中国马鞭草属的新记录--长苞马鞭草

长苞马鞭草(Verbena bracteata Cav.ex Lag.&J.D.Rodriguez)原产北美.2001年春天我们首次在中国大连的马兰水库发现该种植物,它丛生或与其他植物混生,形态与原产地的种一样;因为其苞片通常大、显著且比花萼明显的长,易和原产中国的唯一马鞭草属的V.officinalis L.区分开.     

T-type calcium channels in synaptic plasticity

The role of T-type calcium currents is rarely considered in the extensive literature covering the mechanisms of long-term synaptic plasticity. This situation reflects the lack of suitable T-type channel antagonists that till recently has hampered investigations of the functional roles of these channels. However, with the development of new pharmacological and genetic tools, a clear involvement of T-type channels in synaptic plasticity is starting to emerge. Here, we review a number of studies showing that T-type channels participate to numerous homo- and hetero-synaptic plasticity mechanisms that involve different molecular partners and both pre- and post-synaptic modifications. The existence of T-channel dependent and independent plasticity at the same synapse strongly suggests a subcellular localization of these channels and their partners that allows specific interactions. Moreover, we illustrate the functional importance of T-channel dependent synaptic plasticity in neocortex and thalamus.     

Discovery and evaluation of Cav3.2-selective T-type calcium channel blockers

We identified and characterized a series of pyrrole amides as potent, selective Ca_v3.2-blockers. This series culminated with the identification of pyrrole amides 13b and 26d, with excellent potencies and/or selectivities toward the Ca_v3.1- and Ca_v3.3-channels. These compounds display poor physicochemical and DMPK properties, making their use difficult for in vivo applications. Nevertheless, they are well-suited for in vitro studies.     

Cav1.2在顺铂诱导C57BL/6J小鼠耳蜗螺旋神经元凋亡中的作用*

目的: 探究顺铂(CDDP)诱导C57BL/6J小鼠耳蜗螺旋神经元(SGNs)凋亡过程中Cav1.2的作用及其可能的机制。方法: 动物实验:选取8周龄雄性C57BL/6J小鼠分为以下两组(10只/组):生理盐水组(Control组)和顺铂给药组(Cisplatin组)。Control组每天腹腔注射生理盐水,Cisplatin组每周期前4 d以3 mg/kg的剂量进行顺铂腹腔注射,后10 d每日注射生理盐水,重复三个周期。给药结束后,听性脑干反应(ABR) 检测小鼠听力阈值变化; 小鼠内眦采血,并断颈取耳蜗,超氧化物歧化酶(SOD)以及丙二醛(MDA)试剂盒检测血清及耳蜗组织的SOD活性和MDA含量;免疫印迹法(Western blot)检测耳蜗组织相关凋亡蛋白表达;苏木精-伊红HE染色观察小鼠耳蜗螺旋神经节形态学变化; TUNEL 染色观察小鼠耳蜗SGNs凋亡情况;免疫荧光观察耳蜗SGNs上Cav1.2的分布和表达。细胞实验:原代培养SGNs,根据CCK8选择顺铂5 μmol/L干预12 h并随机分为:对照组(Control)、溶剂组(DMSO)、Cav1.2阻断剂组(N)、顺铂组(Cisplatin)、顺铂与Cav1.2阻断剂共同孵育组(Cisplatin+N)。Western blot检测Cav1.2蛋白表达;Hoechst33342染色观察各组SGNs凋亡情况,流式细胞术检测各组SGNs凋亡率,Western blot检测相关凋亡蛋白的表达,CA²⁺探针检测细胞内钙离子浓度变化,线粒体膜电位检测试剂盒(JC-1)检测膜电位变化,线粒体超氧化物指示剂(MitoSOX^TM-red)检测线粒体释放ROS情况。结果: 动物实验:与Control组相比,Cisplatin组小鼠听力阈值升高(P<0.01), 血清及耳蜗组织MDA含量、耳蜗组织凋亡蛋白 Cleaved-caspase-3、Bax 蛋白水平和TUNEL阳性率、Cav1.2蛋白表达水平等均明显升高(P<0.05, P<0.01);血清及耳蜗组织SOD活性、耳蜗组织抗凋亡蛋白 Bcl-2 蛋白水平和SGCs密度均明显降低(P<0.05,P<0.01)。细胞实验:与Control组相比,Cisplatin组的Cav1.2表达、细胞凋亡率、Cleaved-caspase-3、Bax蛋白水平、细胞内钙离子浓度以及ROS释放均明显增加(P<0.05,P<0.01);而细胞的Bcl-2蛋白水平和线粒体膜电位则明显降低(P<0.01);Cav1.2阻断剂可部分逆转上述改变(P<0.05)。 结论: 顺铂可能通过上调Cav1.2促进钙内流,进而使线粒体ROS增多,引起SGNs氧化应激损伤从而诱导线粒体途径的细胞凋亡。     

