Identification of a novel class of dithiolethiones that prevent hepatic insulin resistance via the adenosine monophosphate-activated protein kinase-p70 ribosomal S6 kinase-1 pathway

ABSTRACT PDK1 activates a group of kinases, including protein kinase B (PKB)/Akt, p70 ribosomal S6 kinase (S6K), and serum and glucocorticoid-induced protein kinase (SGK), that mediate many of the effects of insulin as well as other agonists. PDK1 interacts with phosphoinositides through a pleckstrin homology (PH) domain. To study the role of this interaction, we generated knock-in mice expressing a mutant of PDK1 incapable of binding phosphoinositides. The knock-in mice are significantly small, insulin resistant, and hyperinsulinemic. Activation of PKB is markedly reduced in knock-in mice as a result of lower phosphorylation of PKB at Thr308, the residue phosphorylated by PDK1. This results in the inhibition of the downstream mTOR complex 1 and S6K1 signaling pathways. In contrast, activation of SGK1 or p90 ribosomal S6 kinase or stimulation of S6K1 induced by feeding is unaffected by the PDK1 PH domain mutation. These observations establish the importance of the PDK1-phosphoinositide interaction in enabling PKB to be efficiently activated with an animal model. Our findings reveal how reduced activation of PKB isoforms impinges on downstream signaling pathways, causing diminution of size as well as insulin resistance.

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Role of Long Non-Coding RNAs and the Molecular Mechanisms Involved in Insulin Resistance

International Journal of Molecular Sciences ◽

10.3390/ijms22147256 ◽

2021 ◽

Vol 22 (14) ◽

pp. 7256

Author(s):

Vianet Argelia Tello-Flores ◽

Fredy Omar Beltrán-Anaya ◽

Marco Antonio Ramírez-Vargas ◽

Brenda Ely Esteban-Casales ◽

Napoleón Navarro-Tito ◽

...

Keyword(s):

Insulin Resistance ◽

Protein Kinase ◽

Molecular Mechanisms ◽

Cyclic Adenosine Monophosphate ◽

Adenosine Monophosphate ◽

Biological Species ◽

Necrosis Factor Alpha ◽

Polypyrimidine Tract Binding Protein ◽

Non Coding Rnas

Long non-coding RNAs (lncRNAs) are single-stranded RNA biomolecules with a length of >200 nt, and they are currently considered to be master regulators of many pathological processes. Recent publications have shown that lncRNAs play important roles in the pathogenesis and progression of insulin resistance (IR) and glucose homeostasis by regulating inflammatory and lipogenic processes. lncRNAs regulate gene expression by binding to other non-coding RNAs, mRNAs, proteins, and DNA. In recent years, several mechanisms have been reported to explain the key roles of lncRNAs in the development of IR, including metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), imprinted maternal-ly expressed transcript (H19), maternally expressed gene 3 (MEG3), myocardial infarction-associated transcript (MIAT), and steroid receptor RNA activator (SRA), HOX transcript antisense RNA (HOTAIR), and downregulated Expression-Related Hexose/Glucose Transport Enhancer (DREH). LncRNAs participate in the regulation of lipid and carbohydrate metabolism, the inflammatory process, and oxidative stress through different pathways, such as cyclic adenosine monophosphate/protein kinase A (cAMP/PKA), phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT), polypyrimidine tract-binding protein 1/element-binding transcription factor 1c (PTBP1/SREBP-1c), AKT/nitric oxide synthase (eNOS), AKT/forkhead box O1 (FoxO1), and tumor necrosis factor-alpha (TNF-α)/c-Jun-N-terminal kinases (JNK). On the other hand, the mechanisms linked to the molecular, cellular, and biochemical actions of lncRNAs vary according to the tissue, biological species, and the severity of IR. Therefore, it is essential to elucidate the role of lncRNAs in the insulin signaling pathway and glucose and lipid metabolism. This review analyzes the function and molecular mechanisms of lncRNAs involved in the development of IR.

