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  1. Article ; Online: Discoidin domain receptor 2 signaling through PIK3C2α in fibroblasts promotes lung fibrosis.

    Ling, Song / Kwak, Doyun / Takuwa, Yoh / Ge, Chunxi / Franceschi, Renny / Kim, Kevin K

    The Journal of pathology

    2024  Volume 262, Issue 4, Page(s) 505–516

    Abstract: Pulmonary fibrosis, especially idiopathic pulmonary fibrosis (IPF), portends significant morbidity and mortality, and current therapeutic options are suboptimal. We have previously shown that type I collagen signaling through discoidin domain receptor 2 ( ...

    Abstract Pulmonary fibrosis, especially idiopathic pulmonary fibrosis (IPF), portends significant morbidity and mortality, and current therapeutic options are suboptimal. We have previously shown that type I collagen signaling through discoidin domain receptor 2 (DDR2), a receptor tyrosine kinase expressed by fibroblasts, is critical for the regulation of fibroblast apoptosis and progressive fibrosis. However, the downstream signaling pathways for DDR2 remain poorly defined and could also be attractive potential targets for therapy. A recent phosphoproteomic approach indicated that PIK3C2α, a poorly studied member of the PI3 kinase family, could be a downstream mediator of DDR2 signaling. We hypothesized that collagen I/DDR2 signaling through PIK3C2α regulates fibroblast activity during progressive fibrosis. To test this hypothesis, we found that primary murine fibroblasts and IPF-derived fibroblasts stimulated with endogenous or exogenous type I collagen led to the formation of a DDR2/PIK3C2α complex, resulting in phosphorylation of PIK3C2α. Fibroblasts treated with an inhibitor of PIK3C2α or with deletion of PIK3C2α had fewer markers of activation after stimulation with TGFβ and more apoptosis after stimulation with a Fas-activating antibody. Finally, mice with fibroblast-specific deletion of PIK3C2α had less fibrosis after bleomycin treatment than did littermate control mice with intact expression of PIK3Cα. Collectively, these data support the notion that collagen/DDR2/PIK3C2α signaling is critical for fibroblast function during progressive fibrosis, making this pathway a potential target for antifibrotic therapy. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
    MeSH term(s) Mice ; Animals ; Discoidin Domain Receptor 2/genetics ; Discoidin Domain Receptor 2/metabolism ; Collagen Type I/metabolism ; Fibroblasts/pathology ; Collagen/metabolism ; Idiopathic Pulmonary Fibrosis/metabolism ; Discoidin Domain Receptors/metabolism ; Lung/pathology
    Chemical Substances Discoidin Domain Receptor 2 (EC 2.7.10.1) ; Collagen Type I ; Collagen (9007-34-5) ; Discoidin Domain Receptors (EC 2.7.10.1)
    Language English
    Publishing date 2024-02-09
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 3119-7
    ISSN 1096-9896 ; 0022-3417
    ISSN (online) 1096-9896
    ISSN 0022-3417
    DOI 10.1002/path.6253
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: TGFβ receptor endocytosis and Smad signaling require synaptojanin1, PI3K-C2α-, and INPP4B-mediated phosphoinositide conversions.

    Aki, Sho / Yoshioka, Kazuaki / Takuwa, Noriko / Takuwa, Yoh

    Molecular biology of the cell

    2020  Volume 31, Issue 5, Page(s) 360–372

    Abstract: Phosphoinositide conversion regulates a diverse array of dynamic membrane events including endocytosis. However, it is not well understood which enzymes are involved in phosphoinositide conversions for receptor endocytosis. We found by small interfering ... ...

