Insulin Receptor Substrate Research Articles

Ab initio modeling of human IRS1 protein to find novel target to dock with drug MH to mitigateT2DM diabetes by insulin signaling.

IRS1 is a cytoplasmic adaptor protein that helps incellulargrowth, glucose metabolism, proliferation, anddifferentiation. Highly disordered (insulin receptor substrate 1) IRS1 protein sequence (mol.wt- 131,590.97da) has been used to develop model using ab initio modeling technique by I-Tassar tool and Discovery Studio/ DogSite Server to decipher a novel active site. The constructed protein model has been submitted with PMDB Id- PM0082210. GRAVY index of IRS1 model ( - 0.675) indicated surface protein-water interaction. Protparam tool instability index (75.22) demonstrated disorderedness combined with loops owing to prolines/glycines. After refinement,the Ramachandran plot showed that 88 percent of AAs were presentin the allowed region and only 0.5% in the disallowed region.Novel IRS1 model proteinhas 10 α-helices, 22 β-sheets, 20 β-hairpins, 5 β-bulges, 47 strands, 105 β-turns, and 8 γ-turns. Docking of IRS1 with drug MH demonstrated interaction of Ser-70, Thr-18, and Pro-69 with C-H bonds; Gln-71, and Glu-113 with hydrogen bonds; while both Glu-114 and Glu-113 with salt-bridge connection. Permissible 1.0-1.5Å range of RMSD fluctuation between 20 and 45ns was obtained in simulation of IRS1 and IRS1-met complex confirmed that both complexes were stable during whole simulation process. RMSF result showed that except positions 57AA and 114AA, the binding of drug had no severe effects on the flexibility of the IRS1 and IRS1-met complex. The RoG value of compactness and rigidity showed little change in IRS1 protein. SASA value of IRS1 indicated non-significant fluctuation between IRS1 and drug MH means ligand (drug) and IRS1 receptor form stable structure. Hydrogen bond strength of IRS1 and IRS1-met was 81.2 and 76.4, respectively, which suggested stable interaction.

Association between insulin receptor substrate 1 gene polymorphism rs1801278 and gestational diabetes mellitus: an updated meta- analysis

Objectiveswe performed this meta- analysis to investigate the impact of insulin receptor substrate 1 (IRS1) gene rs1801278 on susceptibility to gestational diabetes mellitus (GDM).MethodsThe pooled odds ratio (OR) and 95% confidence interval (95% CI) were calculated, and p value is used to determine statistical significance. Sensitivity analysis was performed under three models (dominant, recessive and allele model), and the pooled ORs and 95%CI were calculated. Funnel plots and Begger’s regression test were employed to test the publication bias.ResultsThe meta-analysis included 4777 participants (2116 cases and 2661 controls). The IRS1 rs1801278 (C/T) were not significant associated with GDM risk under the dominant and allele models, OR (95%CI) = 1.22 (0.88–1.70) and 1.24 (0.91–1.68), respectively (both p values were more than 0.05). But we also found the IRS1 rs1801278 (C/T) were significant associated with GDM risk under the recessive model, OR (95%CI) = 0.37 (0.16–0.86), p = 0.030. Our results showed that none of the studies affected the quality of the pooled OR. We also found no significant publication bias existed in this meta study for three genetic models, PTT + CT vs. CC = 0.445; PCC+CT vs. TT= 0.095; PC vs. T = 0.697.Conclusionthis meta-analysis indicated that IRS1 rs1801278 (C/T) was associated with the GDM risk under the recessive model but was not associated with the GDM risk under dominant and allele models.

FGF19 Promotes the Proliferation and Insulin Secretion from Human Pancreatic β Cells Via the IRS1/GLUT4 Pathway.

