scholarly journals The AMP-Dependent Protein Kinase (AMPK) Activator A-769662 Causes Arterial Relaxation by Reducing Cytosolic Free Calcium Independently of an Increase in AMPK Phosphorylation

2017 ◽  
Vol 8 ◽  
Author(s):  
Yi Huang ◽  
Corey A. Smith ◽  
Grace Chen ◽  
Bharti Sharma ◽  
Amy S. Miner ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Dependent Protein Kinase ◽  
Ampk Phosphorylation ◽  
Arterial Relaxation ◽  
Dependent Protein

scholarly journals Anti-immunoglobulin M activates nuclear calcium/calmodulin-dependent protein kinase II in human B lymphocytes.

1995 ◽  
Vol 182 (6) ◽  
pp. 1943-1949 ◽  
Author(s):  
M A Valentine ◽  
A J Czernik ◽  
N Rachie ◽  
H Hidaka ◽  
C L Fisher ◽  
...  
Keyword(s):  
Protein Kinase ◽  
B Lymphocytes ◽  
Intracellular Free Calcium ◽  
Free Calcium ◽  
Cam Kinase Ii ◽  
Dependent Manner ◽  
Cam Kinase ◽  
Dependent Protein Kinase ◽  
Calcium Calmodulin Dependent ◽  
Dependent Protein

We and others have previously shown that the nuclear protein, Ets-1, is phosphorylated in a calcium-dependent manner after ligation of immunoglobulin (Ig) M on B lymphocytes. As this phosphorylation was independent of protein kinase C activity, we tested whether a calcium/calmodulin-dependent protein kinase (CaM kinase) might phosphorylate the Ets-1 protein after elevation of intracellular free calcium concentrations. The dephosphorylated form of Ets-1 has been shown to bind to chromatin, suggesting that the operative kinase should be detectable in the nucleus. We prepared nuclear extracts from two human B cell lines in which increased intracellular free calcium levels correlated with increased phosphorylation of the Ets-1 protein. Activity of the CaM kinases was determined using a synthetic peptide substrate both in the absence and presence of an inhibitor specific for the CaM kinase family, KN-62. Stimulation of cells with anti-IgM led to increased activity of a nuclear kinase that could phosphorylate the peptide, and this activity was reduced by 10 microM KN-62. Kinase activity was reduced in lysates preadsorbed using an antibody specific for CaM kinase II. Two-dimensional phosphopeptide maps of the Ets-1 protein from cells incubated with ionomycin or anti-IgM contained two unique phosphopeptides that were absent in untreated cells. Incubation of isolated Ets-1 protein with purified CaM kinase II produced phosphorylation of peptides that migrated identically to those found in cells incubated with either anti-IgM or ionomycin. These data suggest a model of signal transduction by the antigen receptor on B lymphocytes in which increased intracellular free calcium can rapidly activate nuclear CaM kinase II, potentially resulting in phosphorylation and regulation of DNA-binding proteins.

scholarly journals Adiponectin up-regulates the decrease of myocardial autophagic flux induced by β1-adrenergic receptor antibody partly dependent on AMPK

2021 ◽  
Author(s):  
Cong Sun ◽  
Jiebei Lu ◽  
Yaolin Long ◽  
Shuai Guo ◽  
Weiwei Jia ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cardiac Function ◽  
Adrenergic Receptor ◽  
Active Immunization ◽  
Autophagic Flux ◽  
Dependent Protein Kinase ◽  
Compound C ◽  
Ampk Phosphorylation ◽  
Phosphorylation Level ◽  
Dependent Protein

Abstract BackgroundCardiomyocyte autophagy is essential for maintaining cardiac function. Our previous studies have found that β1-adrenergic receptor autoantibody (β1-AA) induced the decreased myocardial autophagic flux, which resulted in cardiomyocytes death and cardiac dysfunction. And other studies demonstrated that β1-AA induced the decrease of AMPK phosphorylation, the key hub of autophagy pathway, while adiponectin up-regulated autophagic flux mediated by AMPK. However, it is not clear whether adiponectin improves the inhibition of myocardial autophagic flux induced by β1-AA by up-regulating the level of AMPK phosphorylation.MethodAPN-KO and WT mice were subcutaneously injected withthe peptide of the second extracellular loop of β1-adrenergic receptor (β1-AR-ECII) as antigen to establish β1-AA active immunization model. The OD value of β1-AA in serum of mice was detected by SA-ELISA to ensure the successful construction of active immunization model. The changes of cardiac function and myocardial fibrosis were detected by small animal ultrasound and Masson trichrome staining. The cardiomyocytes viability was assessed using a Cell Counting Kit-8. The mRNA levels of LC3B and Beclin1 in cardiomyocytes were measured by Real-time PCR. The protein levels of LC3 II, p62, AMP dependent protein kinase (AMP) - activated protein kinase (AMPK) and phosphorylated AMP dependent protein kinase (p-AMPK) in cardiomyocytes were detected by Western blotting.ResultsIn this study, it has been confirmed that β1-AA induced the decrease of AMPK phosphorylation level in both vivo and vitro. Moreover, pretreatment of cardiomyocytes with AMPK inhibitor Compound C could further reduce the autophagic flux induced by β1-AA. Adiponectin deficiency could aggravate the decrease of myocardial AMPK phosphorylation level, autophagic flux and cardiac function induced by β1-AA. Further, exogenous adiponectin could reverse the decline of AMPK phosphorylation level and autophagic flux induced by β1-AA, and even reduce cardiomyocytes death. While pre-treated with the Compound C, the adiponectin treatment did not improve the decreased autophagosome formation, but still improved the decreased autophagosome clearance induced by β1-AA in cardiomyocytes, suggesting that adiponectin up-regulated β1-AA-induced decreased autophagic flux of cardiomyocytes partly depended on the AMPK.ConclusionThis study is the first time to confirm that β1-AA could inhibit myocardial autophagic flux by down regulating AMPK phosphorylation level. Adiponectin could improve the inhibition of myocardial autophagic flux induced by β1-AA partly dependent on AMPK, so as to provide an experimental basis for the treatment of patients with β1-AA-positive cardiac dysfunction.

