Oxymatrine ameliorates insulin resistance in rats with type 2 diabetes by regulating the expression of KSRP, PETN, and AKT in the liver

Targeting Autophagy: A Promising Therapeutic Strategy for Diabetes Mellitus and Diabetic Nephropathy

Diabetes mellitus (DM) significantly impairs patients' quality of life, primarily because of its complications, which are the leading cause of mortality among individuals with the disease. Autophagy has emerged as a key process closely associated with DM, including its complications such as diabetic nephropathy (DN). DN is a major complication of DM, contributing significantly to chronic kidney disease and renal failure. The intricate connection between autophagy and DM, including DN, highlights the potential for new therapeutic targets. This review examines the interplay between autophagy and these conditions, aiming to uncover novel approaches to treatment and enhance our understanding of their underlying pathophysiology. It also explores the role of autophagy in maintaining renal homeostasis and its involvement in the development and progression of DM and DN. Furthermore, the review discusses natural compounds that may alleviate these conditions by modulating autophagy.

Wild Rosa roxburghii Tratt Juices Grown at Different Altitudes Regulate Blood Glucose in Type 1 Diabetic Mice via the PI3K/Akt Pathway

To explore hypoglycemic effect of wild Rosa roxburghii tratt (RRT) juice at different altitudes on type 1 diabetes mellitus (T1DM). The T1DM mouse model was induced by streptozotocin (STZ), and the experiment included a normal group (NC), model group (MC), wild RRT juice groups high (HF), medium (MF), low altitude (DF) and cultivated control group (PC). During experiment, food intake, water intake, body weight, and fasting blood glucose were measured. After 28 days of administration, glucose tolerance, glycogen level, lipid profiles, and antioxidation levels in serum and liver were measured, and histomorphological changes of liver and kidney were observed by hematoxylin and eosin staining. The results showed that wild RRT juice reduced blood glucose level, alleviated liver and kidney tissue damage, improved glucose and lipid metabolism disorders and attenuated oxidative damage in T1DM mice. Western blot showed that wild RRT juice at grown at different altitudes significantly increased protein abundance of PI3K, Akt, and GLUT2 in liver of T1DM mice. In conclusion, wild RRT juice from different altitudes improved glucose and lipid metabolism disorders and oxidative damage in T1DM mice, which may be attributed to activation of PI3K/Akt pathway. Overall effect: MF > PC > HF > DF.

Oxymatrine and insulin resistance: Focusing on mechanistic intricacies involve in diabetes associated cardiomyopathy via SIRT1/AMPK and TGF-β signaling pathway

Cardiomyopathy (CDM) and related morbidity and mortality are increasing at an alarming rate, in large part because of the increase in the number of diabetes mellitus cases. The clinical consequence associated with CDM is heart failure (HF) and is considerably worse for patients with diabetes mellitus, as compared to nondiabetics. Diabetic cardiomyopathy (DCM) is characterized by structural and functional malfunctioning of the heart, which includes diastolic dysfunction followed by systolic dysfunction, myocyte hypertrophy, cardiac dysfunctional remodeling, and myocardial fibrosis. Indeed, many reports in the literature indicate that various signaling pathways, such as the AMP-activated protein kinase (AMPK), silent information regulator 1 (SIRT1), PI3K/Akt, and TGF-β/smad pathways, are involved in diabetes-related cardiomyopathy, which increases the risk of functional and structural abnormalities of the heart. Therefore, targeting these pathways augments the prevention as well as treatment of patients with DCM. Alternative pharmacotherapy, such as that using natural compounds, has been shown to have promising therapeutic effects. Thus, this article reviews the potential role of the quinazoline alkaloid, oxymatrine obtained from the Sophora flavescensin CDM associated with diabetes mellitus. Numerous studies have given a therapeutic glimpse of the role of oxymatrine in the multiple secondary complications related to diabetes, such as retinopathy, nephropathy, stroke, and cardiovascular complications via reductions in oxidative stress, inflammation, and metabolic dysregulation, which might be due to targeting signaling pathways, such as AMPK, SIRT1, PI3K/Akt, and TGF-β pathways. Thus, these pathways are considered central regulators of diabetes and its secondary complications, and targeting these pathways with oxymatrine might provide a therapeutic tool for the diagnosis and treatment of diabetes-associated cardiomyopathy.

