Signaling Pathways In Type Research Articles

Holothuria leucospilota polysaccharides alleviate liver injury via AMPK and NF-κB signaling pathways in type 2 diabetic rats

• HLP modulated the expression of AMPK and GSK3β to increase glycogen synthesis and reduce lipid accumulation in the liver. • HLP activated AMPK/GSK3β/Nrf2/HO-1 pathway to relieve oxidative stress. • HLP alleviated inflammation in the liver of diabetic rats via NF-κB signaling pathway. The study evaluated the beneficial effects of orally administered Holothuria leucospilota polysaccharides (HLP) on liver injury in diabetic rats. The results showed that HLP regulated liver glycogen, glycosylated serum protein, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Simultaneously, HLP significantly reduced lipid accumulation in livers of diabetic rats ( P < 0.05). In addition, HLP exerted anti-oxidant and anti-inflammatory activities, together with repaired histological impairment of liver in diabetes. Moreover, HLP downregulated the mRNA and protein expression of inhibitors of nuclear factor κB kinase β (IKKβ), nuclear factor κB P65 (NF-κB P65) and glycogen synthase kinase 3β (GSK3β), while upregulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and AMP-activated protein kinase α (AMPKα) in the liver. These findings suggested that HLP improved liver injury via AMPK and NF-κB related signaling pathways in type 2 diabetic rats.

The Immunoregulatory Role of the Signal Regulatory Protein Family and CD47 Signaling Pathway in Type 1 Diabetes.

BackgroundThe pathogenesis of type 1 diabetes (T1D) involves complex genetic susceptibility that impacts pathways regulating host immunity and the target of autoimmune attack, insulin-producing pancreatic β-cells. Interactions between risk variants and environmental factors result in significant heterogeneity in clinical presentation among those who develop T1D. Although genetic risk is dominated by the human leukocyte antigen (HLA) class II and insulin (INS) gene loci, nearly 150 additional risk variants are significantly associated with the disease, including polymorphisms in immune checkpoint molecules, such as SIRPG.Scope of ReviewIn this review, we summarize the literature related to the T1D-associated risk variants in SIRPG, which include a protein-coding variant (rs6043409, G>A; A263V) and an intronic polymorphism (rs2281808, C>T), and their potential impacts on the immunoregulatory signal regulatory protein (SIRP) family:CD47 signaling axis. We discuss how dysregulated expression or function of SIRPs and CD47 in antigen-presenting cells (APCs), T cells, natural killer (NK) cells, and pancreatic β-cells could potentially promote T1D development.Major ConclusionsWe propose a hypothesis, supported by emerging genetic and functional immune studies, which states a loss of proper SIRP:CD47 signaling may result in increased lymphocyte activation and cytotoxicity and enhanced β-cell destruction. Thus, we present several novel therapeutic strategies for modulation of SIRPs and CD47 to intervene in T1D.

Breast milk MSCs upregulated β-cells PDX1, Ngn3, and PCNA expression via remodeling ER stress /inflammatory /apoptotic signaling pathways in type 1 diabetic rats

Type 1 diabetes mellitus (T1DM) is one of the autoimmune diseases characterized by beta-cell dysfunction with serious health complications. Br-MSCs represent a novel valid candidate in regenerative medicine disciplines. Yet, the full potential of Br-MSCs in managing type 1 diabetes remains elusive. Indeed, this study was designed to explore a novel approach investigating the possible regenerative capacity of Br-MSCs in type1 diabetic islet on the level of the cellular mRNA expression of different molecular pathways involved in pancreatic beta-cell dysfunction. Sixty adult male Sprague-Dawley rats were randomly assigned into 3 groups (20 rats each); the control group, type1 diabetic group, and the type 1 diabetic Br-MSCs treated group. And, for the first time, our results revealed that intraperitoneally transplanted Br-MSCs homed to the diabetic islet and improved fasting blood glucose, serum insulin level, pancreatic oxidative stress, upregulated pancreatic mRNA expression for: regenerative markers (Pdx1, Ngn3, PCNA), INS, beta-cell receptors (IRS1, IRβ, PPARγ), pancreatic growth factors (IGF-1, VEGFβ1, FGFβ), anti-inflammatory cytokine (IL10) and anti-apoptotic marker (BCL2) too, Br-MSCs downregulated pancreatic mRNA expression for: inflammatory markers (NFKβ, TNFα, IL1β, IL6, IL8, MCP1), apoptotic markers for both intrinsic and extrinsic pathways (FAS, FAS-L, P53, P38, BAX, Caspase3), ER stress markers (ATF6, ATF3, ATF4, BIP, CHOP, JNK, XBP1) and autophagy inhibitor (mTOR). In conclusion, Br-MSCs could be considered as a new insight in beta cell regenerative therapy improving the deteriorated diabetic islet microenvironment via modulating; ER stress, inflammatory, and apoptotic signaling pathways besides, switching on the cellular quality control system (autophagy) thus enhancing beta-cell function.