Type 2 diabetes mellitus (T2DM) is a commonly observed complication associated with obesity. The effect of fibroblast growth factor 19 (FGF19), a promising therapeutic agent for metabolic disorders, on pancreatic β cells in obesity-associated T2DM remains poorly understood. Human pancreatic β cells were cultured with high glucose (HG) and palmitic acid (PA), followed by treatment with FGF19. The cell proliferation, apoptosis, and insulin secretion were evaluated by CCK-8, qRT-PCR, ELISA, flow cytometry, and western blotting. The expression of the insulin receptor substrate (IRS)/glucose transporter (GLUT) pathway was evaluated. The interaction between FGF19 and IRS1 was predicted using the STRING database and verified by co-immunoprecipitation and immunofluorescence. The regulatory effects of the IRS1/GLUT4 pathway on human pancreatic β cells were assessed by overexpressing IRS1 and silencing IRS1 and GLUT4. HG+PA treatment reduced the human pancreatic β cell proliferation and insulin secretion and promoted cell apoptosis. However, FGF19 treatment restored these alterations and significantly increased the expressions of IRS1, GLUT1, and GLUT4 in the IRS/GLUT pathway. Furthermore, FGF19 and IRS1 were found to interact. IRS1 overexpression partially promoted the proliferation of pancreatic β cells and insulin secretion through GLUT4. Additionally, the silencing of IRS1 or GLUT4 attenuated the therapeutic effects of FGF19. In conclusion, FGF19 partly promoted the proliferation and insulin secretion of human pancreatic β cells and inhibited apoptosis by upregulating the IRS1/GLUT4 pathway. These findings establish a theoretical framework for the clinical utilization of FGF19 in the treatment of obesity-associated T2DM.

Anti-diabetic effect of anthocyanin cyanidin-3-O-glucoside: data from insulin resistant hepatocyte and diabetic mouse

BackgroundAnthocyanins are a group of natural products widely found in plants. They have been found to alleviate the disorders of glucose metabolism in type 2 diabetes mellitus (T2DM), while the underlying mechanisms remain unclear.MethodsHepG2 and L02 cells were incubated with 0.2 mM PA and 30 mM glucose for 24 h to induce IR, and cells treated with 5 mM glucose were used as the control. C57BL/6 J male mice and db/db male mice were fed with a chow diet and gavaged with pure water or cyanidin-3-O-glucoside (C3G) solution (150 mg/kg/day) for 6 weeks.ResultsIn this study, the anthocyanin C3G, extracted from red bayberry, was found to alleviate disorders of glucose metabolism, which resulted in increased insulin sensitivity in hepatocytes, and achieved by enhancing the glucose consumption as well as glycogen synthesis in insulin resistance (IR) hepatpcytes. Subsequently, the expression of key proteins involved in IR was detected by western blotting analysis. Protein tyrosine phosphatase-1B (PTP1B), a negative regulator of insulin signaling, could reduce cellular sensitivity to insulin by inhibiting the phosphorylation of insulin receptor substrate-2 (IRS-2). Results of this study showed that C3G inhibited the increase in PTP1B after high glucose and palmitic acid treatment. And this inhibition was accompanied by increased phosphorylation of IRS proteins. Furthermore, the effect of C3G on improving IR in vivo was validated by using a diabetic db/db mouse model.ConclusionThese findings demonstrated that C3G could alleviate IR in vitro and in vivo to increase insulin sensitivity, which may offer a new insight for regulating glucose metabolism during T2DM by using the natural dietary bioactive components.C3G promotes the phosphorylation of IRS-2 proteins by suppressing the expression of PTP1B, and then enhances the sensitivity of hepatocyte to insulin.

Oxidative Stress and ROS Link Diabetes and Cancer

Type 2 diabetes mellitus (T2DM) accounts for one-sixth of deaths globally, whereas cancer is the second leading cause of death in the U.S. T2DM is a known risk factor for many cancers. Reactive oxygen species (ROS)-altered metabolic and signaling pathways link T2DM to cancer. These reprogrammed metabolic and signaling pathways contribute to diabetic complications, impact the redox balance (oxidative stress), and have differential roles in the early and late stages of cancer. A respiratory chain that is highly reduced (as under hyperglycemic conditions) or if reduced cofactors accumulate, ROS are greatly elevated. ROS may cause mutations in mitochondrial DNA (mtDNA) that result in further ROS elevations. The amplification of ROS results in the activation of PKC, an overarching signaling pathway that activates MAPK with a subsequent regulation in several factors that result in pathophysiological manifestations of T2DM and cancer. An upregulation in PKC leads to a deregulation in NF-kß, which regulates the PKB/P13/Akt pathway and orchestrates the cell survival, growth, proliferation, and glucose metabolism manifested in cancer. It also affects Insulin Receptor Substrate (IRS-1), decreasing insulin-stimulated glucose transport and glucose uptake, disrupting subsequent cell signaling pathways contributing to the development of T2DM. Dyslipidemia is a hallmark of T2DM and cancer. ROS-induced lipid peroxidation leads to systemic inflammation, producing inflammatory prostaglandins, cytokines, and chemokines that result in tumor proliferation, rapid tumor growth, and modulation of immunity. The dual role of ROS in the early and late stages of cancer makes antioxidant therapy precarious and may be responsible for controversial results. A system that delivers an antioxidant directly to mitochondria may be useful in inhibiting the formation of ROS early during the pre-diabetic stage, whereas antioxidant therapy must be halted in later stages to retard metastasis.

