Involvement of calmodulin-dependent protein kinase II in carbachol-induced rhythmic activity in the hippocampus of the rat

The role of calcium and protein kinases in rhythmic activity induced by muscarinic receptor activation in the CA1 area in rat hippocampal slices was investigated. Extracellular recording showed that carbachol (20 microM) induced synchronized field potential activity with a dominant frequency of 7.39+/-0.68 Hz. Pretreatment with the membrane permeable Ca(2+) chelator BAPTA-AM (50 microM) or with thapsigargin (1 microM), a compound which depletes intracellular calcium stores, reduced the dominant power of carbachol-induced theta-like activity by 83% and 78%, respectively. Inhibition of calmodulin-dependent protein kinase II (CaMKII) by the cell permeable inhibitor KN-93 (10 microM) reduced the power of carbachol-induced theta-like activity by 80%. In contrast the protein kinase C (PKC) inhibitor calphostin C did not significantly (P>0.05) affect the effect of carbachol. Whole-cell recording indicated that KN-93 also blocked carbachol-induced suppression of slow I(AHP) and strongly inhibited the carbachol-induced plateau potential. Our data suggest that activation of CaMKII by carbachol is crucial for local theta-like activity in the CA1 area of the rat hippocampus in vitro. Furthermore, involvement of CaMKII in carbachol-induced suppression of the slow I(AHP) and the induction of plateau potentials could play a role in the induction of theta-like rhythmic activity by carbachol.     

Puerarin activates endothelial nitric oxide synthase through estrogen receptor-dependent PI3-kinase and calcium-dependent AMP-activated protein kinase

The cardioprotective properties of puerarin, a natural product, have been attributed to the endothelial nitric oxide synthase (eNOS)-mediated production of nitric oxide (NO) in EA.hy926 endothelial cells. However, the mechanism by which puerarin activates eNOS remains unclear. In this study, we sought to identify the intracellular pathways underlying eNOS activation by puerarin. Puerarin induced the activating phosphorylation of eNOS on Ser1177 and the production of NO in EA.hy926 cells. Puerarin-induced eNOS phosphorylation required estrogen receptor (ER)-mediated phosphatidylinositol 3-kinase (PI3K)/Akt signaling and was reversed by AMP-activated protein kinase (AMPK) and calcium/calmodulin-dependent kinase II (CaMKII) inhibition. Importantly, puerarin inhibited the adhesion of tumor necrosis factor (TNF)-α-stimulated monocytes to endothelial cells and suppressed the TNF-α induced expression of intercellular cell adhesion molecule-1. Puerarin also inhibited the TNF-α-induced nuclear factor-κB activation, which was attenuated by pretreatment with N^G-nitro-l-arginine methyl ester, a NOS inhibitor. These results indicate that puerarin stimulates eNOS phosphorylation and NO production via activation of an estrogen receptor-mediated PI3K/Akt- and CaMKII/AMPK-dependent pathway. Puerarin may be useful for the treatment or prevention of endothelial dysfunction associated with diabetes and cardiovascular disease.     

Postnatal maternal deprivation and pubertal stress have additive effects on dopamine D2 receptor and CaMKII beta expression in the striatum

The goal of this study was to determine whether two stressors commonly used to model aspects of neuropsychiatric disease in rats have an additive effect on striatal dopamine type 2 receptor (D2R) expression, a key player in the etiology of neuropsychiatric disease.     

Frequency-dependent acceleration of relaxation in the heart depends on CaMKII,but not phospholamban

Frequency-dependent acceleration of relaxation (FDAR) is an intrinsic physiological mechanism, which allows more rapid ventricular diastolic filling at higher heart rates. FDAR is also observed in isolated myocardial trabeculae and cardiac myocytes, but its mechanism is still poorly understood. We tested the hypothesis that FDAR results mainly from Ca/calmodulin-dependent protein kinase II (CaMKII) dependent stimulation of sarcoplasmic reticulum (SR) Ca transport, but does not require phospholamban. Experiments were performed at 23 or 35 degrees C in isolated ventricular muscle and single myocytes from wild-type (WT) and phospholamban knockout (PLB-KO) mice and rat ventricular myocytes. Isometric twitch force of muscles and unloaded shortening and Ca transients in myocytes were measured ([Ca](o)=1mM) in the absence and presence of CaMKII inhibitors (1 microM KN-93 or 20 microM autocamtide-2 related inhibitory peptide, AIP). Stimulation frequency was altered over a wide range (0.2-8Hz) and post-rest vs steady state twitches were also compared. In both WT and PLB-KO mouse muscles FDAR of twitch force was prominent, but was largely suppressed by KN-93. FDAR of twitch contractions was associated with FDAR of Ca transients in PLB-KO myocytes, and both were inhibited by KN-93. Similarly, a different CaMKII inhibitor (AIP) inhibited FDAR of contraction and Ca transients in rat ventricular myocytes. We conclude that FDAR results mainly from CaMKII-dependent stimulation of SR Ca transport, but does not require phospholamban.     

