1
|
Ahmed M, Biswas T, Mondal S. The strategic involvement of IRS in cancer progression. Biochem Biophys Res Commun 2023; 680:141-160. [PMID: 37738904 DOI: 10.1016/j.bbrc.2023.09.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/13/2023] [Accepted: 09/15/2023] [Indexed: 09/24/2023]
Abstract
Insulin Receptor Substrate (IRS), an intracellular molecule devoid of an intrinsic kinase activity, is activated upon binding to IR which thereby works as a scaffold, organizing all signaling complexes and initiating the signaling process downstream. The level of IRS proteins and their stability in the cell is mostly maintained through the phosphorylation status of their tyrosine and serine residues. IRS is positively regulated by phosphorylation of its Tyr residues whereas a Ser residue phosphorylation attenuates it, although there exist some exceptions as well. Other post-translational modifications like O-linked glycosylation, N-linked glycosylation and acetylation also play a prominent role in IRS regulation. Since the discovery of the Warburg effect, people have been curious to find out all possible signaling networks and molecules that could lead to cancer and no doubt, the insulin signaling pathway is identified as one such pathway, which is highly deregulated in cancers. Eminent studies reveal that IRS is a pertinent regulator of cancer and is highly overexpressed in the five most commonly occurring cancers namely- Prostate, Ovarian, Breast, Colon and Lung cancers. IRS1 and IRS2 family members are actively involved in the progression, invasion and metastasis of these cancers. Recently, less studied IRS4 has also emerged as a contributor in ovarian, breast, colorectal and lung cancer, but no such studies related to IRS4 are found in Prostate cancer. The involvement of other IRS family members in cancer is still undiscovered and so paves the way for further exploration. This review is a time-lapse study of IRSs in the context of cancer done over the past two decades and it highlights all the major discoveries made till date, in these cancers from the perspective of IRS.
Collapse
Affiliation(s)
- Mehnaz Ahmed
- Department of Life Sciences, Presidency University, 86/1 College Street, Kolkata, 700073, West Bengal, India
| | - Tannishtha Biswas
- Department of Life Sciences, Presidency University, 86/1 College Street, Kolkata, 700073, West Bengal, India
| | - Susmita Mondal
- Department of Life Sciences, Presidency University, 86/1 College Street, Kolkata, 700073, West Bengal, India.
| |
Collapse
|
2
|
He X, Wang C, Zhu Y, Jiang X, Qiu Y, Yin F, Xiong W, Liu B, Huang Y. Spirulina compounds show hypoglycemic activity and intestinal flora regulation in type 2 diabetes mellitus mice. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
3
|
Machado-Neto JA, Fenerich BA, Rodrigues Alves APN, Fernandes JC, Scopim-Ribeiro R, Coelho-Silva JL, Traina F. Insulin Substrate Receptor (IRS) proteins in normal and malignant hematopoiesis. Clinics (Sao Paulo) 2018; 73:e566s. [PMID: 30328953 PMCID: PMC6169455 DOI: 10.6061/clinics/2018/e566s] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 07/30/2018] [Indexed: 12/31/2022] Open
Abstract
The insulin receptor substrate (IRS) proteins are a family of cytoplasmic proteins that integrate and coordinate the transmission of signals from the extracellular to the intracellular environment via transmembrane receptors, thus regulating cell growth, metabolism, survival and proliferation. The PI3K/AKT/mTOR and MAPK signaling pathways are the best-characterized downstream signaling pathways activated by IRS signaling (canonical pathways). However, novel signaling axes involving IRS proteins (noncanonical pathways) have recently been identified in solid tumor and hematologic neoplasm models. Insulin receptor substrate-1 (IRS1) and insulin receptor substrate-2 (IRS2) are the best-characterized IRS proteins in hematologic-related processes. IRS2 binds to important cellular receptors involved in normal hematopoiesis (EPOR, MPL and IGF1R). Moreover, the identification of IRS1/ABL1 and IRS2/JAK2V617F interactions and their functional consequences has opened a new frontier for investigating the roles of the IRS protein family in malignant hematopoiesis. Insulin receptor substrate-4 (IRS4) is absent in normal hematopoietic tissues but may be expressed under abnormal conditions. Moreover, insulin receptor substrate-5 (DOK4) and insulin receptor substrate-6 (DOK5) are linked to lymphocyte regulation. An improved understanding of the signaling pathways mediated by IRS proteins in hematopoiesis-related processes, along with the increased development of agonists and antagonists of these signaling axes, may generate new therapeutic approaches for hematological diseases. The scope of this review is to recapitulate and review the evidence for the functions of IRS proteins in normal and malignant hematopoiesis.