Non-Receptor Type PTPases and their Role in Controlling Pathways Related to Diabetes and Liver Cancer Signalling.

The role of non-receptor type Protein Tyrosine Phosphatase (PTPases) in controlling pathways related to diabetes and Hepatocellular Carcinoma (HCC) is significant. The insulin signal transduction pathway is regulated by the steady-state phosphorylation of tyrosyl residues of the insulin receptor and post-receptor substrates. PTPase has been shown to have a physiological role in the regulation of reversible tyrosine phosphorylation. There are several non-receptor type PTPases. PTPase containing the SH-2 domain (SHP-2) and the non-receptor type PTPase (PTP1B; encoded by the PTPN1 gene) are involved in negative regulation of the insulin signaling pathway, thereby indicating that the pathway can be made more efficient by the reduction in the activity of specific PTPases. Reduction in insulin resistance may be achieved by drugs targeting these specific enzymes. The modifications in the receptor and post-receptor events of insulin signal transduction give rise to insulin resistance, and a link between insulin-resistant states and HCC has been established. The cancer cells thrive on higher levels of energy and their growth gets encouraged since insulin-resistant states lead to greater glucose levels. Cancer, hyperglycemia, and hypoglycemia are highly linked through various pathways hence, clarifying the molecular mechanisms through which non-receptor type PTPase regulates the insulin signal transduction is necessary to find an effective target for cancer. Targeting the pathways related to PTPases; both receptor and non-receptor types, may lead to an effective candidate to fight against diabetes and HCC.

The role of adhesion molecules in osteocalcin-induced effects on glucose and lipid metabolism in adipocytes

Recent findings suggest that uncarboxylated osteocalcin (GluOC) promotes glucose and lipid metabolism via its putative receptor GPRC6A; however, its direct effect on adipocytes remains elusive. In this study, we elucidated the effects of GluOC on adipocytes, with an emphasis on the role of cell adhesion molecules. We determined that GluOC promoted the expression of adipocyte adhesion molecule (ACAM) and its transcription factor Krüppel-like factor 4 and enhanced the cortical actin filament assembly, which ameliorated lipid droplet hypertrophy. Additionally, GluOC upregulated the expression of integrin αVβ3 and activation of focal adhesion kinase (FAK) and prevented insulin receptor substrate 1 (IRS1) degradation by inhibiting the ubiquitin–proteasome system via the FAK–PLC–PKC axis, which activated IRS1–Akt-mediated glucose transporter 4 (GLUT4) transport. Furthermore, we showed that GluOC elevated the expression of the insulin-independent glucose transporters GLUT1 and GLUT8, which facilitated insulin stimulation-independent glucose transport. The GluOC-induced activation of integrin αVβ3 signaling promoted microtubule assembly, which improved glucose and lipid metabolism via its involvement in intracellular vesicular transport. GluOC treatment also suppressed collagen type 1 formation, which might prevent adipose tissue fibrosis in obese individuals. Overall, our results imply that GluOC promotes glucose and lipid metabolism via ACAM, integrin αVβ3, and GLUT1 and 8 expression, directly affecting adipocytes.

Glycolipids Derived from the Korean Endemic Plant Aruncus aethusifolius Inducing Glucose Uptake in Mouse Skeletal Muscle C2C12 Cells.

