Regulatory effect of uncarboxylated osteocalcin on osteogenic and adipogenic differentiation of mouse bone marrow mesenchymal stem cells under high-glucose conditions / 中国组织工程研究

BACKGROUND: The method of promoting osteogenic differentiation of bone marrow mesenchymal stem cells under high-glucose conditions to inhibit adipogenic differentiation can provide prevention and treatment ideas for the treatment of bone metabolic diseases such as diabetic osteoporosis. OBJECTIVE: To explore the effects of uncarboxylated osteocalcin on adipogenic and osteogenic differentiation of mouse bone marrow mesenchymal stem cells under high-glucose conditions so as to reveal the action mechanism of uncarboxylated osteocalcin on the differentiation of bone marrow mesenchymal stem cells. METHODS: Mouse bone marrow mesenchymal stem cells were cultured by whole bone marrow culture and adherent purification. Cells were treated with uncarboxylated osteocalcin at different concentrations (0, 1, 3, 10, and 30 μg/L). Cell proliferation was detected by cell counting kit-8 to determine the best mass concentration. Passage 3 bone marrow mesenchymal stem cells were incubated with adipogenic (or osteogenic) differentiation medium, and assigned to four groups: control group, high glucose group, uncarboxylated osteocalci n group, and high glucose + uncarboxylated osteocalcin group. Corresponding groups received the addition of 25.5 mmol/L exogenous glucose and 3 μg/L uncarboxylated osteocalcin. Lipid droplets and calcium nodules were detected by oil red and alizarin red staining. Quantitati ve reverse transcription-polymerase chain reaction was used to detect the relative expression levels of adipogenic marker genes (Fabp4, PPARγ, Adipsin and FAS) and osteogenic differentiation marker genes (Runx2, Osx, alkaline phosphatase, and type I collagen). Kits were used to detect alkaline phosphatase activity and type I collagen levels. The relative expression levels of P-Erk and P-AMPKα were detected using signal pathway specific inhibitors (PD98059 and BML) and western blot assay. RESULTS AND CONCLUSION: (1) Uncarboxylated osteocalcin 3 μg/L promoted cell proliferation (P < 0.01). (2) Uncarboxylated osteocalcin promoted the formation of calcium nodules (P < 0.01) in bone marrow mesenchymal stem cells under high-glucose conditions but inhibited the formation of lipid droplets (P < 0.05), down-regulating the relative expression levels of adipogenic marker genes (PFabp4 < 0.01; PPPARγ < 0.05; PAdipsin < 0.01; PFAS < 0.01), but increasing the relative expression levels of osteogenic differentiation marker genes (PRunx2 < 0.05; POsx < 0.05; PALP < 0.01; PCOLI < 0.01). Uncarboxylated osteocalcin increased alkaline phosphatase activity (P < 0.01) and type I collagen level (P < 0.05). (3) Uncarboxylated osteocalcin up-regulated the expression levels of P-Erk (P < 0.01) and P-AMPKα (P < 0.01) under high-glucose conditions. (4) These results indicate that uncarboxylated osteocalcin promoted osteogenic differentiation of bone marrow mesenchymal stem cells under high-glucose conditions through Erk/AMPKα signaling pathway and inhibited adipogenic differentiation.

Matrine attenuates oxidative stress and cardiomyocyte apoptosis in doxorubicin-induced cardiotoxicity maintaining AMPK/UCP2 pathway

Oxidative stress and cardiomyocyte apoptosis are involved in the pathogenesis of doxorubicin (DOX)-induced cardiotoxicity. Matrine is well-known for its powerful anti-oxidant and anti-apoptotic capacities. Our present study aimed to investigate the effect of matrine on DOX-induced cardiotoxicity and try to unearth the underlying mechanisms. Mice were exposed with DOX to generate DOX-induced cardiotoxicity or normal saline as control. H9C2 cells were used to verify the effect of matrine . DOX injection triggered increased generation of reactive oxygen species (ROS) and excessive cardiomyocyte apoptosis, which were significantly mitigated by matrine. Mechanistically, we found that matrine ameliorated DOX-induced uncoupling protein 2 (UCP2) downregulation, and UCP2 inhibition by genipin could blunt the protective effect of matrine on DOX-induced oxidative stress and cardiomyocyte apoptosis. Besides, 5'-AMP-activated protein kinase 2 () deficiency inhibited matrine-mediated UCP2 preservation and abolished the beneficial effect of matrine in mice. Besides, we observed that matrine incubation alleviated DOX-induced H9C2 cells apoptosis and oxidative stress level activating AMPK/UCP2, which were blunted by either AMPK or UCP2 inhibition with genetic or pharmacological methods. Matrine attenuated oxidative stress and cardiomyocyte apoptosis in DOX-induced cardiotoxicity maintaining AMPK/UCP2 pathway, and it might be a promising therapeutic agent for the treatment of DOX-induced cardiotoxicity.

