Concentrations of calmodulin in sperm in relation to their motility in fertile euspermic and infertile asthenozoospermic men

The relationship between calmodulin and sperm motility was assessed in euspermic and asthenozoospermic men using radioimmunoassay and time-lapse photography, respectively. There was a significant decrease in the % sperm motility, mean sperm velocity, motility index and % of progressively motile sperm in the asthenozoospermic group when compared with euspermic men. The former also exhibited a higher % of sperm with erratic or circular motility. Calmodulin concentration in sperm from the asthenozoospermic men was 4.8 +/- 1.4 micrograms/mg protein compared with 12.6 +/- 2.3 in euspermic men (P less than 0.0005). The differences observed in sperm motility characteristics between the two groups may, thus, be due to the observed differences in the concentration of calmodulin.     

冠心病患者血小板功能和血小板钙调素含量的变化

检测了20例冠心病患者的血小板钙调素含量及血小板部分功能,发现冠心病患者血小板钙调素含量较对照组明显降低,而血小板活性则较对照组明显增高。结果提示,钙调素的含量变化有可能在冠心病的发病过程中起着重要作用。     

Effects of hypophysectomy and growth hormone on cultured islets of Langerhans of the rat

Summary The effects on islet function of addition to the culture medium of rat growth hormone was studied in 4-day cultured islets of Langerhans from normal and hypophysectomised rats. In islets from hypophysectomised rats, rates of insulin release were 34% lower than in control rat islets; rates of insulin plus proinsulin and total protein biosynthesis were also lower by 48% and 16% respectively. The rates of glucose oxidation and the islet content of cyclic AMP were unchanged in islets from hypophysectomised rats but the islet content of calmodulin was decreased by 68%. The presence of rat growth hormone during the culture period restored the secretory response of hypophysectomised rat islets to that seen in control islets cultured without growth hormone but had only a marginal effect on the rate of insulin plus proinsulin biosynthesis, and no significant effect on islet calmodulin content. Glucose oxidation was increased by the presence of growth hormone during the culture period in both control (73% increase) and hypophysectomised (38% increase) rat islets. Addition of growth hormone to the culture medium also enhanced rates of insulin release and biosynthesis in control islets by 116% and 20% respectively. It is suggested that these changes arise primarily from modification of the synthesis of specific islet proteins.     

Cardiac ischaemic stress: cardiomyocyte Ca²⁺, sex and sex steroids

1. Important sex differences exist in ischaemic heart disease. Oestrogen has been conventionally regarded as providing a cardioprotective benefit and testosterone frequently perceived to exert a deleterious effect. However, there is accumulating evidence that argues against this simple dichotomy, suggesting that the influence of oestrogen and testosterone conferring benefit or detriment may be context specific. 2. Cardiomyocyte calcium (Ca(2+)) loading is recognized to be a major factor in acute ischaemia-reperfusion pathology, promoting cell death, contractile dysfunction and arrhythmogenic activity. Ca(2+)/calmodulin-dependent kinase II (CaMKII) is a mediator of many of the cardiomyocyte Ca(2+)-related pathologies in ischaemia-reperfusion. Cardiomyocyte Ca(2+)-handling processes have been shown to be modulated by the actions of oestrogen and testosterone. A role for these sex steroids in influencing CaMKII activation is argued. 3. Although many experimental studies of oestrogen manipulation can identify a cardioprotective role for this sex steroid, there are also numerous reports that fail to demonstrate sex differences in postischaemic recovery. Experimental studies report that testosterone can be protective in ischaemia-reperfusion in males and females in some settings. 4. Further studies of sex steroid influence in the ischaemic heart will allow the development of therapeutic interventions that are specifically targeted for male and female hearts.     

Role of calcium/calmodulin signaling pathway in Vibrio vulnificus cytolysin-induced hyperpermeability

Endothelial hyperpermeability, a hallmark of septicemia, is induced by stress fiber formation, which is primarily regulated by the calcium/calmodulin signaling pathway in endothelial cells. We previously reported that trifluoperazine, a calcium/calmodulin antagonist, blocks Vibrio vulnificus cytolysin (VVC) -induced lethality at in vivo animal model. The object of this study was therefore to examine whether VVC induces stress fiber formation through calcium/calmodulin signaling in endothelial cells. Here, we monitored calcium-influx after treatment of VVC using confocal microscopy in CPAE cells, pulmonary endothelial cell line. Interestingly, we found that VVC-induced dose-dependently increases of [Ca²⁺]_i in CPAE cells. Moreover, VVC-induced stress fiber formation as well as phosphorylation of myosin light chain (MLC) in a dose- and time-dependent manner, which was completely blocked by trifluoperazine. These results suggest that the calcium/calmodulin signaling pathway plays a pivotal role in VVC-induced hyperpermeability.     

