Effect of interferon on the infectivity of Trypanosoma cruzi in cultured HeLa cells

Results are presented on the effects of human lymphoblastoid interferon (HUIFN-α-ly) on the infectivity of metacyclic culture forms of Trypanosoma cruzi in HeLa cells. When cells were pretreated with interferon the parasitisation ratios of the cultures increased with respect to controls. This phenomenon also occurs when interferon was added during the period of parasite-cell interaction. When parasites were pretreated with interferon but cells were not, no increase in the parasitisation ratios was observed.     

A factor produced by human cells in vitro that changes HeLa cell colonial morphology

Summary Colonies of HeLa cells cultured in media supplemented with human or bovine serum or both can be morphologically described as three types: diffuse, intermediate, and compact, with their modal distribution depending on the serum or sera added to the growth medium. We have observed that for a particular medium or serum system, the percentage of compact colonies remains fairly constant under normal culture conditions, 0.2%, whereas the diffuse and intermediate colonies vary over a much wider range. The presence of certain substances as trypsin, heparin and Darvan in the medium favor the increase of compact colonies at the expense of other types. Furthermore, we have discovered that colonial morphology is influenced by cocultivation of the HeLa cells with human fibroblastlike cells, the compact colonies increasing as the density of the fibroblast element introduced into the mixed cultures is increased. Subsequent investigation revealed that conditioned medium from confluent fibroblast and HeLa cell cultures contained a factor(s), that significantly increased the percentage of compact colonies. The factor is nondialyzable, heat-stable and can be neutralized by serum. Recorded in this presentation are preliminary observations on the kinetics of colony formation and the interaction among the three HeLa cell colony types, the diffuse, the intermediate, and the compact. The factor's effect on HeLa cell colonial morphology is time dependent and rapidly reversed if the factor(s) is removed and fresh medium added.     

L-asparaginase produced from soil isolates of Pseudomonas aeruginosa shows potent anti-cancer activity on HeLa cells

Among cancers, acute lymphoblastic leukemia (ALL) occurs in the children <15 years of age. L-asparaginase is an important therapeutic enzyme used for treating ALL. Owing to its therapeutic use and demand, microorganisms have been in use for many years to produce L-asparaginase on an industrial scale. Gram-negative bacteria (Serratia, Erwinia and Escherichia coli) species were used in L-asparaginase. However, earlier studies have documented that the long-term use of enzymes produced from these commercial strains induces hypersensitivity in patients. Therefore, there is a need to discover novel microbial strains producing L-asparaginase with anti-cancer properties, which can be employed for the commercial production of the enzyme. In this study, three strains of Pseudomonas aeruginosa (accession numbers LC425424 (P31), LC425425 (P32), and LC425426 (P34)) isolated from garden soil were screened for the invention of L-asparaginase. Fermented production media was dialyzed to attain the purified enzyme, thus showed a dose-depended cytotoxic effect on HeLa cells, as determined by MTT assay. The IC₅₀s of the different isolates were 86.73, 57.65, and 40.34 µg/mL. These results indicate that pseudomonal L-asparaginase may be used for cancer treatment.     

过表达小鼠UNCV蛋白质对HeLa细胞凋亡的影响

目的研究小鼠UNCV蛋白质对HeLa细胞凋亡的影响。方法将BALB/c小鼠Uncv基因重组质粒转染HeLa细胞,筛选出稳定过表达UNCV蛋白质的HeLa细胞株。通过细胞计数法和流式细胞术,检测过表达UNCV蛋白质对血清饥饿和阿霉素诱导的HeLa细胞凋亡的影响。结果获得稳定正确过表达UNCV蛋白质的HeLa细胞株。细胞计数和流式细胞术结果显示过表达UNCV蛋白质对血清饥饿诱导的HeLa细胞凋亡有抑制作用,对于阿霉素诱导的HeLa细胞凋亡没有显著影响。结论过表达UNCV蛋白质对血清饥饿诱导的HeLa细胞凋亡有抑制作用。     

