Protein–protein interaction in insulin signaling and the molecular mechanisms of insulin resistance

Type 2 diabetes mellitus is a progressive disease that is characterized by the appearance of insulin resistance. The term insulin resistance is very wide and could affect different proteins involved in insulin signaling, as well as other mechanisms. In this review, we have analyzed the main molecular mechanisms that could be involved in the connection between type 2 diabetes and neurodegeneration, in general, and more specifically with the appearance of Alzheimer’s disease. We have studied, in more detail, the different processes involved, such as inflammation, endoplasmic reticulum stress, autophagy, and mitochondrial dysfunction.

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Structural basis for activation of trimeric Gi proteins by multiple growth factor receptors via GIV/Girdin

Molecular Biology of the Cell ◽

10.1091/mbc.e14-05-0978 ◽

2014 ◽

Vol 25 (22) ◽

pp. 3654-3671 ◽

Cited By ~ 40

Author(s):

Changsheng Lin ◽

Jason Ear ◽

Krishna Midde ◽

Inmaculada Lopez-Sanchez ◽

Nicolas Aznar ◽

...

Keyword(s):

Growth Factor ◽

G Proteins ◽

Protein Interaction ◽

Cross Talk ◽

Tyrosine Kinases ◽

Molecular Mechanisms ◽

Growth Factor Receptors ◽

Structural Basis ◽

Nucleotide Exchange ◽

Protein Protein Interaction

A long-standing issue in the field of signal transduction is to understand the cross-talk between receptor tyrosine kinases (RTKs) and heterotrimeric G proteins, two major and distinct signaling hubs that control eukaryotic cell behavior. Although stimulation of many RTKs leads to activation of trimeric G proteins, the molecular mechanisms behind this phenomenon remain elusive. We discovered a unifying mechanism that allows GIV/Girdin, a bona fide metastasis-related protein and a guanine-nucleotide exchange factor (GEF) for Gαi, to serve as a direct platform for multiple RTKs to activate Gαi proteins. Using a combination of homology modeling, protein–protein interaction, and kinase assays, we demonstrate that a stretch of ∼110 amino acids within GIV C-terminus displays structural plasticity that allows folding into a SH2-like domain in the presence of phosphotyrosine ligands. Using protein–protein interaction assays, we demonstrated that both SH2 and GEF domains of GIV are required for the formation of a ligand-activated ternary complex between GIV, Gαi, and growth factor receptors and for activation of Gαi after growth factor stimulation. Expression of a SH2-deficient GIV mutant (Arg 1745→Leu) that cannot bind RTKs impaired all previously demonstrated functions of GIV—Akt enhancement, actin remodeling, and cell migration. The mechanistic and structural insights gained here shed light on the long-standing questions surrounding RTK/G protein cross-talk, set a novel paradigm, and characterize a unique pharmacological target for uncoupling GIV-dependent signaling downstream of multiple oncogenic RTKs.

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Visfatin Induces Inflammation and Insulin Resistance via the NF-κB and STAT3 Signaling Pathways in Hepatocytes

Journal of Diabetes Research ◽

10.1155/2019/4021623 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11 ◽

Cited By ~ 15

Author(s):

Yu Jung Heo ◽

Sung-E Choi ◽

Ja Young Jeon ◽

Seung Jin Han ◽

Dae Jung Kim ◽

...

Keyword(s):