Regulation and specificity of cyclic oligoadenylate synthesis by the Staphylococcus epidermidis Cas10‐Csm complex

CRISPR-Cas10 is a multiprotein complex that uses the sequence information in a bound crRNA to identify foreign RNA transcripts and initiate interference. Recently it was discovered that CRISPR-Cas10 synthesizes a previously unknown class of second messenger molecules upon detecting foreign transcripts, cyclic oligoadenylates (cOA) (1,2). cOA activate the Csm6 nuclease to promote RNA degradation and may also coordinate additional cellular responses. Using the S. epidermidis Cas10-Csm complex, a longstanding model for CRISPR-Cas function, we have reconstituted cOA synthesis and have found that it entails Mg2+ dependent synthesis of 3-6 nt cOAs (3). We have investigated the effect of target-crRNA mismatches on cOA synthesis finding that some single mismatches dramatically reduce cOA synthesis in a position dependent and sequence-context dependent manner. We have found that cOA synthesis is antagonized by Csm3-mediated target RNA cleavage. Altogether, our results establish the requirements for cOA production in a model Type III CRISPR-Cas system. Since the CRISPR-Cas10 system is present in ~20% of all prokaryotic genomes sequenced (4), its role in bacteriophage defense and regulation of horizontal gene transfer are likely important to bacterial physiology in niches such as the human microbiome. 1. Kazlauskiene, M., Kostiuk, G., Venclovas, C., Tamulaitis, G., and Siksnys, V. (2017) A cyclic oligonucleotide signaling pathway in type III CRISPR-Cas systems. Science 357, 605-609 2. Niewoehner, O., Garcia-Doval, C., Rostol, J. T., Berk, C., Schwede, F., Bigler, L., Hall, J., Marraffini, L. A., and Jinek, M. (2017) Type III CRISPR-Cas systems produce cyclic oligoadenylate second messengers. Nature 548, 543-548 3. Nasef, M., Muffly, M. C., Beckman, A. B., Rowe, S. J., Walker, F. C., Hatoum-Aslan, A., and Dunkle, J. A. (2019) Regulation of cyclic oligoadenylate synthesis by the Staphylococcus epidermidis Cas10-Csm complex. RNA 25, 948-962 4. Makarova, K. S., Wolf, Y. I., Alkhnbashi, O. S., Costa, F., Shah, S. A., Saunders, S. J., Barrangou, R., Brouns, S. J., Charpentier, E., Haft, D. H., Horvath, P., Moineau, S., Mojica, F. J., Terns, R. M., Terns, M. P., White, M. F., Yakunin, A. F., Garrett, R. A., van der Oost, J., Backofen, R., and Koonin, E. V. (2015) An updated evolutionary classification of CRISPR-Cas systems. Nat Rev Microbiol 13, 722-736

Bioactive-guided isolation and identification of oligostilbenes as anti-rheumatoid arthritis constituents from the roots of Caragana stenophylla

Ethnopharmacological relevanceThe roots of Caragana stenophylla have been used as folk medicine due to the functions of activating blood, diuresis, analgesic and tonicity, especially in treating rheumatoid arthritis and hypertension. However, the anti-rheumatoid arthritis mechanisms and bioactive ingredients have not previously been fully investigated. Aim of the studyThe aim of this study was to assess the anti-rheumatoid arthritis effects of the roots of Caragana stenophylla ethanol extract (EC), elucidate its mechanism of action and identify its active substances. Materials and methodsAnti-rheumatoid arthritis activity of EC was assessed using type II-collagen induced arthritis in rats. Arthritis severity was evaluated by foot paw volume, arthritis index, joint swelling degree and histopathology. The serum inflammatory cytokines and matrix metalloproteinases (MMPs) were also detected by immunohistochemical analysis. In addition, the protein expression of IκB, p-IκB, iNOS and COX-2 was analyzed by western blot. RAW 264.7 macrophage cells were employed to assess the anti-inflammatory effects of fractions and compounds in vitro. UPLC-Q-TOF-MS was adopted to appraise the ingredients of the active fraction of the roots of C. stenophylla. Furthermore, various chromatographic techniques and spectroscopic methods were used for isolation and structure elucidation of compounds. ResultsThe results showed that EC could reduce type II collagen-induced rheumatoid arthritis model arthritic score and histopathology markedly at dose of 240 mg/kg. Besides, EC could suppress the levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-17, and TNF-α) and matrix metalloproteinases (MMP-3, MMP-9), and the expression levels of COX-2, p-IκB and iNOS also were declined. While, the levels of IL-10 and IκB were increased. The ethyl acetate fraction exhibited potent inhibitory effects against nitric oxide production in RAW 264.7 macrophage cells. Eleven main components including 1 flavonoid and 10 oligostilbenes from active fraction were isolated by mass directed chromatographic techniques. Their structures were determined on the basis of various spectroscopic methods and by comparison with the published NMR data. ConclusionThe roots of C. stenophylla attenuated arthritis severity, restored serum cytokine imbalances by regulating NF-κB signaling pathway in type II collagen-induced rheumatoid arthritis model. Oligostilbenes were essential ingredients in ethyl acetate extract of C. stenophylla roots. Stilbenes and flavonoids should be responsible for its anti-rheumatoid arthritis activities.