Phosphorylation and function of cardiac myosin binding protein-C in health and disease

During the past 5 years there has been an increasing body of literature describing the roles cardiac myosin binding protein C (cMyBP-C) phosphorylation play in regulating cardiac function and heart failure. cMyBP-C is a sarcomeric thick filament protein that interacts with titin, myosin and actin to regulate sarcomeric assembly, structure and function. Elucidating the function of cMyBP-C is clinically important because mutations in this protein have been linked to cardiomyopathy in more than sixty million people worldwide. One function of cMyBP-C is to regulate cross-bridge formation through dynamic phosphorylation by protein kinase A, protein kinase C and Ca²⁺-calmodulin-activated kinase II, suggesting that cMyBP-C phosphorylation serves as a highly coordinated point of contractile regulation. Moreover, dephosphorylation of cMyBP-C, which accelerates its degradation, has been shown to associate with the development of heart failure in mouse models and in humans. Strikingly, cMyBP-C phosphorylation presents a potential target for therapeutic development as protection against ischemic-reperfusion injury, which has been demonstrated in mouse hearts. Also, emerging evidence suggests that cMyBP-C has the potential to be used as a biomarker for diagnosing myocardial infarction. Although many aspects of cMyBP-C phosphorylation and function remain poorly understood, cMyBP-C and its phosphorylation states have significant promise as a target for therapy and for providing a better understanding of the mechanics of heart function during health and disease. In this review we discuss the most recent findings with respect to cMyBP-C phosphorylation and function and determine potential future directions to better understand the functional role of cMyBP-C and phosphorylation in sarcomeric structure, myocardial contractility and cardioprotection.     

Contribution of calcium-dependent facilitation to synaptic plasticity revealed by migraine mutations in the P/Q-type calcium channel

The dynamics, computational power, and strength of neural circuits are essential for encoding and processing information in the CNS and rely on short and long forms of synaptic plasticity. In a model system, residual calcium (Ca(2+)) in presynaptic terminals can act through neuronal Ca(2+) sensor proteins to cause Ca(2+)-dependent facilitation (CDF) of P/Q-type channels and induce short-term synaptic facilitation. However, whether this is a general mechanism of plasticity at intact central synapses and whether mutations associated with human disease affect this process have not been described to our knowledge. In this report, we find that, in both exogenous and native preparations, gain-of-function missense mutations underlying Familial Hemiplegic Migraine type 1 (FHM-1) occlude CDF of P/Q-type Ca(2+) channels. In FHM-1 mutant mice, the alteration of P/Q-type channel CDF correlates with reduced short-term synaptic facilitation at cerebellar parallel fiber-to-Purkinje cell synapses. Two-photon imaging suggests that P/Q-type channels at parallel fiber terminals in FHM-1 mice are in a basally facilitated state. Overall, the results provide evidence that FHM-1 mutations directly affect both P/Q-type channel CDF and synaptic plasticity and that together likely contribute toward the pathophysiology underlying FHM-1. The findings also suggest that P/Q-type channel CDF is an important mechanism required for normal synaptic plasticity at a fast synapse in the mammalian CNS.     

钙调素拮抗剂O-(4-乙氧基-丁基)-小檗胺对人白血病细胞K562和K562/A02生长的抑制作用

目的研究钙调素拮抗剂O-(4-乙氧基-丁基)-小檗胺(EBB)体外抗白血病作用及机制。方法四唑盐(MTT)比色法评价EBB的细胞毒作用;流式细胞术检测细胞凋亡;荧光分光光度计检测细胞ROS水平;激光共聚焦显微镜检测[Ca2+]i含量。结果EBB明显抑制敏感K562和耐药K562/A02细胞增殖,IC50分别为(8.22±1.67)mol.L-1和(8.97±1.48)mol.L-1。EBB作用早期诱导凋亡,晚期引起坏死。K562/A02细胞的ROS静息值是K562细胞的2倍,EBB诱导两种细胞ROS生成呈浓度和时间依赖性,加入SOD明显降低坏死率。K562/A02细胞的[Ca2+]i低于K562细胞。EBB能明显增加两种细胞的[Ca2+]i。结论EBB明显抑制K562和K562/A02细胞增殖。信号分子Ca2+、ROS参与了EBB的细胞毒作用。     