远志对锰中毒小鼠海马区CaMKⅡ表达的影响

目的:探讨远志对锰中毒小鼠学习记忆和海马CaMKII表达的影响。方法:将60只雌性昆明小鼠随机分为对照组(CG),锰中毒组(MG),锰中毒加远志低剂量组(MLG),锰中毒加远志中剂量组(MMG),锰中毒加远志高剂量组(MHG)。氯化锰(15 mg/kg)采用腹腔注射方式,远志干预(2.5,5,10 g/kg)采用灌胃给药。实验后,动物用Morris水迷宫检测其空间学习和记忆成绩。用免疫组织化学的方法检测海马齿状回区(DG)Ca MKII的表达。结果:在水迷宫的定位航行实验中,各组小鼠的逃避潜伏期与锰中毒组相比,对照组平均逃避潜伏期明显降低(P0.01),远志干预低、中、高剂量组平均逃避潜伏期明显降低(P0.01);在空间探索实验中,与锰中毒组相比,对照组穿越平台次数明显增高(P0.01),远志干预低、中、高剂量组穿越平台次数明显增加(P0.01)。免疫组织化学分析,与对照组相比,锰中毒组DG区Ca MKII表达明显下降,(P0.01),而远志干预低、中、高剂量组海马内CaMKII表达比锰中毒组明显增高(P0.01)。结论:锰中毒小鼠海马齿状回Ca MKII的表达下降,药物远志能够改善锰中毒小鼠学习记忆能力的机制可能与CaMKII的表达增加有关。     

CaMKIIδ and cardiomyocyte Ca2+ signalling new perspectives on splice variant targeting

Control of cardiomyocyte cytosolic Ca²⁺ levels is crucial in determining inotropic status and ischemia/reperfusion stress response. Responsive to fluctuations in cellular Ca²⁺, Ca²⁺/calmodulin‐dependent protein kinase II (CaMKII) is a serine/threonine kinase integral to the processes regulating cardiomyocyte Ca²⁺ channels/transporters. CaMKII is primarily expressed either in the δ_B or δ_C splice variant forms, which may mediate differential influences on cardiomyocyte function and pathological response mechanisms. Increases in myocyte Ca²⁺ levels promote the binding of a Ca²⁺/calmodulin complex to CaMKII, to activate the kinase. Activity is also maintained through a series of post‐translational modifications within a critical region of the regulatory domain of the protein. Recent data indicate that the post‐translational modification status of CaMKIIδ_B/δ_C variants may have an important influence on reperfusion outcomes. This study provided the first evidence that the specific type of CaMKII post‐translational modification has a role in determining target selectivity of downstream Ca²⁺ transporters. The study was also able to demonstrate that the phosphorylated form of CaMKII closely co‐localizes with CaMKIIδ_B in the nuclear/myofilament fraction, contrasting with a co‐enrichment of oxidized CaMKII in the membrane fraction with CaMKIIδ_C. It has also been possible to conclude that a hyper‐phosphorylation of CaMKII (Thr287) in reperfused hearts represents a hyper‐activation of the CaMKIIδ_B, which exerts anti‐arrhythmic actions through an enhanced capacity to selectively increase sarcoplasmic reticulum Ca²⁺ uptake and maintain cytosolic Ca²⁺ levels. This suggests that suppression of global CaMKIIδ may not be an efficacious approach to developing optimal pharmacological interventions for the vulnerable heart.     

Inhibition of CaMKII Attenuates Progressing Disruption of Ca2+ Homeostasis Upon Left Ventricular Assist Device Implantation in Human Heart Failure