Ferulic acid alleviates high fat diet-induced cognitive impairment by inhibiting oxidative stress and apoptosis

Cognitive impairment has become a major public health problem. Growing evidence suggests that high-fat diet (HFD) can cause cognitive dysfunction and increase the risk of dementia. However, effective treatment for cognitive impairment is not available. Ferulic acid (FA) is a single phenolic compound with anti-inflammatory and antioxidant properties. Nevertheless, its role in regulating learning and memory in HFD-fed mice and the underlying mechanism remains unclear. In this study, we aimed to identify the neuroprotective mechanisms of FA in HFD induced cognitive impairment. We found that FA improved the survival rate of HT22 cells treated with palmitic acid (PA), inhibited cell apoptosis, and reduced oxidative stress via the IRS1/PI3K/AKT/GSK3β signaling pathway; Furthermore, FA treatment for 24 weeks improved the learning and memory of HFD-fed mice and decreased hyperlipidemia. Moreover, the expression of Nrf2 and Gpx4 proteins were decreased in HFD-fed mice. After FA treatment, the decline of these proteins was reversed. Our study showed that the neuroprotective effect of FA on cognitive impairment was related to the inhibition of oxidative stress and apoptosis and regulation of glucose and lipid metabolism. These findings suggested that FA can be developed as a potential agent for the treatment of HFD-induced cognitive impairment.

Oxymatrine attenuated isoproterenol-induced heart failure via the TLR4/NF-κB and MAPK pathways in vivo and in vitro

Oxymatrine (OMT) is a quinoline alkaloid isolated from the root of the Sophora flavescens that has a variety of biological activities. However, the effect and potential mechanism of OMT on isoproterenol (ISO)-induced heart failure (HF) are not clear. In this study, we found that OMT improved the survival of HL-1 cells induced by ISO. We also demonstrated that OMT significantly inhibited the levels of the inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). OMT decreased the levels of the TLR4 and reduced the phosphorylation levels of nuclear factor-κB (NF-κB) inhibitor (IκB), p65, c-Jun N-terminal kinases (JNK) and p38. The inhibitory effect of the TLR4 inhibitor TAK242 on HL-1 cells was evaluated. The results showed that the effect of OMT on the phosphorylation levels of IκBα and p65 was enhanced in HL-1 cells treated with TAK242. Using animal models, OMT significantly reduced ISO-induced cardiac injury, myocardial necrosis, interstitial edema, and fibrosis. In addition, OMT attenuated TNF-α and IL-6 and inhibited the expression of TLR4/NF-κB and MAPK pathway-related proteins. This finding suggests that OMT may alleviate HF by interfering with the TLR4/NF-κB and MAPK pathways.

m6A transferase METTL3 regulates endothelial-mesenchymal transition in diabetic retinopathy via lncRNA SNHG7/KHSRP/MKL1 axis

Diabetic retinopathy is one of the microvascular complications in diabetic patients and the leading cause of blindness worldwide. The levels of METTL3, lncRNA SNHG7, KHSRP, MKL1, endothelial and mesenchymal markers were determined by RT-qPCR or western blot assays in vitro and in vivo. H&E staining was used to observe the retinal structure in a mouse model of DR. The expression levels of METTL3 and SNHG7 were significantly downregulated in DR patients, DR mice and high glucose-induced HRMECs cells. Notably, METTL3 installed the m6A modification and enhanced the stability of SNHG7. Besides, METTL3 inhibited HRMECs EndoMT by promoting the expression of SNHG7. Additionally, SNHG7 was found to weaken MKL1 mRNA stability by binding to the RNA-binding protein KHSRP. Furthermore, we verified that METTL3 regulated EndoMT in DR through the SNHG7/MKL1 axis. We conclude that METTL3 regulates endothelial-mesenchymal transition in DR via the SNHG7/KHSRP/MKL1 axis, providing a new target for DR treatment.

