title: TIMAP repression by TGFβ and HDAC3-associated Smad signaling regulates macrophage M2 phenotypic phagocytosis.
abstract: TIMAP (TGFβ-inhibited membrane-associated protein) is an endothelium-enriched TGFβ downstream protein and structurally belongs to the targeting subunit of myosin phosphatase; however, the mechanism of TGFβ repressing TIMAP and its functional relevance to TGFβ bioactivity remain largely unknown. Here, we report that TIMAP is reduced in TGFβ-elevated mouse fibrotic kidney and highly expressed in macrophages. TGFβ repression of TIMAP is associated with HDAC3 upregulation and its recruitment by Smad2/3 at the Smad binding element on TIMAP promoter, whereas specific HDAC3 inhibition reversed the TIMAP repression, suggesting that TGFβ transcriptionally downregulates TIMAP through HDAC3-associated Smad signaling. Further investigation showed that TIMAP over-expression interrupted TGFβ-associated Smad signaling and TIMAP repression by TGFβ correlated with TGFβ-induced macrophage M2 polarization markers, migration, and phagocytosis-the processes promoted by phosphorylation of the putative TIMAP substrate myosin light chain (MLC). Consistently, TIMAP dephosphorylated MLC in macrophages and TGFβ induced macrophage migration and phagocytosis in TIMAP- and MLC phosphorylation-dependent manners, suggesting that TIMAP dephosphorylation of MLC constitutes an essential regulatory loop mitigating TGFβ-associated macrophage M2 phenotypic activities. Given that hyperactive TGFβ often causes excessive macrophage phagocytic activities potentially leading to various chronic disorders, the strategies targeting HDAC3/TIMAP axis might improve TGFβ-associated pathological processes.
  
  
  
  TIMAP is enriched in the endothelium and highly expressed in macrophages. TIMAP is suppressed by TGFβ via HDAC3-associated Smad signaling. TIMAP inhibits TGFβ signaling and TGFβ-associated macrophage M2 polarization. TIMAP dephosphorylation of MLC counteracts TGFβ-induced macrophage phagocytosis.
authors.affiliation: Nanjing University School of Medicine, Jiangsu Key Laboratory of Molecular Medicine, 22 Hankou Road, Room 209, Science & Technology Building, Nanjing, 210093, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Nanjing University School of Medicine, Jiangsu Key Laboratory of Molecular Medicine, 22 Hankou Road, Room 209, Science & Technology Building, Nanjing, 210093, China.
authors.forename: Shasha
authors.initials: S
authors.lastname: Yin
authors.affiliation: Nanjing University School of Medicine, Jiangsu Key Laboratory of Molecular Medicine, 22 Hankou Road, Room 209, Science & Technology Building, Nanjing, 210093, China.
authors.forename: Fangfang
authors.initials: F
authors.lastname: Bi
authors.affiliation: Nanjing University School of Medicine, Jiangsu Key Laboratory of Molecular Medicine, 22 Hankou Road, Room 209, Science & Technology Building, Nanjing, 210093, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.affiliation: Nanjing University School of Medicine, Jiangsu Key Laboratory of Molecular Medicine, 22 Hankou Road, Room 209, Science & Technology Building, Nanjing, 210093, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Qin
authors.affiliation: Nanjing University School of Medicine, Jiangsu Key Laboratory of Molecular Medicine, 22 Hankou Road, Room 209, Science & Technology Building, Nanjing, 210093, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Nanjing University School of Medicine, Jiangsu Key Laboratory of Molecular Medicine, 22 Hankou Road, Room 209, Science & Technology Building, Nanjing, 210093, China. wangsencao@nju.edu.cn.
authors.forename: Wangsen
authors.initials: W
authors.lastname: Cao
mesh_terms: D000818:Animals; D016764:Cell Polarity; D015536:Down-Regulation; D057809:HEK293 Cells; D006655:Histone Deacetylases / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D010587:Phagocytosis; D000067996:RAW 264.7 Cells; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism*; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D000099186:Histone Deacetylase 3
chemical_list: D006655:Histone Deacetylases; D008565:Membrane Proteins; D051785:Smad Proteins; D016212:Transforming Growth Factor beta; D000099186:Histone Deacetylase 3; C486763:Ppp1r16b protein, mouse
keywords: HDAC3; MLC phosphorylation; Macrophage polarization; Phagocytosis; TGFβ; TIMAP