MiRNA-148b targeted AMPKα1 mediates high glucose-induced apoptosis in human renal tubular epithelial cells via oxidative stress / 中华肾脏病杂志

Objective To investigate the expression and mechanism of microRNA-148b (miRNA-148b) in high glucose-induced renal tubular injury.Method HK-2 cells cultured in vitro were divided into normal glucose group,mannitol hypertonic control group and high glucose group.After 48 hours of culture,the expression of miRNA-148b was detected by real-time quantitative PCR.2',7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) was used for detecting production of ROS and observed under fluorescence microscope for analysis;The expression of AMPKot1,Bcl-2,NOX2,NOX4,activated caspase3 (cleaved-caspase3) were detected by Western blotting.Results Compared with the normal glucose group,the expression of miRNA-148b was up-regulated in HK-2 cells in high glucose group and hypertonic group (P ＜ 0.01),and the production of ROS increased (P ＜ 0.01).The expression of NOX2 and NOX4 was increased,AMPKα1 and Bcl-2 decreased,and cleaved caspase-3 was increased (all P ＜ 0.01).Conclusions HG up-regulated miRNA-148b expression and down-regulated its target gene AMPKα1 which promotes the expression of NOX2 and NOX4 in HK-2 cells.MiRNA-148b promotes apoptosis of HK-2 cells via increasing production of ROS and enhancing cleaved-caspase3 for Bcl-2 insufficiency.The tubular toxicity of high glucose is partly due to osmotic pressure.MiRNA-148b may be involved in the pathological injury of diabetic nephropathy and is expected to become a new therapeutic target for diabetic nephropathy.

Electroacupuncture for myocardial ischemia injury in rats via AMPK-HDAC5-HIF-1α signaling / 中国针灸

OBJECTIVE@#To explore the impact of electroacupuncture (EA) on the AMPKα-HDAC5-HIF-1α signaling in the heart of the rats with myocardial ischemia (MI) via detecting the expressions of AMP-activated protein kinase α (AMPKα), histone deacetylase 5 (HDAC5), hypoxia inducible factor (HIF-1α) and vascular endothelial growth factor (VEGF).@*METHODS@#Thirty-six healthy male SD rats were randomized into a sham operation group (6 rats), a sham + EA group (6 rats), a model group (12 rats) and an EA group (12 rats). We ligated the left anterior descending artery (LAD) for MI model, and exposed the heart of rats after opening the chest without ligation for the rats in the sham operation gorup and the sham + EA group. On the 2nd day after LAD ligation, EA was applied at "Neiguan" (PC 6) with 2 Hz/15 Hz and 1.5-2 mA for 30 min in the EA group and sham+EA group, once a day for 4 days. The same fixation was used in the sham operation group and the model group, without EA. Myocardial infarction area was observed by TTC staining and serum cardiac troponin T (cTnT) was detected by radioimmunoassay. The expression of VEGF mRNA was detected by real time PCR. The protein expressions of AMPKα, HDAC5, HIF-1α and VEGF were detected by western blot.@*RESULTS@#Compared with the sham operation group, 4 days after LAD ligation, the myocardial infarction was obvious and the expression of serum cTnT increased in the model group (0.05). After EA for 4 days, the myocardial infarction area and cTnT expression decreased in the EA group (both <0.01); the VEGF mRNA and protein expressions and AMPKα, HDAC5, HIF-1α protein expressions increased (<0.05, <0.01).@*CONCLUSION@#EA could regulate the AMPKα-HDAC5-HIF-1α signaling in myocardial tissue, which may activate VEGF expression for angiogenesis signaling, reduce myocardial infarction area so as to achieve cardioprotective effect.

