Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is recognized that obesity contributes to cardiovascular and metabolic disorders through alterations in the levels of adipocyte-derived cytokines (adipokines). Adiponectin is an adipokine that is downregulated in obese individuals. It has beneficial actions on the cardiovascular system by directly acting on the heart and blood vessels, and acute administration of adiponectin can minimize the tissue damage resulting from myocardial infarction. More recent research has been aimed at identifying novel adiponectin-like factors involved in metabolic and cardiovascular regulation. Activation of Akt, a protein kinase involved in cell signaling, has been implicated in the control of skeletal muscle hypertrophy. An experimental mouse model demonstrates that substantial increases in muscle fiber hypertrophy, weight and strength occur upon induction of Akt signaling in skeletal muscle. In a mouse model of obesity, the increase in muscle mass caused by myogenic Akt induction results in diminished fat deposition and improvements in whole body metabolism. Based on these findings a protocol to identify novel muscle-secreted proteins (myokines) that confer the phenotypic changes brought on by myogenic Akt induction has been devised. One of these newly discovered factors, referred to as follistatin-like 1, is able to promote revascularization in ischemic limbs and protect the heart from ischemic stress.
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PMID:Adipokines, myokines and cardiovascular disease. 1904 26

Adiponectin is a peptide hormone secreted by adipose tissue. It is a key hormone responsible for insulin sensitization, and its circulating level is inversely associated with abdominal obesity. Recent studies have shown that a reduced plasma adiponectin level is significantly correlated with the risk of various cancers. However, there are few studies regarding the association of adiponectin and colorectal cancer. To address this issue, we investigated the effect of adiponectin on colorectal cancer cells. Three colorectal cancer cell lines express both AdipoR1 and AdipoR2 receptors. MTT assay revealed that adiponectin inhibited human colorectal cancer cell growth. Furthermore, Western blot analysis revealed that adiponectin activated adenosine monophosphate-activated protein kinase (AMPK) and suppressed mammalian target of rapamycin (mTOR) pathways. Selective AMPK inhibitor compound C abrogated the inhibitory effect of adiponectin on cell growth. Our results clearly demonstrate the novel findings that adiponectin inhibits colorectal cancer cell growth via activation of AMPK, thereby down-regulating the mTOR pathway.
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PMID:Adiponectin inhibits colorectal cancer cell growth through the AMPK/mTOR pathway. 1914 67

Adiponectin is an adipokine with anti-atherogenic, anti-diabetic and insulin sensitizing properties. Its effects on energy homeostasis, glucose and lipid metabolism are mediated by two ubiquitously expressed seven-transmembrane receptors, AdipoR1 and -R2. With the exception of APPL1 and RACK1, no intracellular binding partners of adiponectin receptors are reported and thus signaling pathways downstream of these receptors remain largely unknown. To incorporate adiponectins protective potential in drug development it is essential to understand adiponectin signaling cascades in detail. A yeast two-hybrid approach employing AdipoR1s cytoplasmatic N-terminus led to the identification of the regulatory subunit of protein kinase CK2. We confirmed the interaction in co-immunoprecipitation, ELISA experiments and co-localization analysis in mammalian cells. Furthermore we could localize the interaction site in an N-terminal basic region close to the transmembrane domain. In adiponectin stimulation experiments of C2C12 mouse myotubes and MCF7 cells incorporating CK2 inhibitor 2-dimethylamino-4,5,6,7-tetrabromo-1H-benz-imidazole (DMAT) we found a modulator role of CK2 in adiponectin signaling. Accordingly we identified the regulatory subunit of protein kinase CK2 as a novel intracellular partner of AdipoR1 and have strong evidence of CK2 as an effector molecule in adiponectin signaling. Since CK2 is involved in signaling cascades of other adipokines and hormones, e.g. leptin and insulin, our findings suggest a possible key function in crosstalk between adiponectin and insulin signaling pathways and could provide further insight into the anti-diabetic effects of adiponectin.
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PMID:Protein kinase CK2 interacts with adiponectin receptor 1 and participates in adiponectin signaling. 1923 63

During fasting periods, hepatic glucose production is enhanced by glucagon to provide fuels for other organs. This process is mediated via cAMP-dependent induction of the CREB regulated transcriptional coactivator (CRTC) 2, a critical transcriptional activator for hepatic gluconeogenesis. We have previously shown that CRTC2 activity is regulated by AMP activated protein kinase (AMPK) family members. Here we show that adiponectin and thiazolidinedione directly regulate AMPK to modulate CRTC2 activity in hepatocytes. Adiponectin or thiazolidinedione lowered glucose production from primary hepatocytes. Treatment of both reagents reduced gluconeogenic gene expression as well as cAMP-mediated induction of CRE reporter, suggesting that these reagents directly affect CREB/CRTC2- dependent transcription. Furthermore, adiponectin or thiazolidinedione mediated repression of CRE activity is largely blunted by co-expression of phosphorylation defective mutant CRTC2, underscoring the importance of serine 171 residue of this factor. Taken together, we propose that adiponectin and thiazolidinedione promote the modulation of AMPK-dependent CRTC2 activity to influence hepatic gluconeogenesis.
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PMID:Adiponectin and thiazolidinedione targets CRTC2 to regulate hepatic gluconeogenesis. 1938 Oct 67

