Regulation of Insulin-Stimulated Tyrosine Phosphorylation of Shc and Shc/Grb2 Association in Liver, Muscle, and Adipose Tissue of Epinephrine- and Streptozotocin-Treated Rats

Paez-Espinosa, Veronica; Rocha, Eduardo Melani; Velloso, Lı́cio A.; Saad, Mário José Abdalla

doi:10.1385/endo:14:3:295

Cited by 6 publications

(5 citation statements)

References 36 publications

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“…In VSMCs hyperglycemia results in increased proliferation and migration, and these responses are associated with enhanced MAPK activation (5). Similar observations have been reported in streptozotocin-induced diabetic rats that show an increase in Shc phosphorylation and Grb2 association with insulin stimulation (49). Our studies have shown that this enhanced MAPK activity is dependent upon increased Shc tyrosine phosphorylation and Grb2 association (3,5).…”

Section: Discussionsupporting

confidence: 88%

Insulin-like Growth Factor-I Stimulates Shc-dependent Phosphatidylinositol 3-Kinase Activation via Grb2-associated p85 in Vascular Smooth Muscle Cells

Radhakrishnan¹,

Maile²,

Ling³

et al. 2008

Journal of Biological Chemistry

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Insulin-like growth factor-I (IGF-I) stimulates vascular smooth muscle cell proliferation and migration by activating both MAPK and phosphatidylinositol 3-kinase (PI3K). Vascular smooth muscle cells (VSMCs) maintained in 25 mM glucose sustain MAPK activation via increased Shc phosphorylation and Grb2 association resulting in an enhanced mitogenic response compared with cells grown in 5 mM glucose. PI3K plays a major role in IGF-I-stimulated VSMC migration, and hyperglycemia augments this response. In contrast to MAPK activation the role of Shc in modulating PI3K in response to IGF-I has not been determined. In this study we show that impaired Shc association with Grb2 results in decreased Grb2-p85 association, SHPS-1-p85 recruitment, and PI3K activation in response to IGF-I. Exposure of VSMCs to cell-permeable peptides, which contained polyproline sequences from p85 proposed to mediate Grb2 association, resulted in inhibition of Grb2-p85 binding and AKT phosphorylation. Transfected cells that expressed p85 mutant that had specific prolines mutated to alanines resulted in less Grb2-p85 association, and a Grb2 mutant (W36A/ W193A) that attenuated p85 binding showed decreased association of p85 with SHPS-1, PI3K activation, AKT phosphorylation, cell proliferation, and migration in response to IGF-I. Cellular exposure to 25 mM glucose, which is required for Shc phosphorylation in response to IGF-I, resulted in enhanced Grb2 binding to p85, activation of PI3K activity, and increased AKT phosphorylation as compared with cells exposed to 5 mM glucose. We conclude that in VSMCs exposed to hyperglycemia, IGF-I stimulation of Shc facilitates the transfer of Grb2 to p85 resulting in enhanced PI3K activation and AKT phosphorylation leading to enhanced cell proliferation and migration. Insulin-like growth factor-I (IGF-I)2 stimulates proliferation and migration in vascular smooth muscle cells (VSMCs) (1). IGF-I-stimulated VSMC migration and/or proliferation requires ligand occupancy of the ␣V␤3 integrin (2). Activation of the IGF-I receptor is coupled to downstream signaling events via recruitment and phosphorylation of two major adaptor proteins, Shc or members of the insulin receptor substrate (IRS) family. In VSMCs IGF-I stimulation leads to recruitment of the signaling protein Shc to SHP substrate-1 (SHPS-1) allowing sustained MAPK activation (3). IGF-I stimulation of phosphatidylinositol 3-kinase (PI3K) is also required to induce VSMC migration (4). Hyperglycemia has been shown to increase the responsiveness of smooth muscle cells as well as other cell types to growth factor stimulation (5-9). Following IGF-I stimulation of porcine VSMCs maintained in hyperglycemic conditions (e.g. Ͼ12 mM glucose) there is an increase in Shc phosphorylation and subsequent Grb2 association resulting in sustained MAPK activation and enhanced cell proliferation. In contrast cells grown in 5 mM glucose do not show these changes (5). Mutation of three Shc tyrosine phosphorylation sites, Tyr-239/ 240/317, that are required for Grb2 associatio...

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Section: Discussionsupporting

confidence: 88%

Insulin-like Growth Factor-I Stimulates Shc-dependent Phosphatidylinositol 3-Kinase Activation via Grb2-associated p85 in Vascular Smooth Muscle Cells

Radhakrishnan¹,

Maile²,

Ling³

et al. 2008

Journal of Biological Chemistry

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“…Interestingly, two markers of immature β-cells, Acox2 and Fzd2 [54], were overexpressed in EXP-ILS compared to both HLSC-ILS and human islets, which were respectively less and more differentiated. Notably, three genes for adaptor proteins involved in the transduction of insulin signal (GAB1, NCK1, SORBS1) [78, 79] were expressed at similar or higher levels in EXP-ILS compared to human islets, and were upregulated in respect to HLSC-ILS and HLSC, suggesting an increased activation of the insulin signaling pathway. Similarly, several markers of insulin secretion (CACNA1C, KCNJ11, KCNK3, PFKFB2, PIK3R2, SNAP25, VAMP2) [71, 80–82] were expressed at similar or higher levels in EXP-ILS and human islets and were expressed at lower levels in HLSC and HLSC-ILS, suggesting an increased ability of EXP-ILS to release insulin granules.…”

