PXD071548-1

PXD071548 is an original dataset announced via ProteomeXchange.

Title	ISGylation of H2AX retains MDC1 and facilitates homologous recombination repair causing radioresistance in esophageal adenocarcinoma
Description	High expression of interferon-stimulated gene 15 (ISG15) has been associated with poor survival in patients with esophageal adenocarcinoma (EAC). Like ubiquitin, ISG15 utilizes its C-terminal LRGG motif to post-translationally modify target proteins through a process called ISGylation, thereby influencing their stability, function, and interaction networks. Given ISG15’s role in the replication stress response, we hypothesized that it may also contribute to DNA repair mechanisms. We found that ISG15 is upregulated following ionizing radiation (IR), and its knockdown disrupts the IR-induced G2/M checkpoint, leading to increased radiosensitivity in EAC cells. In synchronized cells, ISG15 expression peaks during the S/G2 phases. Knockdown of ISG15 impairs homologous recombination repair (HRR) with compensatory upregulation of non-homologous end joining (NHEJ). Similarly, cells expressing an ISGylation-defective ISG15LRAA mutant exhibit reduced HRR activity and elevated NHEJ, highlighting the critical role of ISGylation in the DNA damage response (DDR). Further investigation revealed that IR-induced ISG15 modifies H2AX at lysine 120 (K120). Overexpression of an H2AXK120R mutant in EAC cells resulted in diminished MDC1 retention at DNA damage sites, mirroring the phenotype observed with ISG15 knockdown. Additionally, depletion of ISG15 delays RAD51 foci formation at damage sites. Using a tissue microarray of chemoresistant EAC patients, we observed that ISG15 is expressed in almost all cases and that along with high RAD51 expression correlates with poorer prognosis in node-positive patients. Collectively, we identify H2AX as a novel substrate of IR-induced ISGylation, which facilitates efficient recruitment and retention of downstream HRR proteins and may contribute to radioresistance in EAC.
HostingRepository	PRIDE
AnnounceDate	2026-04-27
AnnouncementXML	Submission_2026-04-26_16:39:08.033.xml
DigitalObjectIdentifier
ReviewLevel	Peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Unsupported dataset by repository
PrimarySubmitter	Dipankar Ray
SpeciesList	scientific name: Homo sapiens (Human); NCBI TaxID: NEWT:9606;
ModificationList	ubiquitinylated lysine; monohydroxylated residue; deamidated residue; iodoacetamide derivatized residue
Instrument	Q Exactive HF; Orbitrap Ascend

Revision	Datetime	Status	ChangeLog Entry
0	2025-12-03 15:55:48	ID requested
⏵ 1	2026-04-26 16:39:09	announced

10.1016/j.jbc.2026.111358;

Ghosh A, Ray P, Thomas D, Jeeyar V, Pillai S, Basrur V, Bondarenko IV, Bellile E, Wang DH, Morgan MA, Zhang Q, Beer DG, Lagisetty KH, Lawrence TS, Ray D, H2AX retains MDC1 and facilitates homologous recombination repair causing radioresistance in esophageal adenocarcinoma. J Biol Chem, 302(5):111358(2026) [pubmed]

submitter keyword: radioresistance, H2AX, esophageal adenocarcinoma., homologous recombination repair (HRR),ISGylation

Dipankar Ray
contact affiliation	Departments of Radiation Oncology, The University of Michigan Medical School, Ann Arbor, Michigan 48109.
contact email	dipray@umich.edu
lab head
Dipankar Ray
contact affiliation	University of Michigan
contact email	dipray@umich.edu
dataset submitter

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PRIDE project URI

• PRIDE
  1. PXD071548
     1. Label: PRIDE project
     2. Name: ISGylation of H2AX retains MDC1 and facilitates homologous recombination repair causing radioresistance in esophageal adenocarcinoma