Aruncus spp. has been used as a traditional folk medicine worldwide for its anti-inflammatory, hemostatic, and detoxifying properties. The well-known species A. dioicus var. kamtschaticus has long been used for multifunctional purposes in Eastern Asia. Recently, it was reported that its extract has antioxidant and anti-diabetic effects. In this respect, it is likely that other Aruncus spp. possess various biological activities; however, little research has been conducted thus far. The present study aims to biologically identify active compounds against diabetes in the Korean endemic plant A. aethusifolius and evaluate the underlying mechanisms. A. aethusifolius extract enhanced glucose uptake without toxicity to C2C12 cells. A bioassay-guided isolation of A. aethusifolius yielded two pure compounds, and their structures were characterized as glycolipid derivatives, gingerglycolipid A, and (2S)-3-linolenoylglycerol-O-β-d-galactopyranoside by an interpretation of nuclear magnetic resonance and high-resolution mass spectrometric data. Both compounds showed glucose uptake activity, and both compounds increased the phosphorylation levels of insulin receptor substrate 1 (IRS-1) and 5'-AMP-activated protein kinase (AMPK) and protein expression of peroxisome proliferator-activated receptor γ (PPARγ). Gingerglycolipid A docked computationally into the active site of IRS-1, AMPK1, AMPK2, and PPARγ (-5.8, -6.9, -6.8, and -6.8 kcal/mol).

Identification and analysis of the expression of genes, involved in insulin signals transmission in the development of experimental type 2 diabetes mellitus

Type 2 diabetes mellitus is a significant concern due to its high prevalence and impact on global health. Ongoing scientific research aims to enhance our understanding of the mechanisms involved in the development and progression of diabetes and devise effective strategies for its treatment. This involves the development of new pharmacological treatments, including novel antidiabetic drugs, and the exploration of individualized approaches to therapy. The mechanisms underlying type 2 diabetes are intricate, involving various aspects of physiology and biochemistry. Gaining insight into the development and progression of type 2 diabetes mellitus through modern laboratory diagnostic methods is crucial for the development of effective treatment and prevention strategies for diabetes. The aim of the study is to identify and analyze a panel of genes, involved in insulin signals transmission in the development of experimental type 2 diabetes mellitus. Materials and methods. The analysis of gene expression involved in insulin signal transmission was conducted using real-time reverse transcription-polymerase chain reaction (RT-qPCR) on the CFX-96 Touch™ system (Bio-Rad, USA). The RT2Profiler™ PCR Array Rat Diabetes kit (QIAGEN, Germany) was employed for this purpose. Results. Based on the study results, the activity of the genes involved in insulin signal transmission can be categorized as follows: genes with low expression compared to the control group of animals, where ∆∆Ct <30 (Akt2, Mapk14, Pik3r1); genes in which no significant changes were detected in the samples compared to the control group (Irs1, Irs2, Pik3cd); no genes with high expression were observed compared to the control group. Conclusions. In the development of experimental type 2 diabetes mellitus, genes involved in insulin signal transmission (Akt2, Mapk14, Pik3r1) exhibited significantly low expression levels (Akt2 – 2.9, Mapk14 – 5.01, Pik3r1 – 8.87) where ∆∆Ct <30, compared to the control group of animals. Conversely, no significant changes were observed in the expression of genes Irs1, Irs2, Pik3cd, also involved in insulin signal transmission, during the development of experimental type 2 diabetes mellitus, compared to the control group of experimental animals.

<i>Artocarpus Communis</i> Seed Regulates P53, IRS, HsD17β2, FTO, and CYP11a Genes in Polycystic Ovarian Syndrome Rats

Polycystic ovarian syndrome (PCOS) is a prevalent endocrine illness that affects 5-10% of reproductive women globally. It is a multifaceted hormonal disorder characterized by the involvement of numerous molecular mechanisms that contribute to its development. This study investigates the effect of <em>Artocarpus communis </em>seed on the hormonal imbalance and P53, IRS, HsD17β2, FTO, and CYP11a genes expression in the ovaries of letrozole-induced polycystic ovarian syndrome rats. To induce PCOS in 30 female Wistar rats, letrozole was administered at a dosage of 1 mg/kg. For 12 days, <em>Artocarpus communis </em>seed aqueous extract (100 and 250 mg/kg body weight) and Clomiphene citrate (1 mg/kg body weight), a standard medication, were given. ELISA assessed luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol levels. The levels of P53, IRS, HsD17β2, FTO, and CYP11a gene expression in the ovaries were assessed. The aqueous extract reduced LH and increased FSH levels in Letrozole-induced PCOS rats. Additionally, seed aqueous extract (250 mg/kg bw) regulated the expression of P53, type 2 17-HSD (17-HSD), fat mass and obesity-associated (FTO), 11a-hydroxylase/17,20-desmolase (CYP11a), and insulin receptor substrate (IRS) genes in the ovaries of PCOS rats. Therefore, <em>Artocarpus communis</em> seed might have multifaceted effects on molecular pathways associated with PCOS, potentially normalizing androgen metabolism, hormonal imbalance, and ovarian function.

