scholarly journals A KINETIC ANALYSIS OF MYOGENESIS IN VITRO

1972 ◽  
Vol 52 (1) ◽  
pp. 52-65 ◽  
Author(s):  
Michael C. O'Neill ◽  
Frank E. Stockdale
Keyword(s):  
Cell Cycle ◽  
Cell Fusion ◽  
Tritiated Thymidine ◽  
Culture Conditions ◽  
Complete Fusion ◽  
Low Density ◽  
A Cell ◽  
Muscle Cultures ◽  
S Period

Conditions which yielded reproducible growth kinetics with extensive, relatively synchronous differentiation are described for chick muscle cultures. The effects of cell density and medium changes on the timing of cell fusion were examined. Low-density cultures which received a change of medium at 24 hr after plating show the highest rate of cell fusion, increasing from 15 to 80% fused cells in a 10 hr period. These optimal culture conditions were employed to reexamine two questions from the earlier literature on muscle culture: (a) can cells which normally would fuse at the end of one cell cycle be forced to go through another cell cycle before fusion; and (b) how soon after its final S period can a cell complete fusion? In answer to the first question, it was found that if the medium is changed, many cells which would otherwise fuse can be made to undergo another cell cycle before fusion. In the second case, radioautographs were made from cultures incubated with tritiated thymidine for various times at the beginning of the fusion period. These show labeled nuclei in myotubes as early as 3 hr after the beginning of the incubation period. This indicates that cells can fuse as early as the beginning of the G1 period, and suggests that there is not an obligatory exit from the cell cycle or a prolonged G1 period before cell fusion and differentiation during myogenesis.

scholarly journals Differences in cell cycle characteristics among patients with acute nonlymphocytic leukemia

Blood ◽  
1987 ◽  
Vol 69 (6) ◽  
pp. 1647-1653 ◽  
Author(s):  
A Raza ◽  
Y Maheshwari ◽  
HD Preisler
Keyword(s):  
Cell Cycle ◽  
Tritiated Thymidine ◽  
S Phase ◽  
Total Cell ◽  
Acute Nonlymphocytic Leukemia ◽  
Cell Cycle Time ◽  
Myeloid Leukemias ◽  
History Of

The proliferative characteristics of myeloid leukemias were defined in vivo after intravenous infusions of bromodeoxyuridine (BrdU) in 40 patients. The percentage of S-phase cells obtained from the biopsies (mean, 20%) were significantly higher (P = .00003) than those determined from the bone marrow (BM) aspirates (mean, 9%). The post- BrdU infusion BM aspirates from 40 patients were incubated with tritiated thymidine in vitro. These double-labeled slides were utilized to determine the duration of S-phase (Ts) in myeloblasts and their total cell cycle time (Tc). The Ts varied from four to 49 hours (mean, 19 hours; median, 17 hours). Similarly, there were wide variations in Tc of individual patients ranging from 16 to 292 hours (mean, 93 hours; median, 76 hours). There was no relationship between Tc and the percentage of S-phase cells, but there was a good correlation between Tc and Ts (r = .8). Patients with relapsed acute nonlymphocytic leukemia (ANLL) appeared to have a longer Ts and Tc than those studied at initial diagnosis. A subgroup of patients at either extreme of Tc were identified who demonstrated clinically documented resistance in response to multiple courses of chemotherapy. We conclude that Ts and Tc provide additional biologic information that may be valuable in understanding the variations observed in the natural history of ANLL.

scholarly journals The Anticoagulant Nafamostat Potently Inhibits SARS-CoV-2 S Protein-Mediated Fusion in a Cell Fusion Assay System and Viral Infection In Vitro in a Cell-Type-Dependent Manner

Viruses ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 629 ◽  
Author(s):  
Mizuki Yamamoto ◽  
Maki Kiso ◽  
Yuko Sakai-Tagawa ◽  
Kiyoko Iwatsuki-Horimoto ◽  
Masaki Imai ◽  
...  
Keyword(s):  
Cell Fusion ◽  
Assay System ◽  
Dependent Manner ◽  
Cell Type ◽  
S Protein ◽  
Candidate Drug ◽  
A Cell ◽  
Transmembrane Serine Protease ◽  
Nafamostat Mesylate

