scholarly journals Functional differences between L- and T-plastin isoforms.

1994 ◽  
Vol 127 (6) ◽  
pp. 1995-2008 ◽  
Author(s):  
M Arpin ◽  
E Friederich ◽  
M Algrain ◽  
F Vernel ◽  
D Louvard
Keyword(s):  
Cell Line ◽  
Tissue Specificity ◽  
Cell Function ◽  
Biological Significance ◽  
Epithelial Cell Line ◽  
Functional Differences ◽  
Cell Biol ◽  
Ionic Detergent ◽  
A Cell ◽  
Cell Type Specific

Fimbrins/plastins are a family of highly conserved actin-bundling proteins. They are present in all eukaryotic cells including yeast, but each isoform displays a remarkable tissue specificity. T-plastin is normally found in epithelial and mesenchymal cells while L-plastin is present in hematopoietic cells. However, L-plastin has been also found in tumor cells of non-hematopoietic origin (Lin, C.-S., R. H. Aebersold, S. B. Kent, M. Varma, and J. Leavitt. 1988. Mol. Cell. Biol. 8:4659-4668; Lin, C.-S., R. H. Aebersold, and J. Leavitt. 1990. Mol. Cell. Biol. 10: 1818-1821). To learn more about the biological significance of their tissue specificity, we have overproduced the T- and L-plastin isoforms in a fibroblast-like cell line, CV-1, and in a polarized epithelial cell line, LLC-PK1. In CV-1 cells, overproduction of T- and L-plastins induces cell rounding and a concomitant reorganization of actin stress fibers into geodesic structures. L-plastin remains associated with microfilaments while T-plastin is almost completely extracted after treatment of the cells with non-ionic detergent. In LLC-PK1 cells, T-plastin induces shape changes in microvilli and remains associated with microvillar actin filaments after detergent extraction while L-plastin has no effect on these structures and is completely extracted. The effect of T-plastin on the organization of microvilli differs from that of villin, another actin-bundling protein. Our experiments indicate that these two isoforms play differing roles in actin filament organization, and do so in a cell type-specific fashion. Thus it is likely that these plastin isoforms play fundamentally different roles in cell function.

Quantitative cell fusion: the fusion sensitivity (FS) potential

1981 ◽  
Vol 49 (1) ◽  
pp. 87-97
Author(s):  
D. Rohme
Keyword(s):  
Cell Line ◽  
Cell Fusion ◽  
Cell Lines ◽  
Dose Response ◽  
Sendai Virus ◽  
Biological Significance ◽  
Diploid Cell ◽  
Mammalian Cell Lines ◽  
Virus Dose ◽  
A Cell

The dose response of Sendai virus-induced cell fusion was studied in 10 mammalian cell lines, comprising 5 continuous and 5 diploid cell lines originating from 5 species. The extent of fusion was calculated using a parameter directly proportional to the number of fusion events (t-parameter). At lower levels of fusion the dose response was found to be based on the same simple kinetic rules in all cell lines and was defined by the formula: t = FS. FAU/(I + FS. FAU), where FS (fusion sensitivity) is a cell-specific constant of the fusion rate and FAU (fusion activity units) is the virus dose. The FS potential of a cell line was determined as the linear regression coefficient of the fusion index (t/(I - t)) on the virus dose. At higher levels of fusion, when the fusion extent reached cell-line-specific maximal levels, the dose response was not as uniform. In general, and particularly in the cases of the diploid cell lines, these maximal levels were directly proportional to the FS potentials. Thus, it was concluded that the FS potential is the basic quantitative feature, which expresses the cellular fusion efficiency. The fact that FS varied extensively between cell lines, but at the same time apparently followed certain patterns (being higher in continuous compared to diploid cell lines and being related to the species of origin of the cells), emphasizes it biological significance as well as its possible usefulness in studies of the efficiency of various molecular interactions in the cell membrane/cytoskeleton system.

scholarly journals Interaction of soluble fibroblast surface antigen with fribrinogen and fibrin.

1975 ◽  
Vol 141 (2) ◽  
pp. 497-501 ◽  
Author(s):  
E Ruoslahti ◽  
A Vaheri
Keyword(s):  
Human Plasma ◽  
Low Temperatures ◽  
Serum Proteins ◽  
Biological Significance ◽  
Cell Type ◽  
Fold Enrichment ◽  
Glycoprotein Antigen ◽  
A Cell ◽  
Cell Type Specific ◽  
Cold Insoluble Globulin

