Extracellular ATP (exATP) has been known to be a critical ligand regulating skeletal muscle differentiation and contractibility. ExATP synthesis was greatly increased with the high level of adenylate kinase 1 (AK1) and ATP synthase beta during C2C12 myogenesis. The exATP synthesis was abolished by the knock-down of AK1 but not by that of ATP synthase beta in C2C12 myotubes, suggesting that AK1 is required for exATP synthesis in myotubes. However, membrane-bound AK1beta was not involved in exATP synthesis because its expression level was decreased during myogenesis in spite of its localization in the lipid rafts that contain various kinds of receptors and mediate cell signal transduction, cell migration, and differentiation. Interestingly, cytoplasmic AK1 was secreted from C2C12 myotubes but not from C2C12 myoblasts. Taken together all these data, we can conclude that AK1 secretion is required for the exATP generation in myotubes.
Adenosine Triphosphate/*biosynthesis ; Adenylate Kinase/*metabolism ; Animals ; Cell Line ; Extracellular Space/metabolism ; Isoenzymes/*metabolism ; Mice ; Muscles/cytology/*metabolism

The present study was aimed to clarify the signaling molecular mechanism by which fibroblast growth factor 21 (FGF21) regulates leptin gene expression in adipocytes. Differentiated 3T3-F442A adipocytes were used as study object. The mRNA expression level of leptin was detected by fluorescence quantitative RT-PCR. The phosphorylation levels of proteins of signal transduction pathways were detected by Western blot. The results showed that FGF21 significantly down-regulated the mRNA expression level of leptin in adipocytes, and FGF21 receptor inhibitor BGJ-398 could completely block this effect. FGF21 up-regulated the phosphorylation levels of ERK1/2 and AMPK in adipocytes. Either ERK1/2 inhibitor SCH772984 or AMPK inhibitor Compound C could partially block the inhibitory effect of FGF21, and the combined application of these two inhibitors completely blocked the effect of FGF21. Neither PI3K inhibitor LY294002 nor Akt inhibitor AZD5363 affected the inhibitory effect of FGF21 on leptin gene expression. These results suggest that FGF21 may inhibit leptin gene expression by activating ERK1/2 and AMPK signaling pathways in adipocytes.
3T3 Cells ; Adenylate Kinase ; Adipocytes ; metabolism ; Animals ; Down-Regulation ; Fibroblast Growth Factors ; metabolism ; Leptin ; metabolism ; MAP Kinase Signaling System ; Mice ; Phosphorylation ; Signal Transduction

OBJECTIVEInterferon-γ (IFN-γ) plays an important role in apoptosis and was shown to increase the risk of diabetes. Visfatin, an adipokine, has anti-diabetic, anti-tumor, and regulating inflammatory properties. In this study we investigated the effect of visfatin on IFN-γ-induced apoptosis in rat pancreatic β-cells.

METHODSThe RINm5F (rat insulinoma cell line) cells exposed to IFN-γ were treated with or without visfatin. The viability and apoptosis of the cells were assessed by using MTT and flow cytometry. The expressions of mRNA and protein were detected by using real-time PCR and western blot analysis.

RESULTSThe exposure of RINm5F cells to IFN-γ for 48 h led to increased apoptosis percentage of the cells. Visfatin pretreatment significantly increased the cell viability and reduced the cell apoptosis induced by IFN-γ. IFN-γ-induced increase in expression of p53 mRNA and cytochrome c protein, decrease in mRNA and protein levels of anti-apoptotic protein Bcl-2 were attenuated by visfatin pretreatment. Visfatin also increased AMPK and ERK1/2 phosphorylation and the anti-apoptotic action of visfatin was attenuated by the AMPK and ERK1/2 inhibitor.

CONCLUSIONThese results suggested that visfatin protected pancreatic islet cells against IFN-γ-induced apoptosis via mitochondria-dependent apoptotic pathway. The anti-apoptotic action of visfatin is mediated by activation of AMPK and ERK1/2 signaling molecules.

Adenylate Kinase ; metabolism ; Animals ; Apoptosis ; physiology ; Cell Line ; Cytokines ; physiology ; Flow Cytometry ; Interferon-gamma ; physiology ; Islets of Langerhans ; cytology ; MAP Kinase Signaling System ; Nicotinamide Phosphoribosyltransferase ; physiology ; Rats ; Real-Time Polymerase Chain Reaction ; Signal Transduction

OBJECTIVETo investigate the underlying molecular mechanism of the cholesterol-blocking drug, simvastatin, in treating nonalcoholic fatty liver fibrosis.

