{"doi":"10.1101/2020.09.13.295485","title":"Mpl is activated by dimers of MPN-linked calreticulin mutants stabilized by disulfide bonds and ionic interactions","abstract":"Abstract Myeloproliferative neoplasms (MPNs) are frequently driven by insertions and deletions within the gene encoding calreticulin (CRT). CRT Del52 and CRT Ins5 are recurrent mutations. Although oncogenic transformation requires both mutated CRT and the myeloproliferative leukemia protein (Mpl), the molecular mechanism of CRT-mediated constitutive activation of Mpl is unknown. Our studies reveal that the novel C-domain of CRT Del52 encodes specificity both for Mpl binding and for disulfide-mediated CRT dimerization. Disulfide-stabilized CRT Del52 dimers and multimers are observed in MPN patient-derived platelet lysates and in transfected mammalian cells. Cysteine mutations within both the novel C-domain (C400A and C404A) and the conserved N-domain (C163A) of CRT Del52 are required to reduce disulfide-mediated dimers and multimers of CRT Del52 . Based on these data and published structures of crystalized CRT oligomers, we tested the relevance of ionic interactions between charged residues proximal to C163 at the N-domain dimerization interface. Charge alteration at these residues affected dimerization and multimerization of both wild type and CRT Del52 . Elimination of intermolecular disulfides and disruption of ionic interactions at both proposed dimerization interfaces was required to abrogate the ability of CRT Del52 to induce cytokine-independent cell proliferation via Mpl. Based on these findings, we propose a structural model of the Mpl-activating CRT Del52 unit as a covalently-linked dimer that is stabilized by disulfides and ionic interactions at both the C-domain and N-domain. MPNs exploit a natural dimerization interface of CRT combined with C-domain gain-of-functions to achieve cell transformation.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2020,"id":130985,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.961,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":499811,"name":"Jie Geng","orcid":"0000-0001-8722-2228","position":1,"is_corresponding":false},{"id":262026,"name":"Malathi Kandarpa","orcid":"0000-0002-0440-4964","position":2,"is_corresponding":false},{"id":584286,"name":"Sanjeeva J. Wijeyesakere","orcid":"0000-0002-4275-0438","position":3,"is_corresponding":false},{"id":584943,"name":"Ashwini Bhide","orcid":null,"position":4,"is_corresponding":false},{"id":284124,"name":"Moshe Talpaz","orcid":"0000-0003-3361-3981","position":5,"is_corresponding":false},{"id":428611,"name":"Irina D. Pogozheva","orcid":"0000-0002-3024-9574","position":6,"is_corresponding":false},{"id":292652,"name":"Malini Raghavan","orcid":"0000-0002-1345-9318","position":7,"is_corresponding":false},{"id":584285,"name":"Arunkumar Venkatesan","orcid":"0000-0002-8015-9278","position":0,"is_corresponding":true}],"reference_count":41,"raw_metadata":null,"created_at":"2026-07-18T23:16:00.235845Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}