The AMPK γ1 R70Q mutant regulates multiple metabolic and growth pathways in neonatal cardiac myocytes

2007 ◽  
Vol 293 (6) ◽  
pp. H3456-H3464 ◽  
Author(s):  
Karalyn D. Folmes ◽  
Lee A. Witters ◽  
Michael F. Allard ◽  
Martin E. Young ◽  
Jason R. B. Dyck
Keyword(s):  
Cardiac Hypertrophy ◽  
Cardiac Myocytes ◽  
Glycogen Synthase ◽  
Neonatal Rat ◽  
Mrna Levels ◽  
Glycogen Accumulation ◽  
Regulatory Pathways ◽  
Γ Subunit ◽  
Gsk 3Β ◽  
Glycogen Synthase Activity

Although mutations in the γ-subunit of AMP-activated protein kinase (AMPK) can result in excessive glycogen accumulation and cardiac hypertrophy, the mechanisms by which this occurs have not been well defined. Because >65% of cardiac AMPK activity is associated with the γ1-subunit of AMPK, we investigated the effects of expression of an AMPK-activating γ1-subunit mutant (γ1 R70Q) on regulatory pathways controlling glycogen accumulation and cardiac hypertrophy in neonatal rat cardiac myocytes. Whereas expression of γ1 R70Q displayed the expected increase in palmitate oxidation rates, rates of glycolysis were significantly depressed. In addition, glycogen synthase activity was increased in cardiac myocytes expressing γ1 R70Q, due to both increased expression and decreased phosphorylation of glycogen synthase. The inhibition of glycolysis and increased glycogen synthase activity were correlated with elevated glycogen levels in γ1 R70Q-expressing myocytes. In association with the reduced phosphorylation of glycogen synthase, glycogen synthase kinase (GSK)-3β protein and mRNA levels were profoundly decreased in the γ1 R70Q-expressing myocytes. Consistent with GSK-3β negatively regulating hypertrophy via inhibition of nuclear factor of activated T cells (NFAT), the dramatic downregulation of GSK-3β was associated with increased nuclear activity of NFAT. Together, these data provide important new information about the mechanisms by which a mutation in the γ-subunit of AMPK causes altered AMPK signaling and identify multiple pathways involved in regulating both cardiac myocyte metabolism and growth that may contribute to the development of the γ mutant-associated cardiomyopathy.

scholarly journals Qiliqiangxin Attenuates Phenylephrine-Induced Cardiac Hypertrophy through Downregulation of MiR-199a-5p

2016 ◽  
Vol 38 (5) ◽  
pp. 1743-1751 ◽  
Author(s):  
Haifeng Zhang ◽  
Shanshan Li ◽  
Qiulian Zhou ◽  
Qi Sun ◽  
Shutong Shen ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cardiac Hypertrophy ◽  
Natriuretic Peptide ◽  
Neonatal Rat ◽  
Immunofluorescent Staining ◽  
Mouse Heart ◽  
Mrna Levels ◽  
Elevated Protein ◽  
Ischemic Stress