New insight into the role of isorhamnetin as a regulator of insulin signaling pathway in type 2 diabetes mellitus rat model: Molecular and computational approach

We intended to examine the molecular mechanism of action of isorhamnetin (IHN) to regulate the pathway of insulin signaling. Molecular analysis, immunofluorescence, and histopathological examination were used to assess the anti-hyperglycemic and insulin resistance lowering effects of IHN in streptozotocin /high fat diet-induced type 2 diabetes using Wistar rats. At the microscopic level, treatment with IHN resulted in the restoration of myofibrils uniform arrangement and adipose tissue normal architecture. At the molecular level, treatment with IHN at three different doses showed a significant decrease in m-TOR, IGF1-R & LncRNA-RP11-773H22.4. expression and it up-regulated the expression of AKT2 mRNA, miR-1, and miR-3163 in both skeletal muscle and adipose tissue. At the protein level, IHN treated group showed a discrete spread with a moderate faint expression of m-TOR in skeletal muscles as well as adipose tissues. We concluded that IHN could be used in the in ameliorating insulin resistance associated with type 2 diabetes mellitus.

Effects of swimming and epigallocatechin gallate on interstitial proteins expression of myocardium from type 2 diabetic rats

To observe the effects of swimming training and/or epigallocatechin gallate(EGCG) on the expression of myocardial interstitial protein and its relationship with transforming growth factor-beta(TGF-β)/Smads signaling pathway in type 2 diabetic rats. Male SD rats(SPF grade, 6 weeks old) were fed with high-fat diet for 6 weeks and intraperitoneal injection of streptozotocin(STZ, 30 mg/kg). The rats were randomly divided into four groups: diabetic model group(D), diabetes EGCG group(DG), diabetes exercise group(DE), and diabetes exercise EGCG group(DEG), with 8 rats in each group, and 6 male SD rats in the same batch were added as the normal C group. The rats in the exercise group were given swimming training without load. The swimming time was 15 min/d in the first week, and the time was increased by 15 min a week until it was extended to 90 min/d. The rats in the exercise group were trained for 5 days a week. Rats in the EGCG group(100 mg/kg BW) were intragastrical administered for 7 days. Swimming training and/or EGCG intervention lasted for 12 weeks. 48 hours after the end of the intervention experiment, the rats were fasted overnight for 12 hours. Myocardial collagen I(Col I), collagen IV(Col IV) and fibronectin(FN) protein expression were detected by immunohistochemistry in some left ventricles, hydroxyproline(Hyp) content was detected by colorimetry, TGF-β_1 protein expression was detected by WB, Smad2 and Smad7 mRNA expression were detected by RT-PCR. The levels of blood glucose, Hyp content, TGF-beta1, Smad2 mRNA, Col I, Col IV, FN of the rats from D group were significantly higher than those of the rats from C group(P&lt;0. 01), but the level of Smad7 mRNA was significantly lower than it of the rats from C group(P&lt;0. 01). Compared with D group, blood glucose, TGF-β_1, Smad2 mRNA expression, Hyp content, Col I, Col IV, FN protein expression in DG group, DE group and DEG group were significantly decreased(P&lt;0. 05 or P&lt;0. 01), and the Smad7 mRNA expression increased significantly(P&lt;0. 05 or P&lt;0. 01). Compared with DG group, blood glucose, Smad2 mRNA expression, Hyp content, Col I, Col IV protein expression in DEG group were significantly decreased(P&lt;0. 05 or P&lt;0. 01), and the myocardial Smad7 mRNA expression was significantly increased(P&lt;0. 05). Compared with DE group, the levels of blood glucose, TGF-β_1, Smad2 mRNA, Hyp content, Col I, Col IV protein expression were significantly decreased in the EGCG group(P&lt;0. 05 or P&lt;0. 01), and the expression of Smad7 mRNA was significantly increased(P&lt;0. 05). Blood glucose, Smad2 mRNA expression, Hyp content, Col I, Col Ⅳ, FN protein expression in(DEG group were significantly higher than those in C group(P&lt;0. 05 or P&lt;0. 01). 12 weeks swimming training and/or EGCG administration can reduce the expression of myocardial interstitial protein in type 2 diabetic rats, and the combined intervention effect is better.

