{"doi":"10.1242/jcs.213272","title":"TMEM55a localizes to macrophage phagosomes to downregulate phagocytosis","abstract":"<jats:title>ABSTRACT</jats:title>\n               <jats:p>TMEM55a (also known as PIP4P2) is an enzyme that dephosphorylates the phosphatidylinositol (PtdIns) PtdIns(4,5)P2 to form PtdIns(5)P in vitro. However, the in vivo conversion of the polyphosphoinositide into PtdIns(5)P by the phosphatase has not yet been demonstrated, and the role of TMEM55a remains poorly understood. Here, we found that mouse macrophages (Raw264.7) deficient in TMEM55a showed an increased engulfment of large particles without affecting the phagocytosis of Escherichia coli. Transfection of a bacterial phosphatase with similar substrate specificity to TMEM55a, namely IpgD, into Raw264.7 cells inhibited the engulfment of IgG-erythrocytes in a manner dependent on its phosphatase activity. In contrast, cells transfected with PIP4K2a, which catalyzes PtdIns(4,5)P2 production from PtdIns(5)P, increased phagocytosis. Fluorescent TMEM55a transfected into Raw264.7 cells was found to mostly localize to the phagosome. The accumulation of PtdIns(4,5)P2, PtdIns(3,4,5)P3 and F-actin on the phagocytic cup was increased in TMEM55a-deficient cells, as monitored by live-cell imaging. Phagosomal PtdIns(5)P was decreased in the knockdown cells, but the augmentation of phagocytosis in these cells was unaffected by the exogenous addition of PtdIns(5)P. Taken together, these results suggest that TMEM55a negatively regulates the phagocytosis of large particles by reducing phagosomal PtdIns(4,5)P2 accumulation during cup formation.</jats:p>","journal":"Journal of Cell Science","year":2018,"id":624005,"datarank":0.5819445747812713,"base_score":2.833213344056216,"endowment":2.833213344056216,"self_citation_contribution":0.42498200160843247,"citation_network_contribution":0.15696257317283882,"self_endowment_contribution":0.42498200160843247,"citer_contribution":0.15696257317283882,"corpus_percentile":null,"corpus_rank":null,"citation_count":16,"citer_count":11,"citers_with_citation_signal":9,"citers_with_endowment":9,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1305218,"name":"Kiyomi Nigorikawa","orcid":"0000-0002-4285-9695","position":1,"is_corresponding":false},{"id":1612971,"name":"Eri Okada","orcid":null,"position":2,"is_corresponding":false},{"id":1612972,"name":"Yoshimasa Tanaka","orcid":null,"position":3,"is_corresponding":false},{"id":1612973,"name":"Yoshihiro Kasuu","orcid":null,"position":4,"is_corresponding":false},{"id":1612974,"name":"Miho Yamada","orcid":null,"position":5,"is_corresponding":false},{"id":351873,"name":"Satoshi Kofuji","orcid":"0000-0003-1384-8425","position":6,"is_corresponding":false},{"id":1612975,"name":"Shunsuke Takasuga","orcid":null,"position":7,"is_corresponding":false},{"id":628455,"name":"Hiroki Nakanishi","orcid":"0000-0002-5108-1598","position":8,"is_corresponding":false},{"id":54817,"name":"Takehiko Sasaki","orcid":"0000-0003-1837-3748","position":9,"is_corresponding":false},{"id":1612977,"name":"Kaoru Hazeki","orcid":"0000-0001-8087-0337","position":10,"is_corresponding":false},{"id":1612970,"name":"Shin Morioka","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"TMEM55a localizes to macrophage phagosomes to downregulate phagocytosis","abstract":"<jats:title>ABSTRACT</jats:title>\n               <jats:p>TMEM55a (also known as PIP4P2) is an enzyme that dephosphorylates the phosphatidylinositol (PtdIns) PtdIns(4,5)P2 to form PtdIns(5)P in vitro. However, the in vivo conversion of the polyphosphoinositide into PtdIns(5)P by the phosphatase has not yet been demonstrated, and the role of TMEM55a remains poorly understood. Here, we found that mouse macrophages (Raw264.7) deficient in TMEM55a showed an increased