Collapse
Affiliation(s)
- João Agostinho Machado-Neto
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
- Departamento de Farmacologia do Instituto de Ciencias Biomedicas da Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Bruna Alves Fenerich
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Ana Paula Nunes Rodrigues Alves
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Jaqueline Cristina Fernandes
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Renata Scopim-Ribeiro
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Juan Luiz Coelho-Silva
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Fabiola Traina
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
- *Corresponding author. E-mail:
| |
Collapse
|
4
|
Chawla B, Hedman AC, Sayedyahossein S, Erdemir HH, Li Z, Sacks DB. Absence of IQGAP1 Protein Leads to Insulin Resistance. J Biol Chem 2017; 292:3273-3289. [PMID: 28082684 DOI: 10.1074/jbc.m116.752642] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 01/10/2017] [Indexed: 11/06/2022] Open
Abstract
Insulin binds to the insulin receptor (IR) and induces tyrosine phosphorylation of the receptor and insulin receptor substrate-1 (IRS-1), leading to activation of the PKB/Akt and MAPK/ERK pathways. IQGAP1 is a scaffold protein that interacts with multiple binding partners and integrates diverse signaling cascades. Here we show that IQGAP1 associates with both IR and IRS-1 and influences insulin action. In vitro analysis with pure proteins revealed that the IQ region of IQGAP1 binds directly to the intracellular domain of IR. Similarly, the phosphotyrosine-binding domain of IRS-1 mediates a direct interaction with the C-terminal tail of IQGAP1. Consistent with these observations, both IR and IRS-1 co-immunoprecipitated with IQGAP1 from cells. Investigation of the functional effects of the interactions revealed that in the absence of IQGAP1, insulin-stimulated phosphorylation of Akt and ERK, as well as the association of phosphatidylinositol 3-kinase with IRS-1, were significantly decreased. Importantly, loss of IQGAP1 results in impaired insulin signaling and glucose homeostasis in vivo Collectively, these data reveal that IQGAP1 is a scaffold for IR and IRS-1 and implicate IQGAP1 as a participant in insulin signaling.
Collapse
Affiliation(s)
- Bhavna Chawla
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892
| | - Andrew C Hedman
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892
| | - Samar Sayedyahossein
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892
| | - Huseyin H Erdemir
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892
| | - Zhigang Li
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892
| | - David B Sacks
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland 20892.