Adiponectin (APN) exerts its metabolic regulation largely through AMP-dependent protein kinase (AMPK). However, the role of AMPK in APN's antiapoptotic effect in ischemic-reperfused (I/R) adult cardiomyocytes remains incompletely understood. The present study was designed to determine the involvement of AMPK in the antiapoptotic signaling of APN. Cardiomyocytes from adult male mice overexpressing a dominant-negative alpha(2)-subunit of AMPK (AMPK-DN) or wild-type (WT) littermates were subjected to simulated I/R (SI/R) and pretreated with 2 microg/ml globular domain of APN (gAPN) or vehicle. SI/R-induced cardiomyocyte apoptosis was modestly increased in AMPK-DN cardiomyocytes (P < 0.05). Treatment with gAPN significantly reduced SI/R-induced apoptosis in WT cardiomyocytes as well as in AMPK-DN cardiomyocytes, indicating that the antiapoptotic effect of gAPN is partially AMPK independent. Furthermore, gAPN-induced endothelial nitric oxide synthase (eNOS) phosphorylation was significantly reduced in AMPK-DN cardiomyocytes, suggesting that the APN-eNOS signaling axis is impaired in AMPK-DN cardiomyocytes. Additional experiments demonstrated that treatment of AMPK-DN cardiomyocytes with gAPN reduced SI/R-induced NADPH oxidase overexpression, decreased superoxide generation, and blocked peroxynitrite formation to the same extent as that observed in WT cardiomyocytes. Collectively, our present study demonstrated that although the metabolic and eNOS activation effect of APN is largely mediated by AMPK, the superoxide-suppressing effect of APN is not mediated by AMPK, and this AMPK-independent antioxidant property of APN increased nitric oxide bioavailability and exerted significant antiapoptotic effect.
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PMID:Cardioprotective effect of adiponectin is partially mediated by its AMPK-independent antinitrative action. 1947 Aug 31

Chondrosarcoma is a type of highly malignant tumor with a capacity to invade locally and cause distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. Adiponectin is a protein hormone secreted predominantly by differentiated adipocytes and is involved in energy homeostasis. However, the effect of adiponectin on migration activity in human chondrosarcoma cells is mostly unknown. We found that adiponectin increased the migration and expression of alpha2beta1 integrin in human chondrosarcoma cells. The protein and messenger RNA expression of adiponectin receptor (AdipoR1 and AdipoR2) in chondrosarcoma patients and chondrosarcoma cell lines were significantly higher than the normal cartilage. Moreover, primary chondrosarcoma and chondrosarcoma cell lines (SW1353 and JJ012) were more invasive than normal chondrocytes. Adiponectin-mediated migration and integrin expression was attenuated by 5'-adenosine monophosphate-activated protein kinase (AMPK) small interfering RNA and an AMPK inhibitor (Ara A and compound C). Activation of p38 and nuclear factor-kappa B (NF-kappaB) pathways after adiponectin treatment was demonstrated, and adiponectin-induced expression of integrins and migration activity was inhibited by the specific inhibitor and mutant of p38 and NF-kappaB cascades. This study showed for the first time that adiponectin mediates the migration of human chondrosarcoma cells. One mechanism underlying adiponectin-directed migration was transcriptional upregulation of alpha2beta1 integrin and activation of AdipoR receptor, AMPK, p38 and NF-kappaB pathways.
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PMID:Involvement of AdipoR receptor in adiponectin-induced motility and alpha2beta1 integrin upregulation in human chondrosarcoma cells. 1954 5

Adiponectin is an adipose-derived hormone that has anti-diabetic and anti-atherogenic effects through interaction with AdipoR1 and AdipoR2 (adiponectin receptors 1 and 2), but little is known about the expression and function of adiponectin and its receptors in adventitia and adventitial fibroblasts. In the present study, we have demonstrated that AdipoR1 is highly expressed in rat adventitia and cultured adventitial fibroblasts by quantitative real-time PCR, Western blotting and immunofluorescent staining, whereas Adipo2 is low-expressed. The expression of AdipoR1 have been observed to decrease gradually in adventitial fibroblasts in response to LPS (lipopolysaccharide) treatment. No local expression of adiponectin has been detected in adventitial tissues, indicating that serum adiponectin is the ligand for AdipoR1 in adventitial fibroblasts. In addition, treatment of recombinant adiponectin inhibited LPS-induced proliferation of adventitial fibroblasts via activation of the AMPK (adenosine monophosphate-activated protein kinase). AdipoR1 siRNA (small interfering RNA) transfection potently knocked down the receptor protein. The siRNA-AdipoR1 transfected cells and AMPK inhibitor compound C treated cells showed decreased phosphorylated level of AMPK as determined by Western blot analysis, and increased the proliferation of adventitial fibroblasts as determined by BrdU (5-bromo-29-deoxyuridine) staining. These results demonstrated that adiponectin stimulates the proliferation of adventitial fibroblasts via the AdipoR1 and AMPK signalling pathways.
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PMID:Expression and role of adiponectin receptor 1 in lipopolysaccharide-induced proliferation of cultured rat adventitial fibroblasts. 1994 43

