CAL与mGluR1相互作用抑制mGluR1过度激活诱导的细胞毒性作用

代谢型谷氨酸受体1(mGluR1)过度激活介导的谷氨酸兴奋性毒性是帕金森病(PD)的主要发病机制之一。在临床试验中应用mGluRs的负性变构调节剂缓解PD病人的运动障碍已有报道,但由于精确调控mGluRs表达或活性的局限性,目前,在PD的治疗中仍存在一些问题。因此,寻找能够精确调控mGluR1表达及活性的小分子药物或内源性基因,将有可能成为解决目前PD治疗中存在问题的有效方法。本文通过体内和体外实验,对囊性纤维跨膜调节器相关配体(CAL)在mGluR1过度激活诱导的细胞毒性中的作用和机制进行研究。研究结果显示,在工具细胞HEK293中,应用mGluR1的激动剂激活受体,CAL与mGluR1的相互作用明显增强(P< 0.05),且CAL通过与mGluR1相互作用,抑制mGluR1过度激活诱导的细胞凋亡及其下游信号通路的激活。在鱼藤酮诱导的PD大鼠模型中,过表达CAL通过抑制mGluR1下游通路的激活,减少鱼藤酮引起的神经损伤(P< 0.001)。本文揭示了一种调控mGluR1活性的新机制,希望为神经系统疾病的治疗和相关研究提供新思路。     

Pseudomonas aeruginosa ExoT Induces Mitochondrial Apoptosis in Target Host Cells in a Manner That Depends on Its GTPase-activating Protein (GAP) Domain Activity

Pseudomonas aeruginosa is the most common cause of hospital-acquired pneumonia and a killer of immunocompromised patients. We and others have demonstrated that the type III secretion system (T3SS) effector protein ExoT plays a pivotal role in facilitating P. aeruginosa pathogenesis. ExoT possesses an N-terminal GTPase-activating protein (GAP) domain and a C-terminal ADP-ribosyltransferase (ADPRT) domain. Because it targets multiple non-overlapping cellular targets, ExoT performs several distinct virulence functions for P. aeruginosa, including induction of apoptosis in a variety of target host cells. Both the ADPRT and the GAP domain activities contribute to ExoT-induced apoptosis. The ADPRT domain of ExoT induces atypical anoikis by transforming an innocuous cellular protein, Crk, into a cytotoxin, which interferes with integrin survival signaling. However, the mechanism underlying the GAP-induced apoptosis remains unknown. In this study, we demonstrate that the GAP domain activity is both necessary and sufficient to induce mitochondrial (intrinsic) apoptosis. We show that intoxication with GAP domain results in: (i) JNK1/2 activation; (ii) substantial increases in the mitochondrial levels of activated pro-apoptotic proteins Bax and Bid, and to a lesser extent Bim; (iii) loss of mitochondrial membrane potential and cytochrome c release; and (iv) activation of initiator caspase-9 and executioner caspase-3. Further, GAP-induced apoptosis is partially mediated by JNK1/2, but it is completely dependent on caspase-9 activity. Together, the ADPRT and the GAP domains make ExoT into a highly versatile and potent cytotoxin, capable of inducing multiple forms of apoptosis in target host cells.     

基于蛋白质剪接的BHK细胞Ser~(660)前断裂的CFTR基因转移

利用内含肽(intein)的蛋白质反式剪接技术,研究双载体真核细胞转囊性纤维化跨膜电导调节体(CFTR)基因,通过翻译后连接成为完整的功能性CFTR蛋白.应用基因重组技术,将人CFTRcDNA于剪接反应所需保守残基Ser660前断裂为N端和C端两部分,分别与split Ssp DnaB intein编码序列融合,构建到真核表达载体pEGFP-N1和pEYFP-N1.用脂质体将这对载体共转染至幼年仓鼠肾细胞(BHK),48h后Western印迹观察CFTR蛋白质的连接,并用全细胞和单通道膜片钳技术记录Cl-通道电流.基因共转染细胞可观察到明显的由蛋白质反式剪接形成的完整CFTR蛋白,膜片钳记录到较高的全细胞Cl-电流和与转野生型CFTR基因细胞相似的单Cl-通道开放活性,提示CFTR功能的恢复.内含肽可作为一种技术策略用于双载体转CFTR基因,为应用双腺相关病毒载体(AAV)转基因的囊性纤维化疾病(CF)基因治疗提供了依据.     

The role of erythropoietin and its receptor in growth,survival and therapeutic response of human tumor cells: From clinic to bench — a critical review

Recombinant human erythropoietin (rhEPO) has been used clinically to alleviate cancer- and chemotherapy-related anemia. However, recent clinical trials have reported that rhEPO also may adversely impact disease progression and survival. The expression of functional EPO receptors (EPOR) has been demonstrated in many human cancer cells where, at least in vitro, rhEPO can stimulate cell growth and survival and may induce resistance to selected therapies.     

The psychoactive substance of cannabis Δ9-tetrahydrocannabinol (THC) negatively regulates CFTR in airway cells

Background

Marijuana consumption is on the rise in the US but the health benefits of cannabis smoking are controversial and the impact of cannabis components on lung homeostasis is not well-understood. Lung function requires a fine regulation of the ion channel CFTR, which is responsible for fluid homeostasis and mucocilliary clearance. The goal of this study was to assess the effect that exposure to Δ9-tetrahydrocannabinol (THC), the psychoactive substance present in marijuana, has on CFTR expression and function.

14-3-3 proteins in neurodegeneration

Among the first reported functions of 14-3-3 proteins was the regulation of tyrosine hydroxylase (TH) activity suggesting a possible involvement of 14-3-3 proteins in Parkinson's disease. Since then the relevance of 14-3-3 proteins in the pathogenesis of chronic as well as acute neurodegenerative diseases, including Alzheimer's disease, polyglutamine diseases, amyotrophic lateral sclerosis and stroke has been recognized. The reported function of 14-3-3 proteins in this context are as diverse as the mechanism involved in neurodegeneration, reaching from basal cellular processes like apoptosis, over involvement in features common to many neurodegenerative diseases, like protein stabilization and aggregation, to very specific processes responsible for the selective vulnerability of cellular populations in single neurodegenerative diseases.Here, we review what is currently known of the function of 14-3-3 proteins in nervous tissue focussing on the properties of 14-3-3 proteins important in neurodegenerative disease pathogenesis.     

Mechanical regulation of signaling pathways in bone

A wide range of cell types depend on mechanically induced signals to enable appropriate physiological responses. The skeleton is particularly dependent on mechanical information to guide the resident cell population towards adaptation, maintenance and repair. Research at the organ, tissue, cell and molecular levels has improved our understanding of how the skeleton can recognize the functional environment, and how these challenges are translated into cellular information that can site-specifically alter phenotype. This review first considers those cells within the skeleton that are responsive to mechanical signals, including osteoblasts, osteoclasts, osteocytes and osteoprogenitors. This is discussed in light of a range of experimental approaches that can vary parameters such as strain, fluid shear stress, and pressure. The identity of mechanoreceptor candidates is approached, with consideration of integrins, pericellular tethers, focal adhesions, ion channels, cadherins, connexins, and the plasma membrane including caveolar and non-caveolar lipid rafts and their influence on integral signaling protein interactions. Several mechanically regulated intracellular signaling cascades are detailed including activation of kinases (Akt, MAPK, FAK), β-catenin, GTPases, and calcium signaling events. While the interaction of bone cells with their mechanical environment is complex, an understanding of mechanical regulation of bone signaling is crucial to understanding bone physiology, the etiology of diseases such as osteoporosis, and to the development of interventions to improve bone strength.