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Obikane Y, Toyono T, Kokabu S, Matsuyama K, Kataoka S, Nakatomi M, Hosokawa R, Seta Y. Myogenic differentiation 1 and transcription factor 12 activate the gene expression of mouse taste receptor type 1 member 1. J Oral Biosci 2021; 63:420-428. [PMID: 34492379 DOI: 10.1016/j.job.2021.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Myogenic differentiation 1 (Myod1) is involved in the expression of taste receptor type 1 member 1 (Tas1r1) during myogenic differentiation. Further, the target genes of Myod1 participate in transcriptional control, muscle development, and synaptic function. We examined, for the first time, the function of Myod1 in the transcriptional regulation of Tas1r1. METHODS ENCODE chromatin immunoprecipitation and sequencing (ChIP-seq) data of myogenically differentiated C2C12 cells were analyzed to identify the Myod1 and transcription factor 12 (Tcf12) binding sites in the Tas1r1 promoter region. Luciferase reporter assays, DNA affinity precipitation assays, and co-immunoprecipitation assays were also performed to identify the functions of Myod1, Tcf12, and Krüppel-like factor 5 (Klf5). RESULTS Based on ENCODE ChIP-seq, Myod1 bound to the Tas1r1 promoter region containing E-boxes 1-3. Luciferase reporter assays revealed that site-directed E-box1 mutations significantly reduced promoter activation induced by Myod1 overexpression. According to the DNA affinity precipitation assay and co-immunoprecipitation assay, Myod1 formed a heterodimer with Tcf12 and bound to E-box1. Further, Klf5 bound to the GT box near E-box1, activating Tas1r1 expression. CONCLUSIONS During myogenic differentiation, the Myod1/Tcf12 heterodimer, in collaboration with Klf5, binds to E-box1 and activates Tas1r1 expression.
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Affiliation(s)
- Yui Obikane
- Division of Oral Reconstruction and Rehabilitation, Department of Oral Functions, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan
| | - Takashi Toyono
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan.
| | - Shoichiro Kokabu
- Division of Molecular Signaling and Biochemistry, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan
| | - Kae Matsuyama
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan
| | - Shinji Kataoka
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan
| | - Mitsushiro Nakatomi
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan
| | - Ryuji Hosokawa
- Division of Oral Reconstruction and Rehabilitation, Department of Oral Functions, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan
| | - Yuji Seta
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan
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The role of acetyltransferases for the temporal-specific accessibility of β-catenin to the myogenic gene locus. Sci Rep 2018; 8:15057. [PMID: 30305648 PMCID: PMC6180044 DOI: 10.1038/s41598-018-32888-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 09/13/2018] [Indexed: 12/17/2022] Open
Abstract
Molecules involved in WNT/β-catenin signaling show spatiotemporal-specific expression and play vital roles in muscle development. Our previous study showed that WNT/β-catenin signaling promotes myoblast proliferation and differentiation through the regulation of the cyclin A2 (Ccna2)/cell division cycle 25C (Cdc25c) and Fermitin family homolog 2 (Fermt2) genes, respectively. However, it remains unclear how β-catenin targets different genes from stage to stage during myogenesis. Here, we show that the accessibility of β-catenin to the promoter region of its target genes is regulated by developmental stage-specific histone acetyltransferases (HATs), lysine acetyltransferase 2B (KAT2B), and cAMP-response element-binding protein (CREB)-binding protein (CBP). We found that KAT2B was specifically expressed at the myoblast proliferation stage and formed a complex with β-catenin to induce Ccna2/Cdc25c expression. On the other hand, CBP was specifically expressed during myoblast differentiation and formed a complex with β-catenin to induce Fermt2 expression. Our findings indicate that β-catenin efficiently accesses to its target gene’s promoters by forming a complex with developmental stage-specific acetyltransferases during myogenesis.
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Abstract
Cell-cell fusion is fundamental to a multitude of biological processes ranging from cell differentiation and embryogenesis to cancer metastasis and biomaterial-tissue interactions. Fusogenic cells are exposed to biochemical and biophysical factors, which could potentially alter cell behavior. While biochemical inducers of fusion such as cytokines and kinases have been identified, little is known about the biophysical regulation of cell-cell fusion. Here, we designed experiments to examine cell-cell fusion using bulk metallic glass (BMG) nanorod arrays with varying biophysical cues, i.e. nanotopography and stiffness. Through independent variation of stiffness and topography, we found that nanotopography constitutes the primary biophysical cue that can override biochemical signals to attenuate fusion. Specifically, nanotopography restricts cytoskeletal remodeling-associated signaling, which leads to reduced fusion. This finding expands our fundamental understanding of the nanoscale biophysical regulation of cell fusion and can be exploited in biomaterials design to induce desirable biomaterial-tissue interactions.