    Abstract Phosphoinositide conversion regulates a diverse array of dynamic membrane events including endocytosis. However, it is not well understood which enzymes are involved in phosphoinositide conversions for receptor endocytosis. We found by small interfering RNA (siRNA)-mediated knockdown (KD) that class II PI3K α-isoform (PI3K-C2α), the 5'-phosphatase synaptojanin1 (Synj1), and the 4'-phosphatase INPP4B, but not PI3K-C2β, Synj2, or INPP4A, were required for TGFβ-induced endocytosis of TGFβ receptor. TGFβ induced rapid decreases in PI(4,5)P
    MeSH term(s) Activin Receptors, Type II/metabolism ; Cell Membrane/metabolism ; Cell Nucleus/metabolism ; Endocytosis ; Human Umbilical Vein Endothelial Cells/metabolism ; Humans ; Nerve Tissue Proteins/metabolism ; Phosphatidylinositol 3-Kinases/metabolism ; Phosphatidylinositols/metabolism ; Phosphoric Monoester Hydrolases/metabolism ; Phosphorylation ; Receptor, Transforming Growth Factor-beta Type I/metabolism ; Receptors, Transforming Growth Factor beta/metabolism ; Signal Transduction ; Smad Proteins/metabolism ; Transforming Growth Factor beta/metabolism
    Chemical Substances Nerve Tissue Proteins ; Phosphatidylinositols ; Receptors, Transforming Growth Factor beta ; Smad Proteins ; Transforming Growth Factor beta ; ACVRL1 protein, human (EC 2.7.11.30) ; Activin Receptors, Type II (EC 2.7.11.30) ; Receptor, Transforming Growth Factor-beta Type I (EC 2.7.11.30) ; TGFBR1 protein, human (EC 2.7.11.30) ; synaptojanin (EC 3.1.3.-) ; Phosphoric Monoester Hydrolases (EC 3.1.3.2) ; phosphatidylinositol-3,4-bisphosphate 4-phosphatase (EC 3.1.3.66)
    Language English
    Publishing date 2020-01-08
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1098979-1
    ISSN 1939-4586 ; 1059-1524
    ISSN (online) 1939-4586
    ISSN 1059-1524
    DOI 10.1091/mbc.E19-11-0662
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: The ATG5 interactome links clathrin-mediated vesicular trafficking with the autophagosome assembly machinery.

    Baines, Kiren / Yoshioka, Kazuaki / Takuwa, Yoh / Lane, Jon D

    Autophagy reports

    2022  Volume 1, Issue 1, Page(s) 88–118

    Abstract: Autophagosome formation involves the sequential actions of conserved ATG proteins to coordinate the lipidation of the ubiquitin-like modifier Atg8-family proteins at the nascent phagophore membrane. Although the molecular steps driving this process are ... ...

    Abstract Autophagosome formation involves the sequential actions of conserved ATG proteins to coordinate the lipidation of the ubiquitin-like modifier Atg8-family proteins at the nascent phagophore membrane. Although the molecular steps driving this process are well understood, the source of membranes for the expanding phagophore and their mode of delivery are only now beginning to be revealed. Here, we have used quantitative SILAC-based proteomics to identify proteins that associate with the ATG12-ATG5 conjugate, a crucial player during Atg8-family protein lipidation. Our datasets reveal a strong enrichment of regulators of clathrin-mediated vesicular trafficking, including clathrin heavy and light chains, and several clathrin adaptors. Also identified were PIK3C2A (a phosphoinositide 3-kinase involved in clathrin-mediated endocytosis) and HIP1R (a component of clathrin vesicles), and the absence of either of these proteins alters autophagic flux in cell-based starvation assays. To determine whether the ATG12-ATG5 conjugate reciprocally influences trafficking within the endocytic compartment, we captured the cell surface proteomes of autophagy-competent and autophagy-incompetent mouse embryonic fibroblasts under fed and starved conditions. We report changes in the relative proportions of individual cell surface proteins and show that cell surface levels of the SLC7A5-SLC3A2 amino acid transporter are influenced by autophagy capability. Our data provide evidence for direct regulatory coupling between the ATG12-ATG5 conjugate and the clathrin membrane trafficking system and suggest candidate membrane proteins whose trafficking within the cell may be modulated by the autophagy machinery.
    Language English
    Publishing date 2022-04-07
    Publishing country United States
    Document type Journal Article
    ISSN 2769-4127
    ISSN (online) 2769-4127
    DOI 10.1080/27694127.2022.2042054
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Class II phosphatidylinositol 3-kinase-C2α is essential for Notch signaling by regulating the endocytosis of γ-secretase in endothelial cells.

    Shimizu, Shota / Yoshioka, Kazuaki / Aki, Sho / Takuwa, Yoh

    Scientific reports

    2021  Volume 11, Issue 1, Page(s) 5199

    Abstract: The class II α-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) plays a crucial role in angiogenesis at least in part through participating in endocytosis and, thereby, endosomal signaling of several cell surface receptors including VEGF receptor-2 ... ...

