{"doi":"10.3389/fcell.2021.658820","title":"Phospho-Site Mutations in Transcription Factor Suppressor of Hairless Impact Notch Signaling Activity During Hematopoiesis in Drosophila","abstract":"The highly conserved Notch signaling pathway controls a multitude of developmental processes including hematopoiesis. Here, we provide evidence for a novel mechanism of tissue-specific Notch regulation involving phosphorylation of CSL transcription factors within the DNA-binding domain. Earlier we found that a phospho-mimetic mutation of the Drosophila CSL ortholog Suppressor of Hairless [Su(H)] at Ser 269 impedes DNA-binding. By genome-engineering, we now introduced phospho-specific Su(H) mutants at the endogenous Su(H) locus, encoding either a phospho-deficient [ Su(H) S 269 A ] or a phospho-mimetic [ Su(H) S 269 D ] isoform. Su(H) S 269 D mutants were defective of Notch activity in all analyzed tissues, consistent with impaired DNA-binding. In contrast, the phospho-deficient Su(H) S 269 A mutant did not generally augment Notch activity, but rather specifically in several aspects of blood cell development. Unexpectedly, this process was independent of the corepressor Hairless acting otherwise as a general Notch antagonist in Drosophila . This finding is in agreement with a novel mode of Notch regulation by posttranslational modification of Su(H) in the context of hematopoiesis. Importantly, our studies of the mammalian CSL ortholog (RBPJ/CBF1) emphasize a potential conservation of this regulatory mechanism: phospho-mimetic RBPJ S 221 D was dysfunctional in both the fly as well as two human cell culture models, whereas phospho-deficient RBPJ S 221 A rather gained activity during fly hematopoiesis. Thus, dynamic phosphorylation of CSL-proteins within the DNA-binding domain provides a novel means to fine-tune Notch signal transduction in a context-dependent manner.","journal":"Frontiers in Cell and Developmental Biology","year":2021,"id":174308,"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":23,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9557,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":713331,"name":"Bernd M. Gahr","orcid":"0000-0002-5755-6603","position":1,"is_corresponding":false},{"id":713767,"name":"Hannes Schmid","orcid":null,"position":2,"is_corresponding":false},{"id":713332,"name":"Mirjam Zimmermann","orcid":"0000-0002-0249-9947","position":3,"is_corresponding":false},{"id":713768,"name":"Sebastian Deichsel","orcid":null,"position":4,"is_corresponding":false},{"id":713769,"name":"Philipp Hoffmeister","orcid":null,"position":5,"is_corresponding":false},{"id":713333,"name":"Aleksandra Turkiewicz","orcid":"0000-0002-4386-1180","position":6,"is_corresponding":false},{"id":687142,"name":"Tilman Borggrefe","orcid":null,"position":7,"is_corresponding":false},{"id":658534,"name":"Franz Oswald","orcid":"0000-0002-2923-5765","position":8,"is_corresponding":false},{"id":542591,"name":"Anja C. Nagel","orcid":"0000-0002-2733-3249","position":9,"is_corresponding":false},{"id":713766,"name":"Lisa Frankenreiter","orcid":null,"position":0,"is_corresponding":true}],"reference_count":98,"raw_metadata":null,"created_at":"2026-07-18T23:46:54.772014Z","pmid":"33937259","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":[]}