The actin-related p41ARC subunit contributes to p21-activated kinase-1 (PAK1)–mediated glucose uptake into skeletal muscle cells

Tunduguru, Ragadeepthi; Zhang, Jing; Aslamy, Arianne; Salunkhe, Vishal A.; Brozinick, Joseph T.; Elmendorf, Jeffrey S.; Thurmond, Debbie C.

doi:10.1074/jbc.m117.801340

Cited by 21 publications

(28 citation statements)

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“…Under control conditions, insulin stimulated glucose uptake to a level more than twofold that of basal levels ( Fig. 2c) as has been reported previously [36], while InsRes conditions blocked the insulin response ( Fig. 2c).…”

Section: Doc2b Enrichment Protects Myotubes and Myoblasts From Dysfunsupporting

confidence: 88%

DOC2B promotes insulin sensitivity in mice via a novel KLC1-dependent mechanism in skeletal muscle

Zhang

Merz

et al. 2019

Diabetologia

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Aims/hypothesis Skeletal muscle accounts for >80% of insulin-stimulated glucose uptake; dysfunction of this process underlies insulin resistance and type 2 diabetes. Insulin sensitivity is impaired in mice deficient in the double C2 domain β (DOC2B) protein, while whole-body overexpression of DOC2B enhances insulin sensitivity. Whether insulin sensitivity in the skeletal muscle is affected directly by DOC2B or is secondary to an effect on other tissues is unknown; the underlying molecular mechanisms also remain unclear. Methods Human skeletal muscle samples from non-diabetic or type 2 diabetic donors were evaluated for loss of DOC2B during diabetes development. For in vivo analysis, new doxycycline-inducible skeletal-muscle-specific Doc2b-overexpressing mice fed standard or high-fat diets were evaluated for insulin and glucose tolerance, and insulin-stimulated GLUT4 accumulation at the plasma membrane (PM). For in vitro analyses, a DOC2B-overexpressing L6-GLUT4-myc myoblast/myotube culture system was coupled with an insulin resistance paradigm. Biochemical and molecular biology methods such as site-directed mutagenesis, coimmunoprecipitation and mass spectrometry were used to identify the molecular mechanisms linking insulin stimulation to DOC2B. Results We identified loss of DOC2B (55% reduction in RNA and 40% reduction in protein) in the skeletal muscle of human donors with type 2 diabetes. Furthermore, inducible enrichment of DOC2B in skeletal muscle of transgenic mice enhanced whole-body glucose tolerance (AUC decreased by 25% for female mice) and peripheral insulin sensitivity (area over the curve increased by 20% and 26% for female and male mice, respectively) in vivo, underpinned by enhanced insulin-stimulated GLUT4 accumulation at the PM. Moreover, DOC2B enrichment in skeletal muscle protected mice from high-fat-diet-induced peripheral insulin resistance, despite the persistence of obesity. In L6-GLUT4-myc myoblasts, DOC2B enrichment was sufficient to preserve normal insulin-stimulated GLUT4 accumulation at the PM in cells exposed to diabetogenic stimuli. We further identified that DOC2B is phosphorylated on insulin stimulation, enhancing its interaction with a microtubule motor protein, kinesin light chain 1 (KLC1). Mutation of Y301 in DOC2B blocked the insulin-stimulated phosphorylation of DOC2B and interaction with KLC1, and it blunted the ability of DOC2B to enhance insulin-stimulated GLUT4 accumulation at the PM. Conclusions/interpretation These results suggest that DOC2B collaborates with KLC1 to regulate insulin-stimulated GLUT4 accumulation at the PM and regulates insulin sensitivity. Our observation provides a basis for pursuing DOC2B as a novel drug target in the muscle to prevent/treat type 2 diabetes. Karla E. Merz and Arianne Aslamy contributed equally to this work.Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00125-019-4824-2) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

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Section: Doc2b Enrichment Protects Myotubes and Myoblasts From Dysfunsupporting

confidence: 88%

DOC2B promotes insulin sensitivity in mice via a novel KLC1-dependent mechanism in skeletal muscle

Zhang

Merz

et al. 2019

Diabetologia

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“…Importantly, it is the insulin-stimulated remodeling of F-actin, as opposed to simply its polymerization, is essential for the translocation of GSVs to the PM of skeletal muscle cells ( 125 , 126 ). PAK1 is implicated in both the polymerization and the depolymerization of F-actin in insulin-stimulated GLUT4 vesicle translocation and glucose uptake in L6-GLUT4myc myoblasts and myotubes ( 108 , 127 ).…”