Although infection by SARS-CoV-2, the causative agent of coronavirus pneumonia disease (COVID-19), is spreading rapidly worldwide, no drug has been shown to be sufficiently effective for treating COVID-19. We previously found that nafamostat mesylate, an existing drug used for disseminated intravascular coagulation (DIC), effectively blocked Middle East respiratory syndrome coronavirus (MERS-CoV) S protein-mediated cell fusion by targeting transmembrane serine protease 2 (TMPRSS2), and inhibited MERS-CoV infection of human lung epithelium-derived Calu-3 cells. Here we established a quantitative fusion assay dependent on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S protein, angiotensin I converting enzyme 2 (ACE2) and TMPRSS2, and found that nafamostat mesylate potently inhibited the fusion while camostat mesylate was about 10-fold less active. Furthermore, nafamostat mesylate blocked SARS-CoV-2 infection of Calu-3 cells with an effective concentration (EC)50 around 10 nM, which is below its average blood concentration after intravenous administration through continuous infusion. On the other hand, a significantly higher dose (EC50 around 30 μM) was required for VeroE6/TMPRSS2 cells, where the TMPRSS2-independent but cathepsin-dependent endosomal infection pathway likely predominates. Together, our study shows that nafamostat mesylate potently inhibits SARS-CoV-2 S protein-mediated fusion in a cell fusion assay system and also inhibits SARS-CoV-2 infection in vitro in a cell-type-dependent manner. These findings, together with accumulated clinical data regarding nafamostat’s safety, make it a likely candidate drug to treat COVID-19.

scholarly journals Experimental Study on Cell-free Approach for Articular Cartilage Treatment

2019 ◽  
Vol 5 (1) ◽  
pp. 171-174 ◽  
Author(s):  
Gözde Dursun ◽  
Bernd Markert ◽  
Marcus Stoffel
Keyword(s):  
Articular Cartilage ◽  
Petri Dish ◽  
Treatment Method ◽  
Culture Conditions ◽  
Cyclic Compression ◽  
A Cell ◽  
Static Cultivation ◽  
Promising Treatment ◽  
Bioreactor System

AbstractCell-free based approaches are introduced as a promising treatment method for articular cartilage. The success of this method requires cell colonisation from resident tissue into cell-free implants. The objective of our study is to promote the cell colonisation into cell-free collagen I based implants by mechanical stimulation. Therefore, a new in vitro cellular model consisting chondrocyte-seeded matrix and cell-free implants was developed in a polydimethylsiloxan (PDMS) mold. These constructs were cultured under dynamic and static culture conditions. For the dynamic culture, we have developed an in-house bioreactor system where both the load and the deformation applied to the specimen are recorded. Cyclic compression, with a strain of 5% and frequency of 0.1 Hz, was applied to constructs without any break. At the end of three days of dynamic and static cultivation, the cell-free implants were seperated from cell-seeded matrix and cultured in a petri dish three days long. Afterwards, they were analysed using fluoresence dyes. The microscopic assessment indicated that there was a cell migration into the cell-free implants which were cultured dynamically.

scholarly journals Evidence for a dual role for TC4 protein in regulating nuclear structure and cell cycle progression.

1994 ◽  
Vol 125 (4) ◽  
pp. 705-719 ◽  
Author(s):  
S Kornbluth ◽  
M Dasso ◽  
J Newport
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Nuclear Structure ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Nuclear Assembly ◽  
Egg Extracts ◽  
A Cell ◽  
Xenopus Egg Extracts

TC4, a ras-like G protein, has been implicated in the feedback pathway linking the onset of mitosis to the completion of DNA replication. In this report we find distinct roles for TC4 in both nuclear assembly and cell cycle progression. Mutant and wild-type forms of TC4 were added to Xenopus egg extracts capable of assembling nuclei around chromatin templates in vitro. We found that a mutant TC4 protein defective in GTP binding (GDP-bound form) suppressed nuclear growth and prevented DNA replication. Nuclear transport under these conditions approximated normal levels. In a separate set of experiments using a cell-free extract of Xenopus eggs that cycles between S and M phases, the GDP-bound form of TC4 had dramatic effects, blocking entry into mitosis even in the complete absence of nuclei. The effect of this mutant TC4 protein on cell cycle progression is mediated by phosphorylation of p34cdc2 on tyrosine and threonine residues, negatively regulating cdc2 kinase activity. Therefore, we provide direct biochemical evidence for a role of TC4 in both maintaining nuclear structure and in the signaling pathways that regulate entry into mitosis.

scholarly journals Profiling of Epigenetic Features in Clinical Samples Reveals Novel Widespread Changes in Cancer

Cancers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 723 ◽  
Author(s):  
Roberta Noberini ◽  
Camilla Restellini ◽  
Evelyn Oliva Savoia ◽  
Francesco Raimondi ◽  
Lavinia Ghiani ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Expression Profiles ◽  
Histone H3 ◽  
Gene Expression Profiles ◽  
Culture Conditions ◽  
Clinical Samples ◽  
Post Translational Modifications ◽  
A Cell ◽  
Cancer Types ◽  
Histone Modifying Enzymes

