Dynamics of Signaling during Insulin-stimulated Endocytosis of Its Receptor in Adipocytes

Kublaoui, Bassil; Lee, Jongsoon; Pilch, Paul F.

doi:10.1074/jbc.270.1.59

Cited by 117 publications

(100 citation statements)

References 47 publications

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“…As expected, insulin causes a redistribution of intracellular (LM and HM) GLUT4 to the cell surface (PM) (33). As we demonstrated previously by Western blotting (45), the insulin receptor undergoes ligand-dependent endocytosis, whereas caveolin shows a small insulin-dependent decrease in the LM as a result of apparent redistribution to the PM (37). The change in PM caveolin cannot be accurately measured because of the large amount of caveolin already at the cell surface.…”

Section: Methodsmentioning

confidence: 64%

Immunopurification and Characterization of Rat Adipocyte Caveolae Suggest Their Dissociation from Insulin Signaling

Souto

Vallega

Wharton

et al. 2003

Journal of Biological Chemistry

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Adipocytes play an important role in the insulin-dependent regulation of organismal fuel metabolism and express caveolae at levels as high or higher than any other cell type. Recently, a link between insulin signaling and caveolae has been suggested; nevertheless, adipocyte caveolae have been the subject of relatively few studies, and their contents have been minimally characterized. With the aid of a new monoclonal antibody, we developed a rapid procedure for the immunoisolation of caveolae derived from the plasma membrane of adipocytes, and we characterized their protein content. We find that immunopurified adipocyte caveolae have a relatively limited protein composition, and they lack the raft protein, flotillin, and insulin receptors. Immunogold labeling and electron microscopy of the adipocyte plasma membrane confirmed the lack of insulin receptors in caveolae. In addition to caveolins, the structural components of caveolae, their major protein constituents, are the semicarbazide-sensitive amine oxidase and the scavenger lipoprotein receptor CD36. The results are consistent with a role for caveolae in lipid flux in and of adipocytes.

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Section: Methodsmentioning

confidence: 64%

Immunopurification and Characterization of Rat Adipocyte Caveolae Suggest Their Dissociation from Insulin Signaling

Souto

Vallega

Wharton

et al. 2003

Journal of Biological Chemistry

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100

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“…In addition, similarly to what is occurring in cells expressing IR R252C , IRS 1 phosphorylation could be achieved by IR C860S localised mainly on microvilli supporting the idea that some IR biological signals can be elicited from these surface domains. However, endosome could also be a site of IR signal transduction and biological responsiveness, as suggested by studies of the kinetics of IR kinase activation and of the subcellular localisation of this kinase domain [18,19,20,42].…”

Section: Discussionmentioning

confidence: 99%

“…Likewise, under conditions where IR internalisation is inhibited (incubation at 4°C or expression of a dominant negative mutant of dynamin), IRS 1 is still phosphorylated [15,16,17], suggesting that IR internalisation is not required for the transduction of its biological signal. On the other hand, subcellular fractionation experiments (on 3T3-L1 adipocytes and rat hepatocytes) have shown that the pool of IR present on internal membranes undergoes a higher autophosphorylation in response to insulin than the IR present at the cell surface [18,19], and that IRS 1 is mainly distributed in intracellular compartments, probably endosomes, where it could be tyrosine phosphorylated in the presence of insulin [16,18,19,20]. These studies suggest therefore that IR signalling cascade takes place, at least in part, on endosomes and thus may require IR internalisation.…”

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confidence: 99%

An arginine to cysteine252 mutation in insulin receptors from a patient with severe insulin resistance inhibits receptor internalisation but preserves signalling events