Background/Aims: Qiliqiangxin (QL), a traditional Chinese medicine, has long been used to treat chronic heart failure. Previous studies demonstrated that QL could prevent cardiac remodeling and hypertrophy in response to hypertensive or ischemic stress. However, little is known about whether QL could modulate cardiac hypertrophy in vitro, and (if so) whether it is through modulation of specific hypertrophy-related microRNA. Methods: The primary neonatal rat ventricular cardiomyocytes were isolated, cultured, and treated with phenylephrine (PE, 50 µmol/L, 48 h) to induce hypertrophy in vitro, in the presence or absence of pretreatment with QL (0.5 µg/ml, 48 h). The cell surface area was determined by immunofluorescent staining for α-actinin. The mRNA levels of hypertrophic markers including atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and β-myosin heavy chain (MYH7) were assayed by qRT-PCRs. The protein synthesis of cardiomyocytes was determined by the protein/DNA ratio. The miR-199a-5p expression level was quantified in PE-treated cardiomyocytes and heart samples from acute myocardial infarction (AMI) mouse model. MiR-199a-5p overexpression was used to determine its role in the anti-hypertrophic effect of QL on cardiomyocytes. Results: PE induced obvious enlargement of cell surface in cardiomyocytes, paralleling with increased ANP, BNP, and MYH7 mRNA levels and elevated protein/DNA ratio. All these changes were reversed by the treatment with QL. Meanwhile, miR-199a-5p was increased in AMI mouse heart tissues. Of note, the increase of miR-199a-5p in PE-treated cardiomyocytes was reversed by the treatment with QL. Moreover, overexpression of miR-199a-5p abolished the anti-hypertrophic effect of QL on cardiomyocytes. Conclusion: QL prevents PE-induced cardiac hypertrophy. MiR-199a-5p is increased in cardiac hypertrophy, while reduced by treatment with QL. miR-199a-5p suppression is essential for the anti-hypertrophic effect of QL on cardiomyocytes.

Abstract 2423: B-type Natriuretic Peptide Upregulates Erythropoietin Receptor Gene Expression via Protein Kinase G in Heart Failure

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Yoshiaki Ohyama ◽  
Toru Tanaka ◽  
Takehisa Shimizu ◽  
Hiroshi Doi ◽  
Norimichi Koitabashi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heart Failure ◽  
Protein Kinase ◽  
Cardiac Myocytes ◽  
Natriuretic Peptide ◽  
Neonatal Rat ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Failing Heart ◽  
Epor Expression

Backgroud: Recent studies demonstrated non-hematopoietical effects of Erythropoietin (Epo) and its receptor (EpoR) in a variety of tissues including cardiovascular system. Epo treatment improves cardiac function in patients with heart failure and reduces infarct size after ischemia/reperfusion injury in the heart. However, little attention has been paid for the endogenous regulatory mechanisms regulating EpoR expression. In this study, we hypothesize that B-type natriuretic peptide upregulates EpoR gene expression in failing heart. Methods and Results: Wister rats underwent transverse aortic constriction surgery to induce hypertrophy. RT-PCR analyses of those rats showed that EpoR mRNA levels were increased in the left ventricle and positively correlated with the levels of BNP mRNA (n=10, r=0.67, p<0.05). Next we examined the expression of EpoR in human failing heart by using autopsy specimens and found that EpoR mRNA levels were significantly elevated in patients with dilated cardiomyopathy compared with those in normal heart. Immunohistochemistry of endomyocardial biopsy specimens of failing heart (n=54) showed that EpoR mRNA levels were correlated with severity of cardiac dysfunction estimated by diameter of cardiac chambers, pathomorphology, serum BNP concentration and functional class of New York Heart Association. Interestingly, stimulation of cultured neonatal rat cardiac myocytes with BNP, but not with hypertrophic reagents including endothelin I, angiotensin II and norepinephrine, significantly increased the EpoR mRNA levels in a time-dependent manner. Overexpression of cGMP-dependent protein kinase (PKG) increased EpoR transcript in cultured cardiac myocytes. BNP-induced EpoR expression was abrogated in the presence of KT5823, a specific inhibitor for PKG. Conclusion: These results suggest a role for BNP in mediating an induction of EpoR expression in failing myocardium and indicate that the cardiac EpoR gene is a target of cGMP/PKG signaling.