Insulin Resistance ◽

Signaling Pathways ◽

Western Blotting ◽

Insulin Signaling ◽

Proinflammatory Cytokine ◽

Hepg2 Cells ◽

Molecular Mechanisms ◽

Immunocytochemical Staining ◽

Mrna Levels ◽

Rt Pcr

Background. It has been suggested that visfatin, which is an adipocytokine, exhibits proinflammatory properties and is associated with insulin resistance. Insulin resistance and inflammation are the principal pathogeneses of nonalcoholic fatty liver disease (NAFLD), but the relationship, if any, between visfatin and NAFLD remains unclear. Here, we evaluated the effects of visfatin on hepatic inflammation and insulin resistance in HepG2 cells and examined the molecular mechanisms involved. Methods. After treatment with visfatin, the inflammatory cytokines IL-6, TNF-α, and IL-1β were assessed by real-time polymerase chain reaction (RT-PCR) and immunocytochemical staining in HepG2 cells. To investigate the effects of visfatin on insulin resistance, we evaluated insulin-signaling pathways, such as IR, IRS-1, GSK, and AKT using immunoblotting. We assessed the intracellular signaling molecules including STAT3, NF-κB, IKK, p38, JNK, and ERK by western blotting. We treated HepG2 cells with both visfatin and either AG490 (a JAK2 inhibitor) or Bay 7082 (an NF-κB inhibitor); we examined proinflammatory cytokine mRNA levels using RT-PCR and insulin signaling using western blotting. Results. In HepG2 cells, visfatin significantly increased the levels of proinflammatory cytokines, reduced the levels of proteins (e.g., phospho-IR, phospho-IRS-1 (Tyr612), phospho-AKT, and phospho-GSK-3α/β) involved in insulin signaling, and increased IRS-1 S307 phosphorylation compared to controls. Interestingly, visfatin increased the activities of the JAK2/STAT3 and IKK/NF-κB signaling pathways but not those of the JNK, p38, and ERK pathways. Visfatin-induced inflammation and insulin resistance were regulated by JAK2/STAT3 and IKK/NF-κB signaling; together with AG490 or Bay 7082, visfatin significantly reduced mRNA levels of IL-6, TNF-α and IL-1β and rescued insulin signaling. Conclusion. Visfatin induced proinflammatory cytokine production and inhibited insulin signaling via the STAT3 and NF-κB pathways in HepG2 cells.

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Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00098.2010 ◽

2010 ◽

Vol 299 (2) ◽

pp. E215-E224 ◽

Cited By ~ 27

Author(s):

Nina Brandt ◽

Katrien De Bock ◽

Erik A. Richter ◽

Peter Hespel

Keyword(s):

Insulin Resistance ◽

Exercise Training ◽

Energy Intake ◽

Insulin Signaling ◽

Molecular Mechanisms ◽

Cafeteria Diet ◽

Low Fat ◽

Low Fat Diet ◽

Male Wistar Rats ◽

Syntaxin 4

Excess energy intake via a palatable low-fat diet (cafeteria diet) is known to induce obesity and glucose intolerance in rats. However, the molecular mechanisms behind this adaptation are not known, and it is also not known whether exercise training can reverse it. Male Wistar rats were assigned to 12-wk intervention groups: chow-fed controls (CON), cafeteria diet (CAF), and cafeteria diet plus swimming exercise during the last 4 wk (CAFTR). CAF feeding led to increased body weight (16%, P < 0.01) and increased plasma glucose ( P < 0.05) and insulin levels ( P < 0.01) during an IVGTT, which was counteracted by training. In the perfused hindlimb, insulin-stimulated glucose transport in red gastrocnemius muscle was completely abolished in CAF and rescued by exercise training. Apart from a tendency toward an ∼20% reduction in both basal and insulin-stimulated Akt Ser473 phosphorylation ( P = 0.051) in the CAF group, there were no differences in insulin signaling (IR Tyr1150/1151, PI 3-kinase activity, Akt Thr308, TBC1D4 Thr642, GSK3-α/β Ser21/9) or changes in AMPKα1 or -α2, GLUT4, Munc18c, or syntaxin 4 protein expression or in phosphorylation of AMPK Thr172 among the groups. In conclusion, surplus energy intake of a palatable but low-fat cafeteria diet resulted in obesity and insulin resistance that was rescued by exercise training. Interestingly, insulin resistance was not accompanied by major defects in the insulin-signaling cascade or in altered AMPK expression or phosphorylation. Thus, compared with previous studies of high-fat feeding, where insulin signaling is significantly impaired, the mechanism by which CAF diet induces insulin resistance seems different.

