.ac.uk/news-article/ivan-ahel-appointed-professor-of-chemical-pathology/) |
| Training | MSc Zagreb (2000); PhD (2003); postgraduate research associate at Yale with Dieter Söll; postdoc with Stephen West, Clare Hall Laboratories[5](https://www.path.ox.ac.uk/wp-content/uploads/2023/07/Fusion-12-Michaelmas-2013.pdf) • [6](https://ivanahellab.wixsite.com/ivan-ahel-lab/people) |
| Signature work | "HPF1 completes the PARP active site for DNA damage-induced ADP-ribosylation", *Nature*, 2020[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC7104379/) |
| Honours | EMBO Young Investigator Programme (2012); EMBO Member (2022); Academy of Medical Sciences Fellow (2024)[1](https://orcid.org/0000-0002-9446-3756) • [3](https://people.embo.org/profile/ivan-ahel) • [7](https://acmedsci.ac.uk/fellows/fellows-directory/ordinary-fellows/fellow/Ivan-Ahel-0033z000030vL3ZAAU) |
## Early life and training
Ahel studied at the University of Zagreb in Croatia, obtaining his MSc in Molecular Biology in 2000; according to *Fusion 12*, the Dunn School newsletter, his PhD, awarded in 2003, investigated how microorganisms sense and respond to DNA damage.[5](https://www.path.ox.ac.uk/wp-content/uploads/2023/07/Fusion-12-Michaelmas-2013.pdf) • [1](https://orcid.org/0000-0002-9446-3756) • [6](https://ivanahellab.wixsite.com/ivan-ahel-lab/people) His own laboratory website states that the PhD thesis work was carried out at Yale University between 2000 and 2003; ORCID and a Dunn School interview both record the degree as a University of Zagreb PhD of 2003.[6](https://ivanahellab.wixsite.com/ivan-ahel-lab/people) • [1](https://orcid.org/0000-0002-9446-3756) • [5](https://www.path.ox.ac.uk/wp-content/uploads/2023/07/Fusion-12-Michaelmas-2013.pdf)
After the PhD he joined [Dieter Söll](https://www.edgepedia.org/dieter-soll)'s laboratory at Yale University as a postgraduate research associate, working on the function and evolution of aminoacyl-tRNA synthetases.[5](https://www.path.ox.ac.uk/wp-content/uploads/2023/07/Fusion-12-Michaelmas-2013.pdf) He then returned to DNA repair as a postdoctoral fellow in [Stephen West](https://www.edgepedia.org/stephen-west)'s laboratory at Clare Hall Laboratories, the London Research Institute of Cancer Research UK, joining in 2004.[5](https://www.path.ox.ac.uk/wp-content/uploads/2023/07/Fusion-12-Michaelmas-2013.pdf) • [6](https://ivanahellab.wixsite.com/ivan-ahel-lab/people) ORCID records an EMBO postdoctoral long-term fellowship from 1 April 2005.[1](https://orcid.org/0000-0002-9446-3756)
## Career
In January 2009 Ahel started his first independent position as a junior group leader at the Paterson Institute for Cancer Research, now the Cancer Research UK Manchester Institute.[5](https://www.path.ox.ac.uk/wp-content/uploads/2023/07/Fusion-12-Michaelmas-2013.pdf) • [6](https://ivanahellab.wixsite.com/ivan-ahel-lab/people) In 2013 he moved the laboratory to the Sir William Dunn School of Pathology in Oxford, where ORCID records his Group Leader post from 1 October 2013.[6](https://ivanahellab.wixsite.com/ivan-ahel-lab/people) • [1](https://orcid.org/0000-0002-9446-3756) He was later appointed to the E.P. Abraham Chair of Chemical Pathology, in association with Lincoln College.[2](https://www.path.ox.ac.uk/news-article/ivan-ahel-appointed-professor-of-chemical-pathology/) • [7](https://acmedsci.ac.uk/fellows/fellows-directory/ordinary-fellows/fellow/Ivan-Ahel-0033z000030vL3ZAAU)
## Research: ADP-ribosylation and genome stability
ADP-ribosylation is a protein modification in which poly(ADP-ribose) polymerases (PARPs) attach chains of repeating ADP-ribose units to target proteins, regulating DNA repair, transcription, cell division, and apoptosis; the Dunn School describes Ahel as a world expert in the modification.[5](https://www.path.ox.ac.uk/wp-content/uploads/2023/07/Fusion-12-Michaelmas-2013.pdf) • [2](https://www.path.ox.ac.uk/news-article/ivan-ahel-appointed-professor-of-chemical-pathology/) His Wellcome-funded work identified ADP-ribosylation on serine residues (Ser-ADPr) as the major form of DNA damage-induced ADP-ribosylation, decoded the mechanism for its synthesis by PARP/HPF1 complexes and its removal by cooperation between the ARH3 and PARG hydrolases, and identified tyrosine-linked ADP-ribosylation (Tyr-ADPr) as a novel form.[8](https://wellcome.org/research-funding/funding-portfolio/funded-grants/adp-ribosylation-signalling-genome-stability)