Methyl ferulic acid ameliorates alcohol-induced hepatic insulin resistance via miR-378b-mediated activation of PI3K-AKT pathway

A previous study indicated that microRNA-378b (miR-378b) plays a critical role in controlling hepatic insulin resistance by targeting insulin receptor (IR) and p110α in alcoholic liver disease (ALD). Methyl ferulic acid (MFA), a bioactive ingredient in Securidaca inappendiculata Hassk rhizomes, exhibits multiple pharmacological activities. It has been reported that MFA ameliorates insulin resistance in ALD, whereas the underlying molecular mechanism remains unclear. The objective of study was to evaluate the influence of MFA on insulin sensitivity in ethanol-induced L-02 cells as well as alcohol-fed mice and illuminate the function of miR-378b-mediated phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway in system. MFA was found to remarkably down-regulate miR-378b level and increase IR and p110α expressions. Furthermore, the effect of MFA on modulating miR-378b/PI3K-AKT pathway to enhance insulin sensitivity was corroborated by overexpressing and inhibiting miR-378b. Taken together, MFA exhibited a positive effect against ALD by attenuating the inhibition of miR-378b on IR/p110α and partly activating the insulin signaling to alleviate alcohol-induced hepatic insulin resistance.

Phosphatase and Tensin Homolog in Non-neoplastic Digestive Disease: More Than Just Tumor Suppressor

The Phosphatase and tensin homolog (PTEN) gene is one of the most important tumor suppressor genes, which acts through its unique protein phosphatase and lipid phosphatase activity. PTEN protein is widely distributed and exhibits complex biological functions and regulatory modes. It is involved in the regulation of cell morphology, proliferation, differentiation, adhesion, and migration through a variety of signaling pathways. The role of PTEN in malignant tumors of the digestive system is well documented. Recent studies have indicated that PTEN may be closely related to many other benign processes in digestive organs. Emerging evidence suggests that PTEN is a potential therapeutic target in the context of several non-neoplastic diseases of the digestive tract. The recent discovery of PTEN isoforms is expected to help unravel more biological effects of PTEN in non-neoplastic digestive diseases.

The Effect of Induced Diabetes Mellitus on the Cerebellar Cortex of Adult Male Rat and the Possible Protective Role of Oxymatrine: A Histological, Immunohistochemical and Biochemical Study

Diabetes mellitus (DM) represents a widespread metabolic disease with a well-known neurotoxicity in both central and peripheral nervous systems. Oxymatrine is a traditional Chinese herbal medicine that has various pharmacological activities including: anti-oxidant, anti-apoptotic and anti-inflammatory potentials. The present work aimed to study the impact of diabetes mellitus on the cerebellar cortex of adult male albino rat and to evaluate the potential protective role of oxymatrine. Fifty-five adult male rats were randomly divided into three groups: group I served as control, group II was given oxymatrine (80 mg/kg/day) orally for 8 weeks and group III was given a single dose of streptozotocin (50 mg/kg) intaperitoneally to induce diabetes. Then diabetic rats were subdivided into two subgroups: subgroup IIIa that received no additional treatment and subgroup IIIb that received oxymatrine similar to group II. The diabetic group revealed numerous changes in the Purkinje cell layer in the form of multilayer arrangement of Purkinje cells, shrunken cells with deeply stained nuclei as well as focal loss of the Purkinje cells. A significant increment in glial fibrillary acidic protein (GFAP) and synaptophysin expression were reported in immunohistochemistry compared with the control group. Transmission electron microscopy showed irregularity and splitting of myelin sheaths in the molecular layer, dark shrunken Purkinje cells with ill-defined nuclei, dilated Golgi saccules and dense granule cells with irregular nuclear outlines in the granular layer. In contrast, these changes were less evident in diabetic rats that received oxymatrine. In conclusion, Oxymatrine could protect the cerebellar cortex against changes induced by DM.