Section: Discussionmentioning

confidence: 99%

Islet-Like Structures Generated In Vitro from Adult Human Liver Stem Cells Revert Hyperglycemia in Diabetic SCID Mice

Navarro-Tableros

Gai

Gomez

et al. 2018

Stem Cell Rev and Rep

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A potential therapeutic strategy for diabetes is the transplantation of induced-insulin secreting cells. Based on the common embryonic origin of liver and pancreas, we studied the potential of adult human liver stem-like cells (HLSC) to generate in vitro insulin-producing 3D spheroid structures (HLSC-ILS). HLSC-ILS were generated by a one-step protocol based on charge dependent aggregation of HLSC induced by protamine. 3D aggregation promoted the spontaneous differentiation into cells expressing insulin and several key markers of pancreatic β cells. HLSC-ILS showed endocrine granules similar to those seen in human β cells. In static and dynamic in vitro conditions, such structures produced C-peptide after stimulation with high glucose. HLSC-ILS significantly reduced hyperglycemia and restored a normo-glycemic profile when implanted in streptozotocin-diabetic SCID mice. Diabetic mice expressed human C-peptide and very low or undetectable levels of murine C-peptide. Hyperglycemia and a diabetic profile were restored after HLSC-ISL explant. The gene expression profile of in vitro generated HLSC-ILS showed a differentiation from HLSC profile and an endocrine commitment with the enhanced expression of several markers of β cell differentiation. The comparative analysis of gene expression profiles after 2 and 4 weeks of in vivo implantation showed a further β-cell differentiation, with a genetic profile still immature but closer to that of human islets. In conclusion, protamine-induced spheroid aggregation of HLSC triggers a spontaneous differentiation to an endocrine phenotype. Although the in vitro differentiated HLSC-ILS were immature, they responded to high glucose with insulin secretion and in vivo reversed hyperglycemia in diabetic SCID mice.

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“…The effects of cold upon insulin signalling are tissue specific and within every tissue cold effects seem to be function‐specific, in such a way that they may positively influence some responses controlled by insulin and negatively influences others. Since increased sympathetic tonus is a major characteristic of cold‐exposed rats we believe that further characterization of molecular cross‐talk between insulin and adrenergic receptors (Klein et al 1999; Paez‐Espinosa et al 2001) may prove helpful in advancing the understanding of glucose homeostasis in cold‐exposed animals and disclosing new potential targets for therapeutics in diabetes mellitus.…”

Section: Discussionmentioning

confidence: 99%

Cold Exposure Induces Tissue‐Specific Modulation of the Insulin‐Signalling Pathway in Rattus Norvegicus

Gasparetti

Souza

Pereira-da-Silva

et al. 2003

The Journal of Physiology

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Cold exposure provides a reproducible model of improved glucose turnover accompanied by reduced steady state and glucose-induced insulin levels. In the present report we performed immunoprecipitation and immunoblot studies to evaluate the initial and intermediate steps of the insulin-signalling pathway in white and brown adipose tissues, liver and skeletal muscle of rats exposed to cold. Basal and glucose-induced insulin secretion were significantly impaired, while glucose clearance rates during a glucose tolerance test and the constant for glucose decay during a 15 min insulin tolerance test were increased, indicating a significantly improved glucose turnover and insulin sensitivity in rats exposed to cold. Evaluation of protein levels and insulin-induced tyrosine (insulin receptor, insulin receptor substrates (IRS)-1 and -2, ERK (extracellular signalrelated kinase)) or serine (Akt; protein kinase B) phosphorylation of proteins of the insulin signalling cascade revealed a tissue-specific pattern of regulation of the molecular events triggered by insulin such that in white adipose tissue and skeletal muscle an impaired molecular response to insulin was detected, while in brown adipose tissue an enhanced response to insulin was evident. In muscle and white and brown adipose tissues, increased 2-deoxy-D-glucose (2-DG) uptake was detected. Thus, during cold exposure there is a tissue-specific regulation of the insulin-signalling pathway, which seems to favour heat-producing brown adipose tissue. Nevertheless, muscle and white adipose tissue are able to take up large amounts of glucose, even in the face of an apparent molecular resistance to insulin.

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Regulation of Insulin-Stimulated Tyrosine Phosphorylation of Shc and Shc/Grb2 Association in Liver, Muscle, and Adipose Tissue of Epinephrine- and Streptozotocin-Treated Rats

Cited by 6 publications

References 36 publications

Insulin-like Growth Factor-I Stimulates Shc-dependent Phosphatidylinositol 3-Kinase Activation via Grb2-associated p85 in Vascular Smooth Muscle Cells

Insulin-like Growth Factor-I Stimulates Shc-dependent Phosphatidylinositol 3-Kinase Activation via Grb2-associated p85 in Vascular Smooth Muscle Cells

Islet-Like Structures Generated In Vitro from Adult Human Liver Stem Cells Revert Hyperglycemia in Diabetic SCID Mice

Cold Exposure Induces Tissue‐Specific Modulation of the Insulin‐Signalling Pathway in Rattus Norvegicus

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