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Ha B, Lv Z, Bian Z, Zhang X, Mishra A, Liu Y. 'Clustering' SIRPα into the plasma membrane lipid microdomains is required for activated monocytes and macrophages to mediate effective cell surface interactions with CD47. PLoS One 2013; 8:e77615. [PMID: 24143245 PMCID: PMC3797048 DOI: 10.1371/journal.pone.0077615] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 09/09/2013] [Indexed: 02/04/2023] Open
Abstract
SIRPα, an ITIMs-containing signaling receptor, negatively regulates leukocyte responses through extracellular interactions with CD47. However, the dynamics of SIRPα-CD47 interactions on the cell surface and the governing mechanisms remain unclear. Here we report that while the purified SIRPα binds to CD47 and that SIRPα is expressed on monocytes and monocytic THP-1 or U937, these SIRPα are ineffective to mediate cell binding to immobilized CD47. However, cell binding to CD47 is significantly enhanced when monocytes transmigrating across endothelia, or being differentiated into macrophages. Cell surface labeling reveals SIRPα to be diffused on naïve monocytes but highly clustered on transmigrated monocytes and macrophages. Protein crosslink and equilibrium centrifugation confirm that SIRPα in the latter cells forms oligomerized complexes resulting in increased avidity for CD47 binding. Furthermore, formation of SIRPα complexes/clusters requires the plasma membrane ‘lipid rafts’ and the activity of Src family kinase during macrophage differentiation. These results together suggest that ‘clustering’ SIRPα into plasma membrane microdomains is essential for activated monocytes and macrophages to effectively interact with CD47 and initiate intracellular signaling.
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Affiliation(s)
- Binh Ha
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
| | - Zhiyuan Lv
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
- School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Zhen Bian
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
- School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Xiugen Zhang
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
| | - Aarti Mishra
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
| | - Yuan Liu
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
- * E-mail:
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5
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Zhu D, Pan C, Li L, Bian Z, Lv Z, Shi L, Zhang J, Li D, Gu H, Zhang CY, Liu Y, Zen K. MicroRNA-17/20a/106a modulate macrophage inflammatory responses through targeting signal-regulatory protein α. J Allergy Clin Immunol 2013; 132:426-36.e8. [PMID: 23562609 DOI: 10.1016/j.jaci.2013.02.005] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 01/29/2013] [Accepted: 02/05/2013] [Indexed: 01/28/2023]
Abstract
BACKGROUND Signal-regulatory protein α (SIRPα) is an essential signaling molecule that modulates leukocyte inflammatory responses. However, the regulation of selective SIRPα synthesis and its dynamic changes in leukocytes under inflammatory stimulation remain incompletely understood. OBJECTIVE We sought to identify the microRNAs (miRNAs) that posttranscriptionally regulate SIRPα synthesis and their roles in modulating macrophage inflammatory responses. METHODS SIRPα was induced in SIRPα-negative promyelocytic cells by retinoic acid or phorbol 12-myristate 13-acetate, and the differential expression of miRNAs was assessed by means of microarray and quantitative RT-PCR assays. The roles of identified miRNAs in controlling SIRPα synthesis in leukocytes and leukocyte inflammatory responses were determined. RESULTS We identified SIRPα as a common target gene of miR-17, miR-20a, and miR-106a. During SIRPα induction, levels of these 3 miRNAs were all reduced, and their downregulation by retinoic acid or phorbol 12-myristate 13-acetate occurred through suppression of the c-Myc signaling pathway. All miR-17, miR-20a, and miR-106a specifically bound to the same seed sequence within the SIRPα 3' untranslated region and correlated inversely with SIRPα protein levels in various cells. In macrophages upregulation of miR-17, miR-20a, and miR-106a by LPS served as the mechanism underlying LPS-induced SIRPα reduction and macrophage activation. Both in vitro and in vivo assays demonstrate that miR-17, miR-20a, and miR-106a regulate macrophage infiltration, phagocytosis, and proinflammatory cytokine secretion through targeting SIRPα. CONCLUSION These findings demonstrate for the first time that miR-17, miR-20a, and miR-106a regulate SIRPα synthesis and SIRPα-mediated macrophage inflammatory responses in a redundant fashion, providing a novel pathway in which a panel of miRNAs can modulate immune polarization through regulation of macrophage activation.
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Affiliation(s)
- Dihan Zhu
- Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
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Lauriol J, Kontaridis MI. PTPN11-associated mutations in the heart: has LEOPARD changed Its RASpots? Trends Cardiovasc Med 2012; 21:97-104. [PMID: 22681964 DOI: 10.1016/j.tcm.2012.03.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In this review, we focus on elucidating the cardiac function of germline mutations in the PTPN11 gene, encoding the Src homology-2 (SH2) domain-containing protein tyrosine phosphatase SHP2. PTPN11 mutations cause LEOPARD syndrome (LS) and Noonan syndrome (NS), two disorders that are part of a newly classified family of autosomal dominant syndromes termed "RASopathies," which are caused by germline mutations in components of the RAS/RAF/MEK/ERK mitogen activating protein kinase pathway. LS and NS mutants have opposing biochemical properties, and yet, in patients, these mutations produce similar cardiac abnormalities. Precisely how LS and NS mutations lead to such similar disease etiology remains largely unknown. Recent complementary in vitro, ex vivo, and in vivo analyses reveal new insights into the functions of SHP2 in normal and pathological cardiac development. These findings also reveal the need for individualized therapeutic approaches in the treatment of patients with LS and NS and, more broadly, patients with the other "RASopathy" gene mutations as well.