| |
Collapse
|
5
|
Lanzerstorfer P, Yoneyama Y, Hakuno F, Müller U, Höglinger O, Takahashi SI, Weghuber J. Analysis of insulin receptor substrate signaling dynamics on microstructured surfaces. FEBS J 2015; 282:987-1005. [PMID: 25627174 DOI: 10.1111/febs.13213] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 01/20/2015] [Accepted: 01/21/2015] [Indexed: 12/20/2022]
Abstract
Insulin receptor substrates (IRS) are phosphorylated by activated insulin/insulin-like growth factor I receptor tyrosine kinases, with this comprising an initial key event for downstream signaling and bioactivities. Despite the structural similarities, increasing evidence shows that IRS family proteins have nonredundant functions. Although the specificity of insulin/insulin-like growth factor signaling and biological responses partly reflects which IRS proteins are dominantly phosphorylated by the receptors, the precise properties of the respective IRS interaction with the receptors remain elusive. In the present study, we utilized a technique that combines micropatterned surfaces and total internal reflection fluorescence microscopy for the quantitative analysis of the interaction between IRS proteins and insulin/insulin-like growth factor in living cells. Our experimental set-up enabled the measurement of equilibrium associations and interaction dynamics of these molecules with high specificity. We revealed that several domains of IRS including pleckstrin homology and phosphotyrosine binding domains critically determine the turnover rate of the receptors. Furthermore, we found significant differences among IRS proteins in the strength and kinetic stability of the interaction with the receptors, suggesting that these interaction properties could account for the diverse functions of IRS. In addition, our analyses using fluorescent recovery after photobleaching revealed that kinases such as c-Jun N-terminal kinase and IκB kinase β, which phosphorylate serine/threonine residues of IRS and contribute to insulin resistance, altered the interaction kinetics of IRS with insulin receptor. Collectively, our experimental set-up is a valuable system for quantitifying the physiological interaction of IRS with the receptors in insulin/insulin-like growth factor signaling.
Collapse
Affiliation(s)
- Peter Lanzerstorfer
- School of Engineering and Environmental Sciences, University of Applied Sciences Upper Austria, Wels, Austria
| | | | | | | | | | | | | |
Collapse
|
6
|
Landis J, Shaw LM. Insulin receptor substrate 2-mediated phosphatidylinositol 3-kinase signaling selectively inhibits glycogen synthase kinase 3β to regulate aerobic glycolysis. J Biol Chem 2014; 289:18603-13. [PMID: 24811175 DOI: 10.1074/jbc.m114.564070] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Insulin receptor substrate 1 (IRS-1) and IRS-2 are cytoplasmic adaptor proteins that mediate the activation of signaling pathways in response to ligand stimulation of upstream cell surface receptors. Despite sharing a high level of homology and the ability to activate PI3K, only Irs-2 positively regulates aerobic glycolysis in mammary tumor cells. To determine the contribution of Irs-2-dependent PI3K signaling to this selective regulation, we generated an Irs-2 mutant deficient in the recruitment of PI3K. We identified four tyrosine residues (Tyr-649, Tyr-671, Tyr-734, and Tyr-814) that are essential for the association of PI3K with Irs-2 and demonstrate that combined mutation of these tyrosines inhibits glucose uptake and lactate production, two measures of aerobic glycolysis. Irs-2-dependent activation of PI3K regulates the phosphorylation of specific Akt substrates, most notably glycogen synthase kinase 3β (Gsk-3β). Inhibition of Gsk-3β by Irs-2-dependent PI3K signaling promotes glucose uptake and aerobic glycolysis. The regulation of unique subsets of Akt substrates by Irs-1 and Irs-2 may explain their non-redundant roles in mammary tumor biology. Taken together, our study reveals a novel mechanism by which Irs-2 signaling preferentially regulates tumor cell metabolism and adds to our understanding of how this adaptor protein contributes to breast cancer progression.
