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Ijuin T, Iuchi T, Tawaratsumida H, Masuda Y, Tokushige A, Maeda S, Taniguchi N. Development of a novel animal model of rotator cuff tear arthropathy replicating clinical features of progressive osteoarthritis with subchondral bone collapse. Osteoarthr Cartil Open 2023; 5:100389. [PMID: 37560389 PMCID: PMC10407568 DOI: 10.1016/j.ocarto.2023.100389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 07/21/2023] [Indexed: 08/11/2023] Open
Abstract
OBJECTIVE To establish an animal model of modified cuff tear arthropathy (mCTA) in order to better replicate the pathophysiology associated with rotator cuff tear-induced humeral head collapse. DESIGN mCTA was induced by transection of the rotator cuff, the long head of the biceps brachii (LHB), and superior half of the joint capsule in the right shoulder of 12-week-old rats; the left shoulder underwent sham surgery. The severity of CTA was quantitated using the Murine Shoulder Arthritis Score (MSAS). The trabecular bone of the humeral head and metaphysis was analyzed using bone histomorphometry. The expression of proinflammatory cytokines and catabolic enzymes was evaluated immunohistochemically. RESULTS In the mCTA model, the MSAS increased starting from 2 weeks after induction, and there was notable subchondral bone collapse with fibrous cells at 4 weeks. The mCTA cartilage exhibited positive staining for TNF-α, IL-1β/6, MMP-3/13, and ADAMTS5. The trabecular bone volume was reduced not only in the subchondral bone but also in the metaphysis of the humeri, and bone resorption was enhanced in these areas. In the collapsed subchondral bone, both bone formation and resorption were increased. The fibrous cells showed expression of TNF-α, IL-6, and MMP-13, along with specific markers of mesenchymal stem cells. Furthermore, the fibrous cells showed osteoblastic characteristics (RUNX2-positive) and expressed RANKL. CONCLUSIONS The LHB and the capsuloligamentous complex are critical stabilizers of the glenohumeral joint, serving to prevent the advancement of CTA following massive rotator cuff tears. Fibrous cells appear to play a role in the humeral head bone resorption.
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Affiliation(s)
- T. Ijuin
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
- Department of Medical Joint Materials, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
| | - T. Iuchi
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
| | - H. Tawaratsumida
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
| | - Y. Masuda
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
- Department of Locomotory Organ Regeneration, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
| | - A. Tokushige
- Department of Clinical Pharmacology and Therapeutics, Graduate School of Medicine, University of the Ryukyus, Nakagami Gun Nishihara Cho, Okinawa 903-0213, Japan
| | - S. Maeda
- Department of Bone and Joint Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
| | - N. Taniguchi
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
- Department of Medical Joint Materials, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
- Department of Locomotory Organ Regeneration, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
- Department of Bone and Joint Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Kagoshima 890-8520, Japan
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Okada T, Nishida S, Zhang L, Ibrahim Mohamed NN, Wang T, Ijuin T, Kajimoto T, Nakamura SI. Constitutive activation of S1P receptors at the trans-Golgi network is required for surface transport carrier formation. iScience 2021; 24:103351. [PMID: 34805799 PMCID: PMC8590068 DOI: 10.1016/j.isci.2021.103351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/18/2021] [Accepted: 10/22/2021] [Indexed: 11/10/2022] Open
Abstract
The importance of the G-protein βγ subunits in the regulation of cargo transport from the trans-Golgi network (TGN) to the plasma membrane (PM) is well accepted; however, the molecular mechanism underlying the G-protein activation at the TGN remains unclear. We show here that sphingosine 1-phosphate (S1P) receptors at the PM were trafficked to the TGN in response to a surface transport cargo, temperature-sensitive vesicular stomatitis virus glycoprotein tagged with green fluorescent protein accumulation in the Golgi. The receptor internalization occurred in an S1P-independent manner but required phosphorylation by G-protein receptor kinase 2 and β-arrestin association before internalization. Continuously activated S1P receptors in a manner dependent on S1P at the TGN kept transmitting G-protein signals including the βγ subunits supply necessary for transport carrier formation at the TGN destined for the PM. S1P receptors traffic from the PM to Golgi in a surface cargo-dependent manner S1PR trafficking follows GRK2-dependent phosphorylation and β-arrestin binding S1PRs at the Golgi are continuously activated by S1P while sending G-protein signals S1PR/Gβγ signals at the Golgi are indispensable for surface transport carrier formation
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Affiliation(s)
- Taro Okada
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Susumu Nishida
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Lifang Zhang
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Nesma Nabil Ibrahim Mohamed
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.,Department of Agricultural Biochemistry, Faculty of Agriculture, Ain Shams University, Cairo, Egypt
| | - Tianyou Wang
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Taketoshi Kajimoto
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Shun-Ichi Nakamura
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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Sakakibara N, Ijuin T, Horinouchi T, Yamamura T, Nagano C, Okada E, Ishiko S, Aoto Y, Rossanti R, Ninchoji T, Awano H, Nagase H, Minamikawa S, Tanaka R, Matsuyama T, Nagatani K, Kamei K, Jinnouchi K, Ohtsuka Y, Oka M, Araki Y, Tanaka T, Harada MS, Igarashi T, Kitahara H, Morisada N, Nakamura SI, Okada T, Iijima K, Nozu K. Identification of novel OCRL isoforms associated with phenotypic differences between Dent disease-2 and Lowe syndrome. Nephrol Dial Transplant 2021; 37:262-270. [PMID: 34586410 DOI: 10.1093/ndt/gfab274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Although Lowe syndrome and Dent disease-2 are both caused by OCRL mutations, their clinical severities differ substantially, and their molecular mechanisms remain unclear. Truncating mutations in OCRL exons 1 through 7 lead to Dent disease-2, whereas those in exons 8 through 24 lead to Lowe syndrome. Herein, we identified the mechanism underlying the action of novel OCRL protein isoforms. METHODS mRNA samples extracted from cultured urine-derived cells from a healthy control and the Dent disease-2 patient were examined to detect the 5' end of the OCRL isoform. For protein expression and functional analysis, vectors containing (1) the full-length OCRL transcripts, (2) the isoform transcripts, and (3) transcripts with truncating mutations detected in Lowe syndrome and Dent disease-2 patients were transfected into HeLa cells. RESULTS We successfully cloned the novel isoform transcripts from OCRL exons 6-24, including the translation-initiation codons present in exon 8. In vitro protein-expression analysis detected proteins of two different sizes (105 and 80 kDa) translated from full-length OCRL, whereas only one protein (80 kDa) was found from the isoform and Dent disease-2 variants. No protein expression was observed for the Lowe syndrome variants. The isoform enzyme activity was equivalent to that of full-length OCRL; the Dent disease-2 variants retained > 50% enzyme activity, whereas the Lowe syndrome variants retained < 20% activity. CONCLUSIONS We elucidated the molecular mechanism underlying the two different phenotypes in OCRL-related diseases; the functional OCRL isoform translated starting at exon 8 was associated with this mechanism.