Glucose transport rate and glycogen synthase activity both limit skeletal muscle glycogen accumulation

2002 ◽  
Vol 282 (6) ◽  
pp. E1214-E1221 ◽  
Author(s):  
Jonathan S. Fisher ◽  
Lorraine A. Nolte ◽  
Kentaro Kawanaka ◽  
Dong-Ho Han ◽  
Terry E. Jones ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Muscle Glycogen ◽  
Glycogen Synthase ◽  
Transport Rate ◽  
Prolonged Incubation ◽  
Glycogen Accumulation ◽  
Gf 109203X ◽  
Rate Limiting ◽  
Glycogen Synthase Activity

We varied rates of glucose transport and glycogen synthase I (GS-I) activity (%GS-I) in isolated rat epitrochlearis muscle to examine the role of each process in determining the rate of glycogen accumulation. %GS-I was maintained at or above the fasting basal range during 3 h of incubation with 36 mM glucose and 60 μU/ml insulin. Lithium (2 mM LiCl) added to insulin increased glucose transport rate and muscle glycogen content compared with insulin alone. The glycogen synthase kinase-3β inhibitor GF-109203x (GF; 10 μM) maintained %GS-I about twofold higher than insulin with or without lithium but did not increase glycogen accumulation. When %GS-I was lowered below the fasting range by prolonged incubation with 36 mM glucose and 2 mU/ml insulin, raising rates of glucose transport with bpV(phen) or of %GS-I with GF produced additive increases in glycogen concentration. Phosphorylase activity was unaffected by GF or bpV(phen). In muscles of fed animals, %GS-I was ∼30% lower than in those of fasted rats, and insulin-stimulated glycogen accumulation did not occur unless %GS-I was raised with GF. We conclude that the rate of glucose transport is rate limiting for glycogen accumulation unless %GS-I is below the fasting range, in which case both glucose transport rate and GS activity can limit glycogen accumulation.

scholarly journals Altered Wnt signalling in the teenage suicide brain: focus on glycogen synthase kinase-3β and β-catenin

2013 ◽  
Vol 16 (5) ◽  
pp. 945-955 ◽  
Author(s):  
Xinguo Ren ◽  
Hooriyah S. Rizavi ◽  
Mansoor A. Khan ◽  
Yogesh Dwivedi ◽  
Ghanshyam N. Pandey
Keyword(s):  
Protein Expression ◽  
Glycogen Synthase ◽  
Wnt Signalling ◽  
Signalling Pathway ◽  
Glycogen Synthase Kinase ◽  
Mrna Levels ◽  
Protein Levels ◽  
Wnt Signalling Pathway ◽  
Gsk 3Β ◽  
Teenage Suicide

Abstract Glycogen synthase kinase (GSK)-3β and β-catenin are important components of the Wnt signalling pathway, which is involved in numerous physiological functions such as cognition, brain development and cell survival. Their abnormalities have been implicated in mood disorders and schizophrenia. Teenage suicide is a major public health concern; however, very little is known about its neurobiology. In order to examine if abnormalities of GSK-3β and β-catenin are associated with teenage suicide, we determined the gene and protein expression of GSK-3β and β-catenin in the prefrontal cortex (PFC) and hippocampus obtained from 24 teenage suicide victims and 24 normal control subjects. Protein expression was determined using Western blot with specific antibodies and gene expression (mRNA levels) was determined using the real-time polymerase chain reaction method. No significant change was observed in the GSK-3β protein levels either in the PFC or hippocampus of suicide victims compared to controls. However, protein levels of pGSK-3β-ser9 were significantly decreased in the PFC and hippocampus of suicide victims compared to normal controls. We also found that GSK-3β mRNA levels were significantly decreased in the PFC but not in the hippocampus of teenage suicide victims compared to controls. Mean protein and mRNA levels of β-catenin were significantly decreased in both the PFC and hippocampus of teenage suicide group compared to controls. The observation that there is a decrease in β-catenin and pGSK-3β-ser9 in the PFC and hippocampus of teenage suicide victims does indicate a disturbance in the Wnt signalling pathway in teenage suicide.