The laboratory also works on bacterial ADP-ribosylation systems. As principal investigator he led BBSRC grant BB/R007195/1, worth £651,270, on the DarTG toxin:antitoxin system responsible for a novel DNA modification, and he is co-investigator on the current grant BB/W016613/1, worth £959,151, on ADP-ribosylation of DNA in *Mycobacterium tuberculosis*.[9](https://gow.bbsrc.ukri.org/grants/PersonDetails.aspx?Personid=-267140) He leads a collaborative project with the Ruđer Bošković Institute's Laboratory for Molecular Genetics on protein ADP-ribosylation in the bacterium *Streptomyces coelicolor* and in humans.[10](https://www.irb.hr/eng/Divisions/Division-of-Molecular-Biology/Laboratory-for-Molecular-Genetics/Projects/Protein-ADP-ribosylation-in-a-model-prokaryote-Streptomyces-coelicolor-and-human)
## Representative work
His 2020 *Nature* paper "HPF1 completes the PARP active site for DNA damage-induced ADP-ribosylation" ([doi:10.1038/s41586-020-2013-6](https://doi.org/10.1038/s41586-020-2013-6)) reported a co-structure of HPF1 bound to the catalytic domain of [PARP2](https://www.edgepedia.org/parp2), revealing a composite active site formed by residues from both PARP1/2 and HPF1.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC7104379/) According to *HPF1 completes the PARP active site for DNA damage-induced ADP-ribosylation*, HPF1 is an accessory factor specific for the DNA damage response that switches the amino-acid specificity of PARP1/2 from aspartate and glutamate to serine residues, and DNA damage-induced ADP-ribosylation in human cells is predominantly serine-linked and requires HPF1.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC7104379/) Because HPF1 forms a joint active site with PARP1/2, the authors implicated it as an important determinant of the response to clinical PARP inhibitors.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC7104379/) A companion 2020 *Nature* study determined the cryo-EM structure of human PARP2–HPF1 bound to a nucleosome, showing that PARP2–HPF1 bridges two nucleosomes with the broken DNA aligned in a position suitable for ligation, and that this bridging licenses PARP2 activation; the authors noted that the PARP activation and catalytic cycle mechanisms could explain resistance to PARP inhibitors and aid the development of better cancer inhibitors.[11](https://www.nature.com/articles/s41586-020-2725-7)
In 2023 he was corresponding author of the *Cell* review "ADP-ribosylation from molecular mechanisms to therapeutic implications" ([doi:10.1016/j.cell.2023.08.030](https://doi.org/10.1016/j.cell.2023.08.030)), which, according to the review itself, presented state-of-the-art findings across structural biology, biochemistry, cell biology, and the clinical aspects of ADP-ribosylation, and concluded that the modification is intricately involved in human physiology and pathology and that manipulating it holds enormous therapeutic potential.[12](https://www.cell.com/cell/pdf/S0092-8674%2823%2900962-5.pdf)
## Honours, funding and translation
Ahel was selected for the EMBO Young Investigator Programme in 2012 and became an EMBO Member in 2022, with the listed research topic "ADP-ribosylation in regulation of genome stability" and keywords covering DNA repair, genome stability, PARP, ADP-ribosylation signaling, and infection.[1](https://orcid.org/0000-0002-9446-3756) • [3](https://people.embo.org/profile/ivan-ahel) He was elected a Fellow of the Academy of Medical Sciences in 2024, which describes him as a world leader in ADP-ribosylation with fundamental research uncovering roles in cancer, neurodegeneration, and infectious diseases.[7](https://acmedsci.ac.uk/fellows/fellows-directory/ordinary-fellows/fellow/Ivan-Ahel-0033z000030vL3ZAAU)
