{"doi":"10.1016/j.jbc.2022.101621","title":"The P300 acetyltransferase inhibitor C646 promotes membrane translocation of insulin receptor protein substrate and interaction with the insulin receptor","abstract":"Inhibition of P300 acetyltransferase activity by specific inhibitor C646 has been shown to improve insulin signaling. However, the underlying molecular mechanism of this improvement remains unclear. In this study, we analyzed P300 levels of obese patients and found that they were significantly increased in liver hepatocytes. In addition, large amounts of P300 appeared in the cytoplasm. Inhibition of P300 acetyltransferase activity by C646 drastically increased tyrosine phosphorylation of the insulin receptor protein substrates (IRS1/2) without affecting the tyrosine phosphorylation of the beta subunit of the insulin receptor (IRβ) in hepatocytes in the absence of insulin. Since IRS1/2 requires membrane translocation and binding to inositol compounds for normal functions, we also examined the role of acetylation on binding to phosphatidylinositol(4,5)P2 and found that IRS1/2 acetylation by P300 reduced this binding. In contrast, we show that inhibition of IRS1/2 acetylation by C646 facilitates IRS1/2 membrane translocation. Intriguingly, we demonstrate that C646 activates IRβ′s tyrosine kinase activity and directly promotes IRβ interaction with IRS1/2, leading to the tyrosine phosphorylation of IRS1/2 and subsequent activation of insulin signaling even in the absence of insulin. In conclusion, these data reveal the unique effects of C646 in activating insulin signaling in patients with obesity and diabetes. Inhibition of P300 acetyltransferase activity by specific inhibitor C646 has been shown to improve insulin signaling. However, the underlying molecular mechanism of this improvement remains unclear. In this study, we analyzed P300 levels of obese patients and found that they were significantly increased in liver hepatocytes. In addition, large amounts of P300 appeared in the cytoplasm. Inhibition of P300 acetyltransferase activity by C646 drastically increased tyrosine phosphorylation of the insulin receptor protein substrates (IRS1/2) without affecting the tyrosine phosphorylation of the beta subunit of the insulin receptor (IRβ) in hepatocytes in the absence of insulin. Since IRS1/2 requires membrane translocation and binding to inositol compounds for normal functions, we also examined the role of acetylation on binding to phosphatidylinositol(4,5)P2 and found that IRS1/2 acetylation by P300 reduced this binding. In contrast, we show that inhibition of IRS1/2 acetylation by C646 facilitates IRS1/2 membrane translocation. Intriguingly, we demonstrate that C646 activates IRβ′s tyrosine kinase activity and directly promotes IRβ interaction with IRS1/2, leading to the tyrosine phosphorylation of IRS1/2 and subsequent activation of insulin signaling even in the absence of insulin. In conclusion, these data reveal the unique effects of C646 in activating insulin signaling in patients with obesity and diabetes. Obesity, which has reached alarming levels worldwide, is associated with an increased risk of metabolic abnormalities including type 2 diabetes (T2D). T2D accounts for more than 90% of diabetes cases, while type 1 diabetes (T1D) accounts for about 5 to 10% of diabetes. Insulin deficiency in T1D as well as insulin resistance and insufficient insulin secretion from impaired pancreatic β cells in T2D result in increased glucose production in the liver, which is the major cause of hyperglycemia in diabetic patients (1Magnusson I. Rothman D.L. Katz L.D. Shulman R.G. Shulman G.I. Increased rate of gluconeogenesis in type II diabetes mellitus. A 13C nuclear magnetic resonance study.J. Clin. Invest. 1992; 90: 1323-1327Google Scholar, 2Cheatham B. Kahn C.R. Insulin action and the insulin signaling network.Endocr. Rev. 1995; 16: 117-142Google Scholar, 3Samuel V.T. Shulman G.I. Mechanisms for insulin resistance: Common threads and missing links.Cell. 2012; 148: 852-871Google Scholar, 4van Belle T.L. Coppieters K.T. von Herrath M.G. Type 1 diabetes: Etiology, immunology, and therapeutic strategies.Physiol. Rev. 2011; 91: 79-118Google ","journal":"Journal of Biological Chemistry","year":2022,"id":271394,"datarank":0.5213311792022373,"base_score":2.5649493574615367,"endowment":2.5649493574615367,"self_citation_contribution":0.38474240361923057,"citation_network_contribution":0.13658877558300667,"self_endowment_contribution":0.38474240361923057,"citer_contribution":0.13658877558300667,"corpus_percentile":null,"corpus_rank":null,"citation_count":12,"citer_count":9,"citers_with_citation_signal":7,"citers_with_endowment":7,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9584,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":891396,"name":"Balamurugan Ramatchandirin","orcid":"0000-0003-0390-1878","position":1,"is_corresponding":false},{"id":623617,"name":"Yu Wang","orcid":"0000-0002-4153-7360","position":2,"is_corresponding":false},{"id":892173,"name":"Alexia Pearah","orcid":null,"position":3,"is_corresponding":false},{"id":936319,"name":"Kopperuncholan Namachivayam","orcid":"0000-0003-3556-8870","position":4,"is_corresponding":false},{"id":873875,"name":"Risa M. Wolf","orcid":"0000-0001-7674-520X","position":5,"is_corresponding":false},{"id":250104,"name":"Kimberley E. Steele","orcid":"0000-0001-5096-6549","position":6,"is_corresponding":false},{"id":936759,"name":"Krishnan MohanKumar","orcid":null,"position":7,"is_corresponding":false},{"id":564927,"name":"Liqing Yu","orcid":"0000-0002-5186-9182","position":8,"is_corresponding":false},{"id":695315,"name":"Shaodong Guo","orcid":"0000-0001-5126-731X","position":9,"is_corresponding":false},{"id":502656,"name":"Morris F. White","orcid":"0000-0003-2166-508X","position":10,"is_corresponding":false},{"id":341478,"name":"Akhil Maheshwari","orcid":"0000-0003-1502-7663","position":11,"is_corresponding":false},{"id":241389,"name":"Ling He","orcid":"0000-0001-7038-5848","position":12,"is_corresponding":false},{"id":891394,"name":"Jinghua Peng","orcid":"0000-0002-0665-7666","position":0,"is_corresponding":true}],"reference_count":46,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T00:27:35.206187Z","pmid":"35074429","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":[]}