Melatonin Suppresses Ferroptosis Induced by High Glucose via Activation of the Nrf2/HO-1 Signaling Pathway in Type 2 Diabetic Osteoporosis.

Ferroptosis is recently identified, an iron- and reactive oxygen species- (ROS-) dependent form of regulated cell death. This study was designed to determine the existence of ferroptosis in the pathogenesis of type 2 diabetic osteoporosis and confirm that melatonin can inhibit the ferroptosis of osteoblasts through activating Nrf2/HO-1 signaling pathway to improve bone microstructure in vivo and in vitro. We treated MC3T3-E1 cells with different concentrations of melatonin (1, 10, or 100 μM) and exposed them to high glucose (25.5 mM) for 48 h in vitro. Our data showed that high glucose can induce osteoblast cytotoxicity and the accumulation of lipid peroxide, the mitochondria of osteoblast show the same morphology changes as the erastin treatment group, and the expression of ferroptosis-related proteins glutathione peroxidase 4 (GPX4) and cystine-glutamate antiporter (SLC7A11) is downregulated, but these effects were reversed by ferroptosis inhibitor ferrastatin-1 and iron chelator deferoxamine (DFO). Furthermore, western blot and real-time polymerase chain reaction were used to detect the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1); osteogenic capacity was evaluated by alizarin red S staining and the expression of osteoprotegerin, osteocalcin, and alkaline phosphatase; the results showed that the expression levels of these proteins in osteoblasts with 1, 10, or 100 μM melatonins were significantly higher than the high glucose group, but after using Nrf2-SiRNA interference, the therapeutic effect of melatonin was significantly inhibited. We also performed in vivo experiments in a diabetic rat model treated with two concentrations of melatonin (10, 50 mg/kg). Dynamic bone histomorphometry and micro-CT were used to observe the rat bone microstructure, and the expression of GPX4 and Nrf2 was determined by immunohistochemistry. Here, we first report that high glucose induces ferroptosis via increased ROS/lipid peroxidation/glutathione depletion in type 2 diabetic osteoporosis. More importantly, melatonin significantly reduced the level of ferroptosis and improved the osteogenic capacity of MC3T3-E1 through activating the Nrf2/HO-1 pathway in vivo and in vitro.

ZG02 Improved Hepatic Glucose Metabolism and Insulin Sensitivity via Activation of AMPK/Sirt1 Signaling Pathways in a High-fat Diet/Streptozotocin-induced Type 2 Diabetes Model.

PurposeThe aim of the present study was to investigate the hypoglycemic activity and potential mechanism of tetrahydrocarbazole derivatives ZG02 in high-fat diet/streptozotocin-induced type 2 diabetes model.MethodsC57BL/6 mice (n=30) were randomly assigned to three groups: control group (n=10) was fed with normal diet, the diabetes group (n=10) was fed with high-fat diet for eight weeks followed by intraperitoneal injection of streptozotocin (25 mg/kg) and the ZG02 group (n=10) injected intraperitoneally with ZG02 (30 mg/kg/day) for two weeks after successful modeling. The changes of weight, fasting blood glucose, oral glucose tolerance and fasting blood insulin levels in each group were evaluated. In addition, we also assessed the expression level of total AMPK, phosphorylation AMPK, SIRT1, PGC-1 and the activity of G6PC in liver.ResultsThe results demonstrated that ZG02 could significantly antagonize the high-fat diet/streptozotocin-induced fasting hyperglycemia, restore fasting blood insulin levels and also improve activity of G6PC in liver. The results from Western blot indicated that ZG02 significantly restored the expression level of phosphorylation AMPK, Sirt1 and PGC-1.ConclusionZG02 improve hepatic glucose metabolism and insulin sensitivity via activation AMPK/Sirt1 signaling pathways in type 2 diabetes mice model.

Veratrilla baillonii Franch exerts anti-diabetic activity and improves liver injury through IRS/PI3K/AKT signaling pathways in type 2 diabetic db/db mice

• The water extracts of Veratrilla baillonii Franch (WVBF) improves diabetes pathology. • WVBF protects liver and kidney from injury in diabetic mice. • WVBF alleviates the inflammation and oxidative stress. • WVBF up-regulates IRS/PI3K/AKT/GLUT4 signaling pathways in diabetic mice. • WVBF suppressed the hepatic gluconeogeness. Veratrilla baillonii Franch ( V. baillonii ) is widely consumed as herbal tea or medicine for prevention and treatment of various disorders in the minority areas of Southwest China. In current study, the therapeutic activities of water extracts of V. baillonii (WVBF) and gentiopicroside (GP), a major bioactive compound of WVBF were investigated in db/db diabetic mice. After 6 weeks of WVBF or GP treatment, the efficacy was assessed by fasting blood glucose (FBG), oral glucose tolerance test (OGTT) and homeostasis model assessment (HOMA). The results indicated that WVBF or GP exerted anti-inflammation and anti-oxidant stress actions, and reduced the pathological damages of liver and kidney in db/db diabetic mice. The potential mechanisms were further determined, and the results displayed that IRS-1/PI3K/AKT signal pathway was involved in the anti-diabetic and hepatic protection activities of WVBF. These findings demonstrated that V. baillonii can be a good candidate for developing new anti-diabetic agents.