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Affiliation(s)
- Nana Sakakibara
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomoko Horinouchi
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - China Nagano
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Eri Okada
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan.,Department of Nephrology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Shinya Ishiko
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yuya Aoto
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Rini Rossanti
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Takeshi Ninchoji
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroyuki Awano
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroaki Nagase
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shogo Minamikawa
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Ryojiro Tanaka
- Department of Nephrology, Hyogo Prefectural Kobe Children's Hospital, Kobe, Japan
| | | | - Koji Nagatani
- Department of Pediatrics, Uwajima City Hospital, Uwajima, Japan
| | - Koichi Kamei
- Division of Nephrology and Rheumatology, National Center for Child Health and Development, Tokyo, Japan
| | - Kumiko Jinnouchi
- Department of Pediatrics, Faculty of Medicine, Saga University, Saga, Japan
| | - Yasufumi Ohtsuka
- Department of Pediatrics, Faculty of Medicine, Saga University, Saga, Japan
| | - Masafumi Oka
- Department of Pediatrics, Faculty of Medicine, Saga University, Saga, Japan
| | - Yoshinori Araki
- Department of Pediatrics, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan
| | - Toju Tanaka
- Department of Pediatrics, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan
| | - Mari S Harada
- Department of Pediatrics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Toru Igarashi
- Department of Pediatrics, Nippon Medical School Hospital, Tokyo, Japan
| | - Hikaru Kitahara
- Department of Pediatrics, Osaka Medical College, Takatsuki, Japan
| | - Naoya Morisada
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan.,Department of Clinical Genetics, Hyogo Prefectural Kobe Children's Hospital, Kobe, Japan
| | - Shun-Ichi Nakamura
- Division of Biochemistry, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Taro Okada
- Division of Biochemistry, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kazumoto Iijima
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
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Matovelo SA, Zhang L, Mohamed NNI, Kajimoto T, Ijuin T, Okada T, Nakamura SI. Involvement of Receptor-Mediated S1P Signaling in EGF-Induced Macropinocytosis in COS7 Cells. Kobe J Med Sci 2020; 66:E94-E101. [PMID: 33431782 PMCID: PMC7837661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/02/2020] [Indexed: 06/12/2023]
Abstract
Macropinocytosis is a highly conserved cellular process of endocytosis by which extracellular fluid and nutrients are taken up into cells through large, heterogeneous vesicles known as macropinosomes. Growth factors such as epidermal growth factor (EGF) can induce macropinocytosis in many types of cells, although precise mechanism underlying EGF-induced macropinocytosis remains unclear. In the present studies we have shown the involvement of S1P signaling in EGF-induced macropinocytosis in COS7 cells. First, EGF-induced macropinocytosis was strongly impaired in sphingosine kinase isozymes, SphK1 or SphK2-depleted cells, which was completely rescued by the expression of the corresponding wild-type isozyme but not the catalytically inactive one, suggesting the involvement of sphingosine 1-phosphate (S1P) in this phenomenon. Next, we observed that EGF-induced macropinocytosis was strongly inhibited in S1P type 1 receptor (S1P1R)-knockdown cells, implying involvement of S1P1R in this event. Furthermore, we could successfully demonstrate EGF-induced trans-activation of S1P1R using one-molecular fluorescence resonance energy transfer (FRET) technique. Moreover, for EGF-induced Rac1 activation, a step essential to F-actin formation and subsequent macropinocytosis, S1P signaling is required for its full activation, as judged by FRET analysis. These findings indicate that growth factors such as EGF utilize receptor-mediated S1P signaling for the regulation of macropinocytosis to fulfil vital cell activity.
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Affiliation(s)
- Shubi Ambwene Matovelo
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Lifang Zhang
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
- Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Nesma Nabil Ibrahim Mohamed
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
- Department of Agricultural Biochemistry, Faculty of Agriculture, Ain shams University, Cairo, Egypt
| | - Taketoshi Kajimoto
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Taro Okada
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Shun-Ichi Nakamura
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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5
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Ijuin T. Phosphoinositide phosphatases in cancer cell dynamics-Beyond PI3K and PTEN. Semin Cancer Biol 2019; 59:50-65. [PMID: 30922959 DOI: 10.1016/j.semcancer.2019.03.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 03/18/2019] [Accepted: 03/18/2019] [Indexed: 12/16/2022]
Abstract
Phosphoinositides are a group of lipids that regulate intracellular signaling and subcellular biological events. The signaling by phosphatidylinositol-3,4,5-trisphosphate and Akt mediates the action of growth factors that are essential for cell proliferation, gene transcription, cell migration, and polarity. The hyperactivation of this signaling has been identified in different cancer cells; and, it has been implicated in oncogenic transformation and cancer cell malignancy. Recent studies have argued the role of phosphoinositides in cancer cell dynamics, including actin cytoskeletal rearrangement at the plasma membrane and the organization of intracellular compartments. The focus of this review is to summarize the impact of the activities of phosphoinositide phosphatases on intracellular signaling related to cancer cell dynamics and to discuss how the abnormalities in the activities of the enzymes alter the levels of phosphoinositides in cancer cells.
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Affiliation(s)
- Takeshi Ijuin
- Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Chu-o, Kobe 650-0017, Japan.
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6
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Badawy SMM, Okada T, Kajimoto T, Hirase M, Matovelo SA, Nakamura S, Yoshida D, Ijuin T, Nakamura SI. Extracellular α-synuclein drives sphingosine 1-phosphate receptor subtype 1 out of lipid rafts, leading to impaired inhibitory G-protein signaling. J Biol Chem 2018; 293:8208-8216. [PMID: 29632069 DOI: 10.1074/jbc.ra118.001986] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 04/04/2018] [Indexed: 11/06/2022] Open
Abstract
α-Synuclein (α-Syn)-positive intracytoplasmic inclusions, known as Lewy bodies, are thought to be involved in the pathogenesis of Lewy body diseases, such as Parkinson's disease (PD). Although growing evidence suggests that cell-to-cell transmission of α-Syn is associated with the progression of PD and that extracellular α-Syn promotes formation of inclusion bodies, its precise mechanism of action in the extracellular space remains unclear. Here, as indicated by both conventional fractionation techniques and FRET-based protein-protein interaction analysis, we demonstrate that extracellular α-Syn causes expulsion of sphingosine 1-phosphate receptor subtype 1 (S1P1R) from the lipid raft fractions. S1P1R regulates vesicular trafficking, and its expulsion involved α-Syn binding to membrane-surface gangliosides. Consequently, the S1P1R became refractory to S1P stimulation required for activating inhibitory G-protein (Gi) in the plasma membranes. Moreover, the extracellular α-Syn also induced uncoupling of the S1P1R on internal vesicles, resulting in the reduced amount of CD63 molecule (CD63) in the lumen of multivesicular endosomes, together with a decrease in CD63 in the released exosomes from α-Syn-treated cells. Furthermore, cholesterol-depleting agent-induced S1P1R expulsion from the rafts also resulted in S1P1R uncoupling. Taken together, these results suggest that extracellular α-Syn-induced expulsion of S1P1R from lipid rafts promotes the uncoupling of S1P1R from Gi, thereby blocking subsequent Gi signals, such as inhibition of cargo sorting into exosomal vesicles in multivesicular endosomes. These findings help shed additional light on PD pathogenesis.
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Affiliation(s)
- Shaymaa Mohamed Mohamed Badawy
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Taro Okada
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Taketoshi Kajimoto
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Mitsuhiro Hirase
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Shubi Ambwene Matovelo
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Shunsuke Nakamura
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Daisuke Yoshida
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Shun-Ichi Nakamura
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan.
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Badawy SMM, Okada T, Kajimoto T, Ijuin T, Nakamura SI. DHHC5-mediated palmitoylation of S1P receptor subtype 1 determines G-protein coupling. Sci Rep 2017; 7:16552. [PMID: 29185452 PMCID: PMC5707436 DOI: 10.1038/s41598-017-16457-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 11/13/2017] [Indexed: 01/02/2023] Open
Abstract
Sphingosine 1-phosphate (S1P) is a pleiotropic lipid mediator involved in the regulation of immune cell trafficking and vascular permeability acting mainly through G-protein-coupled S1P receptors (S1PRs). However, mechanism underlying how S1PRs are coupled with G-proteins remains unknown. Here we have uncovered that palmitoylation of a prototypical subtype S1P1R is prerequisite for subsequent inhibitory G-protein (Gi) coupling. We have identified DHHC5 as an enzyme for palmitoylation of S1P1R. Under basal conditions, S1P1R was functionally associated with DHHC5 in the plasma membranes (PM) and was fully palmitoylated, enabling Gi coupling. Upon stimulation, the receptor underwent internalisation leaving DHHC5 in PM, resulting in depalmitoylation of S1P1R. We also revealed that while physiological agonist S1P-induced endocytosed S1P1R readily recycled back to PM, pharmacological FTY720-P-induced endocytosed S1P1R-positive vesicles became associated with DHHC5 in the later phase, persistently transmitting Gi signals there. This indicates that FTY720-P switches off the S1P signal in PM, while switching on its signal continuously inside the cells. We propose that DHHC5-mediated palmitoylation of S1P1R determines Gi coupling and its signalling in a spatio/temporal manner.
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Affiliation(s)
- Shaymaa Mohamed Mohamed Badawy
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - Taro Okada
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - Taketoshi Kajimoto
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - Shun-Ichi Nakamura
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan.
