Serine 332 Phosphorylation of Insulin Receptor Substrate-1 by Glycogen Synthase Kinase-3 Attenuates Insulin Signaling

Liberman, Ziva; Eldar-Finkelman, Hagit

doi:10.1074/jbc.m410610200

Cited by 150 publications

(124 citation statements)

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“…Extensive research has implicated inhibitory Ser/Thr phosphorylations on IRS1 in the development of type II diabetes, a disease characterized by impaired responses to insulin in target tissues (44,58). Several Ser/Thr sites on IRS1 are phosphorylated in response to different stimuli, and mutation of select sites to Ala enhances insulin-mediated activation of targets downstream of IRS1, including PI3K (44,(73)(74)(75)(76)(77). IRS1(Ser 789 ) is among the sites identified as inhibitory to PI3K activation (77,78), and it is dephosphorylated in GCs with FSH in a PP1-and PKA-dependent manner (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Insulin Receptor Substrate 1, the Hub Linking Follicle-stimulating Hormone to Phosphatidylinositol 3-Kinase Activation

Law

Hunzicker-Dunn

2016

Journal of Biological Chemistry

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The ubiquitous phosphatidylinositol 3-kinase (PI3K) signaling pathway regulates many cellular functions. However, the mechanism by which G protein-coupled receptors (GPCRs) signal to activate PI3K is poorly understood. We have used ovarian granulosa cells as a model to investigate this pathway, based on evidence that the GPCR agonist follicle-stimulating hormone (FSH) promotes the protein kinase A (PKA)-dependent phosphorylation of insulin receptor substrate 1 (IRS1) on tyrosine residues that activate PI3K. We report that in the absence of FSH, granulosa cells secrete a subthreshold concentration of insulin-like growth factor-1 (IGF-1) that primes the IGF-1 receptor (IGF-1R) but fails to promote tyrosine phosphorylation of IRS1. FSH via PKA acts to sensitize IRS1 to the tyrosine kinase activity of the IGF-1R by activating protein phosphatase 1 (PP1) to promote dephosphorylation of inhibitory Ser/Thr residues on IRS1, including Ser 789 . Knockdown of PP1␤ blocks the ability of FSH to activate PI3K in the presence of endogenous IGF-1. Activation of PI3K thus requires both PKA-mediated relief of IRS1 inhibition and IGF-1R-dependent tyrosine phosphorylation of IRS1. Treatment with FSH and increasing concentrations of exogenous IGF-1 triggers synergistic IRS1 tyrosine phosphorylation at PI3K-activating residues that persists downstream through protein kinase B (AKT) and FOXO1 (forkhead box protein O1) to drive synergistic expression of genes that underlies follicle maturation. Based on the ability of GPCR agonists to synergize with IGFs to enhance gene expression in other cell types, PP1 activation to relieve IRS1 inhibition may be a more general mechanism by which GPCRs act with the IGF-1R to activate PI3K/AKT.The phosphatidylinositol-3 kinase (PI3K) signaling pathway regulates transcription, translation, proliferation, and apoptosis (1, 2). Whereas PI3K is classically activated by receptor tyrosine kinases, such as the insulin-like growth factor-1 receptor (IGF-1R), 2 PI3K is also activated in many cells by G-proteincoupled receptors (GPCRs). However, the mechanisms by which GPCRs signal to activate PI3K are much less understood compared with classical activation by receptor tyrosine kinases (1). We have used rat ovarian granulosa cells (GCs) as a model to elucidate the mechanism by which the GPCR agonist folliclestimulating hormone (FSH) activates PI3K, based on prior evidence that FSH activates PI3K in a protein kinase A (PKA)-dependent manner (3). FSH is an obligatory regulator of ovarian follicle maturation. During the menstrual cycle, preantral follicles that encompass developing oocytes mature to a preovulatory stage in response to elevated levels of FSH (4). Administration of exogenous FSH also restores follicle development in anovulatory women (5). Finally, mice harboring null alleles for either the FSH receptor or FSH␤ lack preovulatory follicles and are infertile (6, 7). Traditionally, FSH has thus been considered both necessary and sufficient to promote follicle maturation.FSH acts exclusively on GCs wit...