    Abstract The class II α-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) plays a crucial role in angiogenesis at least in part through participating in endocytosis and, thereby, endosomal signaling of several cell surface receptors including VEGF receptor-2 and TGFβ receptor in vascular endothelial cells (ECs). The Notch signaling cascade regulates many cellular processes including cell proliferation, cell fate specification and differentiation. In the present study, we explored a role of PI3K-C2α in Delta-like 4 (Dll4)-induced Notch signaling in ECs. We found that knockdown of PI3K-C2α inhibited Dll4-induced generation of the signaling molecule Notch intracellular domain 1 (NICD1) and the expression of Notch1 target genes including HEY1, HEY2 and NOTCH3 in ECs but not in vascular smooth muscle cells. PI3K-C2α knockdown did not inhibit Dll4-induced endocytosis of cell surface Notch1. In contrast, PI3K-C2α knockdown as well as clathrin heavy chain knockdown impaired endocytosis of Notch1-cleaving protease, γ-secretase complex, with the accumulation of Notch1 at the perinuclear endolysosomes. Pharmacological blockage of γ-secretase also induced the intracellular accumulation of Notch1. Taken together, we conclude that PI3K-C2α is required for the clathrin-mediated endocytosis of γ-secretase complex, which allows for the cleavage of endocytosed Notch1 by γ-secretase complex at the endolysosomes to generate NICD1 in ECs.
    MeSH term(s) Amyloid Precursor Protein Secretases/genetics ; Amyloid Precursor Protein Secretases/metabolism ; Basic Helix-Loop-Helix Transcription Factors/genetics ; Clathrin/genetics ; Endocytosis/genetics ; Endothelial Cells/metabolism ; Human Umbilical Vein Endothelial Cells ; Humans ; Neovascularization, Physiologic/genetics ; Neovascularization, Physiologic/physiology ; Phosphatidylinositol 3-Kinases/genetics ; Receptor, Notch1/genetics ; Receptor, Notch3/genetics ; Receptor, Transforming Growth Factor-beta Type I/genetics ; Repressor Proteins/genetics ; Signal Transduction/genetics ; Vascular Endothelial Growth Factor Receptor-2/genetics
    Chemical Substances Basic Helix-Loop-Helix Transcription Factors ; Clathrin ; HEY2 protein, human ; Hairy, HRT1 protein ; Receptor, Notch1 ; Receptor, Notch3 ; Repressor Proteins ; PIK3C2A protein, human (EC 2.7.1.137) ; Vascular Endothelial Growth Factor Receptor-2 (EC 2.7.10.1) ; Receptor, Transforming Growth Factor-beta Type I (EC 2.7.11.30) ; TGFBR1 protein, human (EC 2.7.11.30) ; Amyloid Precursor Protein Secretases (EC 3.4.-)
    Language English
    Publishing date 2021-03-04
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-021-84548-4
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Class II phosphatidylinositol 3-kinase-C2α is essential for Notch signaling by regulating the endocytosis of γ-secretase in endothelial cells

    Shota Shimizu / Kazuaki Yoshioka / Sho Aki / Yoh Takuwa

    Scientific Reports, Vol 11, Iss 1, Pp 1-

    2021  Volume 17

    Abstract: Abstract The class II α-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) plays a crucial role in angiogenesis at least in part through participating in endocytosis and, thereby, endosomal signaling of several cell surface receptors including VEGF ... ...

    Abstract Abstract The class II α-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) plays a crucial role in angiogenesis at least in part through participating in endocytosis and, thereby, endosomal signaling of several cell surface receptors including VEGF receptor-2 and TGFβ receptor in vascular endothelial cells (ECs). The Notch signaling cascade regulates many cellular processes including cell proliferation, cell fate specification and differentiation. In the present study, we explored a role of PI3K-C2α in Delta-like 4 (Dll4)-induced Notch signaling in ECs. We found that knockdown of PI3K-C2α inhibited Dll4-induced generation of the signaling molecule Notch intracellular domain 1 (NICD1) and the expression of Notch1 target genes including HEY1, HEY2 and NOTCH3 in ECs but not in vascular smooth muscle cells. PI3K-C2α knockdown did not inhibit Dll4-induced endocytosis of cell surface Notch1. In contrast, PI3K-C2α knockdown as well as clathrin heavy chain knockdown impaired endocytosis of Notch1-cleaving protease, γ-secretase complex, with the accumulation of Notch1 at the perinuclear endolysosomes. Pharmacological blockage of γ-secretase also induced the intracellular accumulation of Notch1. Taken together, we conclude that PI3K-C2α is required for the clathrin-mediated endocytosis of γ-secretase complex, which allows for the cleavage of endocytosed Notch1 by γ-secretase complex at the endolysosomes to generate NICD1 in ECs.
    Keywords Medicine ; R ; Science ; Q
    Subject code 572 ; 570
    Language English
    Publishing date 2021-03-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Sphingosine kinase 1 is involved in triglyceride breakdown by maintaining lysosomal integrity in brown adipocytes.