Aberrations in histone post-translational modifications (PTMs), as well as in the histone modifying enzymes (HMEs) that catalyze their deposition and removal, have been reported in many tumors and many epigenetic inhibitors are currently under investigation for cancer treatment. Therefore, profiling epigenetic features in cancer could have important implications for the discovery of both biomarkers for patient stratification and novel epigenetic targets. In this study, we employed mass spectrometry-based approaches to comprehensively profile histone H3 PTMs in a panel of normal and tumoral tissues for different cancer types, identifying various changes, some of which appear to be a consequence of the increased proliferation rate of tumors, while others are cell-cycle independent. Histone PTM changes found in tumors partially correlate with alterations of the gene expression profiles of HMEs obtained from publicly available data and are generally lost in culture conditions. Through this analysis, we identified tumor- and subtype-specific histone PTM changes, but also widespread changes in the levels of histone H3 K9me3 and K14ac marks. In particular, H3K14ac showed a cell-cycle independent decrease in all the seven tumor/tumor subtype models tested and could represent a novel epigenetic hallmark of cancer.

Type II pneumocyte hypertrophy without activation of surfactant biosynthesis after partial pneumonectomy

1993 ◽  
Vol 264 (2) ◽  
pp. L153-L159 ◽  
Author(s):  
B. D. Uhal ◽  
M. D. Etter
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Tritiated Thymidine ◽  
Cell Cycle Distribution ◽  
Type Ii ◽  
Adult Rats ◽  
Type Ii Pneumocyte ◽  
Significant Difference

Hypertrophic and normotrophic type II pneumocytes were isolated from pneumonectomized adult rats by unit gravity (1 g) sedimentation or by fluorescence-activated cell sorting (FACS). In vivo or in vitro, hypertrophic cells incorporated significantly more 5-bromo-2'-deoxyuridine or tritiated thymidine into acid-insoluble material than did normotrophic cells. By FACS analysis of cell subpopulations isolated by 1 g, > 97% of normotrophic cells had G0-phase DNA content. In contrast, the cell cycle distribution of hypertrophic cells was 75% G1, 5% S, and 20% G2/M phases. Rates of incorporation of tritiated choline into total cellular phosphatidylcholine (PC) were identical in type II cells isolated from normal or pneumonectomized rats. The intracellular contents of disaturated phosphatidylcholine (DSPC) and total PC, as well as the ratio of these two lipids, were the same in hypertrophic and normotrophic cells from pneumonectomized rats and in cells isolated from normal rats. No significant difference was observed in the rate at which hypertrophic or normotrophic cells incorporated choline into DSPC. These results demonstrate that type II pneumocyte hypertrophy after pneumonectomy reflects balanced cell growth secondary to cell cycle progression in vivo. The data also indicate that epithelial cell hypertrophy after pneumonectomy, in contrast to that which develops after more acute lung injury, occurs without activation of surfactant biosynthesis or storage.

Long Term Maintenance of Myeloid Leukemia Stem Cell-Like Populations Cultured with Mesenchymal Stromal Cells (MSC)

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3546-3546
Author(s):  
Sawa Ito ◽  
A. John Barrett ◽  
Andre Larochelle ◽  
Nancy F. Hensel ◽  
Keyvan Keyvanfar ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Stem Cell ◽  
Culture Conditions ◽  
Myelogenous Leukemia ◽  
Cell Cycle Analysis ◽  
Remission Induction ◽  
Leukemia Stem Cell

Abstract Abstract 3546 Because MSC support the growth and the differentiation of normal hematopoietic stem cells we hypothesized that MSC might also support leukemia cells, in particular leukemia stem cells (LSC) in vitro. We cultured blast cells from patients with acute myelogenous leukemia (AML) in liquid medium to study persistence of stem-cell-like and differentiated leukemia cell populations by flow cytometry, with and without MSC and additional growth factors. Cryopresrerved peripheral blood mononuclear cells (PBMC) were obtained from 6 AML patients (mean Age 47, range 23–74). Leukemia blasts were isolated by sorting live (propidium iodide (PI)-negative) CD34+ lineage (CD2+, CD3+, CD14+ and CD19+) -negative cells using a FACS ARIA II cell sorter (BD). Sorted blasts (2.5 ×105 cells) were co-cultured with an equal number of irradiated MSC derived from healthy donor bone marrow in RPMI medium supplemented with 10% human serum, with or without a human cytokine (CYTO) mixture (50 ng/ml interleukin 3, 150 ng/ml stem cell factor, and 150ng/ml Flt-3 ligand). MSC were replenished every two weeks. The phenotype of cultured cells was analyzed weekly using fluorescently-conjugated monoclonal antibodies against CD34, CD38, and CD45, plus the lineage panel and a dead cell exclusion dye Cell cycle analysis with Hoeschst 33342 and Pyronin Y was performed on cells co-stained with CD34, CD45 and PI. Primary leukemia samples were phenotypically heterogeneous with respect to proportions of cells (co-)staining for CD34 and CD38 as previously reported: three samples showed CD34+CD38- predominance (LSC-like leukemia), and three were CD34+CD38+ (common myeloid progenitor (CMP)-like leukemia). LSC-like leukemia maintained viable CD34+CD38- cells for at least 6 weeks when co-cultured with MSC alone, in contrast to cultures with cytokines or medium only which showed rapid decline in the LSC populations and no prolonged maintenance of viable cells (p=0.0005) (Figure, left panel). CMP-like leukemia maintained their CD34+CD38+ phenotype when co-cultured with MSC alone but persistence of this subset was not significantly different from the other culture conditions (p=0.5) and no culture remained viable after 4 weeks (Figure, right panel). Cell cycle analysis showed that co-culture with MSC maintained CD34+ blasts in G0 significantly more than other culture conditions (P<0.0001). We conclude that MSC support the maintenance of a leukemia stem cell phenotype in a long- term (6 week) in vitro culture system. The differential capacity of MSC to support LSC- like and CMP- like leukemia may be associated with the different frequency of leukemia initiating cells within each leukemic blast population. NSG mice xenotranplant model experiments are ongoing to confirm this hypothesis. Co-culture of LSC with MSC represents a simple approach to maintain LSC in vitro and could be utilized to screen the drug targeting LSCs. Further study of the effect of MSC on LSC would elucidate a potential mechanism whereby the marrow microenvironment serves as a reservoir of persisting leukemia after remission induction chemotherapy. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Reversal of Growth Suppression by p107 via Direct Phosphorylation by Cyclin D1/Cyclin-Dependent Kinase 4