Effects of microfilament disrupters on microfilament distribution and morphology in maize root cells

Maize root tip cells were examined for the distribution of actin microfilaments in various cell types and to determine the effects of microfilament disrupters. Fluorescence microscopy on fixed, stabilized, squashed cells using the F-actin specific probe, rhodamine-labelled phalloidin, allowed for a three-dimensional visualization of actin microfilaments. Microfilaments were observed as long, meandering structures in root cap cells and meristematic cells, while those in immature vascular parenchyma were abundant in the thin band of cytoplasm and were long and less curved. By modifying standard electron microscopic fixation procedures, microfilaments in plant cells could be easily detected in all cell types. Treatment with cytochalasin B, cytochalasin D and lead acetate, compounds that interfere with microfilament related processes, re-organized the microfilaments into abnormal crossed and highly condensed masses. All the treatments affected not only the microfilaments but also the accumulation of secretory vesicles. The vivid demonstration of the effects of all of these microfilament disrupters on the number and size of Golgi vesicles indicates that these vesicles may depend on microfilaments for intracellular movement.     

Effects of microfilament disrupters on microfilament distribution and morphology in maize root cells

Summary Maize root tip cells were examined for the distribution of actin microfilaments in various cell types and to determine the effects of microfilament disrupters. Fluorescence microscopy on fixed, stabilized, squashed cells using the F-actin specific probe, rhodamine-labelled phalloidin, allowed for a three-dimensional visualization of actin microfilaments. Microfilaments were observed as long, meandering structures in root cap cells and meristematic cells, while those in immature vascular parenchyma were abundant in the thin band of cytoplasm and were long and less curved. By modifying standard electron microscopic fixation procedures, microfilaments in plant cells could be easily detected in all cell types. Treatment with cytochalasin B, cytochalasin D and lead acetate, compounds that interfere with microfilament related processes, re-organized the microfilaments into abnormal crossed and highly condensed masses. All the treatments affected not only the microfilaments but also the accumulation of secretory vesicles. The vivid demonstration of the effects of all of these microfilament disrupters on the number and size of Golgi vesicles indicates that these vesicles may depend on microfilaments for intracellular movement.     

Generation and characterization of a monoclonal antibody, mH1, raised against mitotic HeLa cells

Hybridoma cell lines were prepared from spleen cells of mouse immunized with mitotic HeLa cells. A monoclonal antibody (mH1), which intensively reacted with cleavage furrows of dividing HeLa cells in immunofluorescence, was obtained. In interphase, this antibody diffusely stained whole HeLa cells. Immunoelectron microscopy showed that mH1 antigens were localized at microvillus projections at the surface of dividing HeLa cells, but definite localization of that antigen was not observed in interphasic cells. Immunoblot analysis showed that mH1 is reactive to 42-kDa and 130-kDa components. Further, the 42-kDa component was identified as a gamma-actin homolog by N-terminal amino acid sequence analysis.     

The nucleocytoplasmic microfilament network in protoplasts from cultured soybean cells is a plastic entity that pervades the cytoplasm except the central vacuole

The microfilament network of cultured Glycine max cells (SB-1 line), and protoplasts was visualized with rhodamine-phalloidin under conditions that lysed the protoplast and changed the cell shape. The whole cell had the typical microfilament distribution of a "cage" around the nucleus, from which the large subcortical cables and transvacuolar strands radiated towards the cortex until it reached the cortical microfilament network. Upon cell wall removal, the network conserved its compartmentalization. Thus, the redistribution of the shape where the vacuole becomes a central entity, made the cytoplasm displace peripherally, but the network distribution was conserved. When protoplasts were lysed in a low osmotic medium, the vacuoles were gradually released intact. Under these conditions, the F-actin staining remained within the ghost of the cell, but none was detected in either emerging or almost completely released vacuoles. Most of the released F-actin was found in debris from the cell lysate in the form of microfilaments. When the ghosts were constrained in a coverslip with an air bubble, the shape of the ghost changed accordingly, but the microfilament network distribution remained constant. These results provide further evidence that the vacuole of plant cells does not have detectable associated F-actin. In addition, we demonstrate that the actin microfilament network is a moldable entity that can change its shape but keeps its distribution under constant conditions, in these cultured cells.     