Collapse
Affiliation(s)
- Justine Landis
- From the Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Leslie M Shaw
- From the Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| |
Collapse
|
7
|
Chakraborty C, George Priya Doss C, Bandyopadhyay S, Sarkar BK, Syed Haneef SA. Mapping the Structural Topology of IRS Family Cascades Through Computational Biology. Cell Biochem Biophys 2013; 67:1319-31. [DOI: 10.1007/s12013-013-9664-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
8
|
The AP-1 complex regulates intracellular localization of insulin receptor substrate 1, which is required for insulin-like growth factor I-dependent cell proliferation. Mol Cell Biol 2013; 33:1991-2003. [PMID: 23478262 DOI: 10.1128/mcb.01394-12] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The activation of the insulin/insulin-like growth factor I (IGF-I) receptor and the subsequent tyrosine phosphorylation of insulin receptor substrates (IRSs) are key initial events in a variety of insulin/IGF bioactivities, including mitogenesis. It has been reported that IRS-1 associates with intracellular membrane compartments, and this localization is believed to be important for insulin/IGF signal transduction. However, the molecular mechanisms underlying IRS-1 localization remain unclear. Here we show that in L6 myoblasts, IRS-1 associates with μ1A of the ubiquitously expressed AP-1 complex, which packages cargo proteins into clathrin-coated vesicles derived from intracellular membranes. While wild-type IRS-1 was predominantly localized to vesicular structures, IRS-1 mutants lacking three YXXΦ motifs responsible for binding to μ1A were mislocalized to the mannose-6-phosphate receptor-positive structures, suggesting that AP-1-dependent transport to peripheral vesicles is inhibited in these mutants. Furthermore, deletion of AP-1 binding sites in IRS-1 impaired IGF-I-induced cell proliferation, accompanied by reduced tyrosine phosphorylation of IRS-1 and its association with phosphoinositide (PI) 3-kinase. These data demonstrate the importance of AP-1-dependent localization of IRS-1 in mediating IGF-I-stimulated signaling and maximum mitogenic response.
Collapse
|
9
|
MEMO1, a new IRS1-interacting protein, induces epithelial-mesenchymal transition in mammary epithelial cells. Oncogene 2012; 32:3130-8. [PMID: 22824790 DOI: 10.1038/onc.2012.327] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
MEMO1 (mediator of ErbB2-driven cell motility 1) regulates HER2-dependent cell migration. Increased MEMO1 expression is associated with cancer aggressiveness. Here, we found that MEMO1 is also involved in breast carcinogenesis via regulating insulin-like growth factor-I receptor-dependent signaling events. We showed that MEMO1 binds to insulin receptor substrate 1, activates the downstream PI3K/Akt signaling pathway, leads to upregulation of Snail1 and thereby triggers the epithelial-mesenchymal transition (EMT) program. In addition, MEMO1 overexpression is accompanied by growth factor-independent proliferation, anchorage-independent growth in soft agar, and enhanced metastatic potential. Together, these findings suggest that MEMO1 acts as an oncogene and is a potential therapeutic target for cancer treatment.
Collapse
|
10
|
Abstract
Docking proteins comprise a distinct category of intracellular, noncatalytic signalling protein, that function downstream of a variety of receptor and receptor-associated tyrosine kinases and regulate diverse physiological and pathological processes. The growth factor receptor bound 2-associated binder/Daughter of Sevenless, insulin receptor substrate, fibroblast growth factor receptor substrate 2 and downstream of tyrosine kinases protein families fall into this category. This minireview focuses on the structure, function and regulation of these proteins.
Collapse
Affiliation(s)
- Tilman Brummer
- Centre for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University of Freiburg, Freiburg, Germany
| | | | | |
Collapse
|
11
|
Mardilovich K, Pankratz SL, Shaw LM. Expression and function of the insulin receptor substrate proteins in cancer. Cell Commun Signal 2009; 7:14. [PMID: 19534786 PMCID: PMC2709114 DOI: 10.1186/1478-811x-7-14] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2009] [Accepted: 06/17/2009] [Indexed: 12/13/2022] Open
Abstract
The Insulin Receptor Substrate (IRS) proteins are cytoplasmic adaptor proteins that function as essential signaling intermediates downstream of activated cell surface receptors, many of which have been implicated in cancer. The IRS proteins do not contain any intrinsic kinase activity, but rather serve as scaffolds to organize signaling complexes and initiate intracellular signaling pathways. As common intermediates of multiple receptors that can influence tumor progression, the IRS proteins are positioned to play a pivotal role in regulating the response of tumor cells to many different microenvironmental stimuli. Limited studies on IRS expression in human tumors and studies on IRS function in human tumor cell lines and in mouse models have provided clues to the potential function of these adaptor proteins in human cancer. A general theme arises from these studies; IRS-1 and IRS-4 are most often associated with tumor growth and proliferation and IRS-2 is most often associated with tumor motility and invasion. In this review, we discuss the mechanisms by which IRS expression and function are regulated and how the IRS proteins contribute to tumor initiation and progression.