Resistance exercise-induced increase in muscle 5α-dihydrotestosterone contributes to the activation of muscle Akt/mTOR/p70S6K- and Akt/AS160/GLUT4-signaling pathways in type 2 diabetic rats.

Effects of increase in muscle 5α-dihydrotestosterone (DHT) levels caused by resistance exercise on regulation of mammalian target of rapamycin (mTOR)- and glucose transporter 4 (GLUT4)-signaling pathways in type 2 diabetic rats were assessed. Twenty-week-old type 2 diabetic rats were randomly divided into the resting control, immediately, 1hour, or 3hours after resistance exercise, with or without the pretreatment of 5α-reductase inhibitor. Immediately or 1hour after exercise, levels of 5α-reductase and DHT as well as phosphorylation levels of AMP-activated protein kinase (AMPK), TBC1 domain family member 1 (TBC1D1), and protein kinase B (Akt) in muscle were significantly elevated. Phosphorylation of muscle Akt substrate of 160kDa (AS160) and translocation levels of GLUT4 at 1 and 3hours after resistance exercise were significantly elevated. Additionally, resistance exercise significantly activated the phosphorylation of muscle mTOR immediately, and at 1 and 3hours and of p70 ribosomal S6 kinase (p70S6K) at 1 and 3hours. However, pretreatment with the 5α-reductase inhibitor significantly attenuated the exercise-induced activation of Akt/mTOR/p70S6K and Akt/AS160/GLUT4 signaling, but did not affect AMPK/TBC1D1/GLUT4 signaling. These findings suggest that resistance exercise-induced increase in muscle DHT synthesis may contribute to activation of Akt/mTOR/p70S6K- and Akt/AS160/GLUT4 signaling pathways in type 2 diabetic rats.

Empagliflozin Attenuates Hyperuricemia by Upregulation of ABCG2 via AMPK/AKT/CREB Signaling Pathway in Type 2 Diabetic Mice.

Hyperuricemia (HUA) is a metabolic disease characterized by elevated serum uric acid (SUA). Empagliflozin, a kind of sodium-glucose cotransporter 2 inhibitors, has recently emerged as a new antidiabetic agent by facilitating glucose excretion in urine. Moreover, there was evidence of SUA reduction following treatment with empagliflozin in addition to glycaemic control, while the molecular mechanisms remain unknown. To investigate the potential mechanisms, the model of type 2 diabetes (T2DM) with HUA was established by combination of peritoneal injection of potassium oxonate and intragastric administration of hypoxanthine in KK-Ay mice. A series of method such as RT-PCR, western blot, immunochemistry, immunofluorescence were conducted to explore the mechanism. Our results showed that empagliflozin significantly ameliorated the levels of SUA and blood glucose in T2DM mice with HUA. Furthermore, in both kidney and ileum, empagliflozin obviously promoted protein expression of uric acid (UA) transporter ABCG2, p-AMPK, p-AKT and p-CREB. The same trend was observed in human tubular epithelial (HK-2) cells. Additionally, through application of an AMPK inhibitor (Compound C), it was further confirmed empagliflozin exerted its anti-hyperuricemic effects in an AMPK dependent manner. Meanwhile, with the help of ChIP assay and luciferase reporter gene assay, we found that CREB further activated ABCG2 via binding to the promoter of ABCG2 to induce transcription. Taken together, our study demonstrated that empagliflozin treatment played an essential role in attenuating HUA by upregulation of ABCG2 via AMPK/AKT/CREB signaling pathway.

Antidiabetic effect of Momordica charantia saponins in rats induced by high-fat diet combined with STZ

Background: The harmful effects of type 2 diabetes mellitus and its complications have become a major global public health problem. In this study , the effects of Momordica charantia saponins (MCS) on lipid metabolism, oxidative stress, and insulin signaling pathway in type 2 diabetic rats were investigated. Results: MCS could attenuate the tendency of weight loss of the model rats. It could also improve glucose tolerance; reduce fasting blood glucose, nonesterified fatty acid, triglyceride, and total cholesterol; and increase the insulin content and insulin sensitivity index of the rats. The activity of superoxide dismutase and catalase increased, and the content of malondialdehyde decreased in the liver and pancreas tissues of rats in MCS-treated groups significantly. In addition, the expression of p-IRS-1 (Y612) and p-Akt (S473) increased, and the expression of p-IRS-1 (S307) decreased in the liver tissues and pancreas tissues of rats in MCS-treated groups significantly. Conclusion: MCS has an antidiabetic effect, which may be related to its improving the lipid metabolism disorder, reducing oxidative stress level, and regulating the insulin signaling pathway. Normal 0 false false false ES-CL X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Times New Roman; mso-bidi-theme-font:minor-bidi; mso-ansi-language:ES-CL;}

Gymnemic Acid Ameliorates Hyperglycemia through PI3K/AKT- and AMPK-Mediated Signaling Pathways in Type 2 Diabetes Mellitus Rats.