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Hepatic Mitogen-Activated Protein Kinase Phosphatase 1 Selectively Regulates Glucose Metabolism and Energy Homeostasis

Molecular and Cellular Biology ◽

10.1128/mcb.00503-14 ◽

2014 ◽

Vol 35 (1) ◽

pp. 26-40 ◽

Cited By ~ 33

Author(s):

Ahmed Lawan ◽

Lei Zhang ◽

Florian Gatzke ◽

Kisuk Min ◽

Michael J. Jurczak ◽

...

Keyword(s):

Insulin Resistance ◽

Protein Kinase ◽

Glucose Metabolism ◽

Energy Homeostasis ◽

Mitogen Activated Protein Kinase ◽

Hepatic Insulin Resistance ◽

Fibroblast Growth Factor 21 ◽

High Fat ◽

Mitogen Activated Protein ◽

Fat Feeding

The liver plays a critical role in glucose metabolism and communicates with peripheral tissues to maintain energy homeostasis. Obesity and insulin resistance are highly associated with nonalcoholic fatty liver disease (NAFLD). However, the precise molecular details of NAFLD remain incomplete. The p38 mitogen-activated protein kinase (MAPK) and c-Jun NH2-terminal kinase (JNK) regulate liver metabolism. However, the physiological contribution of MAPK phosphatase 1 (MKP-1) as a nuclear antagonist of both p38 MAPK and JNK in the liver is unknown. Here we show that hepatic MKP-1 becomes overexpressed following high-fat feeding. Liver-specific deletion of MKP-1 enhances gluconeogenesis and causes hepatic insulin resistance in chow-fed mice while selectively conferring protection from hepatosteatosis upon high-fat feeding. Further, hepatic MKP-1 regulates both interleukin-6 (IL-6) and fibroblast growth factor 21 (FGF21). Mice lacking hepatic MKP-1 exhibit reduced circulating IL-6 and FGF21 levels that were associated with impaired skeletal muscle mitochondrial oxidation and susceptibility to diet-induced obesity. Hence, hepatic MKP-1 serves as a selective regulator of MAPK-dependent signals that contributes to the maintenance of glucose homeostasis and peripheral tissue energy balance. These results also demonstrate that hepatic MKP-1 overexpression in obesity is causally linked to the promotion of hepatosteatosis.

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Genistein promotes insulin action through adenosine monophosphate–activated protein kinase activation and p70 ribosomal protein S6 kinase 1 inhibition in the skeletal muscle of mice fed a high energy diet

Nutrition Research ◽

10.1016/j.nutres.2012.06.002 ◽

2012 ◽

Vol 32 (8) ◽

pp. 617-625 ◽

Cited By ~ 23

Author(s):

Elumalai Arunkumar ◽

Carani Venkatraman Anuradha

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Ribosomal Protein ◽

Insulin Action ◽

Adenosine Monophosphate ◽

High Energy ◽

S6 Kinase ◽

Kinase Activation ◽

Ribosomal Protein S6 ◽

Protein Kinase Activation

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Ku-0063794 is a specific inhibitor of the mammalian target of rapamycin (mTOR)

Biochemical Journal ◽

10.1042/bj20090489 ◽

2009 ◽

Vol 421 (1) ◽

pp. 29-42 ◽

Cited By ~ 318

Author(s):

Juan M. García-Martínez ◽

Jennifer Moran ◽

Rosemary G. Clarke ◽

Alex Gray ◽

Sabina C. Cosulich ◽

...