Molecular simulations study of novel 1,4‐dihydropyridines derivatives with a high selectivity for Cav3.1 calcium channel

1,4‐Dihydropyridines (DHPs) have been developed to treat hypertension, angina, and nerve system disease. They are thought to mainly target the L‐type calcium channels, but low selectivity prompts them to block Cav1.2 and Cav3.1 channels simultaneously. Recently, some novel DHPs with different hydrophobic groups have been synthesized and among them M12 has a higher selectivity for Cav3.1. However, the structural information about Cav3.1‐DHPs complexes is not available in the experiment. Thus, we combined homology modeling, molecular docking, molecular dynamics simulations, and binding free energy calculations to quantitatively elucidate the inhibition mechanism of DHPs. The calculated results indicate that our model is in excellent agreement with experimental results. On the basis of conformational analysis, we identify the main interactions between DHPs and calcium channels and further elaborate on the different selectivity of ligands from the micro perspective. In conjunction with energy distribution, we propose that the binding sites of Cav3.1‐DHPs is characterized by several interspersed hydrophobic amino acid residues on the IIIS6 and IVS6 segments. We also speculate the favorable function groups on prospective DHPs. Besides, our model provides important information for further mutagenesis experiments.     

Aristolochiaceae‐ and Asteraceae‐feeding by larvae of Papilio xuthus L. (Lepidoptera: Papilionidae) in Japan: A review

Our recent observations of Aristolochiaceae‐ and Asteraceae‐feeding by larvae of Papilio xuthus L. (Lepidoptera: Papilionidae), which is generally a typical Rutaceae‐feeding swallowtail, inspired us to survey published works describing its host range and aspects of its chemical ecology. Papilio xuthus larvae have been observed feeding on a total of 22 plant species other than members of Rutaceae, including those of Asarum (Aristolochiaceae) and Cosmos (Asteraceae). Most observation records and our current study indicated that Aristolochiaceae‐feeding by P. xuthus larvae was not due to oviposition error, but to larval movement to Asarum from adjacent rutaceous hosts after they had become unsustaining. Many larvae developed on Asarum to further stadia but we confirmed that some did not, indicating that Asarum was unsuitable for some individuals. According to previous and current observations, P. xuthus females oviposit directly on Cosmos and their larvae can develop to adults although, again, their performance on these plants is not always favorable. Host choice by swallowtail butterflies is determined both at the egg‐laying and larval‐feeding stages. Although adult P. xuthus use a mixture of unique secondary metabolites as their host‐location cue, larvae use primary nutrients as their major phagostimulants. Larval feeding on Asarum could suggest a reversion triggered by vestigial chemosensitivity to ancestral olfactory and/or gustatory cues, because several major clades of Papilionidae feed on Aristolochiaceae. Further studies on the phytochemical/chemosensory bases for these associations are needed if we are to understand the evolutionary pathway of host selection in P. xuthus, as indicated by these relatively unusual host‐seeking behaviors.     

Estrogen receptor α promotes Cav1.2 ubiquitination and degradation in neuronal cells and in APP/PS1 mice

Cav1.2 is the pore‐forming subunit of L‐type voltage‐gated calcium channel (LTCC) that plays an important role in calcium overload and cell death in Alzheimer's disease. LTCC activity can be regulated by estrogen, a sex steroid hormone that is neuroprotective. Here, we investigated the potential mechanisms in estrogen‐mediated regulation of Cav1.2 protein. We found that in cultured primary neurons, 17β‐estradiol (E2) reduced Cav1.2 protein through estrogen receptor α (ERα). This effect was offset by a proteasomal inhibitor MG132, indicating that ubiquitin–proteasome system was involved. Consistently, the ubiquitin (UB) mutant at lysine 29 (K29R) or the K29‐deubiquitinating enzyme TRAF‐binding protein domain (TRABID) attenuated the effect of ERα on Cav1.2. We further identified that the E3 ligase Mdm2 (double minute 2 protein) and the PEST sequence in Cav1.2 protein played a role, as Mdm2 overexpression and the membrane‐permeable PEST peptides prevented ERα‐mediated Cav1.2 reduction, and Mdm2 overexpression led to the reduced Cav1.2 protein and the increased colocalization of Cav1.2 with ubiquitin in cortical neurons in vivo. In ovariectomized (OVX) APP/PS1 mice, administration of ERα agonist PPT reduced cerebral Cav1.2 protein, increased Cav1.2 ubiquitination, and improved cognitive performances. Taken together, ERα‐induced Cav1.2 degradation involved K29‐linked UB chains and the E3 ligase Mdm2, which might play a role in cognitive improvement in OVX APP/PS1 mice.     