Effect of various concentrations of acyclovir on cell survival and micronuclei induction on cultured HeLa cells

The HeLa cells were treated with 0, 0.01, 0.1, 1, 10 and 100 μM acyclovir (ACV) for 8 h duration and the growth kinetics, cell survival and micronuclei induction were determined. Treatment of HeLa cells with various concentrations of ACV resulted in a concentration-dependent decline in growth kinetics, cell proliferation indices and cell survival. ACV, 100 μM, completely inhibited cell division, where no appreciable changes in cell number were observed from 1 to 5 days post-treatment. This is reflected in cell survival, where the surviving fraction of cells was reduced to 1/2 at 100 μM ACV. Conversely, the frequency of micronuclei showed a concentration-dependent elevation at 20, 30 and 40 h post-treatment. ACV not only induced one micronuclei-bearing binucleate cell but also binucleate cells bearing two and multiple micronuclei in a concentration-dependent manner. The micronuclei frequency increased with time up to 30 h post-treatment and declined thereafter. The relationship between micronuclei induction and cell survival was determined by plotting the former on Y- and the latter on X-axes, respectively. The surviving fraction of cells declined with the elevation in micronuclei frequency and a best fit was observed for linear quadratic formalism.     

Differential mitotic activation of endogenous c-Src, c-Yes, and Lyn in HeLa cells

Src-family tyrosine kinases (SFKs) play an important role in mitosis. Despite overlapping expression of multiple SFK members, little is known about how individual SFK members are activated in M phase. Here, we examined mitotic activation of endogenous c-Src, c-Yes, and Lyn, which are co-expressed in HeLa cells. c-Src, c-Yes, and Lyn were activated at different levels in M phase, and the activation was inhibited by Cdc2 inactivation. Mitotic c-Src and c-Yes exhibited normal- and retarded-electrophoretic-mobility forms on SDS-polyacrylamide gels, whereas Lyn did not show mobility retardation. Like c-Src, the retardation of electrophoretic mobility of c-Yes was caused by Cdc2-mediated phosphorylation. The normal- and retarded-mobility forms of c-Src were comparably activated, but activation of the retarded-mobility form of c-Yes was higher than that of the normal-mobility form of c-Yes. Thus, these results suggest that endogenous c-Src, c-Yes, and Lyn are differentially activated through Cdc2 activation during M phase.     

Role of passive potassium fluxes in cell volume regulation in cultured HeLa cells

Summary Cultured HeLa cells behave as ideal osmometers when subjected to hyperosmolar media, and show no volume regulatory behavior. In hypoosmolar solutions, cell swelling is not as great as predicted, and this is due largely to a loss of intracellular KCl. In hyperosmolar solutions there is a stimulation of the ouabain-insensitive but loop diuretic-sensitive⁸⁶Rb⁺ (K⁺) pathway. Analysis of the K⁺, Na⁺ and Cl^– dependency of this K⁺ flux pathway demonstrates that the increase is principally due to an increase in its maximal velocity (V _max). The sensitivity of this pathway to diuretic inhibition is unchanged in hyperosmolar media. Diuretic-sensitive⁸⁶Rb⁺ (K⁺) efflux stimulated by hypertonicity shows no marked dependence on external K⁺. The K⁺ loss observed in hypoosmolar media is distinct from the K⁺ transport pathway stimulated by hyperosmolar media on the basis of its sensitivity to furosemide and anion dependence.     