TGF-β1 Signaling Impairs Metformin Action on Glycemic Control.

Hyperglycemia is a hallmark of type 2 diabetes (T2D). Metformin, the first-line drug used to treat T2D, maintains blood glucose within a normal range by suppressing hepatic glucose production (HGP). However, resistance to metformin treatment is developed in most T2D patients over time. Transforming growth factor beta 1 (TGF-β1) levels are elevated both in the liver and serum of T2D humans and mice. Here, we found that TGF-β1 treatment impairs metformin action on suppressing HGP via inhibiting AMPK phosphorylation at Threonine 172 (T172). Hepatic TGF-β1 deficiency improves metformin action on glycemic control in high fat diet (HFD)-induced obese mice. In our hepatic insulin resistant mouse model (hepatic insulin receptor substrate 1 (IRS1) and IRS2 double knockout (DKO)), metformin action on glycemic control was impaired, which is largely improved by further deletion of hepatic TGF-β1 (TKObeta1) or hepatic Foxo1 (TKOfoxo1). Moreover, blockade of TGF-β1 signaling by chemical inhibitor of TGF-β1 type I receptor LY2157299 improves to metformin sensitivity in mice. Taken together, our current study suggests that hepatic TGF-β1 signaling impairs metformin action on glycemic control, and suppression of TGF-β1 signaling could serve as part of combination therapy with metformin for T2D treatment.

Microproteomic-Based Analysis of the Goat Milk Protein Synthesis Network and Casein Production Evaluation.

Goat milk has been consumed by humans since ancient times and is highly nutritious. Its quality is mainly determined by its casein content. Milk protein synthesis is controlled by a complex network with many signal pathways. Therefore, the aim of our study is to clearly depict the signal pathways involved in milk protein synthesis in goat mammary epithelial cells (GMECs) using state-of-the-art microproteomic techniques and to identify the key genes involved in the signal pathway. The microproteomic analysis identified more than 2253 proteins, with 323 pathways annotated from the identified proteins. Knockdown of IRS1 expression significantly influenced goat casein composition (α, β, and κ); therefore, this study also examined the insulin receptor substrate 1 (IRS1) gene more closely. A total of 12 differential expression proteins (DEPs) were characterized as upregulated or downregulated in the IRS1-silenced sample compared to the negative control. The enrichment and signal pathways of these DEPs in GMECs were identified using GO annotation and KEGG, as well as KOG analysis. Our findings expand our understanding of the functional genes involved in milk protein synthesis in goats, paving the way for new approaches for modifying casein content for the dairy goat industry and milk product development.

Effect of Supplementation with Omega-3 Polyunsaturated Fatty Acids on Metabolic Modulators in Skeletal Muscle of Rats with an Obesogenic High-Fat Diet.

Previous studies provided evidence of the benefits of omega-3 polyunsaturated fatty acids (ω-3 PUFA) on the cardiovascular system and inflammation. However, its possible effect on skeletal muscle is unknown. This study aimed to evaluate whether ω-3 PUFA reverses the dysregulation of metabolic modulators in the skeletal muscle of rats on a high-fat obesogenic diet. For this purpose, an animal model was developed using male Wistar rats with a high-fat diet (HFD) and subsequently supplemented with ω-3 PUFA. Insulin resistance was assessed, and gene and protein expression of metabolism modulators in skeletal muscle was also calculated using PCR-RT and Western blot. Our results confirmed that in HFD rats, zoometric parameters and insulin resistance were increased compared to SD rats. Furthermore, we demonstrate reduced gene and protein expression of peroxisome proliferator-activated receptors (PPARs) and insulin signaling molecules. After ω-3 PUFA supplementation, we observed that glucose (24.34%), triglycerides (35.78%), and HOMA-IR (40.10%) were reduced, and QUICKI (12.16%) increased compared to HFD rats. Furthermore, in skeletal muscle, we detected increased gene and protein expression of PPAR-α, PPAR-γ, insulin receptor (INSR), insulin receptor substrate 1 (ISR-1), phosphatidylinositol-3-kinase (PI3K), and glucose transporter 4 (GLUT-4). These findings suggest that ω-3 PUFAs decrease insulin resistance of obese skeletal muscle.