A cell-type specific glycoprotein antigen (SFA) from fibroblast surface appears in human plasma and serum. The amount of SFA in serum was reduced if the blood coagulation clot was removed at a low temperature. SFA could be bound to Sepharose-conjugated fibrinogen and to fibrin powder at 0 degrees C and was subsequently released when the temperature was elevated to plus 37 degrees C. This procedure resulted in a 10-fold enrichment of SFA relative to other serum proteins. SFA was found to be concentrated in the cryoprecipitate fraction of human plasma and was copurified with the cold insoluble globulin (CIG) with procedures published for the purification of the latter component. SFA/CIG is not soluble at low temperatures as such and its appearance in the cryoprecipitate fraction of plasma is likely to be due to its affinity to cryofibrinogen evident from these experiments. The biological significance of the interaction of fibroblast surface SFA moleculres with fibrin(ogen) is not known.

scholarly journals A Cell type-specific Class of Chromatin Loops Anchored at Large DNA Methylation Nadirs

2017 ◽  
Author(s):  
Mira Jeong ◽  
Xingfan Huang ◽  
Xiaotian Zhang ◽  
Jianzhong Su ◽  
Muhammad S. Shamim ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Cell Function ◽  
Cell Types ◽  
Specific Class ◽  
Hematopoietic Stem ◽  
Cell State ◽  
Chromatin Loops ◽  
Stem And Progenitor Cells ◽  
A Cell ◽  
Cell Type Specific

AbstractHigher order chromatin structure and DNA methylation are implicated in multiple developmental processes, but their relationship to cell state is unknown. Here, we found that large (~10kb) DNA methylation nadirs can form long loops connecting anchor loci that may be dozens of megabases apart, as well as interchromosomal links. The interacting loci comprise ~3.5Mb of the human genome. The data are more consistent with the formation of these loops by phase separation of the interacting loci to form a genomic subcompartment, rather than with CTCF-mediated extrusion. Interestingly, unlike previously characterized genomic subcompartments, this subcompartment is only present in particular cell types, such as stem and progenitor cells. Further, we identify one particular loop anchor that is functionally associated with maintenance of the hematopoietic stem cell state. Our work reveals that H3K27me3-marked large DNA methylation nadirs represent a novel set of very long-range loops and links associated with cellular identity.SummaryHi-C and DNA methylation analyses reveal novel chromatin loops between distant sites implicated in stem and progenitor cell function.

Species-specific lens activation of the thymidine kinase promoter by a single copy of the mouse alpha A-CRYBP1 site and loss of tissue specificity by multimerization

1990 ◽  
Vol 10 (12) ◽  
pp. 6813-6816
Author(s):  
C M Sax ◽  
J F Klement ◽  
J Piatigorsky
Keyword(s):  
Epithelial Cell ◽  
Cell Line ◽  
Thymidine Kinase ◽  
Tissue Specificity ◽  
Single Copy ◽  
Lens Epithelial Cell ◽  
Epithelial Cell Line ◽  
Multiple Copies ◽  
Species Specific ◽  
Mouse Lens

One copy of the mouse alpha A-crystallin gene alpha A-CRYBP1 site activated the thymidine kinase (tk) promoter in a mouse lens epithelial cell line but not in primary chicken lens cells; multiple copies further activated the tk promoter and extended expression to fibroblasts, B cells, and chicken lens cultures. The loss of lens specificity by multimerization may place selective constraints on the number of alpha A-CRYBP1 sites in the alpha A-crystallin promoter.

GATA-6 stimulates a cell line-specific activation element in the human lactase promoter

1998 ◽  
Vol 274 (2) ◽  
pp. G314-G324 ◽  
Author(s):  
Kevin Fitzgerald ◽  
Leonard Bazar ◽  
Mark I. Avigan
Keyword(s):  
Cell Line ◽  
Mutational Analysis ◽  
Protein Complexes ◽  
Protein S ◽  
Electrophoretic Analysis ◽  
Specific Protein ◽  
Consensus Motif ◽  
A Cell ◽  
Cell Type Specific ◽  
Development Analysis

Lactase-phlorizin hydrolase (LPH) synthesis is restricted to differentiated small intestinal enterocytes and is highly regulated during development. Analysis of expression of LPH promoter segments fused with luciferase transfected in Caco-2 cells, a line that uniquely expresses LPH mRNA, mapped an 18-base pair (bp) segment 100 bp upstream of the transcription start site that is required for transactivation. Remarkably, the LPH upstream element (LUE) has no stimulatory activity in both human intestinal and nonintestinal lines in which LPH mRNA is absent. Electrophoretic analysis of sequence-specific DNA-nuclear protein complexes demonstrated the presence of a Caco-2 cell-specific protein(s) (CCP), which is uniformly absent in LPH nonproducer cell lines. Mutational analysis of the LUE demonstrated that bases contained within a GATA consensus motif are critical for both CCP binding and transcription from the LPH promoter. Caco-2 cells express high levels of GATA-6 mRNA in a cell line- specific manner, suggesting that GATA-6 is a CCP that complexes with the LUE. When expressed by a plasmid, GATA-6 transactivated the LPH promoter. The stimulation was abrogated with mutations in the GATA consensus motif as well as mutations in a flanking downstream element. These studies are consistent with an important role of an intestinal GATA binding protein in cell type-specific transactivation of the LPH promoter.