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Kajimoto T, Mohamed NNI, Badawy SMM, Matovelo SA, Hirase M, Nakamura S, Yoshida D, Okada T, Ijuin T, Nakamura SI. Involvement of Gβγ subunits of G i protein coupled with S1P receptor on multivesicular endosomes in F-actin formation and cargo sorting into exosomes. J Biol Chem 2017; 293:245-253. [PMID: 29133526 DOI: 10.1074/jbc.m117.808733] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/11/2017] [Indexed: 12/29/2022] Open
Abstract
Exosomes play a critical role in cell-to-cell communication by delivering cargo molecules to recipient cells. However, the mechanism underlying the generation of the exosomal multivesicular endosome (MVE) is one of the mysteries in the field of endosome research. Although sphingolipid metabolites such as ceramide and sphingosine 1-phosphate (S1P) are known to play important roles in MVE formation and maturation, the detailed molecular mechanisms are still unclear. Here, we show that Rho family GTPases, including Cdc42 and Rac1, are constitutively activated on exosomal MVEs and are regulated by S1P signaling as measured by fluorescence resonance energy transfer (FRET)-based conformational changes. Moreover, we detected S1P signaling-induced filamentous actin (F-actin) formation. A selective inhibitor of Gβγ subunits, M119, strongly inhibited both F-actin formation on MVEs and cargo sorting into exosomal intralumenal vesicles of MVEs, both of which were fully rescued by the simultaneous expression of constitutively active Cdc42 and Rac1. Our results shed light on the mechanism underlying exosomal MVE maturation and inform the understanding of the physiological relevance of continuous activation of the S1P receptor and subsequent downstream G protein signaling to Gβγ subunits/Rho family GTPases-regulated F-actin formation on MVEs for cargo sorting into exosomal intralumenal vesicles.
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Affiliation(s)
- Taketoshi Kajimoto
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Nesma Nabil Ibrahim Mohamed
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Shaymaa Mohamed Mohamed Badawy
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Shubi Ambwene Matovelo
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Mitsuhiro Hirase
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Shunsuke Nakamura
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Daisuke Yoshida
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Taro Okada
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Takeshi Ijuin
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan
| | - Shun-Ichi Nakamura
- Department of Biochemistry and Molecular Biology, Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Kobe 650-0017, Japan.
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Fukumoto M, Ijuin T, Takenawa T. PI(3,4)P 2 plays critical roles in the regulation of focal adhesion dynamics of MDA-MB-231 breast cancer cells. Cancer Sci 2017; 108:941-951. [PMID: 28247964 PMCID: PMC5448597 DOI: 10.1111/cas.13215] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 02/17/2017] [Accepted: 02/22/2017] [Indexed: 01/16/2023] Open
Abstract
Phosphoinositides play pivotal roles in the regulation of cancer cell phenotypes. Among them, phosphatidylinositol 3,4‐bisphosphate (PI(3,4)P2) localizes to the invadopodia, and positively regulates tumor cell invasion. In this study, we examined the effect of PI(3,4)P2 on focal adhesion dynamics in MDA‐MB‐231 basal breast cancer cells. Knockdown of SHIP2, a phosphatidylinositol 3,4,5‐trisphosphatase (PIP3) 5‐phosphatase that generates PI(3,4)P2, in MDA‐MB‐231 breast cancer cells, induced the development of focal adhesions and cell spreading, leading to the suppression of invasion. In contrast, knockdown of PTEN, a 3‐phosphatase that de‐phosphorylates PIP3 and PI(3,4)P2, induced cell shrinkage and increased cell invasion. Interestingly, additional knockdown of SHIP2 rescued these phenotypes. Overexpression of the TAPP1 PH domain, which binds to PI(3,4)P2, and knockdown of Lpd, a downstream effector of PI(3,4)P2, resulted in similar phenotypes to those induced by SHIP2 knockdown. Taken together, our results suggest that inhibition of PI(3,4)P2 generation and/or downstream signaling could be useful for inhibiting breast cancer metastasis.
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Affiliation(s)
- Miki Fukumoto
- The Integrated Center for Mass Spectrometry, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tadaomi Takenawa
- Division of Molecular and Cell Biology, Kobe University Graduate School of Medicine, Kobe, Japan
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10
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Ijuin T, Takeuchi Y, Shimono Y, Fukumoto M, Tokuda E, Takenawa T. Regulation of CD44 expression and focal adhesion by Golgi phosphatidylinositol 4-phosphate in breast cancer. Cancer Sci 2016; 107:981-90. [PMID: 27178239 PMCID: PMC4946718 DOI: 10.1111/cas.12968] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 03/29/2016] [Accepted: 05/02/2016] [Indexed: 12/14/2022] Open
Abstract
CD44, a transmembrane receptor, is expressed in the standard or variant form and plays a critical role in tumor progression and metastasis. This protein regulates cell adhesion and migration in breast cancer cells. We previously reported that phosphatidylinositol-4-phosphate (PI(4)P) at the Golgi regulates cell migration and invasion in breast cancer cell lines. In this study, we showed that an increase in PI(4)P levels at the Golgi by knockdown of PI(4)P phosphatase SAC1 increased the expression of standard CD44, variant CD44, and ezrin/radixin phosphorylation and enhanced the formation of focal adhesions mediated by CD44 and ezrin/radixin in MCF7 and SK-BR-3 cells. In contrast, knockdown of PI 4-kinase IIIβ in highly invasive MDA-MB-231 cells decreased these factors. These results suggest that SAC1 expression and PI(4)P at the Golgi are important in tumor progression and metastasis and are potential prognostic markers of breast cancers.
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Affiliation(s)
- Takeshi Ijuin
- Division of Biochemistry, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yukiko Takeuchi
- The Integrated Center for Mass Spectrometry, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yohei Shimono
- Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Miki Fukumoto
- Division of Membrane Biology, Biosignal Research Center, Kobe University, Kobe, Japan
| | - Emi Tokuda
- The Integrated Center for Mass Spectrometry, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tadaomi Takenawa
- Division of Membrane Biology, Biosignal Research Center, Kobe University, Kobe, Japan
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11
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Tamori Y, Tateya S, Ijuin T, Nishimoto Y, Nakajima S, Ogawa W. Negatively-charged residues in the polar carboxy-terminal region in FSP27 are indispensable for expanding lipid droplets. FEBS Lett 2016; 590:750-9. [PMID: 26921608 DOI: 10.1002/1873-3468.12114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 02/03/2016] [Accepted: 02/23/2016] [Indexed: 12/13/2022]
Abstract
FSP27 has an important role in large lipid droplet (LD) formation because it exchanges lipids at the contact site between LDs. In the present study, we clarify that the amino-terminal domain of FSP27 (amino acids 1-130) is dispensable for LD enlargement, although it accelerates LD growth. LD expansion depends on the carboxy-terminal domain of FSP27 (amino acids 131-239). Especially, the negative charge of the acidic residues (D215, E218, E219 and E220) in the polar carboxy-terminal region (amino acids 202-239) is essential for the enlargement of LD. We propose that the carboxy-terminal domain of FSP27 has a crucial role in LD expansion, whereas the amino-terminal domain only has a supportive role.
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Affiliation(s)
- Yoshikazu Tamori
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Chibune General Hospital, Osaka, Japan.,Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Sanshiro Tateya
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan.,Division of Diabetes, Department of Internal Medicine, Kakogawa West City Hospital, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Japan
| | - Yuki Nishimoto
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Shinsuke Nakajima
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Wataru Ogawa
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
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12
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Ijuin T, Hatano N, Takenawa T. Glucose-regulated protein 78 (GRP78) binds directly to PIP3 phosphatase SKIP and determines its localization. Genes Cells 2016; 21:457-65. [PMID: 26940976 DOI: 10.1111/gtc.12353] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 01/31/2016] [Indexed: 11/29/2022]
Abstract
Skeletal muscle and kidney-enriched inositol polyphosphate phosphatase (SKIP), a PIP3 phosphatase, has been implicated in the regulation of insulin signaling in skeletal muscle. SKIP interacts with Pak1 and glucose-regulated protein 78 (GRP78), both of which are necessary for the regulation of insulin signaling. In this study, we showed that GRP78 directly binds to the SKIP C-terminal homology (SKICH) domain of SKIP and that this binding is necessary for the localization of SKIP at the ER. In addition, in vitro binding analysis showed that GRP78 and Pak1 competitively bind to SKIP. Taken together, these findings suggest a model by which GRP78 regulates intracellular localization of SKIP and how SKIP binds to Pak1 on insulin stimulation.
