bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphogenetic response of cultured normal and transformed fibroblasts, and epitheliocytes, to a cylindrical substratum surface Possible role for the actin filament bundle pattern
Authors: Rovensky Yu. A. , Samoilovi V. I. 
Published: April 2021

ABSTRACT
Morphometric characteristics such as cell area, dispersion, elongation and orientation were studied in normal and transformed fibroblasts, and in epitheliocytes cultured on flat or cylindrical substrata. Cylindrical surfaces with a high degree of curvature (12-13 or 25 μm radii) were shown to affect cell size, shape and alignment. The reaction of the cells to the curvature of cylindrical substrata was different in various cell types studied and depended on the pattern of actin microfilament bundles. The cells containing pronounced straight actin bundles (mouse embryo fibroblasts at the polarization stage of spreading, single spread cells of the ‘normal’ epithelial FBT line or the fully transformed epithelial IAR 6-1 line) were relatively resistant to bending around a cylindrical substratum, and became elongated and oriented along the cylinder. Cells with circular actin bundles as the predominant pattern (mouse embryo fibroblasts at the radial stage of spreading, single spread cells of ‘normal’ epithelial IAR 20 line) and cells with insufficient or no actin bundles (transformed fibroblastic L line) were prone to bending around a cylinder with much less pronounced elongation and orientation along its axis. The data obtained indicate that the reaction of cultured cells to the geometry of the substratum surface and, in particular, to a cylindrical surface is determined not only by the presence or absence of actin microfilament bundles but by their pattern in the cell.
A scatter factor-like factor is produced by a metastatic variant of a rat bladder carcinoma cell line
Authors: Savério Bellusci , Moens Ginette , Thiery Jean Paul , Jouanneau Jacqueline 
Published: April 2021

ABSTRACT
The rat bladder carcinoma epithelial NBT-II cell line undergoes, in vitro, a morphological transition to a fibrob- last-like state in the presence of different growth factors. We have selected, in vivo, a metastatic clone, designated M- NBT-II, which has a mesenchymal phenotype and secretes into the culture medium a factor able to dissociate epithe- lial clusters of NBT-II or MDCK cells. This factor was des- ignated scatter factor-like (SFL) by analogy to the HGF/SF, which has the same dissociating effect in these two cell lines. Here, we show that SFL factor and HGF/SF are different factors: (i) no HGF/SF transcripts could be detected using either specific rat HGF/SF cDNA probes or PCR; (ii) blocking antibodies against rat HGF/SF do not inhibit the SFL activity; and (iii) crude culture medium or partially purified SFL factor-containing fractions do not induce MDCK tubulogenesis, a biological assay that is specific for HGF/SF activity in vitro. We report the partial purification of the SFL factor, based on ion exchange and reverse-phase chromatography. The results indicate that the M-NBT-II metastatic variant secretes a dissociating factor sharing some common biological properties with the HGF/SF, which suggests that the SFL factor is a member of the HGF/SF family and may be involved in tumor progression.
Trafficking of interleukin 2 and transferrin in endosomal fractions of T lymphocytes
Authors: Véronique Dupreza , Smoljanovic Marc , Lieb Michèle , Dautry-Varsat Alice 
Published: April 2021

ABSTRACT
The T lymphocyte growth factor interleukin 2 binds to surface high-affinity receptors and is rapidly internalized and degraded in acidic organelles. The α and β chains of high-affinity interleukin 2 receptors are internalized together with interleukin 2. To identify the intracellular pathway followed by interleukin 2, we have compared the subcellular distribution of interleukin 2, transferrin and a fluid-phase marker, horseradish peroxidase, in the human T cell line IARC 301.5. Transferrin was used as a marker of early and recycling endosomes, and horseradish perox- idase to probe for the whole endocytic pathway. Fraction- ation of intracellular organelles on a discontinuous sucrose gradient showed that internalized interleukin 2 is initially mostly found in compartments with similar densities to transferrin, e.g. early and recycling endosomes. The kinetics of entry and exit of interleukin 2 from such organelles was much slower than that of transferrin. Later on, interleukin 2 is predominantly found in dense lysosome- containing fractions. Very little, if any, interleukin 2 was found in fractions corresponding to late endosomes con- taining horseradish peroxidase.
These results suggest that, after endocytosis, interleukin 2 enters early or recycling endosomes before it reaches dense lysosomes.
A possible role for stable microtubules in intracellular transport from the endoplasmic reticulum to the Golgi apparatus
Authors: Mizuno Masahiro , Singer S. J. 
Published: April 2021