[PS 01-18] MECHANISM OF HYPERTENSIVE CARDIAC HYPERTROPHY IN CULTURED NEONATAL RAT VENTRICULAR CARDIAC MYOCYTES

2016 ◽  
Vol 34 (Supplement 1) ◽  
pp. e101
Author(s):  
Gang Sun ◽  
Hui Yu ◽  
Zhanli Wang ◽  
Xiaomin Yang ◽  
Jianwei Yue ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Cardiac Myocytes ◽  
Neonatal Rat

Negative regulation of the rat Na-K-ATPase alpha 3-subunit gene promoter by thyroid hormone

1996 ◽  
Vol 271 (5) ◽  
pp. C1750-C1756 ◽  
Author(s):  
H. He ◽  
S. Chin ◽  
K. Zhuang ◽  
R. Hartong ◽  
J. Apriletti ◽  
...  
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone ◽  
Cardiac Myocytes ◽  
Reporter Gene ◽  
Reporter Gene Expression ◽  
Neonatal Rat ◽  
Proximal Promoter ◽  
Mrna Levels ◽  
Neonatal Rat Cardiac Myocytes ◽  
Rat Cardiac Myocytes

Na-K-ATPase alpha 3-subunit mRNA levels are both positively and negatively controlled by thyroid hormone [3,5,3'triiodothyronine (T3)] in primary cultures of neonatal rat cardiac myocytes. In this study, transient transfection analysis indicated that two regions of the rat alpha 3 gene between nucleotides -116 and -6 and -6 and +80 conferred T3-mediated inhibition of reporter gene expression. Electrophoretic mobility shift assays showed specific binding of T3 receptor monomers and T3 receptor-retinoid X receptor heterodimers at each alpha 3 gene negative T3-response region. The alpha 3 gene region from -116 to -6 base pairs also mediates repression in response to retinoic acid (RA) and binds RA receptor. In the absence of ligand, reporter gene expression driven by the -116 to -6-base pair region is repressed with cotransfection of T3 receptor, whereas it is unaffected by overexpression of RA receptor. These data demonstrate that the proximal promoter of the rat Na-K-ATPase alpha 3 gene contains sequence motifs that mediate repression of alpha 3 gene transcription in response to either T3 or RA in neonatal rat cardiac myocytes.

Glycogen content and contraction regulate glycogen synthase phosphorylation and affinity for UDP-glucose in rat skeletal muscles

2007 ◽  
Vol 293 (6) ◽  
pp. E1622-E1629 ◽  
Author(s):  
Yu-Chiang Lai ◽  
Jorid Thrane Stuenæs ◽  
Chia-Hua Kuo ◽  
Jørgen Jensen
Keyword(s):  
Skeletal Muscles ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Dry Weight ◽  
Kinetic Properties ◽  
Glycogen Accumulation ◽  
Specific Antibodies ◽  
Phosphorylation Pattern ◽  
Gsk 3Β

Glycogen content and contraction strongly regulate glycogen synthase (GS) activity, and the aim of the present study was to explore their effects and interaction on GS phosphorylation and kinetic properties. Glycogen content in rat epitrochlearis muscles was manipulated in vivo. After manipulation, incubated muscles with normal glycogen [NG; 210.9 ± 7.1 mmol/kg dry weight (dw)], low glycogen (LG; 108.1 ± 4.5 mmol/ kg dw), and high glycogen (HG; 482.7 ± 42.1 mmol/kg dw) were contracted or rested before the studies of GS kinetic properties and GS phosphorylation (using phospho-specific antibodies). LG decreased and HG increased GS Km for UDP-glucose (LG: 0.27 ± 0.02 < NG: 0.71 ± 0.06 < HG: 1.11 ± 0.12 mM; P < 0.001). In addition, GS fractional activity inversely correlated with glycogen content ( R = −0.70; P < 0.001; n = 44). Contraction decreased Km for UDP-glucose (LG: 0.14 ± 0.01 = NG: 0.16 ± 0.01 < HG: 0.33 ± 0.03 mM; P < 0.001) and increased GS fractional activity, and these effects were observed independently of glycogen content. In rested muscles, GS Ser641 and Ser7 phosphorylation was decreased in LG and increased in HG compared with NG. GSK-3β Ser9 and AMPKα Thr172 phosphorylation was not modulated by glycogen content in rested muscles. Contraction decreased phosphorylation of GS Ser641 at all glycogen contents. However, contraction increased GS Ser7 phosphorylation even though GS was strongly activated. In conclusion, glycogen content regulates GS affinity for UDP-glucose and low affinity for UDP-glucose in muscles with high glycogen content may reduce glycogen accumulation. Contraction increases GS affinity for UDP-glucose independently of glycogen content and creates a unique phosphorylation pattern.