Curcumin alleviates myocardial inflammation, apoptosis, and oxidative stress induced by acute pulmonary embolism by regulating microRNA-145-5P/insulin receptor substrate 1 axis.

The treatment of patients with acute pulmonary embolism (APE) is extremely challenging due to the complex clinical presentation and prognosis of APE related to the patient's hemodynamic status and insufficient arterial blood flow and right ventricular overload. Protective efficacy against cardiovascular diseases of curcumin, a common natural polyphenolic compound, which has antithrombotic properties and reduces platelet accumulation in the circulation by inhibiting thromboxane synthesis has been demonstrated. However, the direct effect of curcumin on APE has rarely been studied. Therefore, the present study aimed to investigate the therapeutic potential of curcumin in APE and associated myocardial injury to provide new insights into curcumin as a promising competitive new target for the treatment of APE. A suspension of 12 mg/kg microspheres was injected intravenously into rats. An APE rat model was built. Before modeling, intragastric 100 mg/kg curcumin was given, and/or lentiviral plasmid vector targeting microRNA-145-5p or insulin receptor substrate 1 (IRS1) was injected. Pulmonary artery pressure was measured to assess right ventricular systolic pressure (RVSP). Hematoxylin and eosin (H&E) staining was performed on liver tissues and myocardial tissues of APE rats. TUNEL (terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling) staining and immunohistochemical (IHC) staining were conducted to measure apoptosis and CyPA-CD147 expression in the myocardium, respectively. Inflammatory indices interleukin-1beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) were measured by ELISA in cardiac tissues. RT-qPCR and Western blot were performed to determine the expression levels of related genes. In addition, by dual luciferase reporter assay and RIP assay, the relationship between microRNA-145-5p and insulin receptor substrate 1 (IRS1) was confirmed. In results: curcumin improved APE-induced myocardial injury, reduced myocardial tissue edema, and thrombus volume. It attenuated APE-induced myocardial inflammation and apoptosis, as well as reduced lung injury and pulmonary artery pressure. Curcumin promoted microRNA-145-5p expression in APE rat myocardium. MicroRNA-145-5p overexpression protected against APE-induced myocardial injury, and microRNA-145-5p silencing abolished the beneficial effects of curcumin in APE-induced myocardial injury. IRS1 was targeted by microRNA-145-5p. IRS1 silencing attenuated APE-induced myocardial injury, and enhanced therapeutic effect of curcumin on myocardial injury in APE rats. In conclusion, curcumin alleviates myocardial inflammation, apoptosis, and oxidative stress induced by APE by regulating microRNA-145-5p/IRS1 axis.

Kinesin light chain 1 stabilizes insulin receptor substrate 1 to regulate the IGF-1-AKT signaling pathway during myoblast differentiation.

The IGF signaling pathway plays critical role in regulating skeletal myogenesis. We have demonstrated that KIF5B, the heavy chain of kinesin-1 motor, promotes myoblast differentiation through regulating IGF-p38MAPK activation. However, the roles of the kinesin light chain (Klc) in IGF pathway and myoblast differentiation remain elusive. In this study, we found that Klc1 was upregulated during muscle regeneration and downregulated in senescence mouse muscles and dystrophic muscles from mdx (X-linked muscular dystrophic) mice. Gain- and loss-of-function experiments further displayed that Klc1 promotes AKT-mTOR activity and positively regulates myogenic differentiation. We further identified that the expression levels of IRS1, the critical node of IGF-1 signaling, are downregulated in Klc1-depleted myoblasts. Coimmunoprecipitation study revealed that IRS1 interacted with the 88-154 amino acid sequence of Klc1 via its PTB domain. Notably, the reduced Klc1 levels were found in senescence and osteoporosis skeletal muscle samples from both mice and human. Taken together, our findings suggested a crucial role of Klc1 in the regulation of IGF-AKT pathway during myogenesis through stabilizing IRS1, which might ultimately influence the development of muscle-related disorders.

Chronic intermittent hypoxia-induced oxidative stress activates TRB3 and phosphorylated JNK to mediate insulin resistance and cell apoptosis in the pancreas.