Oxymatrine Extends Survival by Attenuating Neuroinflammation in a Mouse Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is one of the leading causes of death associated with neurodegenerative diseases worldwide, and the progression of the disease is characteristically accompanied by severe neuroinflammation. Neuroprotective effects of oxymatrine (OMT) were shown to be due to reduced neuroinflammation in the mouse models of Alzheimer's disease and Parkinson's disease. The present study investigated whether OMT has a therapeutic potential in transgenic SOD1-G93A (TgSOD1-G93A) mice. Daily OMT treatment started at the age of 55 days until the end stage of the disease. Body weight and rotarod motor performance were assessed every 3 days starting from 70 days of age. Footprints were recorded to measure the stride length 40 days and 60 days after the initiation of the treatment. Some animals were sacrificed at the age of 115 days, and the lumbar spinal cord was harvested for immunofluorescence and quantitative real-time polymerase chain reaction (qRT-PCR) to evaluate the neuroinflammatory responses. The results indicated that treatment with OMT delayed body weight loss, improved motor performance, and prolonged the survival of SOD1-G93A mice. Mechanistically, OMT treatment enhanced motor neuronal survival and alleviated the activation of microglia and astrocytes compared with those in the vehicle-treated group. Furthermore, the expression of the proinflammatory mediators was downregulated, and the expression of the anti-inflammatory factors was upregulated in the OMT-treated group compared with those in the vehicle-treated group (P < 0.05). Thus, the treatment with OMT had neuroprotective effects, promoting neuronal survival and extending the lifetime of SOD1-G93A mice by suppressing neuroinflammation.

Effect of oxymatrine on liver gluconeogenesis is associated with the regulation of PEPCK and G6Pase expression and AKT phosphorylation

An increase in liver gluconeogenesis is an important pathological phenomenon in type 2 diabetes mellitus (T2DM) and oxymatrine is an effective natural drug used for T2DM treatment. The present study aimed to explore the effect of oxymatrine on gluconeogenesis and elucidate the underlying mechanism. Male Sprague-Dawley rats were treated with a high-fat diet and streptozotocin for 4 weeks to induce T2DM, and HepG2 cells were treated with 55 mM glucose to simulate T2DM in vitro. T2DM rats were treated with oxymatrine (10 or 20 mg/kg weight) or metformin for 4 weeks, and HepG2 cells were treated with oxymatrine (0.1 or 1 µM), metformin (0.1 µM), or oxymatrine combined with MK-2206 (AKT inhibitor) for 24 h. Fasting blood glucose and insulin sensitivity of rats were measured to evaluate insulin resistance. Glucose production and uptake ability were measured to evaluate gluconeogenesis in HepG2 cells, and the expression of related genes was detected to explore the molecular mechanism. Additionally, the body weight, liver weight and liver index were measured and hematoxylin and eosin staining was performed to evaluate the effects of the disease. The fasting glucose levels of T2DM rats was 16.5 mmol/l, whereas in the control rats, it was 6.1 mmol/l. Decreased insulin sensitivity (K-value, 0.2), body weight loss (weight, 300 g), liver weight gain, liver index increase (value, 48) and morphological changes were observed in T2DM rats, accompanied by reduced AKT phosphorylation, and upregulated expression of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). High-glucose treatment significantly increased glucose production and decreased glucose uptake in HepG2 cells, concomitant with a decrease in AKT phosphorylation and increase of PEPCK and G6Pase expression. In vivo, oxymatrine dose-dependently increased the sensitivity of T2DM rats to insulin, increased AKT phosphorylation and decreased PEPCK and G6Pase expression in the liver, and reversed the liver morphological changes. In vitro, oxymatrine dose-dependently increased AKT phosphorylation and glucose uptake of HepG2 cells subjected to high-glucose treatment, which was accompanied by inhibition of the expression of the gluconeogenesis-related genes, PEPCK and G6Pase. MK-2206 significantly inhibited the protective effects of oxymatrine in high-glucose-treated cells. These data indicated that oxymatrine can effectively prevent insulin resistance and gluconeogenesis, and its mechanism may be at least partly associated with the regulation of PEPCK and G6Pase expression and AKT phosphorylation in the liver.

The Role of Oxymatrine in Amelioration of Acute Lung Injury Subjected to Myocardial I/R by Inhibiting Endoplasmic Reticulum Stress in Diabetic Rats

Background

Oxymatrine (OMT) is the primary pharmacological component of Sophora flavescens Aiton., which has been shown to possess potent antifibrotic, antioxidant, and anti-inflammatory activities. The aim of the present study was to clarify the protective mechanism of OMT on acute lung injury (ALI) subjected to myocardial ischemia/reperfusion (I/R).