In obesity, dysregulation of adipocytokines is involved in several pathological conditions including diabetes and certain cancers. As a member of the adipocytokines, adiponectin plays crucial roles in whole-body energy homeostasis. Recently, it has been reported that the level of plasma adiponectin is reduced in several types of cancer patients. However, it is largely unknown whether and how adiponectin affects colon cancer cell growth. Here, we show that adiponectin suppresses the proliferation of colon cancer cells including HCT116, HT29, and LoVo. In colon cancer cells, adiponectin attenuated cell cycle progression at the G(1)/S boundary and concurrently increased expression of cyclin-dependent kinase inhibitors such as p21 and p27. Adiponectin stimulated AMP-activated protein kinase (AMPK) phosphorylation whereas inhibition of AMPK activity blunted the effect of adiponectin on the proliferation of colon cancer cells. Furthermore, knockdown of adiponectin receptors such as AdipoR1 and AdipoR2 relieved the suppressive effect of adiponectin on the growth of colon cancer cells. In addition, adiponectin repressed the expression of sterol regulatory element binding protein-1c, which is a key lipogenic transcription factor associated with colon cancers. These results suggest that adiponectin could inhibit the growth of colon cancer cells through stimulating AMPK activity.
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PMID:Adiponectin represses colon cancer cell proliferation via AdipoR1- and -R2-mediated AMPK activation. 2044 85

Adenine monophosphate (AMP) activated protein kinase (AMPK) is an important regulator of obesity. The objective of the present work was to study and compare AMPK protein expression in visceral vs. subcutaneous adipose tissue of morbid obese subjects and to correlate it with adipose tissue characteristics. We selected a total population of 17 extreme obese (BMI>or=40 kg/m2) aged 42.8+/-10.2 years were included in this study. We measured anthropometric and body composition parameters. Adiponectin expression by qRT-PCR, isoproterenol-stimulated lipolytic rates, and AMPK alpha subunits expression by Western blot in adipose tissue explants were determined. Finally plasma concentrations of glucose, triacylglycerols, total cholesterol, HDL-c, LDL-c and insulin were also measured. Our results showed that AMPK alpha expression was higher in subcutaneous than in visceral tissue. A positive correlation between AMPK expression and adiponectin expression in human subcutaneous adipose tissue was observed. Furthermore, a positive correlation between AMPK expression and isoproterenol evoked upregulation of lipolysis rate was also observed. In conclusion, AMPK alpha expression differed according to adipose tissue location. The positive correlation between subcutaneous adipose tissue AMPK and adiponectin or the evoked lipolysis rate could indicate a protective role of AMPK in this tissue, counteracting insulin resistance in morbid obese patients.
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PMID:Differences in AMPK expression between subcutaneous and visceral adipose tissue in morbid obesity. 2046 11

Adiponectin is an adipocytokine that was recently shown to be anti-fibrogenic in hepatic fibrosis. Leptin, on the other hand, promotes hepatic fibrosis. The purpose of the present study was to elucidate a mechanism (or mechanisms) whereby adiponectin dampens leptin signaling in activated hepatic stellate cells (HSCs), and prevents excess extracellular matrix production. Activated HSCs, between passages 2 and 5, were cultured and exposed to recombinant human adiponectin and recombinant leptin. Immunoblot analysis for SOCS-3, TIMP-1, and the phosphorylated species of Stat3 and adenosine monophosphate-activated protein kinase (AMPK) were conducted. We also examined MMP-1 activity by immunosorbant fluorimetric analysis. In HSCs, adiponectin-induced phosphorylation of AMPK, and subsequently suppressed leptin-mediated Stat3 phosphorylation and SOCS-3 induction. Adiponectin also blocked leptin-stimulated secretion of TIMP-1, and significantly increased MMP-1 activity, in vitro. To extend this study, we treated adiponectin knockout mice (Ad-/-) daily with 5 mg/kg recombinant leptin and/or carbon tetrachloride (2 ml/kg) for 6 weeks. Post-necropsy analysis was performed to examine for inflammation, and histological changes in the Ad-/- and wild-type mice. There was no significant difference in inflammation, or aminotransferases, between mice receiving carbon tetrachloride and leptin versus carbon tetrachloride alone. As anticipated, the combination of leptin and CCl(4) enhanced hepatic fibrosis in both wild-type and Ad-/- mice, as estimated by amount of collagen in injured livers, but wild-type mice had significantly higher levels of SOCS-3 and significantly lower levels of TIMP-1 mRNA and protein than did adiponectin KO mice exposed to both CCl(4) and leptin. We therefore conclude that the protective effects of adiponectin against liver fibrosis require AMPK activation, and may occur through inhibition of the Jak-Stat signal transduction pathway.
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PMID:Adiponectin activation of AMPK disrupts leptin-mediated hepatic fibrosis via suppressors of cytokine signaling (SOCS-3). 2056 15


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