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A Pathway and Network Oriented Approach to Enlighten Molecular Mechanisms of Type 2 Diabetes Using Multiple Association Studies

10.1101/2020.01.14.905547 ◽

2020 ◽

Author(s):

Burcu Bakir-Gungor ◽

Miray Unlu Yazici ◽

Gokhan Goy ◽

Mustafa Temiz

Keyword(s):

Diabetes Mellitus ◽

Type 2 Diabetes ◽

Protein Interaction ◽

Molecular Mechanisms ◽

Association Studies ◽

Genome Wide Association Studies ◽

Protein Protein Interaction ◽

Ppi Networks ◽

Oriented Approach

AbstractDiabetes Mellitus (DM) is a group of metabolic disorder that is characterized by pancreatic dysfunction in insulin producing beta cells, glucagon secreting alpha cells, and insulin resistance or insulin in-functionality related hyperglycemia. Type 2 Diabetes Mellitus (T2D), which constitutes 90% of the diabetes cases, is a complex multifactorial disease. In the last decade, genome-wide association studies (GWASs) for type 2 diabetes (T2D) successfully pinpointed the genetic variants (typically single nucleotide polymorphisms, SNPs) that associate with disease risk. However, traditional GWASs focus on the ‘the tip of the iceberg’ SNPs, and the SNPs with mild effects are discarded. In order to diminish the burden of multiple testing in GWAS, researchers attempted to evaluate the collective effects of interesting variants. In this regard, pathway-based analyses of GWAS became popular to discover novel multi-genic functional associations. Still, to reveal the unaccounted 85 to 90% of T2D variation, which lies hidden in GWAS datasets, new post-GWAS strategies need to be developed. In this respect, here we reanalyze three meta-analysis data of GWAS in T2D, using the methodology that we have developed to identify disease-associated pathways by combining nominally significant evidence of genetic association with the known biochemical pathways, protein-protein interaction (PPI) networks, and the functional information of selected SNPs. In this research effort, to enlighten the molecular mechanisms underlying T2D development and progress, we integrated different in-silico approaches that proceed in top-down manner and bottom-up manner, and hence presented a comprehensive analysis at protein subnetwork, pathway, and pathway subnetwork levels. Our network and pathway-oriented approach is based on both the significance level of an affected pathway and its topological relationship with its neighbor pathways. Using the mutual information based on the shared genes, the identified protein subnetworks and the affected pathways of each dataset were compared. While, most of the identified pathways recapitulate the pathophysiology of T2D, our results show that incorporating SNP functional properties, protein-protein interaction networks into GWAS can dissect leading molecular pathways, which cannot be picked up using traditional analyses. We hope to bridge the knowledge gap from sequence to consequence.

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Comparative host-coronavirus protein interaction networks reveal pan-viral disease mechanisms

Science ◽

10.1126/science.abe9403 ◽

2020 ◽

Vol 370 (6521) ◽

pp. eabe9403 ◽

Cited By ~ 17

Author(s):

David E. Gordon ◽

Joseph Hiatt ◽

Mehdi Bouhaddou ◽

Veronica V. Rezelj ◽

Svenja Ulferts ◽

...

Keyword(s):

Protein Interaction ◽

Global Economy ◽

Molecular Mechanisms ◽

Protein Localization ◽

Viral Disease ◽

Host Factors ◽

Protein Protein Interaction ◽

Chaperone Protein ◽

Cryo Electron Microscopy ◽

Drug Treatments

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a grave threat to public health and the global economy. SARS-CoV-2 is closely related to the more lethal but less transmissible coronaviruses SARS-CoV-1 and Middle East respiratory syndrome coronavirus (MERS-CoV). Here, we have carried out comparative viral-human protein-protein interaction and viral protein localization analyses for all three viruses. Subsequent functional genetic screening identified host factors that functionally impinge on coronavirus proliferation, including Tom70, a mitochondrial chaperone protein that interacts with both SARS-CoV-1 and SARS-CoV-2 ORF9b, an interaction we structurally characterized using cryo–electron microscopy. Combining genetically validated host factors with both COVID-19 patient genetic data and medical billing records identified molecular mechanisms and potential drug treatments that merit further molecular and clinical study.

