Insulin Stimulates Membrane Fusion and GLUT4 Accumulation in Clathrin Coats on Adipocyte Plasma Membranes

Huang, Shaohui; Lifshitz, Lawrence M.; Jones, Christine C.; Bellvé, Karl D.; Standley, Clive; Fonseca, Sonya G.; Corvera, Silvia; Fogarty, Kevin E.; Czech, Michael P.

doi:10.1128/mcb.01719-06

Cited by 108 publications

(117 citation statements)

References 51 publications

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“…Another mystery is the identity of the target(s) for Akt, other than AS160, that is involved in GSV movement. In this regard, the data of others suggesting that one or more such targets may be at or near the plasma membrane (66,67) are consistent with the lack of obvious candidates in our proteomic analysis of vesicle proteins. As for cargo protein, we identified by semi-quantitative mass spectrometry, the sortilin-related receptor, SORL1 (68), as a relatively abundant, apparently translocating, protein of GSVs (Fig.…”

Section: Discussionsupporting

confidence: 73%

Proteomic Analysis of GLUT4 Storage Vesicles Reveals LRP1 to Be an Important Vesicle Component and Target of Insulin Signaling

Jedrychowski

Gartner

Gygi

et al. 2010

Journal of Biological Chemistry

113

146

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Insulin stimulates the translocation of intracellular GLUT4 to the plasma membrane where it functions in adipose and muscle tissue to clear glucose from circulation. The pathway and regulation of GLUT4 trafficking are complicated and incompletely understood and are likely to be contingent upon the various proteins other than GLUT4 that comprise and interact with GLUT4-containing vesicles. Moreover, not all GLUT4 intracellular pools are insulin-responsive as some represent precursor compartments, thus posing a biochemical challenge to the purification and characterization of their content. To address these issues, we immunodepleted precursor GLUT4-rich vesicles and then immunopurified GLUT4 storage vesicle (GSVs) from primary rat adipocytes and subjected them to semi-quantitative and quantitative proteomic analysis. The purified vesicles translocate to the cell surface almost completely in response to insulin, the expected behavior for bona fide GSVs. In total, over 100 proteins were identified, about 50 of which are novel in this experimental context. LRP1 (low density lipoprotein receptorrelated protein 1) was identified as a major constituent of GSVs, and we show it interacts with the lumenal domains of GLUT4 and other GSV constituents. Its cytoplasmic tail interacts with the insulin-signaling pathway target, AS160 (Akt substrate of 160 kDa). Depletion of LRP1 from 3T3-L1 adipocytes reduces GLUT4 expression and correspondingly results in decreased insulin-stimulated 2-[ 3 H]deoxyglucose uptake. Furthermore, adipose-specific LRP1 knock-out mice also exhibit decreased GLUT4 expression. These findings suggest LRP1 is an important component of GSVs, and its expression is needed for the formation of fully functional GSVs.The insulin-dependent translocation of GLUT4 from intracellular membranes to the cell surface is a well studied paradigm for the effects of signal transduction on membrane trafficking, and this process is of considerable physiological relevance for the regulation of glucose homeostasis, as dysregulation of this process plays a role in insulin resistance and type 2 diabetes mellitus (1). Only about half of the intracellular GLUT4 translocates to the plasma membrane in response to insulin (2-5) suggesting that more than one GLUT4-containing compartment exists. In addition, kinetic analyses of GLUT4 trafficking are consistent with the interpretation that GLUT4 traffics through multiple intracellular compartments (6 -8). These and other data have led to the concept that an ultimate target of insulin signaling is a subpopulation of translocating GLUT4-containing membranes that are commonly referred to as GLUT4 storage vesicles (GSVs) 3 (9, 10). The focus of many groups over the years has been on how these GSVs form, what their protein composition is, and how insulin communicates with them and stimulates their translocation to the cell surface.GLUT4-containing vesicles have been purified and their protein composition analyzed by a number of investigators, first by conventional protein sequencing (11, 12)...