Bepridil up-regulates cardiac Na+ channels as a long-term effect by blunting proteasome signals through inhibition of calmodulin activity

Background and purpose:

Bepridil is an anti-arrhythmic agent with anti-electrical remodelling effects that target many cardiac ion channels, including the voltage-gated Na⁺ channel. However, long-term effects of bepridil on the Na⁺ channel remain unclear. We explored the long-term effect of bepridil on the Na⁺ channel in isolated neonatal rat cardiomyocytes and in a heterologous expression system of human Na_v1.5 channel.

Experimental approach:

Na⁺ currents were recorded by whole-cell voltage-clamp technique. Na⁺ channel message and protein were evaluated by real-time RT-PCR and Western blot analysis.

Key results:

Treatment of cardiomyocytes with 10 µmol·L⁻¹ bepridil for 24 h augmented Na⁺ channel current (I_Na) in a dose- and time-dependent manner. This long-term effect of bepridil was mimicked or masked by application of W-7, a calmodulin inhibitor, but not KN93 [2-[N-(2-hydroxyethyl)-N-(4-methoxy benzenesulphonyl)]-amino-N-(4-chlorocinnamyl)-N-methylbenzylamine], a Ca²⁺/calmodulin-dependent kinase inhibitor. During inhibition of protein synthesis by cycloheximide, the I_Na increase due to bepridil was larger than the increase without cycloheximide. Bepridil and W-7 significantly slowed the time course of Na_v1.5 protein degradation in neonatal cardiomyocytes, although the mRNA levels of Na_v1.5 were not modified. Bepridil and W-7 did not increase I_Na any further in the presence of the proteasome inhibitor MG132 [N-[(phenylmethoxy)carbonyl]-L-leucyl-N-[(1S)-1-formyl-3-methylbutyl]-L-leucinamide]. Bepridil, W-7 and MG132 but not KN93 significantly decreased 20S proteasome activity in a concentration-dependent manner.

Conclusions and implications:

We conclude that long-term exposure of cardiomyocytes to bepridil at therapeutic concentrations inhibits calmodulin action, which decreased degradation of the Na_v1.5 α-subunit, which in turn increased Na⁺ current.     

Ca2+–Calmodulin–Calcineurin Signaling Modulates α-Synuclein Transmission

Background

The intercellular transmission of pathogenic proteins plays a crucial role in the progression of neurodegenerative diseases. Previous research has shown that the neuronal uptake of such proteins is activity-dependent; however, the detailed mechanisms underlying activity-dependent α-synuclein transmission in Parkinson's disease remain unclear.

Objective

To examine whether α-synuclein transmission is affected by Ca²⁺–calmodulin–calcineurin signaling in cultured cells and mouse models of Parkinson's disease.

Methods

Mouse primary hippocampal neurons were used to examine the effects of the modulation of Ca²⁺–calmodulin–calcineurin signaling on the neuronal uptake of α-synuclein preformed fibrils. The effects of modulating Ca²⁺–calmodulin–calcineurin signaling on the development of α-synuclein pathology were examined using a mouse model injected with α-synuclein preformed fibrils.

Results

Modulation of Ca²⁺–calmodulin–calcineurin signaling by inhibiting voltage-gated Ca²⁺ channels, calmodulin, and calcineurin blocked the neuronal uptake of α-synuclein preformed fibrils via macropinocytosis. Different subtypes of voltage-gated Ca²⁺ channel differentially contributed to the neuronal uptake of α-synuclein preformed fibrils. In wild-type mice inoculated with α-synuclein preformed fibrils, we found that inhibiting calcineurin ameliorated the development of α-synuclein pathology.

Conclusion

Our data suggest that Ca²⁺–calmodulin–calcineurin signaling modulates α-synuclein transmission and has potential as a therapeutic target for Parkinson's disease. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.