Collapse
Affiliation(s)
- Katerina Mardilovich
- Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
| | | | | |
Collapse
|
12
|
Liberman Z, Eldar-Finkelman H. Serine 332 phosphorylation of insulin receptor substrate-1 by glycogen synthase kinase-3 attenuates insulin signaling. J Biol Chem 2004; 280:4422-8. [PMID: 15574412 DOI: 10.1074/jbc.m410610200] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ability of glycogen synthase kinase-3 (GSK-3) to phosphorylate insulin receptor substrate-1 (IRS-1) is a potential inhibitory mechanism for insulin resistance in type 2 diabetes. However, the serine site(s) phosphorylated by GSK-3 within IRS-1 had not been yet identified. Using an N-terminal deleted IRS-1 mutant and two IRS-1 fragments, PTB-1 1-320 and PTB-2 1-350, we localized GSK-3 phosphorylation site(s) within amino acid sequence 320-350. Mutations of serine 332 or 336, which lie in the GSK-3 consensus motif (SXXXS) within PTB-2 or IRS-1, to alanine abolished their phosphorylation by GSK-3. This suggested that Ser332 is a GSK-3 phosphorylation site and that Ser336 serves as the "priming" site typically required for GSK-3 action. Indeed, dephosphorylation of IRS-1 prevented GSK-3 phosphorylation. Furthermore, the phosphorylated peptide derived from the IRS-1 sequence was readily phosphorylated by GSK-3, in contrast to the nonphosphorylated peptide, which was not phosphorylated by the enzyme. When IRS-1 mutants S332A(IRS-1), S336A(IRS-1), or S332A/336A(IRS-1) were expressed in Chinese hamster ovary cells overexpressing insulin receptors, their insulin-induced tyrosine phosphorylation levels increased compared with that of wild-type (WT) IRS-1. This effect was stronger in the double mutant S332A/336A(IRS-1) and led to enhanced insulin-mediated activation of protein kinase B. Finally, immunoblot analysis with polyclonal antibody directed against IRS-1 phosphorylated at Ser332 confirmed IRS-1 phosphorylation in cultured cells. Moreover, treatment with the GSK-3 inhibitor lithium reduced Ser332 phosphorylation, whereas overexpression of GSK-3 enhanced this phosphorylation. In summary, our studies identify Ser332 as the GSK-3 phosphorylation target in IRS-1, indicating its physiological relevance and demonstrating its novel inhibitory role in insulin signaling.
Collapse
Affiliation(s)
- Ziva Liberman
- Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | | |
Collapse
|
13
|
Tseng YH, Kriauciunas KM, Kokkotou E, Kahn CR. Differential roles of insulin receptor substrates in brown adipocyte differentiation. Mol Cell Biol 2004; 24:1918-29. [PMID: 14966273 PMCID: PMC350563 DOI: 10.1128/mcb.24.5.1918-1929.2004] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Insulin promotes adipocyte differentiation via a complex signaling network involving multiple insulin receptor substrates (IRSs). In cultured brown preadipocytes, expression of IRS-1 and IRS-2 mRNAs and proteins was at relatively high levels before and after differentiation into mature fat cells, while IRS-3 transcript was not detectable in preadipocytes but increased during the course of differentiation, and IRS-4 mRNA was barely detected in both states. To determine more precisely the roles of various IRS proteins in adipogenesis, we established and characterized brown preadipocyte cell lines from wild-type and IRS knockout (KO) animals. While wild-type, IRS-2 KO, and IRS-4 KO cells fully differentiated into mature adipocytes, IRS-3 KO cells showed a moderate defect in differentiation and IRS-1 KO cells exhibited a severe defect in the process. Cells lacking both IRS-1 and IRS-3 completely failed to differentiate. Expression of the adipogenic markers peroxisome proliferator-activated receptor gamma (PPARgamma), CCAAT/enhancer-binding protein alpha, fatty acid synthase, glucose transporter 4, and the transcription factor signal transducer and activator of transcription 5, as well as the brown-fat-specific markers PPARgamma coactivator 1 alpha and uncoupling protein 1, mirrored the differentiation pattern. Reconstitution of the IRS-1 KO cells with IRS-1 and IRS-4, but not IRS-2 or IRS-3, compensated for the lack of differentiation in IRS-1 KO cells. A chimeric molecule containing the N terminus of IRS-1 and the C terminus of IRS-2, but not one with the N terminus of IRS-2 and the C terminus of IRS-1, also rescued differentiation. Expression of Wnt 10a, a molecule known to inhibit adipogenesis, was dramatically increased in the IRS-1 KO cells, and this could be reduced by overexpression of IRS-1 or IRS-4, which was correlated with restoration of differentiation. These data indicate that both IRS-1 and -3 play important roles in the differentiation of brown adipocytes and that the N terminus of IRS-1 is more important for this function of the molecule. Although IRS-4 is not essential for the process, overexpression of IRS-4 can compensate for the deficiency in differentiation in IRS-1 KO cells.