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Section: Discussionsupporting

confidence: 73%

Proteomic Analysis of GLUT4 Storage Vesicles Reveals LRP1 to Be an Important Vesicle Component and Target of Insulin Signaling

Jedrychowski

Gartner

Gygi

et al. 2010

Journal of Biological Chemistry

113

146

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“…In primary adipocytes, these fusion sites appear as fluorescent 'hotspots' that gradually increase in size over the time course of insulin stimulation and in some cases merge with neighbouring sites (Lizunov et al 2005). These fusion sites may, however, be sites of endocytosis as they have been shown to colocalise with clathrin (Huang et al 2007). Huang et al (2007) have therefore suggested that insulin stimulates the rate of transition between docking and fusion and promotes the transit of GLUT4 to sites of endocytosis within the plasma membrane in preparation for their internalisation following the termination of insulin signalling.…”

Section: Protein Complexes Involved In Docking and Fusion Of Glut4 Vementioning

confidence: 99%

“…Studies in both freshly isolated primary rat adipocytes and 3T3-L1 adipocytes have revealed that in the absence of insulin, highly mobile GLUT4 vesicles are observed in the TIRF zone (Lizunov et al 2005, Bai et al 2007, Huang et al 2007). Many of these vesicles are reported to display longrange lateral movements along predefined trajectories (step 3 in Fig.…”

Section: Pikfyvementioning

confidence: 99%

The molecular basis of insulin-stimulated glucose uptake: signalling, trafficking and potential drug targets

Leney¹,

Tavaré²

2009

Journal of Endocrinology

132

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The search for the underlying mechanism through which insulin regulates glucose uptake into peripheral tissues has unveiled a highly intricate network of molecules that function in concert to elicit the redistribution or 'translocation' of the glucose transporter isoform GLUT4 from intracellular membranes to the cell surface. Following recent technological advances within this field, this review aims to bring together the key molecular players that are thought to be involved in GLUT4 translocation and will attempt to address the spatial relationship between the signalling and trafficking components of this event. We will also explore the degree to which components of the insulin signalling and GLUT4 trafficking machinery may serve as potential targets for the development of orally available insulin mimics for the treatment of diabetes mellitus.

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“…The SNARE complex consisting of syntaxin 4, VAMP2 and SNAP23, likely constitutes the molecular scaffold regulating GLUT4 vesicle docking and fusion to the PM (22). By an in vitro pull down assay from 3T3-L1 cell lysates, CSP1 was shown to interact with syntaxin 4 in 3T3-L1 adipocyetes (6).…”

Section: Csp1 Contributes To Insulin-stimulated Glucose Uptake At Thementioning

confidence: 99%

“…After movement of GLUT4 to the plasma membrane, the final steps by which GLUT4 vesicle facilitates glucose entry into the cell are tethering, docking and fusion (21). Thus, both of Myc-GLUT4 and CSP1 were co-expressed ( Figure 2C) and the fusion of GLUT4 vesicles with the plasma membrane was monitored by Myc-GLUT4 (22). As shown in Figure 2D, surface incorporation of Myc-GLUT4 was significantly reduced after over-expression of CSP1 compared to that of the control.…”

Section: Csp1 Contributes To Insulin-stimulated Glucose Uptake At Thementioning

confidence: 99%

Cysteine string protein 1 (CSP1) modulates insulin sensitivity by attenuating glucose transporter 4 (GLUT4) vesicle docking with the plasma membrane

et al. 2013

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: Insulin stimulates glucose transporter 4 (GLUT4) vesicle recruitment from its intracellular storage site to the plasma membrane. Cysteine string protein 1 (CSP1) is a SNARE-binding protein involved in the vesicular trafficking of neurotransmitters and other exocytic processes. In this study, we investigated the involvement of CSP1 in insulin-dependent GLUT4 recruitment in 3T3-L1 adipocytes. Over-expression of wild-type CSP1 led to attenuated insulin-stimulated glucose uptake without any change in GLUT4 content in the plasma membrane, rather it inhibits docking by blocking the association of VAMP2 with syntaxin 4. In contrast, knockdown of CSP1 enhanced insulin-stimulated glucose uptake. The mRNA and protein expression of CSP1 was elevated in 3T3-L1 adipocytes in insulin resistant states caused by high levels of palmitate and chronic insulin exposure. Taken together, the results of this study suggest that CSP1 is involved in insulin resistance by interrupting GLUT4 vesicle docking with the plasma membrane.

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Insulin Stimulates Membrane Fusion and GLUT4 Accumulation in Clathrin Coats on Adipocyte Plasma Membranes

Cited by 108 publications

References 51 publications

Proteomic Analysis of GLUT4 Storage Vesicles Reveals LRP1 to Be an Important Vesicle Component and Target of Insulin Signaling

Proteomic Analysis of GLUT4 Storage Vesicles Reveals LRP1 to Be an Important Vesicle Component and Target of Insulin Signaling

The molecular basis of insulin-stimulated glucose uptake: signalling, trafficking and potential drug targets

Cysteine string protein 1 (CSP1) modulates insulin sensitivity by attenuating glucose transporter 4 (GLUT4) vesicle docking with the plasma membrane

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