ABSTRACT
The intracellular transport of secretory proteins involves at an early stage the formation of vesicles from transitional elements of the endoplasmic reticulum (ER) containing these proteins and the transfer of these vesicles to the cis-face of the Golgi apparatus. We propose that the latter transfer process does not occur by random diffusion, but is instead mediated by tracking along stable microtubules. To test this proposal, we have carried out double immuno-electron microscopic labeling experiments on frozen sections of HepG2 hepatoma cells secreting the protein human serum albumin (HSA). By a cycloheximide treatment protocol, the stage during which the transfer of newly synthesized HSA from the ER to the Golgi apparatus occurs in vivo was determined. Sections of the cells were then double immunolabled using primary antibodies to HSA and to glu-tubulin, the latter specifically detecting stable microtubules. We observed a significantly high frequency of HSA-containing structures between the ER and the Golgi apparatus with which stable microtubules were closely associated. These results support the proposal that stable microtubules may play a critical role in directing the transfer process from the ER to the Golgi apparatus.
Inter- and intra-site heterogeneity in the expression of fetal-like phenotypic characteristics by gingival fibroblasts: potential significance for wound healing
Authors: Irwin Christopher R. , Picardo Martino , Ellis Ian , Sloan Philip , Grey Anne Marie , McGurk Mark , Schor Seth L. 
Published: April 2021

ABSTRACT
We have previously reported that fetal and adult skin fibroblasts display distinctive migratory phenotypes on 3-D collagen substrata and that these behavioural characteristics may be quantified by a function defined as the cell density migration index(CDMI). Subsequent work indicated that this difference in migratory phenotype was due to the production by fetal fibroblasts of a migration stimulating factor(MSF) that is not produced by normal adult skin fibroblasts. We now present data indicating that: (a) unselected fibroblasts obtained from 14/14 (100%) of adult gingival explants expressed fetal-like CDMI values compared to only 1/10 (10%) of similarly explanted paired skin cells; (b) 12/12 (100%) of these gingival fibroblast lines also produced detectable quantities of MSF compared to 0/9 (0%) of the tested skin cells; (c) by microdissection studies, gingival fibroblasts obtained from different anatomical microdomains consisted of behaviourally distinct subpopulations, with cells derived from the papillary tips (PAP fibroblasts) displaying fetal-like CDMI values and persistent MSF production, whilst cells obtained from the deeper reticular tissue (RET fibroblasts) were adult-like with respect to these two criteria; (d) PAP fibroblasts were also smaller and achieved higher saturation cell densities compared to paired RET cells; (e) PAP fibroblasts passaged in vitro underwent a fetal-to-adult phenotypic transition characterized by the adoption of various RET cell characteristics, including the acquisition of CDMI values falling within the adult range and cessation in MSF production; and (f) early passage PAP fibroblasts incubated in the presence of an affinity-purified anti-MSF rabbit polyclonal antibody were induced to alter their migratory phenotype and exhibited CDMI values falling within the adult range. Statistical analysis indicated a highly significant correlation between the expression of a fetal-like CDMI and production of MSF (P&lt;0.00001, using the Fisher exact contingency test). Taken together, these observations suggest that the production of MSF by PAP fibroblasts is responsible for their characteristically fetal-like migratory behaviour. The existence of such inter- and intra-site phenotypic heterogeneity in populations of skin and gingival fibroblasts is discussed in the context of fibrob-last lineage relationships and the possible contribution of persistently fetal-like fibroblast subpopulations to connective tissue function in wound healing.
Hydra tropomyosin TROP1 is expressed in head-specific epithelial cells and is a major component of the cytoskeletal structure that anchors nematocytes
Authors: López de Haro Maria S. , Salgado Luis M. , David Charles N. , Bosch Thomas C. G. 
Published: April 2021