Occurrence of the Crabtree effect in HeLa cells

The occurrence of a Crabtree effect in HeLa cells was detected. Some properties of pyruvate kinase (PK) were also evaluated. Hexose phosphate, triose-phosphate and phosphoenolpyruvate (PEP) significantly decreased the oxygen consumption of digitonin-permeabilized HeLa cells, which were oxidizing succinate. The Crabtree effect promoted by PEP was concentration-dependent and was lowered by an increase of ADP concentration, suggesting a participation of PK. The dependence of fructose-1,6-bisphosphate (FDP) by HeLa cell PK was observed. The PK of HeLa cells was inhibited by L -alanine only in the absence of FDP, while in the presence of the metabolite, an increase in the activity was observed. PK was also inhibited in the presence of L -histidine and L -leucine, while L -serine promoted activation. L -Cysteine and L -phenylalanine also inhibited the PK of HeLa cells. This, together with the sigmoidal character in relation to substrate concentration, suggests the presence of the K-type of PK in HeLa cells. © 1998 John Wiley & Sons, Ltd.     

Cyclic amp and cell morphology in cultured fibroblasts. Effects on cell shape, microfilament and microtubule distribution, and orientation to substratum

The change in shape of 3T3 and L929 cells due to Bt2cAMP treatment is accompanied by altered intracellular distribution of microfilaments and microtubules. Bt2cAMP added to cells in low density culture causes (a) microfilaments to accumulate in bundles near the plasma membrane, mainly at the cell periphery, and (b) microtubules to accumulate beneath these microfilament bundles. In narrow cell processes that form characteristically in Bt2cAMP-treated L cells, microtubules accumulate in parallel arrays near the center of these processes. A new simple method for evaluating the relative distance of the cell from its underlying substratum is desribed. In normal medium, 3T3 cells attach to their substratum near the nucleus and at the tips of cell processes, bridging irregularities in the plastic surface. With Bt2cAMP treatment, attachment occurs at the cell edge and at many isolated points under the cytoplasm, and the cells conform more closely to irregularities of the underlying substratum. A model of the mechanism by which cAMP modulates cell shape is presented.     

野艾蒿挥发油对HeLa癌细胞形态与结构的影响

采用MTT法检测细胞活力,用倒置显微镜、荧光显微镜和扫描电子显微镜观察细胞形态与结构的变化,用激光共聚焦显微镜观察细胞微管的分布,从而研究了野艾蒿挥发油对HeLa人宫颈癌细胞形态与结构的影响。结果表明:(1)野艾蒿挥发油对HeLa癌细胞的增殖有明显的抑制作用,呈剂量和时间依赖性。(2)野艾蒿挥发油处理HeLa癌细胞24h后,100、200μg/mL实验组细胞体积缩小,核染色质凝集、微绒毛消失、细胞表面有泡状突起,微管解聚,呈现典型的凋亡特征;400μg/mL实验组细胞膜破裂、胞浆内含物外泄,呈明显的坏死特征。(3)野艾蒿挥发油具有抑制HeLa癌细胞增殖的作用,低、中浓度的野艾蒿挥发油诱导细胞凋亡,而高浓度的野艾蒿挥发油引起细胞坏死。     

Ultrastructure of cultured human orbital fibroblasts

The fine structure of cultured human orbital fibroblasts was investigated by transmission electron microscopy. One culture was derived from a patient with severe Graves' ophthalmopathy, the other from a donor without inflammatory orbital disease. Despite their known differences in metabolism, orbital fibroblasts from either source revealed no ultrastructural differences. The cells had extensive thin cytoplasmic processes. The perinuclear areas contained multiple assemblies of Golgi membranes, modest amounts of rough endoplasmic reticulum, intermediate filaments, and lysosome-like structures. Glycogen deposits were noted both in the perinuclear cytoplasm and in the thin processes. These ultrastructural features of orbital fibroblasts are the same as those of fibroblasts from other anatomic regions.     