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Affiliation(s)
- Jessica Lauriol
- Department of Medicine, Division of Cardiology, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA
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Protein tyrosine phosphatase-like A regulates myoblast proliferation and differentiation through MyoG and the cell cycling signaling pathway. Mol Cell Biol 2011; 32:297-308. [PMID: 22106411 DOI: 10.1128/mcb.05484-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Protein tyrosine phosphatase-like A (PTPLa) has been implicated in skeletal myogenesis and cardiogenesis. Mutations in PTPLa correlated with arrhythmogenic right ventricular dysplasia in humans and congenital centronuclear myopathy with severe hypotonia in dogs. The molecular mechanisms of PTPLa in myogenesis are unknown. In this report, we demonstrate that PTPLa is required for myoblast growth and differentiation. The cells lacking PTPLa remained immature and failed to differentiate into mature myotubes. The repressed MyoG expression was responsible for the impaired myoblast differentiation. Meanwhile, impeded cell growth, with an obvious S-phase arrest and compromised G(2)/M transition, was observed in PTPLa-deficient myoblasts. Further study demonstrated that the upregulation of cyclin D1 and cyclin E2 complexes, along with a compromised G(2)/M transition due to the decreased CDK1 (cyclin-dependent kinase 1) activity and upregulated p21, contributed to the mutant cell S-phase arrest and eventually led to the retarded cell growth. Finally, the transcriptional regulation of the PTPLa gene was explored. We identified PTPLa as a new target gene of the serum response factor (SRF). Skeletal- and cardiac-muscle-specific SRF knockouts resulted in significant decreases in PTPLa expression, suggesting a conserved transcriptional regulation of the PTPLa gene in mice.
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Handayaningsih AE, Iguchi G, Fukuoka H, Nishizawa H, Takahashi M, Yamamoto M, Herningtyas EH, Okimura Y, Kaji H, Chihara K, Seino S, Takahashi Y. Reactive oxygen species play an essential role in IGF-I signaling and IGF-I-induced myocyte hypertrophy in C2C12 myocytes. Endocrinology 2011; 152:912-21. [PMID: 21239445 DOI: 10.1210/en.2010-0981] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
IGF-I induces skeletal muscle hypertrophy by stimulating protein synthesis and suppressing the protein degradation pathway; the downstream signaling pathways Akt-mammalian target of rapamycin (mTOR)-p70-kDA-S6-kinase (p70S6K), and Forkhead box O1 (FoxO1) play essential roles in this regulation. Reactive oxygen species (ROS) modulate the signaling of various growth factors via redox regulation. However, the role of ROS in IGF-I signaling is not fully understood. In this study, we investigated whether ROS regulate the signaling and biological action of IGF-I in C2C12 myocytes. We found that IGF-I induces ROS in C2C12 myocytes. While treatment with H(2)O(2) significantly enhanced IGF-I-induced phosphorylation of the IGF-I receptor (IGF-IR), IGF-IR phosphorylation was markedly attenuated when cells were treated with antioxidants. The downstream signaling pathway, Akt-mTOR-p70S6K was subsequently down-regulated. Furthermore, the phosphorylation of FoxO1 by IGF-I decreased concomitantly with the restoration of the expression of its target genes, Atrogin-1 and muscle RING finger 1, which are related to muscle atrophy. Nox4 knockdown, which is reportedly to produce ROS in insulin signaling, attenuated IGF-I-induced IGF-IR phosphorylation, indicating that Nox4 is involved in the regulation of IGF-I signaling. Importantly, antioxidant treatments inhibited IGF-I-induced myocyte hypertrophy, demonstrating that ROS are necessary for IGF-I-induced myocyte hypertrophy in vitro. These results indicate that ROS play an essential role in the signaling and biological action of IGF-I in C2C12 myocytes.
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Affiliation(s)
- Anastasia-Evi Handayaningsih
- Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
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9
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de Oliveira MV, Marin TM, Clemente CF, Costa APD, Judice CC, Franchini KG. SHP-2 regulates myogenesis by coupling to FAK signaling pathway. FEBS Lett 2009; 583:2975-81. [PMID: 19698715 DOI: 10.1016/j.febslet.2009.08.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 08/01/2009] [Accepted: 08/11/2009] [Indexed: 11/30/2022]
Abstract
Transient dephosphorylation of FAK at Tyr-397 is required for cell cycle withdrawal early on during myogenesis. Here, we show that upon serum starvation of C2C12 myoblasts, FAK is transiently dephosphorylated in parallel with SHP-2 activation and association with FAK. SHP-2 knockdown by RNA interference suppressed the transient upregulation of SHP-2 and dephosphorylation of FAK during myogenesis. Furthermore, depletion of SHP-2 retarded the cell cycle withdrawal and the differentiation of serum-starved myoblasts into myotubes. These data provide a mechanistic basis for the reduction in FAK activity in differentiating myoblasts, indicating that myogenesis is critically triggered by FAK/SHP-2 complex.