et al. 2002

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Aims/hypothesis. We examined the properties of a mutant insulin receptor (IR) with an Arg 252 to Cys (IR R252C ) substitution in the α-subunit originally identified in a patient with extreme insulin resistance and acanthosis nigricans. Methods. We studied IR cell biology and signalling pathways in Chinese Hamster Ovary cells overexpressing this IR R252C . Results. Our investigation showed an impairment in insulin binding to IR R252C related mostly to a reduced affinity of the receptor for insulin and to a reduced rate of IR R252C maturation; an inhibition of IR R252C -mediated endocytosis resulting in a decreased insulin degradation and insulin-induced receptor down-regulation; a maintenance of IR R252C on microvilli even in the presence of insulin; a similar autophosphorylation of mutant IR R252C followed by IRS 1/IRS 2 phosphorylation, p85 association with IRS 1 and IRS 2 and Akt phosphorylation similar to those observed in cells expressing wild type IR (IRwt); and finally, a reduced insulin-induced Shc phosphorylation accompanied by decreased ERK1/2 phosphorylation and activity and of thymidine incorporation into DNA in cells expressing IR R252C as compared to cells expressing IRwt. Conclusion/interpretation. These observations suggest that: parameters other than tyrosine kinase activation participate in or control the first steps of IR internalisation or both; IR-mediated IRS 1/2 phosphorylation can be achieved from the cell surface and microvilli in particular; Shc phosphorylation and its subsequent signalling pathway might require IR internalisation; defective IR endocytosis correlates with an enhancement of some biological responses to insulin and attenuation of others. [Diabetologia (2002) 45:657-667]

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“…fractions that also contain phosphorylated IRS 1. Tyrosine phosphorylation of IRS 1 in internal compartments, i.e LDM and cytosol, could be mediated by internalized insulin receptors [36], although tyrosine phosphorylation of IRS l occured in the LDM fraction even at 4 "C, which prevents insulin-receptor internalization [37]. In LDM, activation of PtdIns 3-kinase could result from the association of the enzyme already present in these fractions with tyrosine-phosphorylated IRS 1 and/or from the translocation of new molecules of PtdIns 3-kinase from the cytosol.…”

Section: Discussionmentioning

confidence: 99%

Different Effects of Insulin and Platelet‐Derived Growth Factor on Phosphatidylinositol 3‐Kinase at the Subcellular Level in 3T3‐L1 Adipocytes

Ricort

Tanti

Obberghen

et al. 1996

European Journal of Biochemistry

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Insulin stimulates glucose uptake by induction of the translocation of vesicles that contain the glucose transporter Glut 4 to the plasma membrane. Phosphatidylinositol 3-kinase (Ptdlns 3-kinase), which is thought to be involved in intracellular trafficking, could play a critical role in insulin-induced glucose transport. In 3T3-Ll adipocytes, insulin and platelet-derived-growth-factor (PDGF) stimulated glucose uptake by 5.8-fold and 2.4-fold, respectively, but PDGF had no significant effect on Glut 4 translocation. Nevertheless, both hormones activated PtdIns 3-kinase activity in total cell extracts. However, insulin and PDGF had different effects on the stimulation of PtdIns 3-kinase activity in several subcellular fractions, and the movements of insulin-receptor substrate (IRS) 1 and the p85 subunit of PtdIns 3-kinase between subcellular compartments. PDGF stimulated PtdIns 3-kinase activity almost exclusively in the plasma membrane, and induced translocation of the p85 subunit from the cytosol to the plasma membrane, where the PDGF receptor was phosphorylated on tyrosine residues. In contrast, insulin stimulated Ptdlns 3-kinase activity in the plasma membrane, in low-density microsomes (LDM) and in cytosol. Furthermore, insulin induced the translocation of p85 from the cytosol to LDM and the translocation of IRS 1 from LDM to the cytosol. These data indicate that insulin and PDGF have different effects on the activation of Ptdlns 3-kinase and on the movement of IRS 1 and PtdIns 3-kinase between subcellular compartments. We would like to suggest that a crucial event in the stimulation of glucose uptake by insulin could be that insulin, but not PDGF, induces activation of PtdIns 3-kinase in the cytosol and in LDM, the compartment enriched in Glut-4-containing vesicles.

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Dynamics of Signaling during Insulin-stimulated Endocytosis of Its Receptor in Adipocytes

Cited by 117 publications

References 47 publications

Immunopurification and Characterization of Rat Adipocyte Caveolae Suggest Their Dissociation from Insulin Signaling

Immunopurification and Characterization of Rat Adipocyte Caveolae Suggest Their Dissociation from Insulin Signaling

An arginine to cysteine252 mutation in insulin receptors from a patient with severe insulin resistance inhibits receptor internalisation but preserves signalling events

Different Effects of Insulin and Platelet‐Derived Growth Factor on Phosphatidylinositol 3‐Kinase at the Subcellular Level in 3T3‐L1 Adipocytes

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