scholarly journals MicroRNA-9 Fine-Tunes Dendritic Cell Function by Suppressing Negative Regulators in a Cell-Type-Specific Manner

Cell Reports ◽  
2020 ◽  
Vol 31 (5) ◽  
pp. 107585
Author(s):  
Brendan Cordeiro ◽  
Peter Jeon ◽  
Giselle M. Boukhaled ◽  
Mario Corrado ◽  
Orsolya Lapohos ◽  
...  
Keyword(s):  
Dendritic Cell ◽  
Cell Function ◽  
Dendritic Cell Function ◽  
Cell Type ◽  
Negative Regulators ◽  
Specific Manner ◽  
A Cell ◽  
Cell Type Specific

scholarly journals A new epithelial cell line, SSK from kidney of striped snakehead Channa striatus (Bloch 1793)

2017 ◽  
Vol 64 ◽  
Author(s):  
D. K. Chaudhary ◽  
N. Sood ◽  
D. K. Verma ◽  
T. R. Swaminathan ◽  
B. Kushwaha ◽  
...  
Keyword(s):  
Cell Line ◽  
Neutral Red ◽  
Epithelial Cell Line ◽  
Channa Striatus ◽  
Neutral Red Assay ◽  
Mammalian Expression ◽  
Cytotoxicity Studies ◽  
Different Temperatures ◽  
A Cell ◽  
Foetal Bovine Serum

A cell line was established from striped snakehead Channa striatus kidney. The cell line, named as SSK, has been passaged for over 62 times. Growth studies at different temperatures and foetal bovine serum (FBS) concentrations revealed that SSK cells show optimum growth at 28°C in L-15 medium containing 20% FBS. The chromosome number of SSK cells was 2n=40. Partial sequencing of mitochondrial cytochrome oxidase 1 gene of the cells confirmed that the cell line originated from C. striatus. The SSK cells were primarily epithelial, as determined using immunophenotyping. The cells from SSK cell line were transfected with phrGFP II-N mammalian expression vector. The SSK cell line was stored in liquid nitrogen (-196οC) at different passages and was successfully revived after four months of storage. The cell line could be successfullyemployed for cytotoxicity studies, as revealed by neutral red assay. The cell line can be a valuable surrogate to the whole fish studies.

scholarly journals Differential Use of Rap1 Effectors for Integrin Activation in Platelets and Lymphocytes

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 27-28
Author(s):  
Frederic Lagarrigue ◽  
Hao Sun ◽  
Alexandre R Gingras ◽  
Mark H Ginsberg
Keyword(s):  
T Cells ◽  
Blood Cells ◽  
Cell Function ◽  
Conflicts Of Interest ◽  
Point Mutations ◽  
Immune Functions ◽  
Integrin Activation ◽  
Convergence Point ◽  
A Cell ◽  
Cell Type Specific

Rap1 is a major convergence point of the platelet and lymphocyte signaling pathways that result in talin1 binding to the integrin β-cytoplasmic domain and consequent integrin activation, effective hemostasis and immune functions. The nature of the connection between Rap1 and talin1 in integrin activation is an important remaining gap in our understanding of this process. Deletion of RIAM in T cells partially suppressed αLβ2 and α4β7 integrin activation but did not block activation of α4β1. In sharp contrast, deletion of both Rap1a and Rap1b isoforms or deletion of talin1 profoundly suppressed activation of α4β1 in addition to the other two integrins. The loss of homing of T cells to peripheral lymphoid organs was correlated with the loss of integrin activation in these mutant T cells. We recently identified two Rap1 binding sites in talin1 F0 and F1 domains and generated mice bearing point mutations, which block Rap1 binding to both talin1 F0 and F1 domains (R35E,R118E). In platelets, which lack endogenous RIAM, a talin1 (R35E,R118E) mutation suppresses activation of integrin αIIbβ3 and platelet aggregation to a similar extent to that observed in Rap1a,b null platelets. In contrast, talin1 (R35E,R118E)-expressing T cells manifest only partial loss of integrin activation, whereas RIAM null T cells expressing talin1 (R35E,R118E) exhibit a much more profound defect. Importantly, overexpression of RIAM can completely rescue the integrin activation defect in talin1 (R35E,R118E)-expressing T cells indicating that Rap1 binding to RIAM and talin1 are partially redundant in T cells. These findings reveal that although both Rap1 and talin1 are essential for integrin action in blood cells, the connections between them vary in different blood cells and that the final steps in integrin activation and blood cell function can be manipulated in a cell-type specific manner. Disclosures No relevant conflicts of interest to declare.

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