    Morishige, Jun-Ichi / Yoshioka, Kazuaki / Nakata, Hiroki / Ishimaru, Kazuhiro / Nagata, Naoto / Tanaka, Tamotsu / Takuwa, Yoh / Ando, Hitoshi

    Journal of lipid research

    2023  Volume 64, Issue 11, Page(s) 100450

    Abstract: Sphingosine 1-phosphate (S1P) has been implicated in brown adipose tissue (BAT) formation and energy consumption; however, the mechanistic role of sphingolipids, including S1P, in BAT remains unclear. Here, we showed that, in mice, BAT activation by cold ...

    Abstract Sphingosine 1-phosphate (S1P) has been implicated in brown adipose tissue (BAT) formation and energy consumption; however, the mechanistic role of sphingolipids, including S1P, in BAT remains unclear. Here, we showed that, in mice, BAT activation by cold exposure upregulated mRNA and protein expression of the S1P-synthesizing enzyme sphingosine kinase 1 (SphK1) and S1P production in BAT. Treatment of wild-type brown adipocytes with exogenous S1P or S1P receptor subtype-selective agonists stimulated triglyceride (TG) breakdown only marginally, compared with noradrenaline. However, genetic deletion of Sphk1 resulted in hypothermia and diminished body weight loss upon cold exposure, suggesting that SphK1 is involved in thermogenesis through mechanisms different from receptor-mediated, extracellular action of S1P. In BAT of wild-type mice, SphK1 was localized largely in the lysosomes of brown adipocytes. In the brown adipocytes of Sphk1
    MeSH term(s) Mice ; Animals ; Adipocytes, Brown/metabolism ; Signal Transduction ; Phosphotransferases (Alcohol Group Acceptor)/metabolism ; Sphingosine/metabolism ; Adipose Tissue, Brown/metabolism ; RNA, Messenger/metabolism ; Lysophospholipids/metabolism ; Triglycerides/metabolism
    Chemical Substances sphingosine kinase (EC 2.7.1.-) ; Phosphotransferases (Alcohol Group Acceptor) (EC 2.7.1.-) ; sphingosine 1-phosphate (26993-30-6) ; Sphingosine (NGZ37HRE42) ; RNA, Messenger ; Lysophospholipids ; Triglycerides
    Language English
    Publishing date 2023-09-24
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80154-9
    ISSN 1539-7262 ; 0022-2275
    ISSN (online) 1539-7262
    ISSN 0022-2275
    DOI 10.1016/j.jlr.2023.100450
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Class II phosphatidylinositol 3-kinase α and β isoforms are required for vascular smooth muscle Rho activation, contraction and blood pressure regulation in mice.

    Islam, Shahidul / Yoshioka, Kazuaki / Aki, Sho / Ishimaru, Kazuhiro / Yamada, Hiroki / Takuwa, Noriko / Takuwa, Yoh

    The journal of physiological sciences : JPS

    2020  Volume 70, Issue 1, Page(s) 18

    Abstract: Class II phosphatidylinositol 3-kinases (PI3K), PI3K-C2α and PI3K-C2β, are involved in cellular processes including endocytosis, cilia formation and autophagy. However, the role of PI3K-C2α and PI3K-C2β at the organismal level is not well understood. We ... ...