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Affiliation(s)
- Takeshi Ijuin
- Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki Chu-o, Kobe, 650-0017, Japan
| | - Naoya Hatano
- The Integrated Center for Mass Spectrometry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki Chu-o, Kobe, 650-0017, Japan
| | - Tadaomi Takenawa
- Division of Membrane Biology, Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
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Ijuin T, Hatano N, Hosooka T, Takenawa T. Regulation of insulin signaling in skeletal muscle by PIP3 phosphatase, SKIP, and endoplasmic reticulum molecular chaperone glucose-regulated protein 78. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2015; 1853:3192-201. [DOI: 10.1016/j.bbamcr.2015.09.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 09/08/2015] [Accepted: 09/10/2015] [Indexed: 12/30/2022]
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Ando H, Hirose M, Gainche L, Kawaai K, Bonneau B, Ijuin T, Itoh T, Takenawa T, Mikoshiba K. IRBIT Interacts with the Catalytic Core of Phosphatidylinositol Phosphate Kinase Type Iα and IIα through Conserved Catalytic Aspartate Residues. PLoS One 2015; 10:e0141569. [PMID: 26509711 PMCID: PMC4624786 DOI: 10.1371/journal.pone.0141569] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/10/2015] [Indexed: 11/18/2022] Open
Abstract
Phosphatidylinositol phosphate kinases (PIPKs) are lipid kinases that generate phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), a critical lipid signaling molecule that regulates diverse cellular functions, including the activities of membrane channels and transporters. IRBIT (IP3R-binding protein released with inositol 1,4,5-trisphosphate) is a multifunctional protein that regulates diverse target proteins. Here, we report that IRBIT forms signaling complexes with members of the PIPK family. IRBIT bound to all PIPK isoforms in heterologous expression systems and specifically interacted with PIPK type Iα (PIPKIα) and type IIα (PIPKIIα) in mouse cerebellum. Site-directed mutagenesis revealed that two conserved catalytic aspartate residues of PIPKIα and PIPKIIα are involved in the interaction with IRBIT. Furthermore, phosphatidylinositol 4-phosphate, Mg2+, and/or ATP interfered with the interaction, suggesting that IRBIT interacts with catalytic cores of PIPKs. Mutations of phosphorylation sites in the serine-rich region of IRBIT affected the selectivity of its interaction with PIPKIα and PIPKIIα. The structural flexibility of the serine-rich region, located in the intrinsically disordered protein region, is assumed to underlie the mechanism of this interaction. Furthermore, in vitro binding experiments and immunocytochemistry suggest that IRBIT and PIPKIα interact with the Na+/HCO3− cotransporter NBCe1-B. These results suggest that IRBIT forms signaling complexes with PIPKIα and NBCe1-B, whose activity is regulated by PI(4,5)P2.
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Affiliation(s)
- Hideaki Ando
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
- * E-mail: (HA); (KM)
| | - Matsumi Hirose
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Laura Gainche
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Katsuhiro Kawaai
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Benjamin Bonneau
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
| | - Toshiki Itoh
- Biosignal Research Center, Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan
| | - Tadaomi Takenawa
- Biosignal Research Center, Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama, Japan
- * E-mail: (HA); (KM)
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Ijuin T, Takenawa T. Improvement of insulin signaling in myoblast cells by an addition of SKIP-binding peptide within Pak1 kinase domain. Biochem Biophys Res Commun 2015; 456:41-6. [DOI: 10.1016/j.bbrc.2014.11.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 11/11/2014] [Indexed: 12/26/2022]
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Tokuda E, Itoh T, Hasegawa J, Ijuin T, Takeuchi Y, Irino Y, Fukumoto M, Takenawa T. Phosphatidylinositol 4-phosphate in the Golgi apparatus regulates cell-cell adhesion and invasive cell migration in human breast cancer. Cancer Res 2014; 74:3054-66. [PMID: 24706697 DOI: 10.1158/0008-5472.can-13-2441] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Downregulation of cell-cell adhesion and upregulation of cell migration play critical roles in the conversion of benign tumors to aggressive invasive cancers. In this study, we show that changes in cell-cell adhesion and cancer cell migration/invasion capacity depend on the level of phosphatidylinositol 4-phosphate [PI(4)P] in the Golgi apparatus in breast cancer cells. Attenuating SAC1, a PI(4)P phosphatase localized in the Golgi apparatus, resulted in decreased cell-cell adhesion and increased cell migration in weakly invasive cells. In contrast, silencing phosphatidylinositol 4-kinase IIIβ, which generates PI(4)P in the Golgi apparatus, increased cell-cell adhesion and decreased invasion in highly invasive cells. Furthermore, a PI(4)P effector, Golgi phosphoprotein 3, was found to be involved in the generation of these phenotypes in a manner that depends on its PI(4)P-binding ability. Our results provide a new model for breast cancer cell progression in which progression is controlled by PI(4)P levels in the Golgi apparatus.
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Affiliation(s)
- Emi Tokuda
- Authors' Affiliations: Integrated Center for Mass Spectrometry; Division of Membrane Biology; and Department of Evidence-based Laboratory Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan
| | - Toshiki Itoh
- Authors' Affiliations: Integrated Center for Mass Spectrometry; Division of Membrane Biology; and Department of Evidence-based Laboratory Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan
| | - Junya Hasegawa
- Authors' Affiliations: Integrated Center for Mass Spectrometry; Division of Membrane Biology; and Department of Evidence-based Laboratory Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan
| | - Takeshi Ijuin
- Authors' Affiliations: Integrated Center for Mass Spectrometry; Division of Membrane Biology; and Department of Evidence-based Laboratory Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan
| | - Yukiko Takeuchi
- Authors' Affiliations: Integrated Center for Mass Spectrometry; Division of Membrane Biology; and Department of Evidence-based Laboratory Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan
| | - Yasuhiro Irino
- Authors' Affiliations: Integrated Center for Mass Spectrometry; Division of Membrane Biology; and Department of Evidence-based Laboratory Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan
| | - Miki Fukumoto
- Authors' Affiliations: Integrated Center for Mass Spectrometry; Division of Membrane Biology; and Department of Evidence-based Laboratory Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan
| | - Tadaomi Takenawa
- Authors' Affiliations: Integrated Center for Mass Spectrometry; Division of Membrane Biology; and Department of Evidence-based Laboratory Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan
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17
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Ijuin T, Takenawa T. Role of phosphatidylinositol 3,4,5-trisphosphate (PIP3) 5-phosphatase skeletal muscle- and kidney-enriched inositol polyphosphate phosphatase (SKIP) in myoblast differentiation. J Biol Chem 2012; 287:31330-41. [PMID: 22815484 DOI: 10.1074/jbc.m112.388785] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Insulin-like growth factors (IGFs) are essential for the development, regeneration, and hypertrophy of skeletal muscles. IGF-II promotes myoblast differentiation through phosphatidylinositol 3-kinase (PI 3-kinase), Akt, and mTOR signaling. Here, we report that skeletal muscle- and kidney-enriched inositol polyphosphate phosphatase (SKIP) negatively regulates myogenesis through inhibition of IGF-II production and attenuation of the IGF-II-Akt-mTOR signaling pathway. We also demonstrate that SKIP expression, which was markedly elevated during differentiation, was controlled by MyoD in C2C12 cells. Expression of SKIP inhibited IGF-II at the transcription level. These results indicate that SKIP regulates MyoD-mediated muscle differentiation. Silencing of SKIP increased IGF-II transcription and myoblast differentiation. Furthermore, knockdown of SKIP resulted in thick myotubes with a larger number of nuclei than that in control C2C12 cells. Taken together, these data indicate that SKIP controls the IGF-II-PI 3-kinase-Akt-mTOR auto-regulation loop during myogenesis. Our findings identify SKIP as a key regulator of muscle cell differentiation.
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Affiliation(s)
- Takeshi Ijuin
- Integrated Center for Mass Spectrometry, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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18
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Ijuin T, Takenawa T. Regulation of insulin signaling and glucose transporter 4 (GLUT4) exocytosis by phosphatidylinositol 3,4,5-trisphosphate (PIP3) phosphatase, skeletal muscle, and kidney enriched inositol polyphosphate phosphatase (SKIP). J Biol Chem 2012; 287:6991-9. [PMID: 22247557 DOI: 10.1074/jbc.m111.335539] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The glucose transporter 4 (GLUT4) is responsible for glucose uptake in the skeletal muscle. Insulin-induced translocation of GLUT4 to the plasma membrane requires phosphatidylinositol 3-kinase activation-mediated generation of phosphatidylinositol 3,4,5-trisphosphate PIP(3) and subsequent activation of Akt. Previous studies suggested that skeletal muscle and kidney enriched inositol polyphosphate phosphatase (SKIP) has negative effects on the regulation of insulin signaling in the skeletal muscle cells. Here, we compared its effects on insulin signaling by selective inhibition of SKIP, SHIP2, and phosphatase and tensin homologue on chromosome 10 (PTEN) by short interfering RNA in the C2C12 myoblast cells. Suppression of SKIP significantly increased the insulin-stimulated phosphatidylinositol 3,4,5-trisphosphate levels and Akt phosphorylation. Furthermore, silencing of SKIP, but not of PTEN, increased the insulin-dependent recruitment of GLUT4 vesicles to the plasma membrane. Taken together, these results imply that SKIP negatively regulates insulin signaling and glucose uptake by inhibiting GLUT4 docking and/or fusion to the plasma membrane.