This study explores the potential mechanisms of obstructive sleep apnoea (OSA) complicates type 2 diabetes mellitus (T2DM) by which chronic intermittent hypoxia (CIH) induces insulin resistance and cell apoptosis in the pancreas through oxidative stress. Four- and eight-week CIH rat models were established, and Tempol (100 mg/kg/d), was used as an oxidative stress inhibitor. This study included five groups: 4-week CIH, 4-week CIH-Tempol, 8-week CIH, 8-week CIH-Tempol and normal control (NC) groups. Fasting blood glucose and insulin levels were measured in the serum. The expression levels of 8-hidroxy-2-deoxyguanosine (8-OHdG), tribbles homologue 3 (TRB3), c-Jun N-terminal kinase (JNK), phosphorylated JNK (p-JNK), insulin receptor substrate-1 (IRS-1), phosphorylated IRS-1 (Ser307) (p-IRS-1ser307 ), protein kinase B (AKT), phosphorylated AKT (Ser473) (p-AKTser473 ), B cell lymphoma protein-2 (Bcl-2), cleaved-caspase-3 (Cl-caspase-3), and the islet cell apoptosis were detected in the pancreas. CIH induced oxidative stress in the pancreas. Compared with that in the NC group and CIH-Tempol groups individually, the homeostasis model assessment of insulin resistance (HOMA-IR) and apoptosis of islet cells was increased in the CIH groups. CIH-induced oxidative stress increased the expression of p-IRS-1Ser307 and decreased the expression of p-AKTSer473 . The expression levels of TRB3 and p-JNK were higher in the CIH groups than in both the CIH-Tempol and NC groups. Meanwhile, the expressions of Cl-caspase-3 and Bcl-2 were upregulated and downregulated, respectively, in the CIH groups. Hence, the present study demonstrated that CIH-induced oxidative stress might not only induce insulin resistance but also islet cell apoptosis in the pancreas through TRB3 and p-JNK.

The hypothalamic-pituitary-thyroid axis is intact in male insulin receptor substrate 4 knockout mice.

Loss of function mutations in the insulin receptor substrate 4 (IRS4) gene cause a rare form of X-linked congenital central hypothyroidism in boys and men. Affected individuals show decreased thyroid-stimulation hormone (TSH) secretion. Members of the IRS family canonically act as scaffold proteins between tyrosine kinase receptors and downstream effectors. How loss of IRS4 affects TSH synthesis or secretion is unresolved. We therefore assessed IRS4's role in the hypothalamic-pituitary-thyroid axis of Irs4 knockout mice. We generated two global Irs4 knockout mouse lines harboring either two or four base-pair deletions that result in frameshifts and loss of most of the IRS4 protein. Under normal laboratory conditions, Irs4 knockout males did not exhibit impairments in pituitary expression of TSH subunit genes (Tshb or Cga) or in the thyrotropin-releasing hormone (TRH) receptor. Additionally, their serum thyroid hormone, T3 (triiodothyronine) and T4 (thyroxine), and hypothalamic Trh expression levels were normal. When Irs4 knockouts were rendered hypothyroid with a low-iodine diet supplemented with propylthiouracil (PTU) for 3 weeks, their serum TSH increased similarly to wild-type males. Overall, Irs4 knockout mice do not exhibit central hypothyroidism or otherwise appear to phenocopy IRS4 deficient patients. Compensation by another IRS protein may explain euthyroidism in these animals.

Neddylation of insulin receptor substrate acts as a bona fide regulator of insulin signaling and its implications for cancer cell migration

Irregularities in insulin signaling have significantly increased the risk of various cancers, yet the precise underlying mechanisms remain unclear. Within our study, we observed that inhibiting neddylation enhances cancer cell migration across different cancer types by activating both insulin receptor substrates 1 and 2 (IRS1 and IRS2), along with the PI3K/AKT signaling pathway. Notably, in the context of high-grade serous carcinoma (HGSC) patients, whether they had type 2 diabetes mellitus or not, IRS1 and IRS2 displayed a parallel relationship with each other while exhibiting an inverse relationship with NEDD8. We also identified C-CBL as an E3 ligase responsible for neddylating IRS1 and IRS2, with clinical evidence further confirming a reciprocal relationship between C-CBL and pAKT, thereby reinforcing the tumor suppressive role of C-CBL. Altogether, these findings suggest that neddylation genuinely participates in IRS1 and IRS2-dependent insulin signaling, effectively suppressing cancer cell migration. Thus, caution is advised when considering neddylation inhibitors as a treatment option for cancer patients, particularly those presenting with insulin signaling dysregulations linked to conditions like obesity-related type 2 diabetes or hyperinsulinemia.