    Abstract Class II phosphatidylinositol 3-kinases (PI3K), PI3K-C2α and PI3K-C2β, are involved in cellular processes including endocytosis, cilia formation and autophagy. However, the role of PI3K-C2α and PI3K-C2β at the organismal level is not well understood. We found that double knockout (KO) mice with both smooth muscle-specific KO of PI3K-C2α and global PI3K-C2β KO, but not single KO mice of either PI3K-C2α or PI3K-C2β, exhibited reductions in arterial blood pressure and substantial attenuation of contractile responses of isolated aortic rings. In wild-type vascular smooth muscle cells, double knockdown of PI3K-C2α and PI3K-C2β but not single knockdown of either PI3K markedly inhibited contraction with reduced phosphorylation of 20-kDa myosin light chain and MYPT1 and Rho activation, but without inhibition of the intracellular Ca
    MeSH term(s) Animals ; Blood Pressure/physiology ; Calcium/metabolism ; Cells, Cultured ; Class II Phosphatidylinositol 3-Kinases/genetics ; Class II Phosphatidylinositol 3-Kinases/metabolism ; Disease Models, Animal ; Isoenzymes ; Mice ; Mice, Knockout ; Muscle Contraction/physiology ; Muscle, Smooth, Vascular/cytology ; Muscle, Smooth, Vascular/enzymology ; Muscle, Smooth, Vascular/metabolism ; Muscle, Smooth, Vascular/physiology ; rho GTP-Binding Proteins/genetics ; rho GTP-Binding Proteins/metabolism
    Chemical Substances Isoenzymes ; Class II Phosphatidylinositol 3-Kinases (EC 2.7.1.137) ; rho GTP-Binding Proteins (EC 3.6.5.2) ; Calcium (SY7Q814VUP)
    Language English
    Publishing date 2020-03-19
    Publishing country Japan
    Document type Journal Article
    ZDB-ID 2234472-X
    ISSN 1880-6562 ; 1880-6546
    ISSN (online) 1880-6562
    ISSN 1880-6546
    DOI 10.1186/s12576-020-00745-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Roles of Sphingosine Kinase and Sphingosine-1-Phosphate Receptor 2 in Endotoxin-Induced Acute Retinal Inflammation.

    Ahmed, Tazbir / Suzuki, Takafumi / Terao, Ryo / Yamagishi, Reiko / Fujino, Ryosuke / Azuma, Kunihiro / Soga, Hirotsugu / Ueta, Takashi / Honjo, Megumi / Watanabe, Sumiko / Yoshioka, Kazuaki / Takuwa, Yoh / Aihara, Makoto

    Ocular immunology and inflammation

    2023  , Page(s) 1–15

    Abstract: Purpose: To investigate the roles of sphingosine kinases (SphKs) and sphingosine-1-phosphate receptors (S1PRs) in endotoxin-induced uveitis (EIU) mice.: Methods: EIU model was induced using an intraperitoneal injection of lipopolysaccharide (LPS). ... ...

    Abstract Purpose: To investigate the roles of sphingosine kinases (SphKs) and sphingosine-1-phosphate receptors (S1PRs) in endotoxin-induced uveitis (EIU) mice.
    Methods: EIU model was induced using an intraperitoneal injection of lipopolysaccharide (LPS). The expression of SphKs and S1PRs in the retina was assessed using quantitative polymerase chain reaction (qPCR) and immunofluorescence. The effects of S1PR antagonists on the expression of inflammatory cytokines in the retina were evaluated using qPCR and western blotting. Effects of leukocyte infiltration of the retinal vessels were evaluated to determine the effects of the S1PR2 antagonist and genetic deletion of
    Results: Retinal SphK1 expression was significantly upregulated in EIU. SphK1 was expressed in the GCL, IPL, and OPL and S1PR2 was expressed in the GCL, INL, and OPL. Positive cells in IPL and OPL of EIU retina were identified as endothelial cells. S1PR2 antagonist and genetic deletion of S1PR2 significantly suppressed the expression of IL-1α, IL-6, TNF-α, and ICAM-1, whereas S1PR1/3 antagonist did not. Use of S1PR2 antagonist and
    Conclusion: SphK1/S1P/S1PR2 signaling was upregulated in EIU and S1PR2 inhibition suppressed inflammatory response. Targeting this signaling pathway has potential for treating retinal inflammatory diseases.
    Language English
    Publishing date 2023-12-15
    Publishing country England
    Document type Journal Article
    ZDB-ID 1193873-0
    ISSN 1744-5078 ; 0927-3948
    ISSN (online) 1744-5078
    ISSN 0927-3948
    DOI 10.1080/09273948.2023.2273963
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  9. Article: [Identification of PI3K-C2alpha as the mediator of Ca2+-induced Rho activation and MLC phosphatase inhibition].