Characterization of a calcium/calmodulin-dependent protein phosphatase in the Limulus nervous tissue and its light regulation in the lateral eye

1994 ◽  
Vol 11 (5) ◽  
pp. 851-860 ◽  
Author(s):  
D. Z. Ellis ◽  
S. C. Edwards
Keyword(s):  
Protein Kinase ◽  
Protein Phosphatase ◽  
Regulatory Subunit ◽  
Free Calcium ◽  
Dependent Protein Kinase ◽  
Calmodulin Antagonist ◽  
Calcium Calmodulin Dependent ◽  
Lateral Eye ◽  
Dependent Protein

AbstractCalcium (Ca2+) plays an integral role in the light response of the photoreceptors in both vertebrate and invertebrate organisms. In the ventral eye of the horseshoe crab, Limulus polyphemus, a flash of light delivered to a dark-adapted photoreceptor stimulates a rapid rise in intracellular free calcium concentration ([Ca2+]i), which in turn mediates light adaptation. It has previously been demonstrated that in Limulus photoreceptors light, via Ca2+, activate s a calcium/calmodulin (Ca2+/CaM)-dependent protein kinase which increases the phosphorylation of arrestin. We now have identifie d biochemically, a calcium/calmodulin-dependent protein phosphatase (Ca2+/CaM PP ) in homogenates of the Limulus lateral and ventral eye, brain, and lateral optic nerve using as a substrate, a 32P-labeled peptide fragment of the regulatory subunit of cAMP-dependent protein kinase (RII). This protein phosphatase shares biochemical properties with calcineurin, a Ca2+/CaM-dependent protein phosphatase (type-2B). Its activity is enhanced by Ca2+, calmodulin and Mn2+; and is inhibited by mastoparan, a calmodulin antagonist, and a synthetic peptide corresponding to the autoinhibitory domain of mammalian calcineurin. Most importantly, light regulates the Ca2+/CaM PP activity in the lateral eye. While there is no difference in basal activity in long-term dark- or light-adapted preparations, Ca2+ enhances Ca2+/CaM PP activity only in long-term light-adapted eyes.

scholarly journals Calmodulin-dependent protein kinase kinase-β activates AMPK without forming a stable complex: synergistic effects of Ca2+ and AMP

2010 ◽  
Vol 426 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Sarah Fogarty ◽  
Simon A. Hawley ◽  
Kevin A. Green ◽  
Nazan Saner ◽  
Kirsty J. Mustard ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Synergistic Effects ◽  
Stable Complex ◽  
Dependent Protein Kinase ◽  
Intact Cells ◽  
Ampk Phosphorylation ◽  
Upstream Kinase ◽  
Dependent Protein ◽  
Amp Activated Protein Kinase ◽  
Protein Kinase Kinase

Activation of AMPK (AMP-activated protein kinase) by phosphorylation at Thr172 is catalysed by at least two distinct upstream kinases, i.e. the tumour suppressor LKB1, and CaMKKβ (Ca2+/calmodulin-dependent protein kinase kinase-β). The sequence around Thr172 is highly conserved between the two catalytic subunit isoforms of AMPK and the 12 AMPK-related kinases, and LKB1 has been shown to act upstream of all of them. In the present paper we report that none of the AMPK-related kinases tested could be phosphorylated or activated in intact cells or cell-free assays by CaMKKβ, although we did observe a slow phosphorylation and activation of BRSK1 (brain-specific kinase 1) by CaMKKα. Despite recent reports, we could not find any evidence that the α and/or β subunits of AMPK formed a stable complex with CaMKKβ. We also showed that increasing AMP concentrations in HeLa cells (which lack LKB1) had no effect on basal AMPK phosphorylation, but enhanced the ability of agents that increase intracellular Ca2+ to activate AMPK. This is consistent with the effect of AMP on phosphorylation of Thr172 being due to inhibition of dephosphorylation, and confirms that the effect of AMP is independent of the upstream kinase utilized.

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