Keyword(s):

Protein Kinase ◽

Cell Growth ◽

Mammalian Target Of Rapamycin ◽

Specific Inhibitor ◽

Initiation Factor ◽

Target Of Rapamycin ◽

S6 Kinase ◽

Class 1 ◽

Hydrophobic Motif ◽

Ribosomal S6 Kinase

mTOR (mammalian target of rapamycin) stimulates cell growth by phosphorylating and promoting activation of AGC (protein kinase A/protein kinase G/protein kinase C) family kinases such as Akt (protein kinase B), S6K (p70 ribosomal S6 kinase) and SGK (serum and glucocorticoid protein kinase). mTORC1 (mTOR complex-1) phosphorylates the hydrophobic motif of S6K, whereas mTORC2 phosphorylates the hydrophobic motif of Akt and SGK. In the present paper we describe the small molecule Ku-0063794, which inhibits both mTORC1 and mTORC2 with an IC50 of ∼10 nM, but does not suppress the activity of 76 other protein kinases or seven lipid kinases, including Class 1 PI3Ks (phosphoinositide 3-kinases) at 1000-fold higher concentrations. Ku-0063794 is cell permeant, suppresses activation and hydrophobic motif phosphorylation of Akt, S6K and SGK, but not RSK (ribosomal S6 kinase), an AGC kinase not regulated by mTOR. Ku-0063794 also inhibited phosphorylation of the T-loop Thr308 residue of Akt phosphorylated by PDK1 (3-phosphoinositide-dependent protein kinase-1). We interpret this as implying phosphorylation of Ser473 promotes phosphorylation of Thr308 and/or induces a conformational change that protects Thr308 from dephosphorylation. In contrast, Ku-0063794 does not affect Thr308 phosphorylation in fibroblasts lacking essential mTORC2 subunits, suggesting that signalling processes have adapted to enable Thr308 phosphorylation to occur in the absence of Ser473 phosphorylation. We found that Ku-0063794 induced a much greater dephosphorylation of the mTORC1 substrate 4E-BP1 (eukaryotic initiation factor 4E-binding protein 1) than rapamycin, even in mTORC2-deficient cells, suggesting a form of mTOR distinct from mTORC1, or mTORC2 phosphorylates 4E-BP1. Ku-0063794 also suppressed cell growth and induced a G1-cell-cycle arrest. Our results indicate that Ku-0063794 will be useful in delineating the physiological roles of mTOR and may have utility in treatment of cancers in which this pathway is inappropriately activated.

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Lycopsamine Attenuates Diabetes Mellitus via The Nuclear Factor Kappa B-Induced 5′ Adenosine Monophosphate-Activated Protein Kinase Signal Pathway

Current Topics in Nutraceutical Research ◽

10.37290/ctnr2641-452x.20:169-176 ◽

2021 ◽

Vol 20 (1) ◽

pp. 169-176

Author(s):

Jingfang Hu ◽

Jie Jin ◽

Yan Chen ◽

Jinyi Wei ◽

Hanbei Chen

Keyword(s):

Diabetes Mellitus ◽

Insulin Resistance ◽

Protein Kinase ◽

Nuclear Factor Kappa B ◽

Adenosine Monophosphate ◽

Interleukin 10 ◽

Diabetic Rats ◽

Nuclear Factor ◽

Nonesterified Fatty Acids ◽

Nuclear Factor Kappa

Diabetes mellitus is a metabolic disorder characterized by inflammation, abnormal glycolipid metabolism, insulin resistance, and mitochondrial dysfunction leading to hyperglycemia. The aim of the present investigation was to determine the efficacy of lycopsamine in a rat model of diabetes mellitus to understand its mechanism. Lycopsamine treatment markedly lowered the level of total cholesterol, triglyceride, nonesterified fatty acids, and low-density lipoprotein in diabetic rats. There was also a reduction in interleukin-6, interleukin-10, C-reactive protein, and tumor necrosis factor-α levels. Lycopsamine treatment normalized the metabolism of lipid and glucose, insulin resistance, and body weight of diabetic rats. Findings of immunohistochemical analyses exhibited rise in precipitation of immunocytes in renal cells. Results potentially demonstrated that lycopsamine treatment remarkably reduced the nuclear factor-kappa B level and enhanced the 5′ adenosine monophosphate-activated protein kinase expression. Altogether, administration of lycopsamine suppressed the expression of inflammatory cytokines and attenuated the metabolic symptoms in diabetes mellitus experimental rats.

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