In heart failure, left ventricular assist device (LVAD) implantation is performed to ensure sufficient cardiac output. Whereas some patients are subsequently weaned from LVAD support, other patients still need heart transplantation. To elucidate underlying mechanisms, we assessed the arrhythmogenic SR‐Ca²⁺ leak at the time of LVAD implantation (HF‐Im) and heart transplantation (HF‐Tx) and evaluated the effects of CaMKII‐inhibition. Human left‐ventricular cardiomyocytes were isolated, paced at 1 Hz for 10 beats to ensure SR‐Ca²⁺ loading and scanned for diastolic Ca²⁺ sparks (confocal microscopy). In HF‐Im, the high diastolic spark frequency (CaSpF) of 0.76 ± 0.12 × 100 μm^?1 × s^?1 could be reduced to 0.48 ± 0.10 × 100 μm^?1 × s^?1 by CaMKII inhibition (AIP, 1 μM). The amplitude of Ca²⁺ sparks, width, and length was not significantly altered. In sum, CaMKII inhibition yielded a clear tendency toward a reduction of the SR‐Ca²⁺ leak (n cells/patients = 76/6 vs. 108/6, P = 0.08). In HF‐Tx, we detected an even higher CaSpF of 1.00 ± 0.10 100 μm^?1 × s^?1 and a higher SR‐Ca²⁺ leak compared with HF‐Im (increase by 81 ± 33%, n cells/patients = 156/7 vs. 130/7, P < 0.05), which fits to the further decreased LV function. Here, CaMKII inhibition likewise reduced CaSpF (0.35 ± 0.09 100 μm^?1 × s^?1, P = 0.06) and significantly reduced spark duration (n sparks/patients = 58/3 vs. 159/3, P < 0.05). Conclusively, the SR‐Ca²⁺ leak was reduced by 69 ± 12% in HF‐Tx upon CaMKII inhibition (n cells/patients = 53/3 vs. 91/3, P < 0.05). These data show that the SR‐Ca²⁺ leak correlates with the development of LV function after LVAD implantation and may represent an important pathomechanism. The fact that CaMKII inhibition reduces the SR‐Ca²⁺ leak in HF‐Tx suggests that CaMKII inhibition may be a promising option to beneficially influence clinical course after LVAD implantation.     

Role of CaMKII in the regulation of fatty acids and lipid metabolism

Background & aimsPrevious studies have reported the beneficial roles of the activation of calmodulin-dependent protein kinase (CaMK)II to many cellular functions associated with human health. This review aims at discussing its activation by exercise as well as its roles in the regulation of unsaturated, saturated, omega 3 fatty acids, and lipid metabolism.MethodsA wide literature search was conducted using online database such as ‘PubMed’, ‘Google Scholar’, ‘Researcher’, ‘Scopus’ and the website of World Health Organization (WHO) as well as Control Disease and Prevention (CDC). The criteria for the search were mainly lipid and fatty acid metabolism, diabetes, and metabolic syndrome (MetS). A total of ninety-seven articles were included in the review.ResultsCalmodulin-dependent protein kinase activation by exercise is helpful in controlling membrane lipids related with type 2 diabetes and obesity. CaMKII regulates many health beneficial cellular functions in individuals who exercise compared with those who do not exercise. Regulation of lipid metabolism and fatty acids are crucial in the improvement of metabolic syndrome.ConclusionsApproaches that involve CaMKII could be a new avenue for designing novel and effective therapeutic modalities in the treatment or better management of metabolic diseases such as type 2 diabetes and obesity.     

Melatonin reverses the decreases in hippocampal protein serine/threonine kinases observed in an animal model of autism

Lower global cognitive function scores are a common symptom of autism spectrum disorders (ASDs). This study investigates the effects of melatonin on hippocampal serine/threonine kinase signaling in an experimental ASD model. We found that chronic melatonin (1.0 or 5.0 mg/kg/day, 28 days) treatment significantly rescued valproic acid (VPA, 600 mg/kg)‐induced decreases in CaMKII (Thr286), NMDAR1 (Ser896), and PKA (Thr197) phosphorylation in the hippocampus without affecting total protein levels. Compared with control rats, the immunostaining of pyramidal neurons in the hippocampus revealed a decrease in immunolabeling intensity for phospho‐CaMKII (Thr286) in the hippocampus of VPA‐treated rats, which was ameliorated by chronic melatonin treatment. Consistent with the elevation of CaMKII/PKA/PKC phosphorylation observed in melatonin‐treated rat, long‐term potentiation (LTP) was enhanced after chronic melatonin (5.0 mg/kg) treatment, as reflected by extracellular field potential slopes that increased from 56 to 60 min (133.4 ± 3.9% of the baseline, P < 0.01 versus VPA‐treated rats) following high‐frequency stimulation (HFS) in hippocampal slices. Accordingly, melatonin treatment also significantly improved social behavioral deficits at postnatal day 50 in VPA‐treated rats. Taken together, the increased phosphorylation of CaMKII/PKA/PKC signaling might contribute to the beneficial effects of melatonin on autism symptoms.