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Affiliation(s)
- Michel V de Oliveira
- Department of Internal Medicine, School of Medicine State University of Campinas, Brazil
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Matozaki T, Murata Y, Okazawa H, Ohnishi H. Functions and molecular mechanisms of the CD47-SIRPalpha signalling pathway. Trends Cell Biol 2009; 19:72-80. [PMID: 19144521 DOI: 10.1016/j.tcb.2008.12.001] [Citation(s) in RCA: 336] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 12/30/2022]
Abstract
Signal regulatory protein (SIRP)alpha, also known as SHPS-1 or SIRPA, is a transmembrane protein that binds to the protein tyrosine phosphatases SHP-1 and SHP-2 through its cytoplasmic region and is predominantly expressed in neurons, dendritic cells and macrophages. CD47, a widely expressed transmembrane protein, is a ligand for SIRPalpha, with the two proteins constituting a cell-cell communication system. The interaction of SIRPalpha with CD47 is important for the regulation of migration and phagocytosis. Recent studies have implicated the CD47-SIRPalpha signalling pathway in immune homeostasis and in regulation of neuronal networks. Advances in the structural and functional analyses of the CD47-SIRPalpha signalling pathway now provide exciting hints of the therapeutic benefits of manipulating this signalling system in autoimmune diseases and neurological disorders.
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Affiliation(s)
- Takashi Matozaki
- Laboratory of Biosignal Sciences, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-Machi, Maebashi, Gunma, Japan.
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11
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Umemori H, Sanes JR. Signal regulatory proteins (SIRPS) are secreted presynaptic organizing molecules. J Biol Chem 2008; 283:34053-61. [PMID: 18819922 DOI: 10.1074/jbc.m805729200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Formation of chemical synapses requires exchange of organizing signals between the synaptic partners. Using synaptic vesicle aggregation in cultured neurons as a marker of presynaptic differentiation, we purified candidate presynaptic organizers from mouse brain. A major bioactive species was the extracellular domain of signal regulatory protein alpha (SIRP-alpha), a transmembrane immunoglobulin superfamily member concentrated at synapses. The extracellular domain of SIRP-alpha is cleaved and shed in a developmentally regulated manner. The presynaptic organizing activity of SIRP-alpha is mediated in part by CD47. SIRP-alpha homologues, SIRP-beta and -gamma also have synaptic vesicle clustering activity. The effects of SIRP-alpha are distinct from those of another presynaptic organizer, FGF22: the two proteins induced vesicle clusters of different sizes, differed in their ability to promote neurite branching, and acted through different receptors and signaling pathways. SIRP family proteins may act together with other organizing molecules to pattern synapses.
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Affiliation(s)
- Hisashi Umemori
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, USA.
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12
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Koyama T, Nakaoka Y, Fujio Y, Hirota H, Nishida K, Sugiyama S, Okamoto K, Yamauchi-Takihara K, Yoshimura M, Mochizuki S, Hori M, Hirano T, Mochizuki N. Interaction of scaffolding adaptor protein Gab1 with tyrosine phosphatase SHP2 negatively regulates IGF-I-dependent myogenic differentiation via the ERK1/2 signaling pathway. J Biol Chem 2008; 283:24234-44. [PMID: 18577518 DOI: 10.1074/jbc.m803907200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Grb2-associated binder 1 (Gab1) coordinates various receptor tyrosine kinase signaling pathways. Although skeletal muscle differentiation is regulated by some growth factors, it remains elusive whether Gab1 coordinates myogenic signals. Here, we examined the molecular mechanism of insulin-like growth factor-I (IGF-I)-mediated myogenic differentiation, focusing on Gab1 and its downstream signaling. Gab1 underwent tyrosine phosphorylation and subsequent complex formation with protein-tyrosine phosphatase SHP2 upon IGF-I stimulation in C2C12 myoblasts. On the other hand, Gab1 constitutively associated with phosphatidylinositol 3-kinase regulatory subunit p85. To delineate the role of Gab1 in IGF-I-dependent signaling, we examined the effect of adenovirus-mediated forced expression of wild-type Gab1 (Gab1(WT)), mutated Gab1 that is unable to bind SHP2 (Gab1(DeltaSHP2)), or mutated Gab1 that is unable to bind p85 (Gab1(Deltap85)), on the differentiation of C2C12 myoblasts. IGF-I-induced myogenic differentiation was enhanced in myoblasts overexpressing Gab1(DeltaSHP2), but inhibited in those overexpressing either Gab1(WT) or Gab1(Deltap85). Conversely, IGF-I-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation was significantly repressed in myoblasts overexpressing Gab1(DeltaSHP2) but enhanced in those overexpressing either Gab1(WT) or Gab1(Deltap85). Furthermore, small interference RNA-mediated Gab1 knockdown enhanced myogenic differentiation. Overexpression of catalytic-inactive SHP2 modulated IGF-I-induced myogenic differentiation and ERK1/2 activation similarly to that of Gab1(DeltaSHP2), suggesting that Gab1-SHP2 complex inhibits IGF-I-dependent myogenesis through ERK1/2. Consistently, the blockade of ERK1/2 pathway reversed the inhibitory effect of Gab1(WT) overexpression on myogenic differentiation, and constitutive activation of the ERK1/2 pathway suppressed the enhanced myogenic differentiation by overexpression of Gab1(DeltaSHP2). Collectively, these data suggest that the Gab1-SHP2-ERK1/2 signaling pathway comprises an inhibitory axis for IGF-I-dependent myogenic differentiation.