A human TERT C-terminal polypeptide sensitizes HeLa cells to H2O2-induced senescence without affecting telomerase enzymatic activity

We have constructed a 27-kDa hTERT C-terminal polypeptide (hTERTC27) devoid of domains required for telomerase activity and demonstrated that it is capable of nuclear translocation/telomere-end targeting. Here we showed that expression of a low level of hTERTC27 renders hTERT positive HeLa cells sensitive to H(2)O(2)-induced oxidative stress and subsequent cell senescence. The senescence-associated gene, the cyclin/cdk inhibitor p21(Waf1), was up-regulated. This occurs without changing the expression of endogenous hTERT, causing significant telomere shortening or inhibiting telomerase activity. Results from this study suggest for the first time that in addition to telomerase activity, the C-terminus of hTERT also plays a role in hTERT-mediated cellular resistance to oxidative stress.     

Effects of nystatin on intracellular contents and membrane transport of alkali cations,and cell volume in HeLa cells

Summary Nystatin (50 g/ml) had strong influence on the intracellular contents and membrane transports of monovalent ions and water in HeLa cells. The nystatin-induced changes in the intracellular ion content and cell volume were inhibited by sucrose, and Donnan and osmotic equilibria were attained. Using cells under conditions for these equilibria, the concentrations of intracellular impermeant solutes, their mean valence, the differences of their intra- and extracellular osmotic concentrations, and the circumferential tension of the cell membrane were determined. Stimulation by nystatin of the influx of one cation species, e.g. Rb, was inhibited by another cation species, e.g. Na. The stimulatory effect of nystatin on cation fluxes was reversible within 1 hr after ionophore addition, and after 1-hr treatment the intracellular contents of Na and K became proportional to their extracellular concentrations, provided that the sum of these concentrations was constant (300mm). Similar proportionality was also observed in the presence of choline, provided that the choline concentration was less than those of the alkali cations. The implications of these results in relation to the osmotic properties of cultured cells, and the experimental regulation of alkali cations in the cells, are discussed.     

Improved transfection efficiency of cultured human cells

We simultaneously tested the transfection efficiency of NT2/D1 and HeLa cells with Lipofectamine (Life Technologies) and Effectene (Qiagen) transfection reagents using the pCH110 eukaryotic assay vector, which contains the lacZ reporter gene. Under our culture conditions for NT2/D1 and HeLa cells, Effectene transfection efficiency could be augmented by simply increasing the amount of plasmid DNA 1.5-3 times above the recommended concentration without any visible cytotoxicity. With the Lipofectamine reagent, optimal transfection efficiency was obtained for both cell lines within the recommended concentrations, but at the top of the range. The results indicate that optimization of the transfection process should include plasmid DNA concentrations above the levels suggested by the manufacturers, in order to accomplish the highest transfection efficiency.     

Gene and microRNA expression signatures of human mesenchymal stromal cells in comparison to fibroblasts

Human mesenchymal stromal cells (MSCs) offer great hope for the treatment of tissue degenerative and immune diseases, but their phenotypic similarity to dermal fibroblasts may hinder robust cell identification and isolation from diverse tissue harvests. To identify genetic elements that can reliably discriminate MSCs from fibroblasts, we performed comparative gene and microRNA expression profiling analyses with genome-wide oligonucleotide microarrays. When taken globally, both gene and microRNA expression profiles of MSCs were highly similar to those of fibroblasts, accounting well for their extensive phenotypic and functional overlaps. Scattered expression differences were pooled to yield an MSC-specific molecular signature, consisting of 64 genes and 21 microRNAs whose expressions were at least 10-fold and two-fold higher, respectively, in MSCs compared with fibroblasts. Genes either encoding transmembrane proteins or associated with tumors were relatively abundant in this signature. These data should provide the molecular basis not only for the discovery of novel diagnostic markers discriminating MSCs from fibroblasts, but also for further studies on MSC-specific signaling mechanisms. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Sohyun Bae and Jung Hoon Ahn contributed equally to this work. This research was supported in part by a grant (SC-2140) from Stem Cell Research Center of the 21st Century Frontier Research Program, and in part by Korea Science and Engineering Foundation grant (M10641000037) funded by the Ministry of Education, Science and Technology, Republic of Korea.