Abstract 190: Protein Phosphatase 2Ce Is a Novel Phospholamban Phosphatase that Exacerbates Cell Death and Suppresses Cardiac Contractility

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Toru Akaike ◽  
Gang Lu ◽  
Yibin Wang ◽  
Hongmei Ruan
Keyword(s):  
Cell Death ◽  
Protein Kinase ◽  
Protein Phosphatase ◽  
Ventricular Myocytes ◽  
Cardiac Contractility ◽  
Wild Type ◽  
Dependent Protein Kinase ◽  
Calcium Calmodulin Dependent ◽  
Dependent Protein ◽  
Phospholamban Phosphorylation

Regulation of sarcoplasmic reticulum (SR) calcium-ATPase (SERCA) activity is critical for calcium homeostasis in cardiomyocytes, and has a major impact on contractility and cellular viability of cardiomyocytes. The key regulators for SERCA activity include protein kinases, cAMP dependent protein kinase A and calcium/calmodulin dependent protein kinase II, and protein phosphatase 1. In this report, we have discovered that protein phosphatase 2Ce (PP2Ce) is a novel serine/threonine protein phosphatase specifically targeted to SR membrane in cardiomyocytes. PP2Ce was detected to interact with phosphlamban in heart. Recombinant PP2Ce protein showed a potent and specific activity towards the calcium/calmodulin dependent protein kinase II dependent phospholamban phosphorylation at threonin 17 site with no significant activity to cAMP dependent protein kinase A dependent phospholamban phosphorylation at serine 16 site. Expression of PP2Ce blunted β-adrenergic stimulated increase of phospholamban phosphorylation without affecting phosphorylation of ryanodine recepter or troponin I. PP2Ce expression reduced β-adrenergic stimulated intracellular calcium transient in isolated adult rabbit ventricular myocytes, and promoted hydrogen peroxide induced cell death in cultured neonatal rat ventricular myocytes. Transgenic mice with cardiac specific expression of PP2Ce showed no significant basal phenotype. However, in isolated perfusion heart preparation, β-adrenergic stimulated contractility was significant reduced in PP2Ce transgenic hearts comparing to wild type controls. Furthermore, we observed significantly larger infarct sizes and more impaired functional recovery following global ischemia/reperfusion injury in the transgenic hearts comparing to wild type controls. Therefore, PP2Ce is a novel component of SR calcium regulatory network that has a potentially important role in cell death regulation and cardiac contractility.

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 A Purine Analog Kinase Inhibitor, Calcium/Calmodulin-Dependent Protein Kinase II Inhibitor 59, Reveals a Role for Calcium/Calmodulin-Dependent Protein Kinase II in Insulin-Stimulated Glucose Transport

Endocrinology ◽  
2007 ◽  
Vol 148 (1) ◽  
pp. 374-385 ◽  
Author(s):  
Nicky Konstantopoulos ◽  
Seb Marcuccio ◽  
Stella Kyi ◽  
Violet Stoichevska ◽  
Laura A. Castelli ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Kinase Inhibitor ◽  
Glut4 Translocation ◽  
Wild Type ◽  
Dependent Protein Kinase ◽  
Calcium Calmodulin Dependent ◽  
Protein Kinase Ii ◽  
Dependent Protein