Collapse
Affiliation(s)
- Yu-Hua Tseng
- Research Division, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA
| | | | | | | |
Collapse
|
14
|
Wiedmann M, Tamaki S, Silberman R, de la Monte SM, Cousens L, Wands JR. Constitutive over-expression of the insulin receptor substrate-1 causes functional up-regulation of Fas receptor. J Hepatol 2003; 38:803-10. [PMID: 12763374 DOI: 10.1016/s0168-8278(03)00117-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND/AIMS Insulin- and insulin growth factor-1 stimulated signaling through the insulin receptor substrate-1 (IRS-1) promotes hepatocellular proliferation and survival. IRS-1 over-expression in transgenic (Tg) mouse livers caused constitutive activation of Erk mitogen activated protein kinase (MAPK) and phosphatidylinositol-3 kinase (PI3K) resulting in significantly increased levels of DNA synthesis and larger hepatic masses relative to non-transgenic (non-Tg) littermates. However, the livers eventually ceased to grow but remained approximately 25% larger than non-Tg livers. We hypothesized that this growth homeostasis was achieved by parallel activation of pro-apoptosis pathways. METHODS Since Fas-mediated apoptosis is a common mechanism of hepatocyte destruction, we investigated the potential role of Fas receptor as a regulator of hepatic mass in IRS-1 transgenic mice. RESULTS Significantly increased Fas-receptor levels were detected in the livers of IRS-1 Tg compared to non-Tg mice by Western blot analysis. Functional activation of Fas-receptor in IRS-1 Tg livers was demonstrated by increased hepatocellular apoptosis caused by intravenous injection of anti-Fas (Jo-2). CONCLUSIONS These findings suggest that the increased growth caused by IRS-1 over-expression is balanced by constitutive activation of pro-death mechanisms. Failure of the IRS-1 Tg mice to develop liver cancer may be due to preservation of pro-growth, pro-death homeostasis mechanisms.
Collapse
Affiliation(s)
- Marcus Wiedmann
- Department of Medicine, Liver Research Center, Rhode Island Hospital, Brown University School of Medicine, 55 Claverick Street 4th floor, Providence, RI 02903, USA
| | | | | | | | | | | |
Collapse
|
15
|
Itoh T, Takenawa T. Phosphoinositide-binding domains: Functional units for temporal and spatial regulation of intracellular signalling. Cell Signal 2002; 14:733-43. [PMID: 12034354 DOI: 10.1016/s0898-6568(02)00028-1] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Inositol phospholipid (phosphoinositide) is a versatile lipid characterized by its isomer-specific localization, as well as its molecular diversity attributable to phosphorylation events. Phosphoinositides act as signal mediators in a spatially and temporally controlled manner. Information about the timing and location of their production is received by phosphoinositide-binding proteins and transmitted to multiple lines of intracellular events such as signal transduction, cytoskeletal rearrangement, and membrane trafficking. Among those proteins, a significant portion possess globular structural units, called domains, which are specialized for phosphoinositide binding. The pleckstrin homology (PH) domain was the first phosphoinositide-binding domain identified. It contains the largest number of members and is associated with the formation of signalling complexes on the plasma membrane. Recent studies identified other novel phosphoinositide-binding domains (Fab1p, YOTB, Vps27p, EEA1 (FYVE), Phox homology (PX), and epsin N-terminal homology (ENTH)), thus extending our knowledge of how the functional versatility of phosphoinositides is achieved.