METHODA rat model of nonalcoholic fatty liver fibrosis was established by feeding Wistar rats a fat-rich diet. After treatment with simvastatin (4 mg/kg/day), liver histological specimens were stained with hematoxylin-eosin and Masson's trichrome for microscopic analysis. Expression of adenosine monophosphate-activated protein kinase-alpha (AMPKa) was evaluated by reverse transcription-polymerase chain reaction (RT-PCR; for mRNA) and Western blotting (protein). The levels of serum total cholesterol (TC), triglycerides (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and tumor necrosis factor-alpha (TNFa) were measured by standard biochemical assays. The human hepatic stellate cell line, LX-2 (quiescent or activated), was treated with transforming growth factor-beta 1 (TGF-b1) alone, simvastatin alone, or TGF-b1 + simvastatin. RT-PCR and Western blotting were used to determine changes in AMPKa mRNA and protein expression, respectively.

RESULTSIn the rat model of nonalcoholic fatty liver fibrosis, the extent of pathological changes in hepatic tissues correlated with severity of disease progression. The levels of serum TC, TG, ALT, AST and TNFa were increased significantly in model rats (vs. healthy controls; all, P less than 0.01). AMPKa mRNA expression and activity was significantly decreased in model rats (vs. healthy controls; P less than 0.01 and P less than 0.05, respectively). Simvastatin, treatment significantly improved all of these parameters in model rats (vs. untreated model rats; all, P less than 0.05). In vitro simvastatin treatment of human HSCs significantly increased AMPKa activity (quiescent LX-2: 0.93+/-0.10 vs. 0.72+/-0.09, activated LX-2: 0.72+/-0.10 vs. 0.54+/-0.10, q=7.00, 6.00; all, P less than 0.01), decreased a-smooth muscle actin expression (mRNA: 0.30+/-0.02 vs. 0.36+/-0.02, protein: 0.30+/-0.03 vs. 0.38+/-0.02, q=11.245, 11.216; all, P less than 0.01), and decreased collagen I expression (mRNA: 0.30+/-0.03 vs. 0.37+/-0.03, protein: 0.25+/-0.03 vs. 0.33+/-0.03, q=8.791, 11.163; all, P less than 0.01).

CONCLUSIONSimvastatin may improve nonalcoholic fatty liver fibrosis by inducing AMPK phosphorylation.

Adenylate Kinase ; metabolism ; Animals ; Cell Line ; Fatty Liver ; drug therapy ; metabolism ; pathology ; Hepatic Stellate Cells ; drug effects ; enzymology ; Humans ; Liver Cirrhosis ; metabolism ; pathology ; Male ; Rats ; Rats, Wistar ; Simvastatin ; pharmacology ; therapeutic use

OBJECTIVETo clone the gene encoding adenylate kinase of Thermus thermophilus HB27, an extremely thermophilic bacterium, express the protein in Escherichia coil and study the enzymatic characterization.

METHODSThe DNA fragment encoding adenylate kinase was obtained by PCR from the total DNA of Thermus thermophilus HB27 and cloned into the vector pET-28a. The recombinant plasmid was identified by PCR, restriction endonuclease digestion and sequence analysis. Enzymatic characterization of the expressed protein was carried out using spectrophotometric assays.

RESULTSThe gene coding for adenylate kinase from Thermus thermophilus HB27 was cloned and the protein was overexpressed in Escherichia coli BL21(DE3). The optimum reactive pH and temperature for the enzyme were 8.5 and 90 degrees celsius;, respectively. The Km of the recombinant adenylate kinase for ADP was 68.6 micromol/L, with an V(max)ADP of 0.294 mmol/(L.min). Under the condition of environmental temperature at 70, 80, 90, or 100 degrees celsius; for 7 h, the recombinant adenylate kinase still retained the enzymatic activity with high thermostability. AP5A, a specific adenylate kinase inhibitor, inhibited the enzymatic activity of the protein by 70% at the concentration of 2.0 mmol/L, with a Ki value of 46.39 micromol/L for ADP.

CONCLUSIONThe gene coding for adenylate kinase of Thermus thermophilus HB27 has been successfully cloned and expressed in Escherichia coil, which provides the basis for potential use of the highly thermostable recombinant HB27 adenylate kinase.