Ilex paraguariensis A.St.-Hil. improves lipid metabolism in high-fat diet-fed obese rats and suppresses intracellular lipid accumulation in 3T3-L1 adipocytes via the AMPK-dependent and insulin signaling pathways.

Obesity is closely associated with several chronic diseases, and adipose tissue plays a major role in modulating energy metabolism. This study aimed to determine whether Mate, derived from I. paraguariensis A.St.-Hil., ameliorates lipid metabolism in 3T3-L1 adipocytes and high-fat diet (HFD)-fed obese Sprague-Dawley (SD) rats. 3T3-L1 adipocytes were cultured for 7 days, following which intracellular lipid accumulation and expression levels of lipid metabolism-related factors were examined. Dorsomorphin was used to investigate the potential pathways involved, particularly the adenosine monophosphate-activated protein kinase (AMPK)- dependent pathway. Mate was administered to rat HFD-fed obese SD models for 8 consecutive weeks. The expression of lipid metabolism-related factors in the organs and tissues collected from dissected SD rats was evaluated. Mate suppressed intracellular lipid accumulation in 3T3-L1 adipocytes, increased the protein and gene expression levels of AMPK, hormone sensitive lipase (HSL), calmodulin kinase kinase (CaMKK), liver kinase B1 (LKB1), protein kinase A (PKA), CCAAT/enhancer binding protein β (C/EBPβ), insulin receptor b (IRβ), and insulin receptor substrate 1 (IRS1) (Tyr465), and decreased those of sterol regulatory element binding protein 1C (Srebp1c), fatty acid synthase (FAS), peroxisome-activated receptor γ (PPARγ), and IRS1 (Ser1101). Furthermore, an AMPK inhibitor abolished the effects exerted by Mate on intracellular lipid accumulation and HSL and FAS expression levels. Mate treatment suppressed body weight gain and improved serum cholesterol levels in HFD-fed obese SD rats. Treatment with Mate increased the protein and gene expression levels of AMPK, PKA, Erk1/Erk2 (p44/p42), and uncoupling protein 1 and reduced those of mammalian target of rapamycin, S6 kinase, Srebp1c, ap2, FAS, Il6, Adiponectin, Leptin, and Fabp4 in rat HFD-fed obese SD models. Mate suppressed intracellular lipid accumulation in 3T3-L1 adipocytes and improved lipid metabolism in the epididymal adipose tissue of HFD-fed obese SD rats via the activation of AMPK-dependent and insulin signaling pathways.

Interplay of Angiotensin Peptides, Vasopressin, and Insulin in the Heart: Experimental and Clinical Evidence of Altered Interactions in Obesity and Diabetes Mellitus.

The present review draws attention to the specific role of angiotensin peptides [angiotensin II (Ang II), angiotensin-(1-7) (Ang-(1-7)], vasopressin (AVP), and insulin in the regulation of the coronary blood flow and cardiac contractions. The interactions of angiotensin peptides, AVP, and insulin in the heart and in the brain are also discussed. The intracardiac production and the supply of angiotensin peptides and AVP from the systemic circulation enable their easy access to the coronary vessels and the cardiomyocytes. Coronary vessels and cardiomyocytes are furnished with AT1 receptors, AT2 receptors, Ang (1-7) receptors, vasopressin V1 receptors, and insulin receptor substrates. The presence of some of these molecules in the same cells creates good conditions for their interaction at the signaling level. The broad spectrum of actions allows for the engagement of angiotensin peptides, AVP, and insulin in the regulation of the most vital cardiac processes, including (1) cardiac tissue oxygenation, energy production, and metabolism; (2) the generation of the other cardiovascular compounds, such as nitric oxide, bradykinin (Bk), and endothelin; and (3) the regulation of cardiac work by the autonomic nervous system and the cardiovascular neurons of the brain. Multiple experimental studies and clinical observations show that the interactions of Ang II, Ang(1-7), AVP, and insulin in the heart and in the brain are markedly altered during heart failure, hypertension, obesity, and diabetes mellitus, especially when these diseases coexist. A survey of the literature presented in the review provides evidence for the belief that very individualized treatment, including interactions of angiotensins and vasopressin with insulin, should be applied in patients suffering from both the cardiovascular and metabolic diseases.