Collapse
Affiliation(s)
- Toshiki Itoh
- Department of Biochemistry, Institute of Medical Science, University of Tokyo and CREST, Japan Science and Technology Corporation, 4-6-1 Shirokanedai, Minato-ku, Tokyo, Japan
| | | |
Collapse
|
16
|
Fujioka T, Kim JH, Adachi H, Saito K, Tsujimoto M, Yokoyama S, Ui M. Further evidence for the involvement of insulin receptor substrates in epidermal growth factor-induced activation of phosphatidylinositol 3-kinase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:4158-68. [PMID: 11488908 DOI: 10.1046/j.1432-1327.2001.02327.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In accordance with our recent results obtained with cultured rat hepatocytes [Fujioka, T. & Ui, M. (2001) Eur. J. Biochem. 268, 25-34], epidermal growth factor (EGF) gave rise to transient tyrosine phosphorylation of insulin receptor substrates (IRS-1 and IRS-2), thereby activating the bound phosphatidylinositol 3-kinase in human epidermoid carcinoma A431 cells normally abundant in EGF receptors (EGFR) and Chinese hamster ovary (CHO) cells transfected with full-length EGFR. These actions of EGF, although much smaller in magnitude than those of insulin or IGF-I in the same cells, were accompanied by tyrosine phosphorylation of EGFR rather than insulin or IGF-I receptors, never observed in wild-type CHO cells expressing no EGFR, and totally inhibited by an inhibitor of EGFR kinase, AG1478, that was without effect on insulin or IGF-I actions. Recombinant IRS-1 was phosphorylated on tyrosines upon incubation with purified EGFR from A431 cells and 32P-labeled ATP. When CHO cells were transfected with C-terminal truncated EGFR lacking three NPXY motifs responsible for direct binding to phosphotyrosine-binding domains of IRSs, no effect of EGF could be observed. We suggest that tyrosine phosphorylation of IRS-1 or IRS-2 could mediate EGFR-induced activation of phosphatidylinositol 3-kinase in mammalian cells.
Collapse
Affiliation(s)
- T Fujioka
- Ui Laboratory, Institute of Physical and Chemical Research, Hirosawa, Wako, Japan
| | | | | | | | | | | | | |
Collapse
|
17
|
Lin YL, Mettling C, Chou CK. Complexes formation between insulin receptor and extracellular signal-regulated kinases ERKs. MOLECULAR CELL BIOLOGY RESEARCH COMMUNICATIONS : MCBRC 2000; 4:234-8. [PMID: 11409918 DOI: 10.1006/mcbr.2001.0286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A property of signal transduction pathways that might explain their efficiency and specificity is the formation of signaling complexes. The recent demonstration that adaptor proteins can interact with many components of the extracellular signal-regulated kinases (ERKs) signaling cascade leads us to investigate whether such complexes may include the transmembrane receptor. The present work shows that in human hepatoma Hep3B cells, insulin receptor (IR) can be coimmunoprecipitated with other components of the ERKs cascade: insulin receptor substrate (IRS), Raf-1, and ERKs. Furthermore, these complexes formed near the cytoplasmic membrane even prior to insulin stimulation.
Collapse
Affiliation(s)
- Y L Lin
- Institut de Génétique Humaine, Centre National de la Recherche Scientifique, 141 rue de la Cardonille, Montpellier Cedex 5, 34396, France
| | | | | |
Collapse
|