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Affiliation(s)
- Tatsuya Koyama
- Department of Structural Analysis, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka, Japan
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13
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Eminaga S, Bennett AM. Noonan syndrome-associated SHP-2/Ptpn11 mutants enhance SIRPalpha and PZR tyrosyl phosphorylation and promote adhesion-mediated ERK activation. J Biol Chem 2008; 283:15328-38. [PMID: 18378677 PMCID: PMC2397460 DOI: 10.1074/jbc.m801382200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 03/27/2008] [Indexed: 11/06/2022] Open
Abstract
Noonan syndrome (NS) is an autosomal dominant disorder that is associated with multiple developmental abnormalities. Activated mutations of the protein-tyrosine phosphatase, SHP-2/PTPN11, have been reported in approximately 50% of NS cases. Despite being activated, NS-associated SHP-2 mutants require plasma membrane proximity to evoke disease-associated signaling. Here we show that NS-associated SHP-2 mutants induce hypertyrosyl phosphorylation of the transmembrane glycoproteins, SIRPalpha (signal-regulatory protein alpha) and PZR (protein zero-related), resulting in their increased association with NS-associated SHP-2 mutants. NS-associated SHP-2 mutants enhanced SIRPalpha and PZR tyrosyl phosphorylation either by impairing SIRPalpha dephosphorylation or by promoting PZR tyrosyl phosphorylation. Importantly, during embryogenesis in a mouse model of NS, SIRPalpha and PZR were hypertyrosyl-phosphorylated and bound increased levels of the NS-associated SHP-2 mutant. SIRPalpha and PZR have been implicated in extracellular matrix-dependent signaling. Mouse embryonic fibroblasts derived from a mouse model of NS displayed enhanced ERK activation in response to fibronectin plating. Knockdown of SIRPalpha and PZR in these cells attenuated the enhanced activation of ERK following fibronectin plating. Thus, SIRPalpha and PZR serve as scaffolds that facilitate plasma membrane recruitment and signaling of NS-associated SHP-2 mutants.
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Affiliation(s)
| | - Anton M. Bennett
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
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Zhao XT, Qian YK, Chan AWS, Madhavan R, Peng HB. Regulation of ACh receptor clustering by the tyrosine phosphatase Shp2. Dev Neurobiol 2007; 67:1789-801. [PMID: 17659592 DOI: 10.1002/dneu.20556] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
At the vertebrate neuromuscular junction (NMJ), postsynaptic aggregation of muscle acetylcholine receptors (AChRs) depends on the activation of MuSK, a muscle-specific tyrosine kinase that is stimulated by neural agrin and regulated by muscle-intrinsic tyrosine kinases and phosphatases. We recently reported that Shp2, a tyrosine phosphatase containing src homology two domains, suppressed MuSK-dependent AChR clustering in cultured myotubes, but how this effect of Shp2 is controlled has remained unclear. In this study, biochemical assays showed that agrin-treatment of C2 mouse myotubes enhanced the tyrosine phosphorylation of signal regulatory protein alpha1 (SIRPalpha1), a known activator of Shp2, and promoted SIRPalpha1's interaction with Shp2. Moreover, in situ experiments revealed that treatment of myotubes with the Shp2-selective inhibitor NSC-87877 increased spontaneous and agrin-induced AChR clustering, and that AChR clustering was also enhanced in myotubes ectopically expressing inactive (dominant-negative) Shp2; in contrast, AChR clustering was reduced in myotubes expressing constitutively active Shp2. Significantly, expression of truncated (nonShp2-binding) and full-length (Shp2-binding) forms of SIRPalpha1 in myotubes also increased and decreased AChR clustering, respectively, and coexpression of truncated SIRPalpha1 with active Shp2 and full-length SIRPalpha1 with inactive Shp2 reversed the actions of the exogenous Shp2 proteins on AChR clustering. These results suggest that SIRPalpha1 is a novel downstream target of MuSK that activates Shp2, which, in turn, suppresses AChR clustering. We propose that an inhibitory loop involving both tyrosine kinases and phosphatases sets the level of agrin/MuSK signaling and constrains it spatially to help generate high-density AChR clusters selectively at NMJs.
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MESH Headings
- Animals
- Blotting, Western
- Enzyme Inhibitors/pharmacology
- Immunoprecipitation
- Mice
- Microscopy, Fluorescence
- Models, Neurological
- Muscle Fibers, Skeletal/metabolism
- Protein Tyrosine Phosphatase, Non-Receptor Type 11/drug effects
- Protein Tyrosine Phosphatase, Non-Receptor Type 11/metabolism
- RNA, Messenger
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptors, Cholinergic/drug effects
- Receptors, Cholinergic/metabolism
- Receptors, Immunologic/metabolism
- Transfection
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Affiliation(s)
- Xiaotao T Zhao
- Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Wadley GD, Konstantopoulos N, Macaulay L, Howlett KF, Garnham A, Hargreaves M, Cameron-Smith D. Increased insulin-stimulated Akt pSer473 and cytosolic SHP2 protein abundance in human skeletal muscle following acute exercise and short-term training. J Appl Physiol (1985) 2006; 102:1624-31. [PMID: 17185494 DOI: 10.1152/japplphysiol.00821.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of the present study was to determine in human skeletal muscle whether a single exercise bout and 7 days of consecutive endurance (cycling) training 1) increased insulin-stimulated Akt pSer(473) and 2) altered the abundance of the protein tyrosine phosphatases (PTPases), PTP1B and SHP2. In healthy, untrained men (n = 8; 24 +/- 1 yr), glucose infusion rate during a hyperinsulinemic euglycemic clamp, when compared with untrained values, was not improved 24 h following a single 60-min bout of endurance cycling but was significantly increased ( approximately 30%; P < 0.05) 24 h following completion of 7 days of exercise training. Insulin-stimulated Akt pSer(473) was approximately 50% higher (P < 0.05) 24 h following the acute bout of exercise, with this effect remaining after 7 days of training (P < 0.05). Insulin-stimulated insulin receptor and insulin receptor substrate-1 tyrosine phosphorylation were not altered 24 h after acute exercise and short-term training. Insulin did not acutely regulate the localization of the PTPases, PTP1B or SHP2, although cytosolic protein abundance of SHP2 was increased (P < 0.05; main effect) 24 h following acute exercise and short-term training. In conclusion, insulin-sensitive Akt pSer(473) and cytosolic SHP2 protein abundance are higher after acute exercise and short-term training, and this effect appears largely due to the residual effects of the last bout of prior exercise. The significance of exercise-induced alterations in cytosolic SHP2 and insulin-stimulated Akt pSer(473) on the improvement in insulin sensitivity requires further elucidation.