Gymnemic acid (GA) isolated from Gymnema sylvestre (Retz.) Schult. has been shown to have antihyperglycemic activity; however, the molecular mechanisms governing these effects are unclear. In this study, GA (40 and 80 mg kg-1 day-1) was evaluated by type 2 diabetes mellitus (T2DM) rats to explore its hypoglycemic activity and underlying mechanisms of action. The results indicated that GA decreased fasting blood glucose (FBG) concentrations by 26.7% and lowered insulin concentrations by 16.1% after oral administration of GA at a dose of 80 mg kg-1 day-1 for 6 weeks in T2DM rats. Our data showed that real-time polymerase chain reaction and western blot indicated that GA upregulated the level of phosphatidylinositol-3-kinase (PI3K) and glycogen synthesis (GS) and promoted the phosphorylation of protein kinase B (Akt) while downregulated the expression of glycogen synthesis kinase-3β (GSK-3β) in T2DM rats. In addition, key proteins involved in adenosine monophosphate (AMP)-activated protein kinase (AMPK)-mediated gluconeogenesis [such as phosphoenolpyruvate carboxy kinase (PEPCK) and glucose-6-phosphatase (G6Pase)] were downregulated in GA-treated T2DM rats. In summary, the hypoglycemic mechanisms of GA may be related to promoting insulin signal transduction and activating PI3K/Akt- and AMPK-mediated signaling pathways in T2DM rats.

The renal protection of flavonoid-rich ethanolic extract from silkworm green cocoon involves in inhibiting TNF-α-p38 MAP kinase signalling pathway in type 2 diabetic mice

BackgroundDiabetic nephropathy (DN) is one of the major complications of diabetes. Sericin and flavonoids are two bioactive substances which have been demonstrated to have some therapeutical effect on diabetic nephropathy. The aim of this paper is to investigate the effect of ethanolic extract (EE) rich in quercetin and kaempferol and their glucosides from the green cocoon of silkworm Bombyx mori on DN in type 2 diabetic (T2D) mice induced by high-fat and streptozotocin (STZ). MethodsEthanolic extract from the green cocoon shell of silkworm Bombyx mori was used as material. Diabetic mice were orally treated with three doses (150, 250 and 350 mg/kg) of the extract for 7 weeks, then the levels of oxidases and related inflammatory factors were measured in kidneys. ResultsCompared with the negative control, EE administration resulted in an evident reduction in blood glucose levels and an improvement of the body weight in diabetic mice. Oral EE could inhibit the expressions of renal tumour necrosis factor TNF-α, monocyte chemoattractant protein-1 (MCP-1), fibronectin (FN) and P38 mitogen-activated protein kinase (p38 MAPK) in T2D mice. Moreover, the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) were significantly elevated in T2D mice treated with EE. ConclusionsThe activities of anti-fibrosis and anti-inflammation contributed to the renal protective effects by reducing oxidative stress, which might be mediated by the inhibition of the TNF-α-p38 MAP kinase signalling pathway. It is suggested that the ethanolic extract from silkworm green cocoon might be potential as an herbal medicine for DN.

Signaling Pathways of Type I and Type III Interferons and Targeted Therapies in Systemic Lupus Erythematosus

Type I and type III interferons (IFNs) share several properties in common, including the induction of signaling pathways, the activation of gene transcripts, and immune responses, against viral infection. Recent advances in the understanding of the molecular basis of innate and adaptive immunity have led to the re-examination of the role of these IFNs in autoimmune diseases. To date, a variety of IFN-regulated genes, termed IFN signature genes, have been identified. The expressions of these genes significantly increase in systemic lupus erythematosus (SLE), highlighting the role of type I and type III IFNs in the pathogenesis of SLE. In this review, we first discussed the signaling pathways and the immunoregulatory roles of type I and type III IFNs. Next, we discussed the roles of these IFNs in the pathogenesis of autoimmune diseases, including SLE. In SLE, IFN-stimulated genes induced by IFN signaling contribute to a positive feedback loop of autoimmunity, resulting in perpetual autoimmune inflammation. Based on this, we discussed the use of several specific IFN blocking strategies using anti-IFN-α antibodies, anti-IFN-α receptor antibodies, and IFN-α-kinoid or downstream small molecules, which intervene in Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathways, in clinical trials for SLE patients. Hopefully, the development of novel regimens targeting IFN signaling pathways will shed light on promising future therapeutic applications for SLE patients.