Electroacupuncture activates phosphorylated AMPKαto regulate the expression of the mTOR gene in rats with functional dyspepsia / 中华物理医学与康复杂志

Objective To investigate how electroacupuncture activates the AMPKαpathway in the treatment of functional dyspepsia ( FD) . Methods Tail clipping stimulation was combined with an irregular diet to induce FD in 20 Sprague-Dawley rats. They were randomly divided into a model group and an electroacupuncture group, each of 10. Ten others had no FD induced and formed a normal group. The rats in the electroacupuncture group were given 10 days of electroacupuncture treatment, while those in the normal and model groups were restrained and fixed like those in the electroacupuncture group, but not given electroacupuncture. The expression of phosphorylated adenosine mono-phosphate-activated protein kinase alpha (p-AMPKα), phosphorylated tuberin (p-TSC2) and Rheb protein in the stomachs and small intestines of each group were detected using the western blotting. Levels of mTOR mRNA were quantified using the reverse-transcription polymerase chain reaction ( RT-PCR) . Results The western blotting re-sults showed that compared with the normal group, the expression levels of p-AMPKα and p-TSC2 in the stomachs and small intestines of the model group decreased significantly, while that of Rheb protein increased significantly. Compared with the model group, the expression of p-AMPKαand p-TSC2 increased significantly after the electroacu-puncture treatment, while that of Rheb protein decreased significantly. According to the RT-PCR results, the expres-sion of mTOR mRNA in the stomachs and small intestines of the model group was up-regulated significantly compared with the normal group. Compared with the model group, expression of mTOR mRNA in the electroacupuncture group was significantly down-regulated. Conclusion Electroacupuncture can activate the AMPKα pathway, up-regulate the expression of the related protein p-TSC2, and decrease the expression of Rheb protein, thereby down-regulating the transcription of the mTOR gene. That would serve to treat FD.

The activation of α₂-adrenergic receptor in the spinal cord lowers sepsis-induced mortality

The effect of clonidine administered intrathecally (i.t.) on the mortality and the blood glucose level induced by sepsis was examined in mice. To produce sepsis, the mixture of D-galactosamine (GaLN; 0.6 g/10 ml)/lipopolysaccharide (LPS; 27 µg/27 µl) was treated intraperitoneally (i.p.). The i.t. pretreatment with clonidine (5 µg/5 µl) increased the blood glucose level and attenuated mortality induced by sepsis in a dose-dependent manner. The i.t. post-treatment with clonidine up to 3 h caused an elevation of the blood glucose level and protected sepsis-induced mortality, whereas clonidine post-treated at 6, 9, or 12 h did not affect. The pre-treatment with oral D-glucose for 30 min prior to i.t. post-treatment (6 h) with clonidine did not rescue sepsis-induced mortality. In addition, i.t. pretreatment with pertussis toxin (PTX) reduced clonidine-induced protection against mortality and clonidine-induced hyperglycemia, suggesting that protective effect against sepsis-induced mortality seems to be mediated via activating PTX-sensitive G-proteins in the spinal cord. Moreover, pretreatment with clonidine attenuated the plasma tumor necrosis factor α (TNF-α) induced by sepsis. Clonidine administered i.t. or i.p. increased p-AMPKα1 and p-AMPKα2, but decreased p-Tyk2 and p-mTOR levels in both control and sepsis groups, suggesting that the up-regulations of p-AMPKα1 and p-AMPKα2, or down-regulations of p-mTOR and p-Tyk2 may play critical roles for the protective effect of clonidine against sepsis-induced mortality.

The second-generation antipsychotic drugs induced dyslipidemia: a review of research and mechanisms / 中国药学杂志

Chronic administration of the second-generation antipsychotic drugs (SGAs) is associated with elevated risks of weight gain, obesity and other metabolic disorders, which further leads to an increase in incidence of cardiovascular diseases and the reduced life expectancy in patients. Dyslipidemia is a critical causative factor for the metabolic syndrome. In this article, the potential molecular mechanisms in SGA-induced dyslipidemia were focused on SREBPs/AMPKα/PPAR pathways, as well as the induction of insulin resistance in peripheral tissues (liver and white fat tissue).

Emerging role of microRNAs in lipid metabolism

microRNAs (miRNAs or miRs) are small non-coding RNAs that are involved in post-transcriptional regulation of their target genes in a sequence-specific manner. Emerging evidence demonstrates that miRNAs are critical regulators of lipid synthesis, fatty acid oxidation and lipoprotein formation and secretion. Dysregulation of miRNAs disrupts gene regulatory network, leading to metabolic syndrome and its related diseases. In this review, we introduced epigenetic and transcriptional regulation of miRNAs expression. We emphasized on several representative miRNAs that are functionally involved into lipid metabolism, including miR-33/33(⁎), miR122, miR27a/b, miR378/378(⁎), miR-34a and miR-21. Understanding the function of miRNAs in lipid homeostasis may provide potential therapeutic strategies for fatty liver disease.