Methods

A myocardial I/R-induced ALI model was achieved in diabetic rats by occluding the left anterior descending coronary artery for 1 h, followed by reperfusion for 1 h. The levels of inflammatory factors (tumor necrosis factor-α, interleukin- (IL-) 6, and IL-17) in bronchoalveolar lavage fluid were assessed using commercially available kits. The index of myocardial injury, including the detection of cardiac troponin I (cTnI), cardiac troponin T (cTnT), lactate dehydrogenase (LDH), and creatine kinase-MB (CK-MB), was also determined using commercially available kits. Hematoxylin and eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling were used to identify histological changes. The expression levels of endoplasmic reticulum chaperone BiP (GRP78), DNA damage-inducible transcript 3 protein (CHOP), eukaryotic translation initiation factor 2-alpha kinase 3 (PERK), inositol dependent enzyme 1α (IRE1α), ATF6, caspase-3, -9, and-12, Bcl-2, and Bax were determined by Western blotting. The mRNA expression levels of GRP78 and CHOP were detected by reverse transcription-quantitative PCR.

Results

Myocardial I/R increased the levels of cTnI, cTnT, LDH, and CK-MB in diabetic rats. Damaged and irregularly arranged myocardial cells were also observed, as well as more serious ALI with higher lung injury scores and WET/DRY ratios and lower PaO₂. Moreover, the expression of key proteins of endoplasmic reticulum stress (ERS) was increased by I/R injury, including phosphorylated- (p-) PERK, p-IRE1ɑ, and ATF6, as well as decreased levels of apoptosis. These effects were all significantly reversed by OMT treatment.

Conclusions

OMT protects against ALI subjected to myocardial I/R by inhibiting ERS in diabetic rats.

mRNA Post-Transcriptional Regulation by AU-Rich Element-Binding Proteins in Liver Inflammation and Cancer

AU-rich element-binding proteins (AUBPs) represent important post-transcriptional regulators of gene expression. AUBPs can bind to the AU-rich elements present in the 3'-UTR of more than 8% of all mRNAs and are thereby able to control the stability and/or translation of numerous target mRNAs. The regulation of the stability and the translation of mRNA transcripts by AUBPs are highly complex processes that occur through multiple mechanisms depending on the cell type and the cellular context. While AUBPs have been shown to be involved in inflammatory processes and the development of various cancers, their important role and function in the development of chronic metabolic and inflammatory fatty liver diseases (FLDs), as well as in the progression of these disorders toward cancers such as hepatocellular carcinoma (HCC), has recently started to emerge. Alterations of either the expression or activity of AUBPs are indeed significantly associated with FLDs and HCC, and accumulating evidence indicates that several AUBPs are deeply involved in a significant number of cellular processes governing hepatic metabolic disorders, inflammation, fibrosis, and carcinogenesis. Herein, we discuss our current knowledge of the roles and functions of AUBPs in liver diseases and cancer. The relevance of AUBPs as potential biomarkers for different stages of FLD and HCC, or as therapeutic targets for these diseases, are also highlighted.

Berberine Improves Inflammatory Responses of Diabetes Mellitus in Zucker Diabetic Fatty Rats and Insulin-Resistant HepG2 Cells through the PPM1B Pathway