    Takuwa, Yoh

    Nihon yakurigaku zasshi. Folia pharmacologica Japonica

    2007  Volume 129, Issue 4, Page(s) 253–257

    MeSH term(s) Calcium/metabolism ; Calcium/physiology ; Cardiovascular Diseases/etiology ; Class II Phosphatidylinositol 3-Kinases ; Humans ; Intracellular Signaling Peptides and Proteins/metabolism ; Muscle Contraction ; Muscle, Smooth, Vascular ; Myosin-Light-Chain Phosphatase/antagonists & inhibitors ; Phosphatidylinositol 3-Kinases/physiology ; Protein-Serine-Threonine Kinases/metabolism ; Signal Transduction/physiology ; rho-Associated Kinases
    Chemical Substances Intracellular Signaling Peptides and Proteins ; Phosphatidylinositol 3-Kinases (EC 2.7.1.-) ; Class II Phosphatidylinositol 3-Kinases (EC 2.7.1.137) ; Protein-Serine-Threonine Kinases (EC 2.7.11.1) ; rho-Associated Kinases (EC 2.7.11.1) ; Myosin-Light-Chain Phosphatase (EC 3.1.3.53) ; Calcium (SY7Q814VUP)
    Language Japanese
    Publishing date 2007-01-01
    Publishing country Japan
    Document type Journal Article ; Review
    ZDB-ID 1097532-9
    ISSN 1347-8397 ; 0015-5691
    ISSN (online) 1347-8397
    ISSN 0015-5691
    DOI 10.1254/fpj.129.253
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: The class II phosphoinositide 3-kinases PI3K-C2α and PI3K-C2β differentially regulate clathrin-dependent pinocytosis in human vascular endothelial cells.

    Aung, Khin Thuzar / Yoshioka, Kazuaki / Aki, Sho / Ishimaru, Kazuhiro / Takuwa, Noriko / Takuwa, Yoh

    The journal of physiological sciences : JPS

    2018  Volume 69, Issue 2, Page(s) 263–280

    Abstract: Pinocytosis is an important fundamental cellular process that is used by the cell to transport fluid and solutes. Phosphoinositide 3-kinases (PI3Ks) regulate a diverse array of dynamic membrane events. However, it is not well-understood which PI3K ... ...

    Abstract Pinocytosis is an important fundamental cellular process that is used by the cell to transport fluid and solutes. Phosphoinositide 3-kinases (PI3Ks) regulate a diverse array of dynamic membrane events. However, it is not well-understood which PI3K isoforms are involved in specific mechanisms of pinocytosis. We performed knockdown studies of endogenous PI3K isoforms and clathrin heavy chain (CHC) mediated by small interfering RNA (siRNA). The results demonstrated that the class II PI3K PI3K-C2α and PI3K-C2β, but not the class I or III PI3K, were required for pinocytosis, based on an evaluation of fluorescein-5-isothiocyanate (FITC)-dextran uptake in endothelial cells. Pinocytosis was partially dependent on both clathrin and dynamin, and both PI3K-C2α and PI3K-C2β were required for clathrin-mediated-but not clathrin-non-mediated-FITC-dextran uptake at the step leading up to its delivery to early endosomes. Both PI3K-C2α and PI3K-C2β were co-localized with clathrin-coated pits and vesicles. However, PI3K-C2β, but not PI3K-C2α, was highly co-localized with actin filament-associated clathrin-coated structures and required for actin filament formation at the clathrin-coated structures. These results indicate that PI3K-C2α and PI3K-C2β play differential, indispensable roles in clathrin-mediated pinocytosis.
    MeSH term(s) Actin Cytoskeleton/metabolism ; Animals ; Cells, Cultured ; Class II Phosphatidylinositol 3-Kinases/metabolism ; Clathrin/metabolism ; Endothelial Cells/metabolism ; Endothelial Cells/physiology ; Human Umbilical Vein Endothelial Cells ; Humans ; Phosphatidylinositol 3-Kinases/metabolism ; Pinocytosis/physiology ; RNA, Small Interfering/metabolism
    Chemical Substances Clathrin ; RNA, Small Interfering ; Phosphatidylinositol 3-Kinases (EC 2.7.1.-) ; Class II Phosphatidylinositol 3-Kinases (EC 2.7.1.137) ; PIK3C2A protein, human (EC 2.7.1.137) ; PIK3C2B protein, human (EC 2.7.1.137)
    Language English
    Publishing date 2018-10-29
    Publishing country Japan
    Document type Journal Article
    ZDB-ID 2234472-X
    ISSN 1880-6562 ; 1880-6546
    ISSN (online) 1880-6562
    ISSN 1880-6546
    DOI 10.1007/s12576-018-0644-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

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