PKD1 Inhibits AMPKα2 through Phosphorylation of Serine 491 and Impairs Insulin Signaling in Skeletal Muscle Cells

Coughlan, Kimberly A.; Valentine, Rudy J.; Sudit, Bella S.; Allen, Katherine M.; Dagon, Yossi; Kahn, Barbara B.; Ruderman, Neil B.; Saha, Asish K.

doi:10.1074/jbc.m115.696849

Cited by 51 publications

(50 citation statements)

References 28 publications

(39 reference statements)

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“…Others have recently reported that the murine PKCµ orthologue, PKD1, phosphorylates AMPKα2 in vitro and is responsible for PMA-stimulated AMPKα2 Ser491 phosphorylation in a mouse myotube cell line [18]. In the present study, PKCµ inhibition did not significantly attenuate VEGF-stimulated AMPKα1 Ser487 phosphorylation, indicating that PKCµ cannot be the principal VEGF-stimulated AMPKα1 Ser487 kinase.…”

Section: Discussioncontrasting

confidence: 60%

“…As neither PMA nor OAG stimulated detectable AMPKα2 Ser491 phosphorylation, this suggests that human AMPKα2 Ser491 is not a PKC substrate in endothelial cells and may be an autophosphorylation target, regulated independently of Ser487 as reported recently [17]. The different results reported in this and the study of Coughlan and co-workers [18] may reflect a species-specific role for PKCµ/PKD1. Indeed, the PKCµ inhibitor, CRT0066101, inhibited VEGF-stimulated ACC phosphorylation without affecting AMPK activity in immunoprecipitates, suggesting stimulation of PKCµ is not associated with AMPK inactivation in human endothelial cells.…”

Section: Discussionsupporting

confidence: 47%

“…While this manuscript was in preparation, it was reported that PKD1 (the mouse orthologue of human PKCμ) phosphorylates AMPKα2 Ser491 in vitro with similar efficiency to Akt and that PMA stimulated AMPKα2 Ser491 in a mouse muscle cell line in a PKD1-dependent manner [18]. VEGF markedly increased PKCµ Ser916 phosphorylation in HAECs, an autophosphorylation site that correlates with PKCµ activity [40], and this was entirely blocked by the PKCµ inhibitor CRT0066101 (Figure 7).…”

Section: Resultsmentioning

confidence: 99%

“…Recently, phosphorylation of AMPKα1/α2 at Ser487/491 (human sequence, equivalent to rodent Ser485/491) has been reported to inhibit AMPK activity [12–18]. Several studies have demonstrated that Akt phosphorylates AMPKα1 Ser487 in response to insulin or IGF-1 (insulin-like growth factor) in heart, adipocytes, vascular smooth muscle cells (VSMCs) and tumour cell lines [13–17].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, transfection of a murine muscle cell line with AMPKα2 Ser491Ala has been recently reported to attenuate the inhibition of insulin signalling by phorbol 12-myristate 13-acetate (PMA) [18]. These studies suggest that increased AMPKα1/α2 Ser487/491 phosphorylation may underlie the reduced AMPK activity reported in insulin-resistant states [18,27]. Despite this, the AMPKα1/α2 Ser487/491 phosphorylation status in human insulin resistance has not been reported.…”

Section: Introductionmentioning

confidence: 99%

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Protein kinase C phosphorylates AMP-activated protein kinase α1 Ser487

Heathcote

Mancini

Strembitska

et al. 2016

Biochemical Journal

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The key metabolic regulator, AMP-activated protein kinase (AMPK), is reported to be down-regulated in metabolic disorders, but the mechanisms are poorly characterised. Recent studies have identified phosphorylation of the AMPKα1/α2 catalytic subunit isoforms at Ser487/491, respectively, as an inhibitory regulation mechanism. Vascular endothelial growth factor (VEGF) stimulates AMPK and protein kinase B (Akt) in cultured human endothelial cells. As Akt has been demonstrated to be an AMPKα1 Ser487 kinase, the effect of VEGF on inhibitory AMPK phosphorylation in cultured primary human endothelial cells was examined. Stimulation of endothelial cells with VEGF rapidly increased AMPKα1 Ser487 phosphorylation in an Akt-independent manner, without altering AMPKα2 Ser491 phosphorylation. In contrast, VEGF-stimulated AMPKα1 Ser487 phosphorylation was sensitive to inhibitors of protein kinase C (PKC) and PKC activation using phorbol esters or overexpression of PKC-stimulated AMPKα1 Ser487 phosphorylation. Purified PKC and Akt both phosphorylated AMPKα1 Ser487 in vitro with similar efficiency. PKC activation was associated with reduced AMPK activity, as inhibition of PKC increased AMPK activity and phorbol esters inhibited AMPK, an effect lost in cells expressing mutant AMPKα1 Ser487Ala. Consistent with a pathophysiological role for this modification, AMPKα1 Ser487 phosphorylation was inversely correlated with insulin sensitivity in human muscle. These data indicate a novel regulatory role of PKC to inhibit AMPKα1 in human cells. As PKC activation is associated with insulin resistance and obesity, PKC may underlie the reduced AMPK activity reported in response to overnutrition in insulin-resistant metabolic and vascular tissues.