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Affiliation(s)
- Takeshi Ijuin
- Department of Lipid Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe 650-0017, Japan
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Wang F, Ijuin T, Itoh T, Takenawa T. Regulation of IGF-1/PI3K/Akt signalling by the phosphoinositide phosphatase pharbin. J Biochem 2011; 150:83-93. [DOI: 10.1093/jb/mvr037] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Ikonomov OC, Sbrissa D, Ijuin T, Takenawa T, Shisheva A. Sac3 is an insulin-regulated phosphatidylinositol 3,5-bisphosphate phosphatase: gain in insulin responsiveness through Sac3 down-regulation in adipocytes. J Biol Chem 2009; 284:23961-71. [PMID: 19578118 DOI: 10.1074/jbc.m109.025361] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-regulated stimulation of glucose entry and mobilization of fat/muscle-specific glucose transporter GLUT4 onto the cell surface require the phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P(2)) pathway for optimal performance. The reduced insulin responsiveness observed under ablation of the PtdIns(3,5)P(2)-synthesizing PIKfyve and its associated activator ArPIKfyve in 3T3L1 adipocytes suggests that dysfunction of the PtdIns(3,5)P(2)-specific phosphatase Sac3 may yield the opposite effect. Paradoxically, as uncovered recently, in addition to turnover Sac3 also supports PtdIns(3,5)P(2) biosynthesis by allowing optimal PIKfyve-ArPIKfyve association. These opposing inputs raise the key question as to whether reduced Sac3 protein levels and/or hydrolyzing activity will produce gain in insulin responsiveness. Here we report that small interfering RNA-mediated knockdown of endogenous Sac3 by approximately 60%, which resulted in a slight but significant elevation of PtdIns(3,5)P(2) in 3T3L1 adipocytes, increased GLUT4 translocation and glucose entry in response to insulin. In contrast, ectopic expression of Sac3(WT), but not phosphatase-deficient Sac3(D488A), reduced GLUT4 surface abundance in the presence of insulin. Endogenous Sac3 physically assembled with PIKfyve and ArPIKfyve in both membrane and soluble fractions of 3T3L1 adipocytes, but this remained insulin-insensitive. Importantly, acute insulin markedly reduced the in vitro C8-PtdIns(3,5)P(2) hydrolyzing activity of Sac3. The insulin-sensitive Sac3 pool likely controls a discrete PtdIns(3,5)P(2) subfraction as the high pressure liquid chromatography-measurable insulin-dependent elevation in total [(3)H]inositol-PtdIns(3,5)P(2) was minor. Together, our data identify Sac3 as an insulin-sensitive phosphatase whose down-regulation increases insulin responsiveness, thus implicating Sac3 as a novel drug target in insulin resistance.
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Affiliation(s)
- Ognian C Ikonomov
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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Kanzaki N, Ogita H, Komura H, Ozaki M, Sakamoto Y, Majima T, Ijuin T, Takenawa T, Takai Y. Involvement of the nectin-afadin complex in PDGF-induced cell survival. J Cell Sci 2008; 121:2008-17. [DOI: 10.1242/jcs.024620] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The nectin-afadin complex is involved in the formation of cell-cell junctions, such as adherens junctions (AJs) and tight junctions (TJs). Nectins are Ca2+-independent immunoglobulin-like cell-cell adhesion molecules, whereas afadin is an intracellular nectin-binding protein that connects nectins to the cadherin-catenin system at AJs and to the claudin–zona-occludens (ZO) protein system at TJs. Afadin–/– mice show embryonic lethality, resulting from impaired migration and improper differentiation of cells due to disorganization of cell-cell junctions during gastrulation. However, it remains to be elucidated whether disruption of afadin affects apoptosis. In the present study, we first found that embryoid bodies derived from afadin-knockout embryonic stem (ES) cells contained many more apoptotic cells than those derived from wild-type ES cells. We also revealed that apoptosis induced by serum starvation or Fas-ligand stimulation was increased in cultured NIH3T3 cells when afadin or nectin-3 was knocked down. The nectin-afadin complex was involved in the platelet-derived growth factor (PDGF)-induced activation of phosphatidylinositol 3-kinase (PI3K)-Akt signaling for cell survival. This complex was associated with PDGF receptor on the plasma membrane at cell-cell adhesion sites. Thus, the nectin-afadin complex is involved in PDGF-induced cell survival, at least through the PI3K-Akt signaling pathway.
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Affiliation(s)
- Noriyuki Kanzaki
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Osaka, Japan
| | - Hisakazu Ogita
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Osaka, Japan
| | - Hitomi Komura
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Osaka, Japan
| | - Misa Ozaki
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Osaka, Japan
| | - Yasuhisa Sakamoto
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Osaka, Japan
| | - Takashi Majima
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Osaka, Japan
| | - Takeshi Ijuin
- Division of Lipid Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - Tadaomi Takenawa
- Division of Lipid Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - Yoshimi Takai
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Osaka, Japan
- Division of Molecular and Cellular Biology, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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Sbrissa D, Ikonomov OC, Fu Z, Ijuin T, Gruenberg J, Takenawa T, Shisheva A. Core protein machinery for mammalian phosphatidylinositol 3,5-bisphosphate synthesis and turnover that regulates the progression of endosomal transport. Novel Sac phosphatase joins the ArPIKfyve-PIKfyve complex. J Biol Chem 2007; 282:23878-91. [PMID: 17556371 DOI: 10.1074/jbc.m611678200] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Perturbations in phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2)-synthesizing enzymes result in enlarged endocytic organelles from yeast to humans, indicating evolutionarily conserved function of PtdIns(3,5)P2 in endosome-related events. This is reinforced by the structural and functional homology of yeast Vac14 and human Vac14 (ArPIKfyve), which activate yeast and mammalian PtdIns(3,5)P2-producing enzymes, Fab1 and PIKfyve, respectively. In yeast, PtdIns(3,5)P2-specific phosphatase, Fig4, in association with Vac14, turns over PtdIns(3,5)P2, but whether such a mechanism operates in mammalian cells and what the identity of mammalian Fig4 may be are unknown. Here we have identified and characterized Sac3, a Sac domain phosphatase, as the Fig4 mammalian counterpart. Endogenous Sac3, a widespread 97-kDa protein, formed a stable ternary complex with ArPIKfyve and PIKfyve. Concordantly, Sac3 cofractionated and colocalized with ArPIKfyve and PIKfyve. The intrinsic Sac3(WT) phosphatase activity preferably hydrolyzed PtdIns(3,5)P2 in vitro, although the other D5-phosphorylated polyphosphoinositides were also substrates. Ablation of endogenous Sac3 by short interfering RNAs elevated PtdIns(3,5)P2 in (32)P-labeled HEK293 cells. Ectopically expressed Sac3(WT) in COS cells colocalized with and dilated EEA1-positive endosomes, consistent with the PtdIns(3,5)P2 requirement in early endosome dynamics. In vitro reconstitution of carrier vesicle formation from donor early endosomes revealed a gain of function upon Sac3 loss, whereas PIKfyve or ArPIKfyve protein depletion produced a loss of function. These data demonstrate a coupling between the machinery for PtdIns(3,5)P2 synthesis and turnover achieved through a physical assembly of PIKfyve, ArPIKfyve, and Sac3. We suggest that the tight regulation in PtdIns(3,5)P2 homeostasis is mechanistically linked to early endosome dynamics in the course of cargo transport.