Berberine (BBR), a natural compound extracted from a Chinese herb, has been shown to effectively attenuate insulin resistance (IR) and inflammation in the clinic. However, its ameliorative mechanism against IR is not well defined. This study is aimed at investigating the effect of BBR and protein phosphatase, Mg²⁺/Mn²⁺-dependent 1B (PPM1B) on IR. Biochemical measurements and liver histopathology were detected using the biochemical analyzer and HE staining in ZDF rats, respectively. Microarray analysis of liver tissues was performed, and differentially expressed gene (DEG) levels were examined by quantitative real-time PCR (qPCR) and Western blot. Additionally, the effect of BBR was also explored in HepG2-IR cells. The glucose oxidase method and the fluorescent glucose analog were used to detect glucose consumption and uptake, respectively. The PKA inhibitor H89, ELISA, qPCR, Western blot, and immunofluorescence staining were employed to estimate the expression levels of related signaling pathways. To evaluate the roles of PPM1B, HepG2-IR cells were stably infected with lentivirus targeting PPM1B. The administration of BBR drastically decreased the body weight, urine volume, blood glucose, blood urea nitrogen (BUN), CHOL, hepatic index levels, and pathologic changes and improved ALB levels in ZDF rats with PPM1B upregulation. Furthermore, BBR effectively improves glucose consumption, uptake, and inflammation in HepG2-IR cells. The knockdown of PPM1B expression aggravated the inflammatory response and glycometabolism disorder in HepG2-IR cells. Mechanistically, a reversal in the expression of cAMP, PKA, PPM1B, PPARγ, LRP1, GLUT4, NF-κB p65, JNK, pIKKβ Ser181, IKKβ, IRS-1 Ser307, IRS-1, IRS-2 Ser731, IRS-2, PI3K p85, and AKT Ser473 contributes to ameliorate IR in HepG2-IR cells with BBR treatment. Altogether, these results suggest that BBR might regulate IR progression through the regulation of the cAMP, PKA, PPM1B, PPARγ, LRP1, GLUT4, NF-κB p65, JNK, pIKKβ Ser181, IKKβ, IRS-1 Ser307, IRS-1, IRS-2 Ser731, IRS-2, PI3K p85, and AKT Ser473 expression in the liver.

Vanadium and insulin: Partners in metabolic regulation

Since the 1970s, the biological role of vanadium compounds has been discussed as insulin-mimetic or insulin-enhancer agents. The action of vanadium compounds has been investigated to determine how they influence the insulin signaling pathway. Khan and coworkers proposed key proteins for the insulin pathway study, introducing the concept "critical nodes". In this review, we also considered critical kinases and phosphatases that participate in this pathway, which will permit a better comprehension of a critical node, where vanadium can act: a) insulin receptor, insulin receptor substrates, and protein tyrosine phosphatases; b) phosphatidylinositol 3'-kinase, 3-phosphoinositide-dependent protein kinase and mammalian target of rapamycin complex, protein kinase B, and phosphatase and tensin homolog; and c) insulin receptor substrates and mitogen-activated protein kinases, each node having specific negative modulators. Additionally, leptin signaling was considered because together with insulin, it modulates glucose and lipid homeostasis. Even in recent literature, the possibility of vanadium acting against metabolic diseases or cancer is confirmed although the mechanisms of action are not well understood because these critical nodes have not been systematically investigated. Through this review, we establish that vanadium compounds mainly act as phosphatase inhibitors and hypothesize on their capacity to affect kinases, which are critical to other hormones that also act on common parts of the insulin pathway.

Ultra-performance liquid chromatography-mass spectrometry-based metabolomics reveals Huangqiliuyi decoction attenuates abnormal metabolism as a novel therapeutic opportunity for type 2 diabetes

Background: As a typical chronic metabolic disease, type 2 diabetes mellitus causes a heavy health-care burden to society. In this study, we applied the metabolomics strategy to explore the potential molecular mechanism of the Huangqiliuyi decoction (HQLYD) for type-2 diabetes (T2D). Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) combined with pattern recognition methods was utilized to select specific metabolites closely associated with HQLYD. Biomarker pathway analysis and biological network were utilized to uncover the therapeutic effect and action mechanism related to HQLYD. A total of twenty-five biomarkers were identified in the animal model, in which sixteen biomarkers are associated with HQLYD treatment for T2D. They attenuated the abnormalities of metabolic pathways such as phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism, and the citrate cycle. HQLYD also significantly elevated the serum FINS and SOD, GSP-x level in the liver and kidney, and reduced the serum TC, TG, HDL, LDL, urea, Scr, AST, ALT, FBG, IRS, MDA, and CAT level. We found that the therapeutic mechanism of HQLYD against T2D affected amino acid metabolism, glucose metabolism and lipid metabolism. Metabolomics revealed that the Huangqiliuyi decoction attenuates abnormal metabolism as a novel therapeutic opportunity for type 2 diabetes.