Adenylate Kinase ; biosynthesis ; genetics ; metabolism ; Amino Acid Sequence ; Cloning, Molecular ; Enzyme Stability ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Molecular Sequence Data ; Recombinant Proteins ; biosynthesis ; genetics ; metabolism ; Thermus thermophilus ; enzymology

OBJECTIVEThe effect of mesenchymal stem cells (MSCs) transplantation is poor because of the harsh environment post infarction. Our previous studies have proven that Statins could enhance the implanted bone marrow MSCs survival, but the exact mechanism remained to be clarified. We hypothesized that atorvastatin (Ator) could protect MSCs from hypoxia and serum-free (H/SF) induced apoptosis and investigated the potential mechanisms.

METHODSChinese mini-swine's bone marrow derived MSCs were cultured in vitro and exposed to hypoxia and H/SF, Ator of various concentrations (0.001 - 10 µmol/L), AMPK inhibitor-compound C (CC), PI3K inhibitor-LY294002 (LY), Ator + CC and Ator + LY. Cell apoptosis was assessed using Annexin V/Prospidine Iodine kit by flow cytometry. Phosphorylation of AMPK, Akt, endothelial nitric oxide synthase (eNOS) level and phosphorylation were tested with Western blot. Real Time-PCR was performed to analyze the gene expression of AMPK, Akt and eNOS.

RESULTSMSCs apoptosis in Ator (0.01 - 10 µmol/L) treated H/SF groups was significantly reduced compared with H/SF group (1.94% - 6.10% vs. 10.94%, P < 0.01 or 0.05). Apoptosis was higher in Ator + CC group than in 1 µmol/L Ator group (4.94% ± 0.98% vs. 2.59% ± 0.84%, P < 0.01) and similar between Ator + LY and 1 µmol/L Ator group (2.02% ± 0.45% vs. 2.59% ± 0.84%, P > 0.05). The gene expressions of AMPK, Akt and eNOS were significantly upregulated in atorvastatin treated groups. Meanwhile, phosphorylation of AMPK and eNOS increased in MSCs treated with atorvastatin (P < 0.01 or 0.05). Phosphorylation of eNOS significantly correlated with AMPK phosphorylation (r = 0.599, P = 0.004), but not with Akt phosphorylation (P = 0.263).

CONCLUSIONSAtorvastatin can protect MSCs from H/SF induced apoptosis through AMPK pathway, which resulting in activation of eNOS.

Adenylate Kinase ; metabolism ; Animals ; Apoptosis ; drug effects ; Atorvastatin Calcium ; Bone Marrow Cells ; cytology ; metabolism ; Culture Media, Serum-Free ; Heptanoic Acids ; pharmacology ; Mesenchymal Stromal Cells ; cytology ; metabolism ; Nitric Oxide Synthase Type III ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; metabolism ; Pyrroles ; pharmacology ; Signal Transduction ; Swine

According to our previous studies together with others, GnRH, a hypothalamic decapeptide, has been known to be a major regulator for LH release and its subunit biosynthesis in anterior pituitary gonadotropes. But the precise mechanisms by which GnRH exerts stimulatory effects on LH release and its subunit biosynthesis have not been clearly understood. In the present study we examined the effect of GnRH on protein kinase C (PKC) activity and intracellular cAMP content in cultured anterior pituitary cells of rat to clarify whether PKC or cAMP are involved in GnRH action. Moreover, we examined the effects of staurosporine (ST), a PKC inhibitor and 2',3'-dideoxyadenosine (2',3'-DDA), an adenylate cyclase inhibitor, on LH release and steady state LH beta subunit mRNA levels in cultured anterior pituitary cells of rat. PKC activity was rapidly increased within 30 min after GnRH treatment whereas intracellular cAMP level was elevated 18 h after GnRH treatment. ST significantly inhibited GnRH-induced LH release and LH beta subunit mRNA levels in a dose-dependent manner, showing an half maximal response at 50 nM ST. 2',3'-DDA inhibited GnRH-induced LH release and LH beta subunit mRNA levels in a dose-dependent manner in pituitary cells. From these results, it is suggested that GnRH stimulates LH beta subunit mRNA level as well as LH release in anterior pituitary cells and this GnRH action might be mediated by PKC activation and cAMP stimulation.
Adenylate Cyclase/*antagonists & inhibitors ; Alkaloids/*pharmacology ; Animal ; Cells, Cultured ; Cyclic AMP/metabolism ; Dideoxyadenosine/*pharmacology ; Female ; Gonadorelin/*pharmacology ; Luteinizing Hormone/*biosynthesis/*metabolism ; Pituitary Gland, Anterior/*drug effects/metabolism ; Protein Kinase C/*antagonists & inhibitors/metabolism ; Rats ; Rats, Sprague-Dawley ; Staurosporine ; Support, Non-U.S. Gov't