Abstract P198: Aberrant Activation of γ2-AMPK Causes Cardiac Hypertrophy Independent of Glycogen Storage

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Maengjo Kim ◽  
Roger Hunter ◽  
Kei Sakamoto ◽  
Christine E Seidman ◽  
Jonathan G Seidman ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Double Mutant ◽  
Glycogen Synthase ◽  
Mammalian Target Of Rapamycin ◽  
Point Mutations ◽  
Glycogen Storage ◽  
Energy Deficit ◽  
Heart Weight ◽  
Glycogen Accumulation ◽  
Mtor Activity

AMP-activated protein kinase (AMPK) is an energy sensor and a key regulator of cell metabolism, hence a promising drug target. The cardiac functions of AMPK have not been understood. Point mutations in the regulatory γ2-subunit (encoded by PRKAG2 gene) have been shown to cause a unique form of cardiomyopathy in humans characterized by cardiac hypertrophy, arrhythmias and glycogen storage. We have previously shown that PRKAG2 mutation caused aberrant activation of AMPK in the absence of energy deficit and subsequently triggered re-routing of excessive glucose into glycogen pool. In this study, we addressed two questions: 1) whether cardiac hypertrophy in PRKAG2 cardiomyopathy was secondary of glycogen storage; 2) which hypertrophic signaling pathways are involved. We sought to reduce glycogen storage in transgenic mice expressing a mutant PRKAG2 (N488I) in the heart (TGγ2 N488I ) by crossing them to knock-in mice harboring a mutation in the muscle form of glycogen synthase (GYS1 KI ) that greatly reduced GYS activity in response to glucose-6-phosphate. Compared to TGγ2 N488I , TGγ2 N488I -GYS1-KI (double mutant) hearts showed lower GYS activity (0.7 ± 0.07 vs. 6.9 ± 0.49 nmol/min/mg, p<0.0001) and reduced glycogen content (35 ± 4.5 vs. 169 ± 40 umol/g, p<0.0001). Nonetheless, cardiac hypertrophy remained in the double mutant. The heart weight to body weight ratios were 6.8 ± 0.7 mg/g for TGγ2 N488I , 6.7 ± 0.5 mg/g for the double mutant compared to 4.0 ± 0.2 mg/g in the wild type. Furthermore, we have observed significant changes in FOXO (forkhead-O transcription factor) and mTOR (mammalian target of rapamycin) pathways in the TGγ2 N488I hearts. Increased phosphorylation of FOXO3a (Ser321, Ser253) and FoxO1a (Ser256) led to nuclear exclusion and degradation of FOXO proteins. Increased mTOR activity was evidenced by enhanced phosphorylation of Ser2448 as well as its downstream targets S6 and 4E-BP. Taken together these data indicate that aberrant γ2-AMPK activation causes cardiac hypertrophy independent of excessive glycogen accumulation. We found that increased mTOR activity and decreased FOXO signaling contributes to cardiac hypertrophy in TGγ2 N488I mice, suggesting novel mechanisms underlying cardiac hypertrophy caused by abnormal γ2-AMPK activity.