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Affiliation(s)
- Glenn D Wadley
- 1School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia.
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16
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Fornaro M, Burch PM, Yang W, Zhang L, Hamilton CE, Kim JH, Neel BG, Bennett AM. SHP-2 activates signaling of the nuclear factor of activated T cells to promote skeletal muscle growth. ACTA ACUST UNITED AC 2006; 175:87-97. [PMID: 17015617 PMCID: PMC2064501 DOI: 10.1083/jcb.200602029] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The formation of multinucleated myofibers is essential for the growth of skeletal muscle. The nuclear factor of activated T cells (NFAT) promotes skeletal muscle growth. How NFAT responds to changes in extracellular cues to regulate skeletal muscle growth remains to be fully defined. In this study, we demonstrate that mice containing a skeletal muscle-specific deletion of the tyrosine phosphatase SHP-2 (muscle creatine kinase [MCK]-SHP-2 null) exhibited a reduction in both myofiber size and type I slow myofiber number. We found that interleukin-4, an NFAT-regulated cytokine known to stimulate myofiber growth, was reduced in its expression in skeletal muscles of MCK-SHP-2-null mice. When SHP-2 was deleted during the differentiation of primary myoblasts, NFAT transcriptional activity and myotube multinucleation were impaired. Finally, SHP-2 coupled myotube multinucleation to an integrin-dependent pathway and activated NFAT by stimulating c-Src. Thus, SHP-2 transduces extracellular matrix stimuli to intracellular signaling pathways to promote skeletal muscle growth.
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Affiliation(s)
- Mara Fornaro
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
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17
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Dong XP, Li XM, Gao TM, Zhang EE, Feng GS, Xiong WC, Mei L. Shp2 Is Dispensable in the Formation and Maintenance of the Neuromuscular Junction. Neurosignals 2006; 15:53-63. [PMID: 16837792 DOI: 10.1159/000094484] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Accepted: 05/04/2006] [Indexed: 01/23/2023] Open
Abstract
SHP2, a protein tyrosine phosphatase with two SH2 domains, has been implicated in regulating acetylcholine receptor (AChR) gene expression and cluster formation in cultured muscle cells. To understand the role of SHP2 in neuromuscular junction (NMJ) formation in vivo, we generated mus cle-specific deficient mice by using a loxP/Cre strategy since Shp2 null mutation causes embryonic lethality. Shp2(floxed/floxed) mice were crossed with mice expressing the Cre gene under the control of the human skeletal alpha-actin (HSA) promoter. Expression of SHP2 was reduced or diminished specifically in skeletal muscles of the conditional knockout (CKO) mice. The mutant mice were viable and fertile, without apparent muscle defects. The mRNA of the AChR alpha subunit and AChR clusters in CKO mice were localized in a narrow central region surrounding the phrenic nerve primary branches, without apparent change in intensity. AChR clusters colocalized with markers of synaptic vesicles and Schwann cells, suggesting proper differentiation of presynaptic terminals and Schwann cells. In comparison with age-matched littermates, no apparent difference was observed in the size and length of AChR clusters in CKO mice. Both the frequency and amplitude of mEPPs in CKO mice were similar to those in controls, suggesting normal neurotransmission when SHP2 was deficient. These results suggest that Shp2 is not required for NMJ formation and/or maintenance.