Monocytes contribute to DNA sensing through the TBK1 signaling pathway in type 1 diabetes patients

BackgroundThe aberrant recognition of self-nucleic acids by the innate immune system contributes to the pathology of several autoimmune diseases. Although microbial DNA and, in certain instances, self-DNA that is released from damaged cells are primarily recognized by Toll-like receptor 9 (TLR9), recent evidence suggests that other cytosolic sequence-nonspecific DNA sensors contribute to DNA recognition. In this study, we focused on the sensing of microbial and host DNA in type 1 diabetes (T1D) patients. MethodsPeripheral blood mononuclear cells (PBMCs) and monocytes from pediatric patients with T1D and from healthy donors were stimulated with microbial DNA (CpG) or with self-DNA (DNA contained within neutrophil extracellular traps, NETs). The production of cytokines was measured by flow cytometry and multiplex bead assays. The internalization of microbial DNA and its colocalization with STING was detected by image cytometry. Furthermore, the involvement of the TBK1 kinase was investigated by detecting its phosphorylation with phospho-flow cytometry or by using a TBK1 inhibition assay. ResultsWe observed a prominent proinflammatory response in T1D PBMCs, especially pDCs and monocytes, to microbial DNA in comparison to that in controls. We further confirmed that monocytes could bind and internalize DNA and respond by releasing proinflammatory cytokines in a more pronounced manner in T1D patients than those in controls. Surprisingly, this cytokine production was not affected by TLR9 blockade, suggesting the involvement of intracellular receptors in DNA recognition. We further identified TBK1 and STING as two crucial molecules in the DNA-sensing pathway that were involved in CpG-DNA sensing by T1D cells. A similar DNA-sensing pathway that was dependent on intracellular DNA sensors and the STING-TBK1 interaction was employed in response to NETs, which were used to model self-DNA. ConclusionsHere, we show that there were significant differences in DNA sensing in T1D patients compared to that in controls. We demonstrate that monocytes from T1D patients are able to sense microbial- and self-DNA, leading to proinflammatory cytokine secretion through the adaptor protein STING and the TBK1 kinase.

Aerobic Training-induced Increase In Follistatin-like 1 Secretion Is Associated With eNOS Phosphorylation In Diabetic Rats.

INTRODUCTIN: Aerobic exercise training reduces arterial stiffness via elevation of nitric oxide (NO) production in type 2 diabetes. Follistatin-like 1 (FSTL1) is a muscle-derived myokine and stimulates protein kinase B (Akt)/endothelial nitric oxide synthase (eNOS) signaling via binding to receptor (DIP2A) in endothelial cells. However, it is unclear whether FSTL1 secretion induced by aerobic exercise training is related to a reduction of arterial stiffness in type 2 diabetic rats. PURPOSE: This study aimed to investigate whether FSTL1 secretion induced by aerobic exercise training is related to a reduction of arterial stiffness with activation of aortic eNOS phosphorylation in type 2 diabetic rats. METHODS: Twenty-week-old male type 2 diabetic (OLETF) rats were randomly divided into sedentary control (OLETF-Con: n=7) and aerobic exercise training (OLETF-Ex: treadmill running for 60min at 25m/min, 5days/week: n=7) groups. In addition, 7 male LETO rats were used as healthy sedentary control. After 8-week experiment, we measured carotid-femoral pulse wave velocity (cfPWV: as an index of arterial stiffness), and thoracic aorta was isolated after collection of blood. RESULTS: Fasting blood glucose and cfPWV significantly increased (p<0.05) and aortic Akt and eNOS phosphorylation levels, plasma nitrate/nitrite (NOx) level, and serum FSTL1 protein level significantly decreased (p<0.05) in OLETF-Con as compared to LETO. OLETF-Ex showed significant decrease in fasting blood glucose and cfPWV (p<0.05), and significant increase in aortic Akt and eNOS phosphorylation, plasma NOx, and serum FSTL1 protein levels (p<0.05) as compared to OLETF-Con. However, no significant difference in aortic DIP2A protein level among three groups was seen. Serum FSTL1 protein level was positively correlated with aortic eNOS phosphorylation level (p<0.05, r=0.630), and plasma NOx level was negatively correlated with cfPWV (p<0.05, r=-0.546). CONCLUSION: The results suggest that the increase in FSTL1 secretion induced by aerobic exercise training is associated with the reduction of arterial stiffness via activation of arterial NO production-related signaling pathway in type 2 diabetic rats. Supported by Grants-in-Aid for Scientific Research (#17H02182, #16K13059, M. Iemitsu)

Evidence for protein kinase involvement in the 5-HT-[Ca2+ ]i -pannexin-1 signalling pathway in type II glial cells of the rat carotid body.