ABSTRACT
A cDNA clone encoding a 253 amino acid tropomyosin was isolated from Hydra in a differential screen for headspecific genes. The Hydra tropomyosin gene, designated trop1, is a single copy gene, lacks introns and is strongly expressed in tentacle-specific epithelial cells. Analysis of protein synthesis in head and gastric tissue indicated a high rate of tropomyosin synthesis in head tissue. Immunolocalization of tropomyosin in tentacle tissue revealed a cushion-like tropomyosin-containing structure within battery cells at the base of nematocytes. The structure appears to form part of the cytoskeletal anchor for nematocytes. Tropomyosin cushions were also observed in epithelial cells along the body column, which contain mounted stenotele nematocytes.
RNA polymerase II transcription is concentrated outside replication domains throughout S-phase
Authors: Wansink Derick G. , Manders Erik E. M. , Kraan Ineke van der , Aten Jacob A. , Driel Roel van , Jong Luitzen de 
Published: April 2021

ABSTRACT
Transcription and replication are, like many other nuclear functions and components, concentrated in nuclear domains. Transcription domains and replication domains may play an important role in the coordination of gene expression and gene duplication in S-phase. We have investigated the spatial relationship between transcription and replication in S-phase nuclei after fluorescent labelling of nascent RNA and nascent DNA, using confocal immunofluorescence microscopy. Permeabilized human bladder carcinoma cells were labelled with 5-bromouridine 5′-triphosphate and digoxigenin-11-deoxyuridine 5′-triphosphate to visualize sites of RNA synthesis and DNA synthesis, respectively. Transcription by RNA polymerase II was localized in several hundreds of domains scattered throughout the nucleoplasm in all stages of S-phase. This distribution resembled that of nascent DNA in early S-phase. In contrast, replication patterns in late S-phase consisted of fewer, larger replication domains. In double-labelling experiments we found that transcription domains did not colocalize with replication domains in late S-phase nuclei. This is in agreement with the notion that late replicating DNA is generally not actively transcribed. Also in early S-phase nuclei, transcription domains and replication domains did not colocalize. We conclude that nuclear domains exist, large enough to be resolved by light microscopy, that are characterized by a high activity of either transcription or replication, but never both at the same time. This probably means that as soon as the DNA in a nuclear domain is being replicated, transcription of that DNA essentially stops until replication in the entire domain is completed.
Localization of a kinesin-related protein to the central pair apparatus of the Chlamydomonas reinhardtii flagellum
Authors: Johnson Karl A. , Haas Michael A. , Rosenbaum Joel L. 
Published: April 2021

ABSTRACT
Affinity-purified polyclonal antibodies raised against the conserved motor domain of Drosophila kinesin (αHD) rec- ognized a 110 kDa component of the Chlamydomonas flagellar axoneme. Whole-mount immunogold labeling of splayed axonemes showed the striking localization of this antigen along one of the two microtubules of the central pair apparatus. Interestingly, the αHD antigen was also localized along the central axis of mutant axonemes lacking the central pair microtubules. These results suggest that a 110 kDa kinesin-related protein is a structural component of the flagellar central pair apparatus and that it is correctly targeted even in the absence of the central pair microtubules.
The presence or absence of a vimentin-type intermediate filament network affects the shape of the nucleus in human SW-13 cells
Authors: Sarria Alfonso J. , Lieber Jonathan G. , Nordeen Steven K. , Evans Robert M. 
Published: April 2021

ABSTRACT
Human SW-13 cells express the intermediate filament protein vimentin in a mosaic pattern (Hedberg, K. K. and Chen, L. B. (1986). Exp. Cell Res. 163, 509-517). We have isolated SW-13 clones that do (vim+) or do not (vim−) syn- thesize vimentin as analyzed using anti-intermediate filament immunofluorescence, electron microscopy and two-dimensional gel analysis of detergent-extracted prepa- rations. Vimentin is the only cytoplasmic intermediate filament protein present in the vim+ cells, and the vim− cells do not contain any detectable cytoplasmic intermediate filament system. The presence or absence of intermediate filaments did not observably affect the distribution of mito- chondria, endoplasmic reticulum, microtubules or actin stress fibers when these structures were visualized by fluo- rescence microscopy. However, electron microscopy and anti-lamin A/C immunofluorescence studies showed that nuclear morphology in vim− cells was frequently charac- terized by large folds or invaginations, while vim+ cells had a more regular or smooth nuclear shape. When vim− cells were transfected with a mouse vimentin expression plasmid, the synthesis of a mouse vimentin filament network restored the smooth nuclear morphology charac- teristic of vim+ cells. Conversely, when vim+ cells were transfected with a carboxy-terminally truncated mutant vimentin, expression of the mutant protein disrupted the organization of the endogenous vimentin filaments and resulted in nuclei with a prominently invaginated mor- phology. These results indicated that in SW-13 cells the vimentin filament system affects the shape of the nucleus.
Involvement of cell-cell adhesion in the expression of the cell cohesion molecule gp80 in Dictyostelium discoideum
Authors: Desbarats Laurie , Brar Simuran K. , Siu Chi-Hung 
Published: April 2021