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HMNPPID—human malignant neoplasm protein–protein interaction database

Human Genomics ◽

10.1186/s40246-019-0223-5 ◽

2019 ◽

Vol 13 (S1) ◽

Author(s):

Qingqing Li ◽

Zhihao Yang ◽

Zhehuan Zhao ◽

Ling Luo ◽

Zhiheng Li ◽

...

Keyword(s):

Protein Interaction ◽

Protein Interactions ◽

Molecular Mechanisms ◽

Malignant Neoplasm ◽

Biomedical Literature ◽

Malignant Neoplasms ◽

Protein Protein Interactions ◽

Protein Protein Interaction ◽

Interaction Database ◽

Protein Interaction Database

Abstract Background Protein–protein interaction (PPI) information extraction from biomedical literature helps unveil the molecular mechanisms of biological processes. Especially, the PPIs associated with human malignant neoplasms can unveil the biology behind these neoplasms. However, such PPI database is not currently available. Results In this work, a database of protein–protein interactions associated with 171 kinds of human malignant neoplasms named HMNPPID is constructed. In addition, a visualization program, named VisualPPI, is provided to facilitate the analysis of the PPI network for a specific neoplasm. Conclusions HMNPPID can hopefully become an important resource for the research on PPIs of human malignant neoplasms since it provides readily available data for healthcare professionals. Thus, they do not need to dig into a large amount of biomedical literatures any more, which may accelerate the researches on the PPIs of malignant neoplasms.

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Comprehensive functional screening of miRNAs involved in fat cell insulin sensitivity among women

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00251.2016 ◽

2017 ◽

Vol 312 (6) ◽

pp. E482-E494 ◽

Cited By ~ 13

Author(s):

Ingrid Dahlman ◽

Yasmina Belarbi ◽

Jurga Laurencikiene ◽

Annie M. Pettersson ◽

Peter Arner ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Sensitivity ◽

Differential Expression ◽

Insulin Signaling ◽

Molecular Mechanisms ◽

Functional Screening ◽

Fat Cell ◽

Subcutaneous White Adipose Tissue ◽

Micro Rnas

The key pathological link between obesity and type 2 diabetes is insulin resistance, but the molecular mechanisms are not entirely identified. micro-RNAs (miRNA) are dysregulated in obesity and may contribute to insulin resistance. Our objective was to detect and functionally investigate miRNAs linked to insulin sensitivity in human subcutaneous white adipose tissue (scWAT). Subjects were selected based on the insulin-stimulated lipogenesis response of subcutaneous adipocytes. Global miRNA profiling was performed in abdominal scWAT of 18 obese insulin-resistance (OIR), 21 obese insulin-sensitive (OIS), and 9 lean women. miRNAs demonstrating differential expression between OIR and OIS women were overexpressed in human in vitro-differentiated adipocytes followed by assessment of lipogenesis and identification of miRNA targets by measuring mRNA/protein expression and 3′-untranslated region analysis. Eleven miRNAs displayed differential expression between OIR and OIS states. Overexpression of miR-143-3p and miR-652-3p increased insulin-stimulated lipogenesis in human in vitro differentiated adipocytes and directly or indirectly affected several genes/proteins involved in insulin signaling at transcriptional or posttranscriptional levels. Adipose expression of miR-143-3p and miR-652-3p was positively associated with insulin-stimulated lipogenesis in scWAT independent of body mass index. In conclusion, miR-143-3p and miR-652-3p are linked to scWAT insulin resistance independent of obesity and influence insulin-stimulated lipogenesis by interacting at different steps with insulin-signaling pathways.