His laboratory is funded by the [Wellcome Trust](https://www.edgepedia.org/wellcome-trust) (grants 210634 and 223107), BBSRC, the Ovarian Cancer Research Alliance (813369), and Cancer Research UK.[13](https://doi.org/10.1042/bst20220749) Wellcome awarded him a 2021 grant, "Reversible ADP-ribosylation signaling in the control of coronavirus infection".[14](https://wellcome.org/research-funding/funding-portfolio/funded-grants/reversible-adp-ribosylation-signaling-control) The Academy of Medical Sciences records that he has established commercial collaborations to develop molecules that inhibit ADP-ribosylation systems involved in cancer and infectious disease, including inhibitors against an anti-[SARS-CoV-2](https://www.edgepedia.org/sars-cov-2) protein target and the discovery of novel cancer biomarkers; the Dunn School likewise notes that he has begun developing potent and specific ADP-ribosylation inhibitors for conditions including COVID.[7](https://acmedsci.ac.uk/fellows/fellows-directory/ordinary-fellows/fellow/Ivan-Ahel-0033z000030vL3ZAAU) • [2](https://www.path.ox.ac.uk/news-article/ivan-ahel-appointed-professor-of-chemical-pathology/)
## Recent developments
In 2024, according to the Academy of Medical Sciences, he was elected to the Academy of Medical Sciences.[7](https://acmedsci.ac.uk/fellows/fellows-directory/ordinary-fellows/fellow/Ivan-Ahel-0033z000030vL3ZAAU) A PLOS Biology paper published on 2 April 2026 showed that ADP-ribosylation on serine- and glutamate-linked peptides can be ubiquitinated by the RING-DTC domains of DTX2 and DTX3L in vitro and recognized by RNF114, RNF138, and RNF166 for ubiquitin chain elongation, and demonstrated that DTX2, rather than DTX3L, produces ADPr-ubiquitin at DNA damage sites to recruit those ligases in an HPF1-independent manner.[15](https://journals.plos.org/plosbiology/article?id=10.1371%2Fjournal.pbio.3003747)
## References
1. Ivan Ahel (0000-0002-9446-3756), ORCID. https://orcid.org/0000-0002-9446-3756
2. Ivan Ahel appointed Professor of Chemical Pathology, Sir William Dunn School of Pathology. https://www.path.ox.ac.uk/news-article/ivan-ahel-appointed-professor-of-chemical-pathology/
3. Ivan Ahel, EMBO Member profile. https://people.embo.org/profile/ivan-ahel
4. HPF1 completes the PARP active site for DNA damage-induced ADP-ribosylation, *Nature* (2020), PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC7104379/
5. Fusion 12, Michaelmas 2013, Dunn School newsletter. https://www.path.ox.ac.uk/wp-content/uploads/2023/07/Fusion-12-Michaelmas-2013.pdf
6. Ivan Ahel Lab, Current Members. https://ivanahellab.wixsite.com/ivan-ahel-lab/people
7. Professor Ivan Ahel, Academy of Medical Sciences Fellows Directory. https://acmedsci.ac.uk/fellows/fellows-directory/ordinary-fellows/fellow/Ivan-Ahel-0033z000030vL3ZAAU
8. ADP-ribosylation signalling in genome stability, Wellcome funded grants. https://wellcome.org/research-funding/funding-portfolio/funded-grants/adp-ribosylation-signalling-genome-stability
9. BBSRC Portfolio Analyser, Dr Ivan Ahel. https://gow.bbsrc.ukri.org/grants/PersonDetails.aspx?Personid=-267140
10. Protein ADP-ribosylation in *Streptomyces coelicolor* and human, Ruđer Bošković Institute. https://www.irb.hr/eng/Divisions/Division-of-Molecular-Biology/Laboratory-for-Molecular-Genetics/Projects/Protein-ADP-ribosylation-in-a-model-prokaryote-Streptomyces-coelicolor-and-human
11. Bridging of DNA breaks activates PARP2–HPF1 to modify chromatin, *Nature* (2020). https://www.nature.com/articles/s41586-020-2725-7
12. ADP-ribosylation from molecular mechanisms to therapeutic implications, *Cell* (2023). https://www.cell.com/cell/pdf/S0092-8674%2823%2900962-5.pdf
13. The function and regulation of ADP-ribosylation in the DNA damage response, *Biochemical Society Transactions* (2023). https://doi.org/10.1042/bst20220749
14. Reversible ADP-ribosylation signaling in the control of coronavirus infection, Wellcome funded grants. https://wellcome.org/research-funding/funding-portfolio/funded-grants/reversible-adp-ribosylation-signaling-control
15. Specificity and recognition of the ADP-ribosyl-ubiquitin modification in the DNA damage response, *PLOS Biology* (2026). https://journals.plos.org/plosbiology/article?id=10.1371%2Fjournal.pbio.3003747
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*Topic: Encyclopedia › Life and health › Life and health scientists › Life scientists › Researchers in molecular and cell biology › DNA replication, repair, and recombination*
*Initially written Sep 21, 2026 · Reviewed: Sep 25, 2026; Sep 30, 2026 · Edited: Sep 25, 2026; Sep 30, 2026; Oct 11, 2026; Oct 15, 2026; Oct 21, 2026 · Last review: Sep 30, 2026*
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