ABSTRACT
Soon after the initiation of the developmental cycle of Dictyostelium discoideum, cells acquire EDTA-sensitive cellcell binding sites mediated by the glycoprotein gp24. Cells at the aggregation stage display a second type of cell adhesion site, the EDTA-resistant cell-cell binding sites, mediated by the glycoprotein gp80. The gene encoding gp80 is first turned on to a low basal level of expression in the preaggregation stage. At the onset of the aggregation stage, cells produce pulses of low levels of cAMP, which greatly augment the expression of gp80. To investigate the role of cell-cell adhesion in the regulation of gp80 expression, cells were developed in the presence of EDTA or carnitine to block the EDTA-sensitive cell binding sites. Alternatively, cell cohesion was disrupted by shaking lowdensity cultures at high shearing forces. In all three instances, gp80 was expressed at a substantially reduced level. In addition, exogenous cAMP pulses, which normally were capable of stimulating a precocious and enhanced expression of gp80, failed to restore the high level of gp80 expression. However, if the formation of cell-cell contact was permitted, exogenous cAMP pulses were able to rescue the expression of gp80 even when the cAMP signal relay was blocked. These results indicate that previous cell-cell contact, provided by the EDTA-sensitive binding sites, is required for the activation of the cAMP-mediated signal transduction pathway producing high levels of gp80 expression.
A calcineurin-like gene ppb1
+ in fission yeast: mutant defects in cytokinesis, cell polarity, mating and spindle pole body positioning
Authors: Yoshida Tetsuya , Toda Takashi , Yanagida Mitsuhiro 
Published: April 2021

ABSTRACT
A calcineurin (type 2B)-like protein phosphatase gene designated ppb1+ was isolated from the fission yeast Schizosac-charomyces pombe. The predicted amino acid sequence was 57% identical to rat PP2Bα. ppb1 null mutant could form colonies at 33°C but the size of the colonies was small at 22°C. Cytokinesis was greatly delayed at 22°C, and a large number of multi-septate cells were produced. The cell polarity control was impaired, causing branched cells. ppb1 null was virtually sterile. These phenotypes were rescued by a plasmid carrying the ppb1+ gene. Multi-septate cells were also produced in wild type at 22°C by cyclosporin A, an inhibitor of calcineurin. This drug effect was enhanced in stst1 null mutant, which was hypersensitive to various drugs and cations. ppb1 null was not affected by cyclosporin A, consistent with the hypothesis that ppb1 is its target. Double-mutant analysis indicated that ppb1 had a function related to that of two other phosphatases, type 1-like dis2 and 2A-like ppa2. ppb1 null-sts1 null showed the severe multi-septate phenotype in the absence of cyclosporin A. ppb1+ and sts1+ gene functions are related. The double mutant ppb1-sts5 was lethal, indicating that the ppb1+ gene shared an essential function with the sts5+ gene. Overexpression of ppb1+ caused anomalies in cell and nuclear shape, microtubule arrays and spindle pole body positioning in interphase cells. Thus the ppb1+ gene appears to be involved in cytokinesis, mating, transport, nuclear and spindle pole body positioning, and cell shape.
Regulation of myosin regulatory light chain phosphorylation via cyclic GMP during chemotaxis of Dictyostelium
Authors: Liu Gang , Newell Peter C. 
Published: April 2021