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TWEAK prevents TNF-α-induced insulin resistance through PP2A activation in human adipocytes

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00589.2012 ◽

2013 ◽

Vol 305 (1) ◽

pp. E101-E112 ◽

Cited By ~ 18

Author(s):

Ana Vázquez-Carballo ◽

Victòria Ceperuelo-Mallafré ◽

Matilde R. Chacón ◽

Elsa Maymó-Masip ◽

Margarita Lorenzo ◽

...

Keyword(s):

Insulin Resistance ◽

Adipose Tissue ◽

Insulin Signaling ◽

Visceral Fat ◽

Molecular Mechanisms ◽

Physiological Role ◽

Metabolic Effects ◽

Human Adipocytes ◽

Fat Depots ◽

Tnf Α

Visceral fat is strongly associated with insulin resistance. Obesity-associated adipose tissue inflammation and inflammatory cytokine production are considered key mediators of insulin signaling inhibition. TWEAK is a relatively new member of the TNF cytokine superfamily, which can exist as full length membrane-associated (mTWEAK) and soluble (sTWEAK) isoforms. Although TWEAK has been shown to have important functions in chronic inflammatory diseases its physiological role in adipose tissue remains unresolved. In this study, we explore the molecular mechanisms involved in the modulation of TNF-α-induced effects on insulin sensitivity by sTWEAK in a human visceral adipose cell line and also in primary human adipocytes obtained from visceral fat depots. Our data reveal that sTWEAK ameliorates TNF-α-induced insulin resistance on glucose uptake, GLUT4 translocation and insulin signaling without affecting other metabolic effects of TNF-α such as lipolysis or apoptotis. Co-immunoprecipitation experiments in adipose cells revealed that pretreatment with sTWEAK specifically inhibits TRAF2 association with TNFR1, but not with TNFR2, which mediates insulin resistance. However, sTWEAK does not affect other downstream molecules activated by TNF-α, such as TAK1. Rather, sTWEAK abolishes the stimulatory effect of TNF-α on JNK1/2, which is directly involved in the development of insulin resistance. This is associated with an increase in PP2A activity upon sTWEAK treatment. Silencing of the PP2A catalytic subunit gene overcomes the dephosphorylation effect of sTWEAK on JNK1/2, pointing to PP2A as a relevant mediator of sTWEAK-induced JNK inactivation. Overall, our data reveal a protective role of TWEAK in glucose homeostasis and identify PP2A as a new driver in the modulation of TNF-α signaling by sTWEAK.

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Role of inhibitory κB kinase and c-Jun NH2-terminal kinase in the development of hepatic insulin resistance in critical illness diabetes

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00148.2011 ◽

2011 ◽

Vol 301 (3) ◽

pp. G454-G463 ◽

Cited By ~ 16

Author(s):

Shaoning Jiang ◽

Joseph L. Messina

Keyword(s):

Insulin Resistance ◽

Critical Illness ◽

Insulin Signaling ◽

Molecular Mechanisms ◽

Adenovirus Vector ◽

Dominant Negative ◽

Serine Phosphorylation ◽

Hepatic Insulin Resistance ◽

Mortality And Morbidity ◽

Hepatic Insulin Signaling

Hyperglycemia and insulin resistance induced by acute injuries or critical illness are associated with increased mortality and morbidity, as well as later development of type 2 diabetes. The molecular mechanisms underlying the acute onset of insulin resistance following critical illness remain poorly understood. In the present studies, the roles of serine kinases, inhibitory κB kinase (IKK) and c-Jun NH2-terminal kinase (JNK), in the acute development of hepatic insulin resistance were investigated. In our animal model of critical illness diabetes, activation of hepatic IKK and JNK was observed as early as 15 min, concomitant with the rapid impairment of hepatic insulin signaling and increased serine phosphorylation of insulin receptor substrate 1. Inhibition of IKKα or IKKβ, or both, by adenovirus vector-mediated expression of dominant-negative IKKα or IKKβ in liver partially restored insulin signaling. Similarly, inhibition of JNK1 kinase by expression of dominant-negative JNK1 also resulted in improved hepatic insulin signaling, indicating that IKK and JNK1 kinases contribute to critical illness-induced insulin resistance in liver.

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