What is the central question of this study? The mammalian carotid body (CB) is a peripheral chemoreceptor organ involved in O2 and CO2 /H+ homeostasis. Recent studies suggest that 5-HT, released from CB receptor cells, can stimulate adjacent glial-like typeII cells, leading to an increase in intracellular Ca2+ (Δ[Ca2+ ]i ) and activation of ATP-permeable pannexin-1 (Panx-1) channels. The aim of this study was to elucidate the role of protein kinases in the 5-HT-[Ca2+ ]i -Panx-1 signalling pathway. What is the main finding and its importance? Src family kinase and protein kinaseA, acting downstream from Δ[Ca2+ ]i , played central roles in 5-HT-mediated Panx-1 channel activation. This provides new insight into mechanisms regulating CB excitation, especially in pathophysiological conditions. Chemoreceptor (typeI) cells of the rodent carotid body (CB) synthesize and release several neurotransmitters/neuromodulators, including 5-hydroxytryptamine (5-HT), implicated in enhanced CB excitation after exposure to chronic intermittent hypoxia, e.g. sleep apnoea. However, recent studies suggest that 5-HT can robustly stimulate adjacent glial-like typeII cells via ketanserin-sensitive 5-HT2 receptors, leading to intracellular Ca2+ elevation (Δ[Ca2+ ]i ) and activation of ATP-permeable pannexin-1 (Panx-1) channels. Using dissociated rat CB cultures, we investigated the role of protein kinases in the intracellular signalling pathways in typeII cells. In isolated typeII cells, 5-HT activated a Panx-1-like inward current (I5-HT ) that was reversibly inhibited by the Src family kinase inhibitor PP2 (1μm), but not by its inactive analogue, PP3 (1μm). Moreover, I5-HT was reversibly inhibited (>90%) by H89 (1μm), a protein kinaseA blocker, whereas the protein kinaseC blocker GF109203X (2μm) was largely ineffective. In contrast, the P2Y2R agonist UTP (100μm) activated Panx-1-like currents that were reversibly inhibited (∼60%) by either H89 or GF109203X. Using fura-2 spectrofluorimetry, the 5-HT-induced Δ[Ca2+ ]i was unaffected by PP2, H89 and GF109293X, suggesting that the kinases acted downstream of the Ca2+ rise. Given that intracellular Ca2+ chelation was previously shown to block receptor-mediated Panx-1 current activation in typeII cells, these data suggest that CB neuromodulators use overlapping, but not necessarily identical, signalling pathways to activate Panx-1 channels and release ATP, a CB excitatory neurotransmitter. In conclusion, these studies provide new mechanistic insight into 5-HT signalling in the CB that has pathophysiological relevance.

Metformin regulates atrial SK2 and SK3 expression through inhibiting the PKC/ERK signaling pathway in type 2 diabetic rats

BackgroundOur previous study showed that metformin regulates the mRNA and protein levels of type 2 small conductance calcium-activated potassium channel (SK2) and type 3 small conductance calcium-activated potassium channels (SK3) in atrial tissue as well as the ion current of atrial myocytes in rats with type 2 diabetes mellitus (T2DM), but the underlying signaling mechanism is unknown. This study aimed to investigate whether metformin regulates atrial SK2 and SK3 protein expression in T2DM rats though the protein kinase C (PKC)/extracellular signal-regulated kinase (ERK) signaling pathway.MethodsA T2DM rat model was established using a high-fat and high-sugar diet combined with a low-dose intraperitoneal injection of streptozotocin (STZ). The rats were randomly divided into the following five groups: the control group, the untreated T2DM group, the metformin-treated only group, the phorbol 12-myristate 13-acetate (PMA; a PKC agonist administered by intraperitoneal injection) treatment group, and the recombinant human epidermal growth factor (rh-EGF; an ERK agonist administered by tail vein injection) treatment group. The activity of PKC in atrial tissues was assayed by a PKC kinase activity assay kit. The protein expression of SK2, SK3, and phosphorylated ERK (pERK) were determined by western blotting and immunohistochemistry.ResultsCompared with the Control group, atrial PKC activity and pERK and SK3 protein expression were increased, while SK2 protein expression was decreased in atrial tissues of T2DM rats. Eight weeks of metformin treatment inhibited the PKC activity and pERK and SK3 expression, and elevated SK2 expression compared with the T2DM group. Compared with the metformin-treated only group, the injection of rh-EGF increased pERK and SK3 expression, and decreased SK2 expression; the injection of PMA increased PKC activity and SK3 expression, and decreased SK2 expression. In addition, the injection with PMA significantly elevated the expression of pERK.ConclusionsThe PKC/ERK signaling pathway is involved in the downregulation of SK2 expression and the upregulation of SK3 expression in the atrium of T2DM rats. Long-term metformin treatment prevents the SK2 downregulation and the SK3 upregulation through inhibiting the PKC/ERK signaling pathway.