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Section: Discussionmentioning

confidence: 99%

Insulin Receptor Substrate 1, the Hub Linking Follicle-stimulating Hormone to Phosphatidylinositol 3-Kinase Activation

Law

Hunzicker-Dunn

2016

Journal of Biological Chemistry

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“…The GSK-3 phosphorylation site on IRS-1 is Ser 332 and its phosphorylation can be detected by a specific antibody (33). IRS-1 phosphorylation increases significantly when co-expressed with GSK-3.…”

Section: The Effect Of Gsk-3 Mutant Proteins On Glycogen Synthase Actmentioning

confidence: 99%

“…␤-Catenin is a key downstream target in Wnt signaling pathway and a substrate of GSK-3 phosphorylated at Ser 33,37 and Thr 41 (44). Phosphorylation of Ser 45 in ␤-catenin by casein kinase-1 (CKI), serves as a priming site for subsequent phosphorylation by GSK3 (44,45).…”

Section: The Effect Of Gsk-3 Mutant Proteins On Glycogen Synthase Actmentioning

confidence: 99%

“…pCREB-EGFP plasmid was purchased from BD Biosciences Clontech (Palo Alto, CA). pCMV4IRS-1 plasmid was described (33). GFP-␤-catenin was kindly provided by Dr. Rina Abersfeld from Tel Aviv University.…”

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confidence: 99%

“…) and anti-phospho-CREB (Ser 133 ) antibodies were obtained from Upstate Biotechnology (Lake Placid, NY), anti-phospho-CREB (Ser 129/133 ) was obtained from BioSource International, Inc (Camarillo, CA), CREB antibody, anti-phospho-␤-catenin, or ␤-catenin antibody were obtained from Cell Signaling Technology (Beverly, MA) and anti-phospho-IRS-1 (Ser 332 ) were described before (33). Radioactive materials were purchased from Amersham Biosciences.…”

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confidence: 99%

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Identification of Novel Glycogen Synthase Kinase-3β Substrate-interacting Residues Suggests a Common Mechanism for Substrate Recognition

Ilouz

Kowalsman

Eisenstein

et al. 2006

Journal of Biological Chemistry

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Substrate recognition and specificity are essential for the reliability and fidelity of protein kinase function. GSK-3 has a unique substrate specificity that requires prior phosphorylation of its substrates. However, how the enzyme selects its phosphorylated substrates is unknown. Here, we combined in silico modeling with mutagenesis and biological studies to identify GSK-3-substrate interaction sites located within its binding cleft. Protein-protein docking of GSK-3␤ and the phosphorylated cAMP responsive element binding protein (pCREB) (using the available experimentally determined structures), identified Phe 67 , Gln 89 , and Asn 95 of GSK-3␤ as putative binding sites interacting with the CREB phosphorylation motif. Mutations of these residues to alanine impaired GSK-3␤ phosphorylation of several substrates, without abrogating its autocatalytic activity. Subsequently, expression of the GSK-3␤ mutants in cells resulted in decreased phosphorylation of substrates CREB, IRS-1, and ␤-catenin, and prevented their suppression of glycogen synthase activity as compared with cells expressing the wildtype GSK-3␤. Our studies provide important additional understanding of how GSK-3␤ recognizes its substrates: In addition to prior phosphorylation typically required in GSK-3 substrates, substrate recognition involves interactions with GSK-3␤ residues: Phe 67 , Gln 89 , and Asn 95 , which confer a common basis for substrate binding and selectivity, yet allow for substrate diversity. Glycogen synthase kinase 3 (GSK-3)4 is a ubiquitous serine/ threonine kinase expressed as two isoforms (␣ and ␤) (1), and has been implicated in many biological processes, including glucose metabolism, cell apoptosis, and embryonic development (reviewed in Refs. 2-4). The cellular activity of GSK-3 is stringently controlled in response to growth factors and hormones. However, unlike most protein kinases, GSK-3 is constitutively active in resting cells and becomes inhibited upon stimulation of the cells. This inhibition is achieved through direct phosphorylation of N-terminal serine residues (Ser 21 or Ser 9 in ␣, ␤, respectively) by several protein kinases, such as PKB, p90RSK, PKA, and PKC (2-4). GSK-3 also may be phosphorylated on Tyr 216 located in the activation loop (5). This phosphorylation is an autophosphorylation event as demonstrated by in vitro and in vivo cell systems (5-7).Elevated activity of GSK-3 is associated with several diseases, including type 2 diabetes, neurodegenerative diseases, and affective disorders (8 -10). Hence, selective inhibitors of GSK-3 may be of therapeutic value and are currently under extensive development (11)(12)(13)(14). Thus, understanding of how GSK-3 interacts with its substrates may pave the way for design and development of new specific substrate competitive GSK-3 inhibitors.Substrate specificity of protein kinases is a fundamental determinant for the integrity and fidelity of signaling pathways. Previous studies formulated consensus sequences for optimal phosphorylation motifs of protein kinases usi...