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Affiliation(s)
- Xian-Ping Dong
- Program of Developmental Neurobiology, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912, USA
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18
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Kang B, Liang Y, Shan Y, Guo M, Liu S, Fu X, Cao H, Wu M, Wang H. SIRPα negatively regulates differentiation of PC12 cell. ACTA ACUST UNITED AC 2005; 138:205-14. [PMID: 15964662 DOI: 10.1016/j.molbrainres.2005.04.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2004] [Revised: 03/22/2005] [Accepted: 04/18/2005] [Indexed: 02/04/2023]
Abstract
Signal regulatory protein alpha (SIRPalpha) is an Ig superfamily protein whose cytoplasmic region contains immunoreceptor tyrosine-based inhibitory motif (ITIM), which when tyrosine phosphorylated binds the SH2-domain containing phosphatase 2 (SHP-2). Both SIRPalpha and SHP-2 are highly expressed in brain. Murine cerebellar cells cultured on SIRPalpha-coated surface exhibit enhanced neurite outgrowth and SIRPalpha is localized at sites of synaptogenesis in postnatal mouse brain. In this study, we show that nerve growth factor (NGF) stimulation resulted in elevated SIRPalpha expression during PC12 differentiation. We also show that NGF-induced morphological differentiation, but not growth arrest response, was inhibited by ectopic SIRPalpha expression. PC12 cells stably expressing SIRPalpha proliferated more rapidly than mock-transfected cells. The activity of c-jun N-terminal kinase (JNK) decreased in SIRPalpha-transfected PC12 cells, whereas nuclear factor-kappaB (NF-kappaB) activity increased. Collectively, our results suggest that SIRPalpha may stabilize synaptic connections by inhibiting improper neurite outgrowth and might realize its neuronal function, at least in part, by modulating JNK and NF-kappaB activity.
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Affiliation(s)
- Bin Kang
- International Cooperation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Institute, Second Military Medical University, Shanghai 200438, China
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19
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Kontaridis MI, Eminaga S, Fornaro M, Zito CI, Sordella R, Settleman J, Bennett AM. SHP-2 positively regulates myogenesis by coupling to the Rho GTPase signaling pathway. Mol Cell Biol 2004; 24:5340-52. [PMID: 15169898 PMCID: PMC419889 DOI: 10.1128/mcb.24.12.5340-5352.2004] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Myogenesis is an intricate process that coordinately engages multiple intracellular signaling cascades. The Rho family GTPase RhoA is known to promote myogenesis, however, the mechanisms controlling its regulation in myoblasts have yet to be fully elucidated. We show here that the SH2-containing protein tyrosine phosphatase, SHP-2, functions as an early modulator of myogenesis by regulating RhoA. When MyoD was expressed in fibroblasts lacking functional SHP-2, muscle-specific gene activity was impaired and abolition of SHP-2 expression by RNA interference inhibited muscle differentiation. By using SHP-2 substrate-trapping mutants, we identified p190-B RhoGAP as a SHP-2 substrate. When dephosphorylated, p190-B RhoGAP has been shown to stimulate the activation of RhoA. During myogenesis, p190-B RhoGAP was tyrosyl dephosphorylated concomitant with the stimulation of SHP-2's phosphatase activity. Moreover, overexpression of a catalytically inactive mutant of SHP-2 inhibited p190-B RhoGAP tyrosyl dephosphorylation, RhoA activity, and myogenesis. These observations strongly suggest that SHP-2 dephosphorylates p190-B RhoGAP, leading to the activation of RhoA. Collectively, these data provide a mechanistic basis for RhoA activation in myoblasts and demonstrate that myogenesis is critically regulated by the actions of SHP-2 on the p190-B Rho GAP/RhoA pathway.
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Affiliation(s)
- Maria I Kontaridis
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
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20
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Yusa SI, Campbell KS. Src homology region 2-containing protein tyrosine phosphatase-2 (SHP-2) can play a direct role in the inhibitory function of killer cell Ig-like receptors in human NK cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:4539-47. [PMID: 12707331 DOI: 10.4049/jimmunol.170.9.4539] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The inhibitory forms of killer cell Ig-like receptors (KIR) are MHC class I-binding receptors that are expressed by human NK cells and prevent their attack of normal cells. Substantial evidence indicates that the mechanism of KIR-mediated inhibition involves recruitment of the protein tyrosine phosphatase, Src homology region 2-containing protein tyrosine phosphatase (SHP)-1, to phosphorylated immunoreceptor tyrosine-based inhibitory motifs (ITIMs). However, the functional significance of parallel recruitment of a SHP-1-related phosphatase, SHP-2, to KIR ITIMs has not been addressed. In the present study, our results with mutant forms of a classical KIR, KIR3DL1, show a direct correlation between SHP-2 recruitment and functional inhibition of target cell conjugation and cytotoxicity. In addition, KIR3DL1 inhibition of target cell cytotoxicity is blocked by overexpression of a dominant-negative form of SHP-2. Finally, KIR3DL1 fused directly with the catalytic domain of SHP-2 inhibits both target cell conjugation and cytotoxicity responses. These results strongly indicate that SHP-2 catalytic activity plays a direct role in inhibitory KIR functions, and SHP-2 inhibits NK cell activation in concert with SHP-1.
