H2S relaxes isolated human airway smooth muscle cells via the sarcolemmal KATP channel

Here we explored the impact of hydrogen sulfide (H₂S) on biophysical properties of the primary human airway smooth muscle (ASM)–the end effector of acute airway narrowing in asthma. Using magnetic twisting cytometry (MTC), we measured dynamic changes in the stiffness of isolated ASM, at the single-cell level, in response to varying doses of GYY4137 (1–10 mM). GYY4137 slowly released appreciable levels of H₂S in the range of 10–275 μM, and H₂S released was long lived. In isolated human ASM cells, GYY4137 acutely decreased stiffness (i.e. an indicator of the single-cell relaxation) in a dose-dependent fashion, and stiffness decreases were sustained in culture for 24 h. Human ASM cells showed protein expressions of cystathionine-γ-lyase (CSE; a H₂S synthesizing enzyme) and ATP-sensitive potassium (K_ATP) channels. The K_ATP channel opener pinacidil effectively relaxed isolated ASM cells. In addition, pinacidil-induced ASM relaxation was completely inhibited by the treatment of cells with the K_ATP channel blocker glibenclamide. Glibenclamide also markedly attenuated GYY4137-mediated relaxation of isolated human ASM cells. Taken together, our findings demonstrate that H₂S causes the relaxation of human ASM and implicate as well the role for sarcolemmal K_ATP channels. Finally, given that ASM cells express intrinsic enzymatic machinery of generating H₂S, we suggest thereby this class of gasotransmitter can be further exploited for potential therapy against obstructive lung disease.     

A critical life-supporting role for cystathionine γ-lyase in the absence of dietary cysteine supply

This study examined the important relationship between cystathionine γ-lyase (CSE) functionality and cysteine supply for normal growth and life span. Mice with a targeted deletion of the CSE gene (CSE-KO) were fed a cysteine-limited diet and their growth and survival patterns as well as levels of cysteine, homocysteine, glutathione, and hydrogen sulfide (H2S) were measured. CSE-KO mice fed a cysteine-limited diet exhibited growth retardation; decreased levels of cysteine, glutathione, and H2S; and increased plasma homocysteine level. However, histological examinations of liver did not reveal any abnormality and plasma levels of aspartate aminotransferase, alanine aminotransferase, and albumin were normal in these animals. No CSE-KO mice survived after 12 weeks of feeding with the cysteine-limited diet. Supplementation of H2S to the CSE-KO mice failed to reverse the aforementioned abnormalities. On the other hand, supplementation of cysteine in the drinking water of the CSE-KO mice significantly increased plasma cysteine and glutathione levels. This eventually led to an increase in body weight and rescued the animals from death. In conclusion, CSE is critical for cysteine biosynthesis through the transsulfuration pathway and the combination of CSE deficiency and lack of dietary cysteine supply would threaten life sustainability.     

核层蛋白A前体的法尼基化与衰老

编码核层蛋白A(lamin A)的LMNA基因突变导致法尼基化的核层蛋白A前体(prelamin A)不能被进一步加工成成熟的核层蛋白A,从而导致一种Hutchinson-Gilford早老症综合征(Hutchinson-Gilford progeria syndrome,HGPS)。一种更严重的早老症——限制性皮肤病(restrictive dermopathy,RD),是由于缺失核层蛋白A前体加工过程中的剪切酶ZMPSTE24引起的。ZMPSTE24的缺失阻止了法尼基化的核层蛋白A前体不能正常加工成为成熟的核层蛋白A,同时导致法尼基化的核层蛋白A前体的堆积。在HGPS和RD病人的成纤维细胞中,发现法尼基化的核层蛋白A前体都定位在核膜,从而影响细胞核膜的完整性,并导致细胞核形的异常,进而导致衰老。最近研究表明经过法尼基酰转移酶抑制剂(farnesyltransferase inhibitor,FTI)处理后的细胞的核形异常减少。同时,FTI能够改善HGPS和RD小鼠的早老症状。本文就核层蛋白A前体的法尼基化对衰老的影响有关研究进展作一综述。     