14-3-3τ Promotes Surface Expression of Cav2.2 (α1B) Ca2+ Channels

Surface expression of voltage-gated Ca²⁺ (Cav) channels is important for their function in calcium homeostasis in the physiology of excitable cells, but whether or not and how the α1 pore-forming subunits of Cav channels are trafficked to plasma membrane in the absence of the known Cav auxiliary subunits, β and α2δ, remains mysterious. Here we showed that 14-3-3 proteins promoted functional surface expression of the Cav2.2 α1B channel in transfected tsA-201 cells in the absence of any known Cav auxiliary subunit. Both the surface to total ratio of the expressed α1B protein and the current density of voltage step-evoked Ba²⁺ current were markedly suppressed by the coexpression of a 14-3-3 antagonist construct, pSCM138, but not its inactive control, pSCM174, as determined by immunofluorescence assay and whole cell voltage clamp recording, respectively. By contrast, coexpression with 14-3-3τ significantly enhanced the surface expression and current density of the Cav2.2 α1B channel. Importantly, we found that between the two previously identified 14-3-3 binding regions at the α1B C terminus, only the proximal region (amino acids 1706–1940), closer to the end of the last transmembrane domain, was retained by the endoplasmic reticulum and facilitated by 14-3-3 to traffic to plasma membrane. Additionally, we showed that the 14-3-3/Cav β subunit coregulated the surface expression of Cav2.2 channels in transfected tsA-201 cells and neurons. Altogether, our findings reveal a previously unidentified regulatory function of 14-3-3 proteins in promoting the surface expression of Cav2.2 α1B channels.     

江苏海涂苇田芦毒蛾的生态控制

１９９２￣１９９５年江苏海涂苇田的调查表明,芦毒蛾种群数量消长的主要影响因子是糙叶苔、苇田干湿度以及芦毒蛾黑卵蜂和寄生菌等。提出了以生态控制为基础的综合防治措施,包括因地制宜地赶火烧滩;利用苇田内高湿或浅灌消灭越冬幼虫;清除糙叶苔;保护和利用芦毒蛾黑犷睡其他防治措施的协调运用等。     

Mechanical stretch increases L-type calcium channel stability in cardiomyocytes through a polycystin-1/AKT-dependent mechanism

The L-type calcium channel (LTCC) is an important determinant of cardiac contractility. Therefore, changes in LTCC activity or protein levels could be expected to affect cardiac function. Several studies describing LTCC regulation are available, but only a few examine LTCC protein stability. Polycystin-1 (PC1) is a mechanosensor that regulates heart contractility and is involved in mechanical stretch-induced cardiac hypertrophy. PC1 was originally described as an unconventional Gi/o protein-coupled receptor in renal cells. We recently reported that PC1 regulates LTCC stability in cardiomyocytes under stress; however, the mechanism underlying this effect remains unknown. Here, we use cultured neonatal rat ventricular myocytes and hypo-osmotic stress (HS) to model mechanical stretch. The model shows that the Cavβ2 subunit is necessary for LTCC stabilization in cardiomyocytes during mechanical stretch, acting through an AKT-dependent mechanism. Our data also shows that AKT activation depends on the G protein-coupled receptor activity of PC1, specifically its G protein-binding domain, and the associated Gβγ subunit of a heterotrimeric Gi/o protein. In fact, over-expression of the human PC1 C-terminal mutant lacking the G protein-binding domain blunted the AKT activation-induced increase in Cav1.2 protein in cardiomyocytes. These findings provide novel evidence that PC1 is involved in the regulation of cardiac LTCCs through a Giβγ-AKT-Cavβ2 pathway, suggesting a new mechanism for regulation of cardiac function.