engulfment of large particles without affecting the phagocytosis of Escherichia coli. Transfection of a bacterial phosphatase with similar substrate specificity to TMEM55a, namely IpgD, into Raw264.7 cells inhibited the engulfment of IgG-erythrocytes in a manner dependent on its phosphatase activity. In contrast, cells transfected with PIP4K2a, which catalyzes PtdIns(4,5)P2 production from PtdIns(5)P, increased phagocytosis. Fluorescent TMEM55a transfected into Raw264.7 cells was found to mostly localize to the phagosome. The accumulation of PtdIns(4,5)P2, PtdIns(3,4,5)P3 and F-actin on the phagocytic cup was increased in TMEM55a-deficient cells, as monitored by live-cell imaging. Phagosomal PtdIns(5)P was decreased in the knockdown cells, but the augmentation of phagocytosis in these cells was unaffected by the exogenous addition of PtdIns(5)P. Taken together, these results suggest that TMEM55a negatively regulates the phagocytosis of large particles by reducing phagosomal PtdIns(4,5)P2 accumulation during cup formation.</jats:p>","is_dataset_classified":null,"base_score":2.833213344056216,"endowment":2.833213344056216,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"29378918","pmcid":null,"openalex_id":"https://openalex.org/W2787147358","authors":[],"funders":[{"funder_name":"Home for Innovative Researchers and Academic Knowledge Users","grant_id":"","title":null}],"total_grants":1,"fwci":0.4227,"citation_percentile":0.55672774,"influential_citations":0,"citation_trend":[{"year":2018,"count":1},{"year":2019,"count":3},{"year":2021,"count":1},{"year":2022,"count":4},{"year":2023,"count":2},{"year":2024,"count":2},{"year":2025,"count":1},{"year":2026,"count":2}],"oa_status":"bronze","license":"http://www.biologists.com/user-licence-1-1/","oa_locations":[{"url":"https://jcs.biologists.org/content/joces/131/5/jcs213272.full.pdf","host_type":"journal"},{"url":"https://jcs.biologists.org/content/joces/131/5/jcs213272.full.pdf","host_type":"publisher"},{"url":"https://syndication.highwire.org/content/doi/10.1242/jcs.213272","host_type":"publisher"},{"url":"https://journals.biologists.com/jcs/article-pdf/doi/10.1242/jcs.213272/3504738/jcs213272.pdf","host_type":"publisher"},{"url":"http://journals.biologists.com/jcs/article-pdf/doi/10.1242/jcs.213272/2059052/jcs_213272v1.pdf","host_type":"publisher"},{"url":"https://doi.org/10.1242/jcs.213272","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/29378918","host_type":"repository"},{"url":"http://jcs.biologists.org/cgi/content/short/131/5/jcs213272","host_type":"repository"}],"fields_of_study":["Phagocytosis and Immune Regulation","Cellular transport and secretion","Erythrocyte Function and Pathophysiology","Animals","Cell Membrane","Macrophages","Mice","Phagocytosis","Phagosomes","Phosphatidylinositol 3-Kinases","Phosphatidylinositol 4,5-Diphosphate","Phosphatidylinositols","Phosphoinositide Phosphatases","Phosphotransferases (Alcohol Group Acceptor)","Protein Binding","RAW 264.7 Cells","Vesicular Transport Proteins"],"mesh_terms":["RAW 264.7 Cells","Phosphoinositide Phosphatases","Animals","Cell Membrane","Macrophages","Phagocytosis","Phagosomes","Phosphatidylinositols","Protein Binding","Phosphotransferases (Alcohol Group Acceptor)","Phosphatidylinositol 4,5-Diphosphate","Phosphatidylinositol 3-Kinases","Vesicular Transport Proteins","Mice"],"keywords":["Phagosome","Phagocytosis","Biology","Cell biology","Phosphatase","Transfection","Macrophage","Phosphatidylinositol","Molecular biology","In vitro","Signal transduction","Biochemistry","Phosphorylation","F-actin","Ipgd","Tmem55a","Phosphatidylinositol(4,5)-bisphosphate 4-Phosphatase"],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-04T02:16:54.488632Z","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":[]}