病原菌Pst DC3000侵染拟南芥导致自噬和光合作用的抑制

在病原菌侵染下,植物体是如何通过超敏反应限制病原菌扩增的,到目前为止还不清楚。最近的研究显示自噬起了必要的作用,可见,研究自噬和超敏反应的机制非常重要。本研究通过观察在非寄主病原菌突变体丁香假单胞菌番茄致病变种(Pseudomonas syringae pv.tomatoDC3000,Pst DC3000)的侵染下,拟南芥光合功能的变化及自噬现象出现的情况,以为进一步研究植物抗病机理提供实验基础。以野生型拟南芥为材料,采用光谱分析和叶绿素荧光成像分析手段,研究不同浓度的Pst DC3000侵染对拟南芥离体叶片光合功能的影响;以转基因野生型拟南芥(绿色荧光蛋白标记的自噬基因8a)幼根为材料,应用共聚焦显微镜,研究不同浓度的Pst DC3000诱导拟南芥自噬的情况。实验发现,OD600=0.2的Pst DC3000侵染,可显著诱导拟南芥叶片活性氧的积累和迸发,并会引起拟南芥叶片光合作用效率的下降。同时发现,该病原菌处理2 h,可导致拟南芥根中自噬小体的产生。用2',7'-二氯二氢荧光素二乙酯(2',7'-dichlorodihydrofluorescein diacetate,H2DCFDA)标记活性氧,检测了P...     

镉胁迫对拟南芥的毒害作用及自噬现象的观测

镉离子(Cd2+)具有强植物毒性,可抑制植物生长,甚至导致植物死亡。为了研究重金属镉对拟南芥的毒害作用,采用叶绿素荧光技术、流式细胞技术、激光共聚焦技术及半定量RT-PCR技术,检测光合参数的变化、活性氧(reactive oxygen species,ROS)的累积、自噬的发生,以及病原相关蛋白(pathogenesis-related protein,PR)基因表达的变化。实验结果显示,随着50μmol/L CdCl2处理时间的延长,ROS和Cd2+在细胞中大量积累。而在镉胁迫的初期,会观察到自噬的发生及PR基因表达的变化。说明植物受到外界Cd2+作用的初期,会通过自噬及增强PR基因表达来抵抗外界胁迫。但随着处理时间的延长,植物细胞内累积了大量的ROS和Cd2+,当植物不足以通过自噬途径抵抗胁迫时,就会导致生长受阻,最终对光合系统造成损伤。     

光学分子影像技术及其在药物研发领域的应用

光学分子影像技术是一种发展迅速的生物医学影像技术,能够利用生物发光技术或荧光蛋白等,对生物体内特定的生物过程进行无创的定性或定量研究。应用该技术可以对药物进行筛选,选取具有潜在治疗效果的药物进行后续研究,而终止对可能无效药物的研究,同时可以评价药物对肿瘤的代谢、增殖、血管形成、凋亡和组织乏氧等方面的影响。本文主要介绍光学分子影像技术及其在药物研发,尤其是抗肿瘤药物研发领域的应用。     

Interaction of hydrogen sulfide and estrogen on the proliferation of vascular smooth muscle cells

Hydrogen sulfide (H(2)S) can be endogenously generated from cystathionine gamma-lyase (CSE) in cardiovascular system, offering a cardiovascular protection. It is also known that the lower risk of cardiovascular diseases in female is partially attributed to the protective effect of estrogen. The current study explores the interaction of H(2)S and estrogen on smooth muscle cell (SMC) growth. In the present study, we found that the proliferation of cultured vascular SMCs isolated from wild-type mice (WT-SMCs) was inhibited, but that from CSE gene knockout mice (CSE-KO-SMCs) increased, by estrogen treatments. The expression of estrogen receptor α (ERα), but not ERβ, was significantly decreased in CSE-KO-SMCs compared with that in WT-SMCs. Exogenously applied H(2)S markedly increased ERα but not ERβ expression. In addition, the inhibition of ER activation and knockdown of ERα expression in WT-SMCs or the overexpression of ERα in CSE-KO-SMCs reversed the respective effects of estrogen on cell proliferation. The expression of cyclin D1 was reduced in WT-SMCs but increased in CSE-KO-SMCs after estrogen treatments, which was reversed by knockdown of ERα in WT-SMCs or overexpression of ERα in CSE-KO-SMCs, respectively. The overexpression of cyclin D1 in WT-SMCs or knockdown of cyclin D1 expression in CSE-KO-SMCs reversed the effects of estrogen on cell proliferation. These results suggest that H(2)S mediates estrogen-inhibited proliferation of SMCs via selective activation of ERα/cyclin D1 pathways.