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Affiliation(s)
- Diego Sbrissa
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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Furutani M, Tsujita K, Itoh T, Ijuin T, Takenawa T. Application of phosphoinositide-binding domains for the detection and quantification of specific phosphoinositides. Anal Biochem 2006; 355:8-18. [PMID: 16814242 DOI: 10.1016/j.ab.2006.05.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Revised: 05/07/2006] [Accepted: 05/11/2006] [Indexed: 11/16/2022]
Abstract
In mammals, seven phosphoinositides are known to play crucial roles as signaling molecules in a variety of cellular processes. Their synthesis and degradation are thought to be strictly controlled by metabolic enzymes such as phosphoinositide kinases and phosphatases, and their aberrant activities cause diseases. Thus, there is great interest in convenient and high-throughput measurement of such activities for the screening of drugs that enhance or block them. To date, radioactive labeling and colorimetric detection of released inorganic phosphates are mainly used to measure phosphoinositide kinase and phosphatase activities, respectively. Here, we describe a novel method for detecting and quantifying individual phosphoinositides via phosphoinositide-binding domains that exhibit high specificity and affinity toward this lipid. Enzyme-linked immunosorbent assay wells are modified with alkyl chains (C16), which enables more uniform and quantitative immobilization of phosphoinositide-containing liposomes onto the well surfaces. Phosphoinositides, as the substrate or the product, are detected by pleckstrin homology domains that specifically bind to each phosphoinositide. By this method, phosphoinositide contents are measured with higher sensitivities than those by conventional methods. More importantly, both phosphoinositide kinase and phosphatase activities can be measured for purified enzymes and crude cellular lysates. This assay is easy, sensitive, and quantitative and thus may have a variety of applications in the development of diagnostic tests or the screening of therapeutic treatments for diseases such as cancer and diabetes which may be caused by abnormal phosphoinositide metabolism.
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Affiliation(s)
- Masahiro Furutani
- Department of Biochemistry, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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Furutani M, Itoh T, Ijuin T, Tsujita K, Takenawa T. Thin Layer Chromatography–Blotting, a Novel Method for the Detection of Phosphoinositides. ACTA ACUST UNITED AC 2006; 139:663-70. [PMID: 16672266 DOI: 10.1093/jb/mvj076] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Phosphoinositides are believed to be involved in fundamental cellular events such as signal transduction and vesicular trafficking. Aberrant metabolisms of this lipid, caused by mutations in phosphoinositide kinases, phosphatases and lipases are known to be related to variety of human disorders such as diabetes and cancer. While the majority of such information is obtained by analyzing genetic and biochemical properties of phosphoinositide-metabolic enzymes, direct measurement of cellular content of the lipid is hindered by the lack of a simple method that is sensitive enough to measure phosphoinositides present in trace amounts in vivo. Here, we describe a novel, thin layer chromatography (TLC)-based method by which cellular phosphoinositides are separated, transferred and detected by specific phosphoinositide-binding domains. This method was applied to follow the generation of minor phosphoinositides, such as PtdIns(3,4,5)P3 and PtdIns(3,4)P2 in response to insulin and to compare PtdIns(4,5)P2 and PtdIns(3,4,5)P3 levels in several cancer cell lines. The method has potential application not only in investigating the physiological roles of phosphoinositides, but also in diagnosing metabolic disease and cancer by directly assessing phosphoinositide levels in samples obtained from patients.
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Affiliation(s)
- Masahiro Furutani
- Department of Biochemistry, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639
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Oikawa T, Yamaguchi H, Itoh T, Kato M, Ijuin T, Yamazaki D, Suetsugu S, Takenawa T. PtdIns(3,4,5)P3 binding is necessary for WAVE2-induced formation of lamellipodia. Nat Cell Biol 2004; 6:420-6. [PMID: 15107862 DOI: 10.1038/ncb1125] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Accepted: 03/26/2004] [Indexed: 11/08/2022]
Abstract
Polarized cell movement is triggered by the development of a PtdIns(3,4,5)P(3) gradient at the membrane, which is followed by rearrangement of the actin cytoskeleton. The WASP family verprolin homologous protein (WAVE) is essential for lamellipodium formation at the leading edge by activating the Arp2/3 complex downstream of Rac GTPase. Here, we report that WAVE2 binds to PtdIns(3,4,5)P(3) through its basic domain. The amino-terminal portion of WAVE2, which includes the PtdIns(3,4,5)P(3)-binding sequence, was localized at the leading edge of lamellipodia induced by an active form of Rac (RacDA) or by treatment with platelet-derived growth factor (PDGF). Production of PtdIns(3,4,5)P(3) at the cell membrane by myristoylated phosphatidylinositol-3-OH kinase (PI(3)K) is sufficient to recruit WAVE2 in the presence of dominant-negative Rac and latrunculin, demonstrating that PtdIns(3,4,5)P(3) alone is able to recruit WAVE2. Expression of a full-length mutant of WAVE2 that lacks the lipid-binding activity inhibited proper formation of lamellipodia induced by RacDA. These results suggest that one of the products of PI(3)K, PtdIns(3,4,5)P(3), recruits WAVE2 to the polarized membrane and that this recruitment is essential for lamellipodium formation at the leading edge.
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Affiliation(s)
- Tsukasa Oikawa
- Department of Biochemistry, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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26
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Cheon MS, Kim SH, Ovod V, Kopitar Jerala N, Morgan JI, Hatefi Y, Ijuin T, Takenawa T, Lubec G. Protein levels of genes encoded on chromosome 21 in fetal Down syndrome brain: challenging the gene dosage effect hypothesis (Part III). Amino Acids 2004; 24:127-34. [PMID: 12624744 DOI: 10.1007/s00726-002-0340-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Down syndrome (DS) is the most frequent genetic disorder with mental retardation and caused by trisomy 21. Although the gene dosage effect hypothesis has been proposed to explain the impact of extra chromosome 21 on the pathology of DS, a series of evidence that challenge this hypothesis has been reported. The availability of the complete sequences of genes on chromosome 21 serves now as starting point to find functional information of the gene products, but information on gene products is limited so far. We therefore evaluated expression levels of six proteins whose genes are encoded on chromosome 21 (synaptojanin-1, chromosome 21 open reading frame 2, oligomycin sensitivity confering protein, peptide 19, cystatin B and adenosine deaminase RNA-specific 2) in fetal cerebral cortex from DS and controls at 18-19 weeks of gestational age using Western blot analysis. Synaptojanin-1 and C21orf2 were increased in DS, but others were comparable between DS and controls, suggesting that the DS phenotype cannot be simply explained by gene dosage effects. We are systematically quantifying all proteins whose genes are encoded on chromosome 21 in order to provide a better understanding of the pathobiochemistry of DS at the protein level. These studies are of significance as they show for the first time protein levels that are carrying out specific function in human fetal brain with DS.
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Affiliation(s)
- M S Cheon
- Department of Pediatrics, University of Vienna, Vienna, Austria
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27
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Tsujita K, Itoh T, Ijuin T, Yamamoto A, Shisheva A, Laporte J, Takenawa T. Myotubularin regulates the function of the late endosome through the gram domain-phosphatidylinositol 3,5-bisphosphate interaction. J Biol Chem 2004; 279:13817-24. [PMID: 14722070 DOI: 10.1074/jbc.m312294200] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myotubularin and related proteins constitute a large and highly conserved family possessing phosphoinositide 3-phosphatase activity, although not all members possess this activity. This family contains a conserved region called the GRAM domain that is found in a variety of proteins associated with membrane-coupled processes and signal transduction. Mutations of myotubularin are found in X-linked myotubular myopathy, a severe muscle disease. Mutations in the GRAM domain are responsible for this condition, suggesting crucial roles for this region. Here, we show that the GRAM domain of myotubularin binds to phosphoinositide with the highest affinity to phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P(2)). In patients with myotubular myopathy, mutations in the myotubularin GRAM domain eliminate this binding, indicating that the PtdIns(3,5)P(2) binding ability of the GRAM (glucosyltransferases, Rablike GTPase activators and myotubularin) domain is crucial for the functions of myotubularin in vivo. Stimulation of epidermal growth factor recruits myotubularin to the late endosomal compartment in a manner dependent on the phosphoinositide binding. Overexpression of myotubularin inhibits epidermal growth factor receptor trafficking from late endosome to lysosome and induces the large endosomal vacuoles. Thus, our data suggest that myotubularin phosphatase physiologically functions in late endosomal trafficking and vacuolar morphology through interaction with PtdIns(3,5)P(2).