ABSTRACT
Previous studies on the chemotactic movement of Dictyostelium have indicated a role for cyclic GMP in regulating the association of myosin II with the cytoskeleton. In this study we have examined the part played by phosphorylation of the 18 kDa myosin regulatory light chain in this event. Using streamer F mutant NP368 (which is deficient in the structural gene for cyclic GMP-specific phosphodiesterase) we find that, for the regulatory light chain kinase, the major peak of phosphorylation is delayed compared to the parental control strain XP55, occurring at 80 seconds rather than about 30 seconds in XP55. In two independently derived mutants that are unable to increase their cellular concentration of cyclic GMP (above basal levels) in response to a chemotactic stimulus of cyclic AMP (KI-10 and SA219), no increase in the phosphorylation of the light chain occurred, or movement of myosin II to the cytoskeleton. We also find a smaller peak of light chain phosphorylation that occurs within 10 seconds of cyclic AMP stimulation of the amoebae, and which is absent in the cyclic GMP-unresponsive strains. We conclude that cyclic GMP is involved in regulating light chain phosphorylation in this system. The possible significance of these findings is discussed and a model that relates these findings to published data on cytoskeletal myosin changes during chemotaxis is presented.
Sites in human nuclei where DNA damaged by ultraviolet light is repaired: visualization and localization relative to the nucleoskeleton
Authors: Jackson Dean A. , Balajee A. S. , Mullenders Leon , Cook Peter R. 
Published: April 2021

ABSTRACT
The repair of damage induced in DNA by ultraviolet light involves excision of the damage and then repair synthesis to fill the gap. We investigated the sites of repair synthesis using MRC-5 fibroblasts and HeLa cells in G1 phase. Cells were encapsulated in agarose microbeads to protect them during manipulation, irradiated, incubated to allow repair to initiate, and permeabilized with streptolysin O to allow entry of labelled triphosphates; [32P]dTTP was incorporated into acid-insoluble material in a dose-dependent manner. Incubation with biotin-16-dUTP allowed sites of incorporation to be indirectly immunolabelled using a FITC-conjugated antibody; sites were not diffusely spread throughout nuclei but concentrated in discrete foci. This is similar to sites of S phase activity that are attached to an underlying nucleoskeleton. After treatment with an endonuclease, most repaired DNA electroeluted from beads with chromatin fragments; this was unlike nascent DNA made during S phase and suggests that repaired DNA is not as closely associated with the skeleton. However, the procedure destroyed repair activity, so repaired DNA might be attached in vivo through a polymerase that was removed electrophoretically. Therefore this approach cannot be used to determine decisively whether repair sites are associated with a skeleton in vivo.
Transfection of rat dermal papilla cells with a gene encoding a temperature-sensitive polyomavirus large T antigen generates cell lines retaining a differentiated phenotype
Authors: Filsell Wendy , Little Julie C. , Stones Amanda J. , Granger Stewart P. , Bayley Susan A. 
Published: April 2021

ABSTRACT
The dermal papilla is a discrete group of cells at the base of the hair follicle and is implicated in controlling the hair growth cycle. Early passage dermal papilla cells can induce hair growth in vivo, but, upon further culturing, this property is lost. In order to study the events occurring in hair induction, a representative dermal papilla cell line was required. We have transfected passage 1 rat vibrissa dermal papilla cells with a polyomavirus large T gene encoding a temperature-sensitive T antigen, and generated permanent cell lines in which the immortalizing function can be switched off by temperature shift. The cells established without crisis, resembled cells in the starting population, and retained the aggregative properties of early passage dermal papilla cells. Growth studies were performed on the immortalized cell lines, which showed that transferring the cells to the restrictive temperature for the large T gene product resulted in cell senescence or quiescence, and changes in morphology. Implantation of cell pellets into the ears of immunologically compatible rats showed that the immortal cells retained hair-inductive ability.
Cytokines are believed to have an important role in the control of hair growth. The pattern of cytokine gene expression in the immortal cell lines was compared with early passage dermal papilla cells and a non-hair-inducing dermal papilla cell line, using reverse transcriptase-polymerase chain reaction. Epidermal growth factor, tumour necrosis factor, and interleukin-1a were detected in the immortalized and non-hair-inducing dermal papilla cell lines, but were absent in passage 2 dermal papilla cells. All other cytokines examined were detected in all the cell types under study.
These results demonstrate that the polyomavirus large Ttsa-immortalized dermal papilla cell lines are very similar to passage 2 dermal papilla cells and thus provide a good model for hair growth studies. Cytokine expression profiles indicate that the expression of several cytokines may be implicated in hair induction. Further studies are under way to investigate the relationship between cytokine expression and the hair growth cycle.