Section: Actin Cytoskeleton Remodeling and Glut4 Traffickingmentioning

confidence: 99%

“…Knockdown of ARP3 or the ARPC2 subunit of the ARP2/3 complex in skeletal muscle cells abrogated insulin-induced F-actin remodeling and GLUT4 translocation to the PM ( 111 ). Intriguingly, PAK1 directly phosphorylates p41-ARC/ARPC1, a regulatory subunit of the ARP2/3 complex, to initiate actin remodeling, in multiple cell types including in skeletal muscle cells ( 127 , 141 , 142 ). Although the ARP2/3 complex can initiate branched actin filament nucleation, it requires the actions of nucleation promoting factors (NPFs), such as neural Wiskott–Aldrich syndrome protein ( N -WASP), WAVE, and cortactin, to stimulate its activity and carry out actin polymerization (Table 1 ).…”

Section: Actin Cytoskeleton Remodeling and Glut4 Traffickingmentioning

confidence: 99%

Promoting Glucose Transporter-4 Vesicle Trafficking along Cytoskeletal Tracks: PAK-Ing Them Out

Tunduguru

Thurmond

2017

Front. Endocrinol.

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Glucose is the principal cellular energy source in humans and maintenance of glucose homeostasis is critical for survival. Glucose uptake into peripheral skeletal muscle and adipose tissues requires the trafficking of vesicles containing glucose transporter-4 (GLUT4) from the intracellular storage compartments to the cell surface. Trafficking of GLUT4 storage vesicles is initiated via the canonical insulin signaling cascade in skeletal muscle and fat cells, as well as via exercise-induced contraction in muscle cells. Recent studies have elucidated steps in the signaling cascades that involve remodeling of the cytoskeleton, a process that underpins the mechanical movement of GLUT4 vesicles. This review is focused upon an alternate phosphoinositide-3 kinase-dependent pathway involving Ras-related C3 botulinum toxin substrate 1 signaling through the p21-activated kinase p21-activated kinase 1 and showcases related signaling events that co-regulate both the depolymerization and re-polymerization of filamentous actin. These new insights provide an enriched understanding into the process of glucose transport and yield potential new targets for interventions aimed to improve insulin sensitivity and remediate insulin resistance, pre-diabetes, and the progression to type 2 diabetes.

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“…Interestingly, ACSL1 is complexed to FATP1, the major insulin-stimulated LCFA importer, which in turn is transported to the plasma membrane by another S6K1* target, phospho-EPRS Gargiulo et al, 1999;Richards et al, 2006). These transport processes might be facilitated by CTTN, an actin-binding protein required for insulin-stimulated translocation of vesicles containing the Glut4 glucose transporter to the plasma membrane (Nazari et al, 2011;Tunduguru et al, 2017). This mechanism is supported by evidence that Cdk5 is stimulated by insulin and plays a key role in Glut4-mediated glucose uptake and FATP1-mediated LCFA uptake in adipocytes Lalioti et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Multisite Phosphorylation of S6K1 Directs a Kinase Phospho-code that Determines Substrate Selection

et al. 2019

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Graphical Abstract Highlights d Insulin-stimulated phosphorylation of EPRS Ser 999 by S6K1 requires mTORC1 and Cdk5 d C terminus phosphorylation of S6K1 by Cdk5 is required for EPRS phosphorylation d S6K1 exhibits a phospho-site dependent, target-selective phospho-code d Multisite phosphorylated S6K1 induces a metabolon driving adipocyte lipid metabolism SUMMARY Multisite phosphorylation of kinases can induce onoff or graded regulation of catalytic activity; however, its influence on substrate specificity remains unclear.Here, we show that multisite phosphorylation of ribosomal protein S6 kinase 1 (S6K1) alters target selection. Agonist-inducible phosphorylation of glutamyl-prolyl tRNA synthetase (EPRS) by S6K1 in monocytes and adipocytes requires not only canonical phosphorylation at Thr 389 by mTORC1 but also phosphorylation at Ser 424 and Ser 429 in the C terminus by cyclin-dependent kinase 5 (Cdk5). S6K1 phosphorylation at these additional sites induces a conformational switch and is essential for highaffinity binding and phosphorylation of EPRS, but not canonical S6K1 targets, e.g., ribosomal protein S6. Unbiased proteomic analysis identified additional targets phosphorylated by multisite phosphorylated S6K1 in insulin-stimulated adipocytesnamely, coenzyme A synthase, lipocalin 2, and cortactin. Thus, embedded within S6K1 is a targetselective kinase phospho-code that integrates signals from mTORC1 and Cdk5 to direct an insulin-stimulated, post-translational metabolon determining adipocyte lipid metabolism.

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The actin-related p41ARC subunit contributes to p21-activated kinase-1 (PAK1)–mediated glucose uptake into skeletal muscle cells

Cited by 21 publications

References 55 publications

DOC2B promotes insulin sensitivity in mice via a novel KLC1-dependent mechanism in skeletal muscle

DOC2B promotes insulin sensitivity in mice via a novel KLC1-dependent mechanism in skeletal muscle

Promoting Glucose Transporter-4 Vesicle Trafficking along Cytoskeletal Tracks: PAK-Ing Them Out

Multisite Phosphorylation of S6K1 Directs a Kinase Phospho-code that Determines Substrate Selection

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