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Apolipoprotein B100 acts as a molecular link between lipid-induced endoplasmic reticulum stress and hepatic insulin resistance #

Tsai

et al. 2009

Hepatology

100

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Accumulation of unfolded and misfolded proteins in the endoplasmic reticulum (ER) results in ER stress and lipid overload-induced ER stress has been implicated in the development of insulin resistance. Here, evidence is provided for a molecular link between hepatic apolipoprotein B100 (apoB100), induction of ER stress, and attenuated insulin signaling. First, in vivo upregulation of hepatic apoB100 by a lipogenic diet was found to be closely associated with ER stress and attenuated insulin signaling in the liver. Direct in vivo overexpression of human apoB100 in a mouse transgenic model further supported the link between excessive apoB100 expression and hepatic ER stress. Human apoB100 transgenic mice exhibited hypertriglyceridemia and hyperglycemia. In vitro, accumulation of cellular apoB100 by free fatty acid ( P erturbations in lipid metabolism and lipid signaling underlie the pathogenesis of a cluster of chronic metabolic diseases, including insulin resistance, type 2 diabetes, fatty liver disease, and atherosclerosis.The atherogenic dyslipidemia commonly associated with insulin-resistant states consists of hypertriglyceridemia, a high level of very low-density lipoprotein (VLDL), a low level of high-density lipoprotein (HDL) cholesterol, 1 and elevated small, low-density lipoprotein (LDL). High dietary fat intake has been shown to induce insulin resistance (IR) and the lipid synthetic rate by way of increased free fatty acid (FFA) flux, as well as assembly and secretion of both VLDL-apolipoprotein B (apoB) and triglyceride (TG) in animal and human models. 2,3 The association of IR and increased VLDL secretion is thought to be derived from increased FFA delivery to the liver resulting from increased lipolysis in adipose tissue, a phenomenon accompanied by increased hepatic lipogenesis, increased hepatic microsomal triglyceride transfer protein (MTP) level and activity, and loss of apoB regulation by insulin.Recent studies implicate hepatic ER stress as a central abnormality linking obesity, hepatic IR, and hepatic steatosis. 4,5 Ozcan et al. 4 have demonstrated that obesityinduced ER stress leads to hepatic IR by activating c-Jun N-terminal kinase (JNK) through inositol-requiring enzyme-1 (IRE-1), with subsequent inhibition of insulin receptor signaling. ER stress has also been linked to increased hepatic lipogenesis. 6,7 However, loss of MTP activity in mouse hepatocytes by either gene disruption or

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Serine 332 Phosphorylation of Insulin Receptor Substrate-1 by Glycogen Synthase Kinase-3 Attenuates Insulin Signaling

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.

Cited by 150 publications

References 60 publications

Insulin Receptor Substrate 1, the Hub Linking Follicle-stimulating Hormone to Phosphatidylinositol 3-Kinase Activation

Insulin Receptor Substrate 1, the Hub Linking Follicle-stimulating Hormone to Phosphatidylinositol 3-Kinase Activation

Identification of Novel Glycogen Synthase Kinase-3β Substrate-interacting Residues Suggests a Common Mechanism for Substrate Recognition

Apolipoprotein B100 acts as a molecular link between lipid-induced endoplasmic reticulum stress and hepatic insulin resistance #

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