丙型肝炎病毒NS4B对p53表达及细胞凋亡的影响

目的研究丙型肝炎病毒（HCV）非结构蛋白4B（NS4B）对肝细胞内抑癌基因野生型p53表达及细胞凋亡的影响。方法通过脂质体介导法,将空白载体PCXN2、HCVNS4B重组质粒PCXN2-NS4B、野生型p53表达质粒分别或共引入Chang肝细胞内,并以C418筛选作稳定传代,lit—PCR法鉴定质粒成功转染入肝细胞内,原位杂交法分别检测载体组、NS4B组、p53组、NS4B—p53组的p53mRNA表达情况;TUNEL法流式细胞术观察四组的肝细胞凋亡率。结果与载体组比较,NS4B组未促进或抑制p53mRNA表达（P〉0．05）;与p53组比较,NS4B—p53组的正常肝细胞p53mRNA降低（P〈0．01）;载体组、NS4B组、p53组、NS4B—053组的细胞凋亡率分别为（17．02±1．24）％、（11．94±2．24）％、（25．84±3．49）％、（18．34±1．55）％。结论NS4B可抑制p53基因表达及肝细胞凋亡,可能通过抑制p53表达抑制细胞凋亡。     

Nucleostemin knocking-down causes cell cycle arrest and apoptosis in human T-cell acute lymphoblastic leukemia MOLT-4 cells via p53 and p21Waf1/Cip1 up-regulation

Objectives

Nucleostemin (NS), a recently discovered nucleolar protein, is essential for maintaining self-renewal and proliferation of embryonic and adult stem cells as well as cancerous cells. The aim of this study was to determine biological function of NS in MOLT-4 cells as a human T-cell acute lymphocytic leukemia (T-ALL) model.

Methods

Efficacy of a specific small interference RNA on NS depletion was studied by quantitative polymerase chain reaction and western blotting. The growth rate and viability were analyzed by trypan blue exclusion test. Fluorescent microscopy was used for detecting apoptosis. Cell cycle and apoptosis were mechanistically studied by flow cytometry and western blotting.

Results

Knockdown of NS inhibited proliferation, arrested the cell cycle, and induced apoptosis through p53 and p21^Waf1/Cip1 pathways in MOLT-4 cells.

Discussion

These findings demonstrate critical roles of NS in MOLT-4 cells and may implicate on its therapeutic potential in this human T-ALL model.     

Dying a thousand deaths: redundant pathways from different organelles to apoptosis and necrosis

Cell death is an essential event in normal life and development, as well as in the pathophysiological processes that lead to disease. Although the literature on cell death has grown enormously in size and complexity, a pattern has emerged that each of several distinct organelles (plasma membrane, mitochondrion, nucleus, endoplasmic reticulum, lysosome) gives rise to signals that induce cell death. Most often these signals converge on mitochondria to initiate a common pathway to either caspase-dependent apoptosis or ATP depletion-dependent necrosis. This brief overview emphasizes the multiple and often redundant pathways between different organelles that lead ultimately to a cell's demise.