Modified Si-Miao-San (mSMS) is composed of Rhizoma Coptidis, Cortex Phellodendri, Rhizoma Coptidis Semen Coicis and Atractylodes Rhizome. The prescription is used for the management of diabetes and insulin resistance in the clinic. This study aims to investigate its regulation of glucose disposal in adipocytes. Differentiated 3T3-L1 adipocytes were stimulated with conditioned medium derived from activated macrophages to induce insulin resistance and observed the effects of Mac-CM on insulin-mediated glucose uptake along the insulin receptor substrate-1/PI3K/Akt signaling pathway. Moreover, its regulation of AMPK phosphorylation was also investigated. mSMS enhanced AMPK phosphorylation and promoted basal glucose uptake in adipocytes; mSMS inhibited NF-κB activation by reducing P65 phosphorylation and improved insulin-stimulated IRS-1 tyrosine and Akt phosphorylation, leading to the restoration of insulin-mediated glucose uptake when cells were exposed to inflammatory stimulation. These beneficial effects were diminished in the presence of the AMPK inhibitor compound C. mSMS positively regulated AMPK activity, and this action contributed to improving insulin PI3K signaling by the beneficial regulation of IRS-1 function through inhibition of inflammation in adipocytes.
3T3-L1 Cells ; Adenosine Monophosphate ; metabolism ; Adenylate Kinase ; metabolism ; Adipocytes ; drug effects ; metabolism ; Animals ; Atractylodes ; Coix ; Coptis ; Diabetes Mellitus ; drug therapy ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Glucose ; metabolism ; Glucose Transporter Type 4 ; metabolism ; Inflammation ; metabolism ; prevention & control ; Insulin ; metabolism ; Insulin Receptor Substrate Proteins ; metabolism ; Insulin Resistance ; Mice ; NF-kappa B ; metabolism ; Phellodendron ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphorylation ; Phytotherapy ; Proto-Oncogene Proteins c-akt ; metabolism ; Signal Transduction

OBJECTIVETo investigate the effects of Chang-Chul-Eui-Ee-In-Tang ([see text], CCEET), modififi ed CCEET (MCCEET), and Semen Coicis (SC, a major component of CCEET) on energy and glucose homeostasis. The possible mechanism of action of CCEET was also determined.

METHODSA total of 100 Sprague Dawley female rats were randomly assigned to 5 groups, with 20 in each group. Rats in 4 groups were fed with a high fat diet supplementation (2 g/kg body weight), and water extracts of CCEET, MCCEET, SC, and cellulose (negative control), respectively. The last group was fed with a low-fat diet as a positive control.

RESULTSCCEET and MCCEET decreased body weight and body fat (mesenteric and retroperitoneal fat) more than SC. This decrease was due to decreased energy intake and increased energy expenditure and fat oxidation. The improvement in energy homeostasis was associated with the enhancement of the hypothalamic leptin signalling pathway involving potentiating the phosphorylation of the signal transducer and activator of transcription-3, as well as attenuating the phosphorylation of 5' adenosine monophosphate-activated protein kinase (AMPK). Both CCEET and MCCEET improved glucose tolerance without changing serum insulin levels during an oral glucose tolerance test but MCCEET had a better effect than CCEET.

CONCLUSIONSBoth CCEET and MCCEET safely exerted anti-obesity effects by enhancing energy balance in female rats with diet-induced obesity; MCCEET showed a better effect on glucose homeostasis.

Adenylate Kinase ; metabolism ; Adipose Tissue ; drug effects ; Animals ; Anti-Obesity Agents ; adverse effects ; pharmacology ; therapeutic use ; Blood Glucose ; metabolism ; Body Weight ; drug effects ; Calorimetry ; Diet ; Drugs, Chinese Herbal ; adverse effects ; pharmacology ; therapeutic use ; Energy Metabolism ; drug effects ; Female ; Glucose Tolerance Test ; Homeostasis ; drug effects ; Hypothalamus ; drug effects ; enzymology ; Leptin ; metabolism ; Motor Activity ; drug effects ; Obesity ; blood ; drug therapy ; pathology ; physiopathology ; Phosphorylation ; drug effects ; Rats ; Rats, Sprague-Dawley ; STAT3 Transcription Factor ; metabolism ; Signal Transduction ; drug effects