Olomoucine is known as a cyclin-dependent kinase inhibitor. We found that olomoucine blocked insulin’s ability to stimulate glucose transport. It did so without affecting the activity of known insulin signaling proteins. To identify the olomoucine-sensitive kinase(s), we prepared analogs that could be immobilized to an affinity resin to isolate binding proteins. One of the generated analogs inhibited insulin-stimulated glucose uptake with increased sensitivity compared with olomoucine. The IC50 for inhibition of insulin-stimulated glucose uptake occurred at analog concentrations as low as 0.1 μm. To identify proteins binding to the analog, [35S]-labeled cell lysates prepared from 3T3-L1 adipocytes were incubated with analog chemically cross-linked to a resin support and binding proteins analyzed by SDS-PAGE. The major binding species was a doublet at 50–60 kDa, which was identified as calcium/calmodulin-dependent protein kinase II (CaMKII) by N-terminal peptide analysis and confirmed by matrix-assisted laser desorption ionization-mass spectrometry as the δ- and β-like isoforms. To investigate CaMKII involvement in insulin-stimulated glucose uptake, 3T3-L1 adipocytes were infected with retrovirus encoding green fluorescent protein (GFP)-hemagluttinin tag (HA)-tagged CaMKII wild-type or the ATP binding mutant, K42M. GFP-HA-CaMKII K42M cells had less kinase activity than cells expressing wild-type GFP-HA-CaMKII. Insulin-stimulated glucose transport was significantly decreased (∼80%) in GFP-HA-CaMKII K42M cells, compared with nontransfected cells, and cells expressing either GFP-HA-CaMKII or GFP-HA. There was not a concomitant decrease in insulin-stimulated GLUT4 translocation in GFP-HA-CaMKII K42M cells when compared with GFP-HA alone. However, insulin-stimulated GLUT4 translocation in GFP-HA-CaMKII cells was significantly higher, compared with either GFP-HA or GFP-HA-CaMKII K42M cells. Our results implicate the involvement of CaMKII in glucose transport in a permissive role.

scholarly journals Ischemia-Induced Neuronal Damage: A Role for Calcium/Calmodulin-Dependent Protein Kinase II

1996 ◽  
Vol 16 (1) ◽  
pp. 1-6 ◽  
Author(s):  
M. Neal Waxham ◽  
James C. Grotta ◽  
Alcino J. Silva ◽  
Roger Strong ◽  
Jaroslaw Aronowski
Keyword(s):  
Protein Kinase ◽  
Neuronal Damage ◽  
Alpha Subunit ◽  
Cam Kinase ◽  
Wild Type ◽  
Dependent Protein Kinase ◽  
Knock Out ◽  
Calcium Calmodulin Dependent ◽  
Protein Kinase Ii ◽  
Dependent Protein

Calcium/calmodulin-dependent protein kinase II (CaM-kinase) is a central enzyme in regulating neuronal processes. Imbalances in the activity and distribution of this enzyme have been reported following in vivo ischemia, and sustained decreases in activity correlate with subsequent neuronal death. In this report, mice that had been rendered deficient in the alpha subunit of CaM-kinase using gene knock-out technology were utilized to determine whether this enzyme is causally related to ischemic damage. Using a focal model of cerebral ischemia, we showed that homozygous knock-out mice lacking the alpha subunit exhibited an infarct volume almost twice that of wild-type litter mates. Heterozygous mice exhibited slightly less damage following ischemia than did homozygous mice, but infarct volumes remained significantly larger than those of wild-type litter mates. We conclude that reduced amounts of the alpha subunit of CaM-kinase predisposes neurons to increased damage following ischemia and that any perturbation that decreases the amount or activity of the enzyme will produce enhanced susceptibility to neuronal damage.

scholarly journals Interaction between Salt-inducible Kinase 2 and Protein Phosphatase 2A Regulates the Activity of Calcium/Calmodulin-dependent Protein Kinase I and Protein Phosphatase Methylesterase-1

2014 ◽  
Vol 289 (30) ◽  
pp. 21108-21119 ◽  
Author(s):  
Chia-Wei Lee ◽  
Fu-Chia Yang ◽  
Hsin-Yun Chang ◽  
Hanyi Chou ◽  
Bertrand Chin-Ming Tan ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Dependent Protein Kinase ◽  
Calcium Calmodulin Dependent ◽  
Phosphatase 2A ◽  
Dependent Protein

scholarly journals A specific inhibitor of calcium/calmodulin-dependent protein kinase-II provides neuroprotection against NMDA- and hypoxia/hypoglycemia-induced cell death

1995 ◽  
Vol 15 (5) ◽  
pp. 4093-4101 ◽  
Author(s):  
I Hajimohammadreza ◽  
AW Probert ◽  
LL Coughenour ◽  
SA Borosky ◽  
FW Marcoux ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Kinase ◽  
Specific Inhibitor ◽  
Dependent Protein Kinase ◽  
Calcium Calmodulin Dependent ◽  
Protein Kinase Ii ◽  
Dependent Protein
Sign in / Sign up

Export Citation Format

Share Document