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Affiliation(s)
- Kazuya Tsujita
- Department of Biochemistry, Institute of Medical Science, University of Tokyo and Japan Science and Technology Corporation, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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Ijuin T, Takenawa T. SKIP negatively regulates insulin-induced GLUT4 translocation and membrane ruffle formation. Mol Cell Biol 2003; 23:1209-20. [PMID: 12556481 PMCID: PMC141139 DOI: 10.1128/mcb.23.4.1209-1220.2003] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2002] [Revised: 10/03/2002] [Accepted: 11/08/2002] [Indexed: 01/02/2023] Open
Abstract
Skeletal muscle and kidney enriched inositol phosphatase (SKIP) is an inositol polyphosphate 5-phosphatase that hydrolyzes phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] to downregulate intracellular levels. In this study, we show that SKIP inhibits phosphoinositide 3-kinase signaling in insulin-stimulated CHO cells. Ectopic expression of SKIP did not inhibit insulin-induced PI(3,4,5)P3 generation but did rapidly decrease insulin-induced intracellular PI(3,4,5)P3 levels compared with those in control cells. Further, insulin-induced phosphorylation of some downstream targets such as Akt and p70 S6 kinase was markedly inhibited by the ectopic expression of SKIP, whereas phosphorylation of mitogen-activated protein kinase was not. In contrast, downregulation of intracellular SKIP levels by antisense oligonucleotides dramatically enhanced Akt (protein kinase B) phosphorylation in response to insulin, suggesting that endogenous SKIP downregulates insulin signaling. SKIP also markedly inhibited GLUT4 translocation and membrane ruffle formation. We conclude that SKIP preferentially regulates glucose transport and actin cytoskeletal rearrangement among a variety of PI(3,4,5)P3 downstream events.
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Affiliation(s)
- Takeshi Ijuin
- Department of Biochemistry, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
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Sayama K, Yamasaki K, Hanakawa Y, Shirakata Y, Tokumaru S, Ijuin T, Takenawa T, Hashimoto K. Phosphatidylinositol 3-kinase is a key regulator of early phase differentiation in keratinocytes. J Biol Chem 2002; 277:40390-6. [PMID: 12183446 DOI: 10.1074/jbc.m112423200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The survival and growth of epithelial cells depend on adhesion to the extracellular matrix. Because epidermal keratinocytes differentiate as they leave the basement membrane, an adhesion signal may regulate the initiation of differentiation. Phosphatidylinositol 3-kinase (PI3K) is a fundamental signaling molecule that regulates the adhesion signal. Transfection of a dominant negative form of PI3K into keratinocytes using an adenovirus vector resulted in significant morphological changes comparable to differentiation and the induction of differentiation markers, keratin (K) 1 and K10. In turn, transfection with the constitutively active form of PI3K almost completely abolished the induction of K1 and K10 by differentiation in suspension cultures using polyhydroxyethylmethacrylate-coated dishes. PI3K activity was lost in suspension culture, except by cells bearing the constitutively active form of PI3K. These data demonstrate that blockade of PI3K results in differentiation and that activation of PI3K prevents differentiation. Furthermore, expression of the dominant negative form of PI3K significantly inhibited keratinocyte adhesion to the extracellular matrix and reduced the surface expression of alpha(6) and beta(1) integrins in suspension culture. Moreover, expression of the active form of PI3K restored the mRNA levels of adhesion molecules that were reduced in suspension culture, including alpha(3), alpha(6), and beta(1) integrins, BP180, and BP230. In conclusion, loss of PI3K activity results in keratinocytes leaving the basement membrane and the initiation of a "default" differentiation mechanism.
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Affiliation(s)
- Koji Sayama
- Department of Dermatology, Ehime University School of Medicine, Ehime 791-0295, Japan.
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30
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Abstract
We investigated the expression of synaptojanin, which has been mapped on 21q22.2 on human chromosome, in the cerebral cortex of patients with Down syndrome (DS), using immunohistochemistry and immunoblotting. Synaptojanin expression was observed in Cajal-Retzius cells, cortical plate neurons, subplate neurons, intermediate neurons, germinal matrix cells and the ventricular neuroepithelium of the fetal cerebrum in both controls and DS. After birth, synaptojanin immunoreactivity was mainly observed in cytoplasm of cortical neurons and neurophils. These expressions of synaptojanin suggest a broader role in not only synaptic vesicle recycling, but also the regulation of neuronal migration and synaptogenesis in the fetal period. In comparison with controls, DS brains clearly showed higher immunoreactivity of synaptojanin in every structure, and most of the large neurons showed immunoreactivity. Western blotting with synaptojanin confirmed the increased expression in DS brains. Although the reason for excessive expression of synaptojanin in DS brains is obscured, one possibility can be explained on the basis of a gene dosage effect. As another possibility, on the assumption that synaptojanin modulates synaptic transmission and plays roles in clathrin-mediated synaptic vesicle endocytosis and signaling, the excessive expression of synaptojanin may be involved in compensatory mechanisms occurring in developing DS brains, such as neuronal loss, atrophic basilar dendrites, decreased spines and abnormal synaptic density and length.
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Affiliation(s)
- Yasuhiro Arai
- Department of Clinical Laboratory, National Center Hospital for Mental, Nervous and Muscular Disorders, Japan
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Arai Y, Ijuin T, Itoh M, Takenawa T, Takashima S, Becker LE. Developmental changes of synaptojanin expression in the human cerebrum and cerebellum. Brain Res Dev Brain Res 2001; 129:1-9. [PMID: 11454408 DOI: 10.1016/s0165-3806(01)00140-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Synaptojanin is a highly abundant polyphosphoinositide phosphatase in nerve terminals, and has been thought to play roles in clathrin-mediated synaptic vesicle endocytosis and signaling. In order to determine the broader role of synaptojanin in the central nervous system, we examined synaptojanin expression in the cerebrum and cerebellum from the fetal to the adult period by means of immunohistochemical and Western blot analyses. Immunohistochemistry consistently revealed the localization of synaptojanin in Cajal--Retzius cells, cortical plate neurons, subplate neurons, intermediate neurons, germinal matrix cells and the ventricular neuroepithelium of the fetal cerebrum. In the fetal cerebellum, synaptojanin immunoreactivity was localized in the external granular cell layer, Purkinje cell layer neuropil, cytoplasm of Purkinje cells and internal granular cells. The immunoreactivity in these structures was decreased around birth. After birth, the synaptojanin immunoreactivity of cortical neurons in the cerebrum, Purkinje cell layer neuropil, and internal granular cells and Purkinje cells in the cerebellum increased and reached a plateau after 11 years of age. These results were consistent with the intensity observed on Western blot analysis. These developmental changes of synaptojanin suggest a broader role in not only synaptic vesicle recycling, but also the regulation of neuronal migration and synaptogenesis in the fetal cerebrum and cerebellum.
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Affiliation(s)
- Y Arai
- Department of Clinical Laboratory, National Center Hospital for Mental, Nervous and Muscular Disorders, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8551, Japan.
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Minagawa T, Ijuin T, Mochizuki Y, Takenawa T. Identification and characterization of a sac domain-containing phosphoinositide 5-phosphatase. J Biol Chem 2001; 276:22011-5. [PMID: 11274189 DOI: 10.1074/jbc.m101579200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have characterized a novel Sac domain-containing inositol phosphatase, hSac2. It was ubiquitously expressed but especially abundant in the brain, heart, skeletal muscle, and kidney. Unlike other Sac domain-containing proteins, hSac2 protein exhibited 5-phosphatase activity specific for phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. This is the first time that the Sac domain has been reported to possess 5-phosphatase activity. Its 5-phosphatase activity for phosphatidylinositol 4,5-bisphosphate (K(m) = 14.3 microm) was comparable with those of Type II 5-phosphatases. These results imply that hSac2 functions as an inositol polyphosphate 5-phosphatase.