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Section: Discussioncontrasting

confidence: 60%

Section: Discussionsupporting

confidence: 47%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Protein kinase C phosphorylates AMP-activated protein kinase α1 Ser487

Heathcote

Mancini

Strembitska

et al. 2016

Biochemical Journal

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Regulation of AMPK activity by type 10 adenylyl cyclase: contribution to the mitochondrial biology, cellular redox and energy homeostasis

Jayarajan

Appukuttan

Aslam

et al. 2019

Cell. Mol. Life Sci.

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The downregulation of AMP-activated protein kinase (AMPK) activity contributes to numerous pathologies. Recent reports suggest that the elevation of cellular cAMP promotes AMPK activity. However, the source of the cAMP pool that controls AMPK activity remains unknown. Mammalian cells possess two cAMP sources: membranebound adenylyl cyclase (tmAC) and intracellularly localized, type 10 soluble adenylyl cyclase (sAC). Due to the localization of sAC and AMPK in similar intracellular compartments, we hypothesized that sAC may control AMPK activity. In this study, sAC expression and activity were manipulated in H9C2 cells, adult rat cardiomyocytes or endothelial cells. sAC knockdown depleted the cellular cAMP content and decreased AMPK activity in an EPAC-dependent manner. Functionally, sAC knockdown reduced cellular ATP content, increased mitochondrial ROS formation and led to mitochondrial depolarization. Furthermore, sAC downregulation led to EPAC-dependent mitophagy disturbance, indicated by an increased mitochondrial mass and unaffected mitochondrial biogenesis. Consistently, sAC overexpression or stimulation with bicarbonate significantly increased AMPK activity and cellular ATP content. In contrast, tmAC inhibition or stimulation produced no effect on AMPK activity. Therefore, the sAC-EPAC axis may regulate basal and induced AMPK activity and supports mitophagy, cellular energy and redox homeostasis. The study argues for sAC as a potential target in treating pathologies associated with AMPK downregulation.

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Muscle-specific deletion of Prkaa1 enhances skeletal muscle lipid accumulation in mice fed a high-fat diet

Zhang

et al. 2017

J Physiol Biochem

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Excessive intramyocellular triacylglycerols (IMTGs, muscle lipids) are associated with the abnormal energy metabolism and insulin resistance of skeletal muscle. AMP-activated protein kinase (AMPK), a crucial cellular energy sensor, consists of α, β and γ subunits. Researchers have not clearly determined whether Prkaa1 (also known as AMPKα1) affects IMTG accumulation in skeletal muscle. Here, we show an important role of Prkaa1 in skeletal muscle lipid metabolism. Deletion of muscle Prkaa1 leads to the delayed development of skeletal muscles but does not affect glucose tolerance or insulin sensitivity in animals fed a normal diet. Notably, when animals are fed a high-fat diet, the skeletal muscle of muscle-specific Prkaa1 knockout mice accumulates more lipids than the skeletal muscle of wild-type (WT) mice, with concomitant upregulation of adipogenic gene expressions and downregulation of the expression of genes associated with mitochondrial oxidation. Muscle-specific Prkaa1 ablation also results in hyperlipidemia, which may contribute to the increased IMTG levels. Furthermore, Prkaa1 deletion activates skeletal muscle mTOR signalling, which has a central role in lipid metabolism and mitochondrial oxidation. Collectively, our study provides new insights into the role of Prkaa1 in skeletal muscle. This knowledge may contribute to the treatment of related metabolic diseases.

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PKD1 Inhibits AMPKα2 through Phosphorylation of Serine 491 and Impairs Insulin Signaling in Skeletal Muscle Cells

Cited by 51 publications

References 28 publications

Protein kinase C phosphorylates AMP-activated protein kinase α1 Ser487

Protein kinase C phosphorylates AMP-activated protein kinase α1 Ser487

Regulation of AMPK activity by type 10 adenylyl cyclase: contribution to the mitochondrial biology, cellular redox and energy homeostasis

Muscle-specific deletion of Prkaa1 enhances skeletal muscle lipid accumulation in mice fed a high-fat diet

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