Abstract 283: The Coupling of Tumor Endothelial Marker-8 and Capillary Morphogenesis Gene-2 Receptors to Contractile-Related Signaling Pathway in Cardiac Myocytes

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Damir Nizamutdinov ◽  
Honey B Golden ◽  
Hao Feng ◽  
Fnu Gerilechaogetu ◽  
Donald M Foster ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
Anthrax Toxin ◽  
Neonatal Rat ◽  
Regulatory Pathways ◽  
Capillary Morphogenesis ◽  
Downstream Signaling ◽  
Signaling Mechanisms ◽  
Toxin Receptor ◽  
Tumor Endothelial Marker 8 ◽  
Endothelial Marker

Recent molecular and pharmacological studies performed on non-cardiac tissues suggest that tumor endothelial marker-8 (TEM-8), also known as anthrax toxin receptor 1 (ANTXR1) and capillary morphogenesis gene-2 (CMG-2), known as anthrax toxin receptor 2 (ANTXR2) regulate survival, proliferation, cell shape, as well as polarity, adhesion, migration and differentiation. However, downstream signaling mechanisms and function of these molecules have not been studied. Recent studies indicate that activation of protein kinase B (Akt) and c-Jun N-terminal kinases (JNK) have been associated with hypertrophic growth, as well as regulation of contractility in cardiac myocytes (CM). In this study we’ve investigated the role of ANTXR1 and ANTXR2 receptors in intracellular pathways of contractility regulation in neonatal rat ventricular myocytes (NRVM). Primary culture of NRVM was used to determine the effects of ANTXR1/ANTXR2 activation on Akt and JNK phosphorylation by Western blot analysis. Flow cytometry and immunostaining of alive CM were used to determine expression levels and distribution of anthrax receptors throughout the cells. Furin-activated form of anthrax protective antigen (PA 63 ) was used in order to selectively stimulate ANTXR1/ANTXR2 receptors and get understanding of downstream signaling mechanisms coupled to them. The treatments with angiotensin II, type1 receptor (AT 1 ) inhibitors were used in order to separate responses of distinct regulatory pathways of contractility. All treatments were done at variable time courses started in seconds and finished in half of hour to determine a sequence of phosphorylation reactions going from cellular membrane to deep inside of cell. As a result, abundant expression of both receptors was observed in cardiac myocytes. Activation of one phospho-site of focal adhesion kinase (FAK 861 ) was started in 15 sec with subsequent phosphorylation of JNK and Akt 473 in 5 and 10 minutes. Involvement of new molecules was observed in cascade chain reaction of contractility regulation. In conclusion, ANTXR1/ANTXR2 were demonstrated to couple to mechano-sensor molecules: FAK, Akt and JNK, as well as interact with the AT 1 receptors to mediate downstream signaling events responsible for regulation of contractility.

scholarly journals Pioglitazone Protected against Cardiac Hypertrophy via Inhibiting AKT/GSK3βand MAPK Signaling Pathways

PPAR Research ◽  
2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Wen-Ying Wei ◽  
Zhen-Guo Ma ◽  
Si-Chi Xu ◽  
Ning Zhang ◽  
Qi-Zhu Tang
Keyword(s):  
Protein Kinase ◽  
Cardiac Hypertrophy ◽  
Glycogen Synthase ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Neonatal Rat ◽  
Aortic Banding ◽  
Hypertrophic Response

Peroxisome proliferator activated receptorγ(PPARγ) has been closely involved in the process of cardiovascular diseases. This study was to investigate whether pioglitazone (PIO), a PPARγagonist, could protect against pressure overload-induced cardiac hypertrophy. Mice were orally given PIO (2.5 mg/kg) from 1 week after aortic banding and continuing for 7 weeks. The morphological examination and biochemical analysis were used to evaluate the effects of PIO. Neonatal rat ventricular cardiomyocytes were also used to verify the protection of PIO against hypertrophy in vitro. The results in our study demonstrated that PIO remarkably inhibited hypertrophic response induced by aortic banding in vivo. Besides, PIO also suppressed cardiac fibrosis in vivo. PIO treatment also inhibited the activation of protein kinase B (AKT)/glycogen synthase kinase-3β(GSK3β) and mitogen-activated protein kinase (MAPK) in the heart. In addition, PIO alleviated angiotensin II-induced hypertrophic response in vitro. In conclusion, PIO could inhibit cardiac hypertrophy via attenuation of AKT/GSK3βand MAPK pathways.

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