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MESH Headings
- Adjuvants, Immunologic/biosynthesis
- Adjuvants, Immunologic/genetics
- Adjuvants, Immunologic/physiology
- Amino Acid Motifs/genetics
- Amino Acid Motifs/immunology
- Amino Acid Sequence
- Animals
- Catalytic Domain/genetics
- Catalytic Domain/immunology
- Cell Line
- Cytotoxicity Tests, Immunologic
- Cytotoxicity, Immunologic/genetics
- Cytotoxicity, Immunologic/immunology
- Genetic Vectors
- Humans
- Intracellular Signaling Peptides and Proteins
- Killer Cells, Natural/enzymology
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Mice
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Protein Phosphatase 2
- Protein Tyrosine Phosphatase, Non-Receptor Type 11
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/biosynthesis
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/physiology
- Receptors, Immunologic/antagonists & inhibitors
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Receptors, KIR
- Receptors, KIR3DL1
- SH2 Domain-Containing Protein Tyrosine Phosphatases
- Sequence Deletion
- Tumor Cells, Cultured
- Tyrosine/genetics
- src Homology Domains/genetics
- src Homology Domains/immunology
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Affiliation(s)
- Sei-Ichi Yusa
- Division of Basic Science, Fox Chase Cancer Center, Institute for Cancer Research, Philadelphia, PA 19111, USA
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21
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Sordella R, Jiang W, Chen GC, Curto M, Settleman J. Modulation of Rho GTPase signaling regulates a switch between adipogenesis and myogenesis. Cell 2003; 113:147-58. [PMID: 12705864 DOI: 10.1016/s0092-8674(03)00271-x] [Citation(s) in RCA: 303] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Mature adipocytes and myocytes are derived from a common mesenchymal precursor. While IGF-1 promotes the differentiation of both cell types, the signaling pathways that specify the distinct cell fates are largely unknown. Here, we show that the Rho GTPase and its regulator, p190-B RhoGAP, are components of a critical switch in the adipogenesis-myogenesis "decision." Cells derived from embryos lacking p190-B RhoGAP exhibit excessive Rho activity, are defective for adipogenesis, but undergo myogenesis in response to IGF-1 exposure. In vitro, activation of Rho-kinase by Rho inhibits adipogenesis and is required for myogenesis. The activation state of Rho following IGF-1 signaling is determined by the tyrosine-phosphorylation status of p190-B RhoGAP and its resulting subcellular relocalization. Moreover, adjusting Rho activity is sufficient to alter the differentiation program of adipocyte and myocyte precursors. Together, these results identify the Rho GTPase as an essential modulator of IGF-1 signals that direct the adipogenesis-myogenesis cell fate decision.
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Affiliation(s)
- Raffaella Sordella
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13th Street, Charlestown, MA 02129, USA
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22
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Kontaridis MI, Liu X, Zhang L, Bennett AM. Role of SHP-2 in fibroblast growth factor receptor-mediated suppression of myogenesis in C2C12 myoblasts. Mol Cell Biol 2002; 22:3875-91. [PMID: 11997521 PMCID: PMC133814 DOI: 10.1128/mcb.22.11.3875-3891.2002] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ligand activation of the fibroblast growth factor receptor (FGFR) represses myogenesis and promotes activation of extracellular signal-regulated kinases 1 and 2 (Erks). The precise mechanism through which the FGFR transmits both of these signals in myoblasts remains unclear. The SH2 domain-containing protein tyrosine phosphatase, SHP-2, has been shown to participate in the regulation of FGFR signaling. However, no role for SHP-2 in FGFR myogenic signaling is known. In this study, we show that stimulation of C2C12 myoblasts with FGF-2 induces SHP-2 complex formation with tyrosyl-phosphorylated FGFR substrate 2 alpha (FRS-2 alpha). Both the catalytic activity and, to a much lesser extent, the Grb2 binding-tyrosyl phosphorylation sites of SHP-2 are required for maximal FGF-2-induced Erk activity and Elk-1 transactivation. When overexpressed in C2C12 myoblasts, wild-type SHP-2, but not a catalytically inactive SHP-2 mutant, potentiates the suppressive effects of FGF-2 on muscle-specific gene expression. In addition, expression of a constitutively active mutant of SHP-2 is sufficient to prevent myogenesis. The constitutively active mutant of SHP-2 induces hyper-tyrosyl phosphorylation of FRS-2 alpha but fails to stimulate or potentiate either FGF-2-induced Erk activation or Elk-1 transactivation. These data suggest that in myoblasts, SHP-2 represses myogenesis via a pathway that is independent of the Erks. We propose that SHP-2 plays a pivotal role in FGFR signaling in myoblasts via both Erk-dependent and Erk-independent pathways.
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Affiliation(s)
- Maria I Kontaridis
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520-8066, USA
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23
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Oshima K, Ruhul Amin ARM, Suzuki A, Hamaguchi M, Matsuda S. SHPS-1, a multifunctional transmembrane glycoprotein. FEBS Lett 2002; 519:1-7. [PMID: 12023008 DOI: 10.1016/s0014-5793(02)02703-5] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Src homology 2 (SH2) domain-containing protein tyrosine phosphatase substrate 1 (SHPS-1) is a member of the signal regulatory protein (SIRP) family. The amino-terminal immunoglobulin-like domain of SHPS-1 is necessary for interaction with CD47, a ligand for SHPS-1, which plays an important role in cell-cell interaction. The intracellular region of SHPS-1, on the other hand, may act as a scaffold protein, binding to various adapter proteins. Interestingly, increasing evidence has shown that SHPS-1 is involved in various biological phenomena, including suppression of anchorage-independent cell growth, negative regulation of immune cells, self-recognition of red blood cells, mediation of macrophage multinucleation, skeletal muscle differentiation, entrainment of circadian clock, neuronal survival and synaptogenesis. Recent progress has been made in attributing these novel exciting functions. Here we discuss how this interesting molecule works and consider its true role in biology.
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Affiliation(s)
- Kumi Oshima
- Department of Molecular Pathogenesis, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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