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Affiliation(s)
- T Minagawa
- Department of Biochemistry, The Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108-8639 Japan
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Ijuin T, Mochizuki Y, Fukami K, Funaki M, Asano T, Takenawa T. Identification and characterization of a novel inositol polyphosphate 5-phosphatase. J Biol Chem 2000; 275:10870-5. [PMID: 10753883 DOI: 10.1074/jbc.275.15.10870] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified a cDNA encoding a novel inositol polyphosphate 5-phosphatase. It contains two highly conserved catalytic motifs for 5-phosphatase, has a molecular mass of 51 kDa, and is ubiquitously expressed and especially abundant in skeletal muscle, heart, and kidney. We designated this 5-phosphatase as SKIP (Skeletal muscle and Kidney enriched Inositol Phosphatase). SKIP is a simple 5-phosphatase with no other motifs. Baculovirus-expressed recombinant SKIP protein exhibited 5-phosphatase activities toward inositol 1,4,5-trisphosphate, inositol 1,3,4,5-tetrakisphosphate, phosphatidylinositol (PtdIns) 4,5-bisphosphate, and PtdIns 3,4, 5-trisphosphate but has 6-fold more substrate specificity for PtdIns 4,5-bisphosphate (K(m) = 180 microM) than for inositol 1,4, 5-trisphosphate (K(m) = 1.15 mM). The ectopic expression of SKIP protein in COS-7 cells and immunostaining of neuroblastoma N1E-115 cells revealed that SKIP is expressed in cytosol and that loss of actin stress fibers occurs where the SKIP protein is concentrated. These results imply that SKIP plays a negative role in regulating the actin cytoskeleton through hydrolyzing PtdIns 4,5-bisphosphate.
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Affiliation(s)
- T Ijuin
- Department of Biochemistry, The Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
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Itoh T, Ijuin T, Takenawa T. A novel phosphatidylinositol-5-phosphate 4-kinase (phosphatidylinositol-phosphate kinase IIgamma) is phosphorylated in the endoplasmic reticulum in response to mitogenic signals. J Biol Chem 1998; 273:20292-9. [PMID: 9685379 DOI: 10.1074/jbc.273.32.20292] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Here, we identify a novel rat phosphatidylinositol-5-phosphate 4-kinase, phosphatidylinositol-phosphate kinase IIgamma (PIPKIIgamma). PIPKIIgamma comprises 420 amino acids with a molecular mass of 47,048 Da, showing greater homology to the type IIalpha and IIbeta isoforms (61.1 and 63.7% amino acid identities, respectively) of phosphatidylinositol-phosphate kinase than to the type I isoforms. It is predominantly expressed in kidney, with low expression in almost all other tissues. PIPKIIgamma was found to have phosphatidylinositol-5-phosphate 4-kinase activity as demonstrated in other type II kinases such as PIPKIIalpha. The PIPKIIgamma that is present endogenously in rat fibroblasts, PC12 cells, and rat whole brain lysate or that is exogenously overexpressed in COS-7 cells shows a doublet migrating pattern on SDS-polyacrylamide gel electrophoresis. Alkaline phosphatase treatment and metabolic labeling in [32P]orthophosphate experiments revealed that PIPKIIgamma is phosphorylated in vivo, resulting in a shift in its electrophoretic mobility. Phosphorylation is induced by treatment of mitogens such as serum and epidermal growth factor. Immunostaining experiments and subcellular fractionation revealed that PIPKIIgamma localizes dominantly in the endoplasmic reticulum (ER). Phosphorylation also occurs in the ER. Thus, PIPKIIgamma may have an important role in the synthesis of phosphatidylinositol bisphosphate in the ER.
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Affiliation(s)
- T Itoh
- Department of Biochemistry, Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108, Japan
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Abstract
OBJECTIVES To investigate the effect of menopause on regional and total body lean mass. METHODS Evaluation of 123 healthy premenopausal women (40.6 +/- 10.8 years) and 123 healthy postmenopausal women (61.8 +/- 7.5 years). All subjects were right side dominant. Regional (head, bilateral arms, trunk, and bilateral legs) and total body lean mass were measured using whole-body scanning by dual-energy X-ray absorptiometry. Baseline characteristics including age, height, weight, and menopausal state were recorded. These variables were compared between pre- and postmenopausal women. In all subjects, correlations between regional or total body lean mass and baseline characteristics were investigated using univariate and multiple regression analyses. RESULTS Height, and lean mass of the trunk, bilateral legs and total body were significantly lower in postmenopausal women than in premenopausal women, while lean mass of the bilateral arms did not differ between the two groups. On univariate regression analysis, bilateral arms lean mass was positively correlated with height (P < 0.001). Trunk, bilateral legs, and total body lean mass were inversely correlated with age and menopausal state (P < 0.001), but were positively correlated with height (P < 0.001). After adjusting for age and height, trunk lean mass was still correlated with menopausal state (P < 0.01). CONCLUSIONS Menopause induces lean mass loss, independent of aging and height. Trunk lean mass is more prone to decline with menopause than lean mass of other sites.
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Affiliation(s)
- T Douchi
- Department of Obstetrics and Gynecology, Faculty of Medicine, Kagoshima University, Japan
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Abstract
OBJECTIVE To investigate whether there is evidence of thyroid dysfunction in women with maternity blues. METHODS Twenty women with maternity blues and 20 age-matched normal controls were enrolled in our study. The serum levels of 6 kinds of thyroid hormones, cortisol, and prolactin (PRL) of the 2 groups were compared, and obstetric variables were recorded for each subject. In addition, significant variables correlating with the development of maternity blues were determined by stepwise regression analysis. RESULTS The serum-free triiodothyronine (FT3) level at 5 days puerperium was lower in the maternity blues group (p < 0.05) than in the control group. In the maternity blues group, the FT3 level at 5 days puerperium was lower than that at 37 weeks of pregnancy and at 1 month puerperium (p < 0.05). The reverse T3 levels and TSH levels at 5 days postpartum were higher in women with maternity blues than among the controls (p < 0.05). The proportion of primiparous women was higher in the maternity blues group (p < 0.01). Stepwise regression analysis revealed that the low FT3 level and primiparity were significantly correlated with the development of maternity blues (R2 = 0.281, p < 0.001). CONCLUSION Thyroid dysfunction might be associated with the development of maternity blues.
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Affiliation(s)
- T Ijuin
- Department of Obstetrics and Gynecology, Faculty of Medicine, Kagoshima University, Japan
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Ijuin T. [New members of regulating phosphoinositide metabolism]. Tanpakushitsu Kakusan Koso 1997; 42:385-93. [PMID: 9162975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- T Ijuin
- Department of Biochemistry, University of Tokyo, Japan
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Ijuin T, Kitajima K, Song Y, Kitazume S, Inoue S, Haslam SM, Morris HR, Dell A, Inoue Y. Isolation and identification of novel sulfated and nonsulfated oligosialyl glycosphingolipids from sea urchin sperm. Glycoconj J 1996; 13:401-13. [PMID: 8781971 DOI: 10.1007/bf00731473] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Novel sulfated and nonsulfated oligosialylglycosphingolipids were isolated from sperm of the sea urchin, Hemicentrotus pulcherrimus, and their structures were established as follows: [formula: see text] This provides the first evidence for the natural occurrence of a tetrasialic acid structure in glycosphingolipids. The finding of sulfated oligosialyl chains is especially noteworthy in that the sulfate group exclusively resides on the C-8 of the nonreducing terminal residues of oligo/polysialyl chains and that sulfation appears to be a termination signal for elongation of oligosialyl chains. Sulfation at the nonreducing terminal Neu5Ac residues of oligosialyl chains was also found to facilitate the formation of an inter-residue lactone between the carboxyl group at the nonreducing terminal sulfated Neu5Ac and the hydroxyl group at C-9 of the penultimate Neu5Ac residue. The long chain base was 4-hydroxysphinganine (t18:0) and the major fatty acid species were identified as C20:1, C21:1, and C22:1.
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Affiliation(s)
- T Ijuin
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Japan
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Abstract
The effect of 14 types of nonionic surfactants on the permeation of Tenoxicam (TEN) through guinea pigs from propylene glycol solution was investigated in vitro. The flux of TEN was significantly enhanced by polyoxyethylene alkyl ether and polyoxyethylene monoalkyl carboxylate as hydrophilic surfactants, and by polyglyceryl trialkylate, glyceryl monoalkylate, sorbitan monoalkyl carboxylate and sorbitan trialkyl carboxylate as hydrophobic surfactants. In the presence of these surfactants, the flux was increased about 2 to 4 times, as compared to the flux without them. The mechanism of nonionic surfactant action was analyzed and classified by recent methods. the including HLB of surfactants, the solubility of the drugs in vehicle and the hemolysis of erythrocytes. The results suggested that vital factors in the enhancement of skin permeation by nonionic surfactants include the affinity of the surfactants to the stratum corneum, the solubility of the drugs in vehicle and the penetration of surfactants to the stratum corneum.
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Affiliation(s)
- M Endo
- Pola R & D Laboratories, Pola Corporation, Yokohama, Japan
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