2002 ◽  
Vol 22 (7) ◽  
pp. 2242-2254 ◽  
Author(s):  
Xiaohong Leng ◽  
Martin Noble ◽  
Peter D. Adams ◽  
Jun Qin ◽  
J. Wade Harper
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Control Cell ◽  
Growth Suppression ◽  
Cyclin Dependent Kinase ◽  
Culture Cells ◽  
Cycle Arrest ◽  
A Cell ◽  
Control Cell Division

ABSTRACT p107 functions to control cell division and development through interaction with members of the E2F family of transcription factors. p107 is phosphorylated in a cell cycle-regulated manner, and its phosphorylation leads to its release from E2F. Although it is known that p107 physically associates with E- and A-type cyclin/cyclin-dependent kinase 2 (Cdk2) complexes through a cyclin-binding RXL motif located in the spacer domain, the mechanisms underlying p107 inactivation via phosphorylation remain poorly defined. Recent genetic evidence indicates a requirement for cyclin D1/Cdk4 complexes in p107 inactivation. In this work, we provide direct biochemical evidence for the involvement of cyclin D1/Cdk4 in the inactivation of p107's growth-suppressive function. While coexpression of cyclin D1/Cdk4 can reverse the cell cycle arrest properties of p107 in Saos-2 cells, we find that p107 in which the Lys-Arg-Arg-Leu sequence of the RXL motif is replaced by four alanine residues is largely refractory to inactivation by cyclin D/Cdk4, indicating a role for this motif in p107 inactivation without a requirement for its tight interaction with cyclin D1/Cdk4. We identified four phosphorylation sites in p107 (Thr-369, Ser-640, Ser-964, and Ser-975) that are efficiently phosphorylated by Cdk4 but not by Cdk2 in vitro and are also phosphorylated in tissue culture cells. Growth suppression by p107 containing nonphosphorylatable residues in these four sites is not reversed by coexpression of cyclin D1/Cdk4. In model p107 spacer region peptides, phosphorylation of S640 by cyclin D1/Cdk4 is strictly dependent upon an intact RXL motif, but phosphorylation of this site in the absence of an RXL motif can be partially restored by replacement of S643 by arginine. This suggests that one role for the RXL motif is to facilitate phosphorylation of nonconsensus Cdk substrates. Taken together, these data indicate that p107 is inactivated by cyclin D1/Cdk4 via direct phosphorylation and that the RXL motif of p107 plays a role in its inactivation by Cdk4 in the absence of stable binding.

scholarly journals Sequential Assessment of Cell Cycle S Phase in Flow Cytometry: A Non-Isotopic Method to Measure Lymphocyte ActivationIn Vitro

1997 ◽  
Vol 14 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Ch. Kohler ◽  
M. N. Kolopp‐Sarda ◽  
A. De March‐Kennel ◽  
A. Barbaud ◽  
M. C. Béné ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Flow Cytometry ◽  
Cellular Proliferation ◽  
Tritiated Thymidine ◽  
S Phase ◽  
Phase Cell ◽  
Isotopic Method ◽  
Isotopic Methods ◽  
Recall Antigen

Lymphocyte multiplication can be inducedin vitroby mitogens or specific antigens, and is usually measured using isotopic methods involving tritiated thymidine. Cellular proliferation can also be analyzed by flow cytometry techniques based on cell cycle analysis through the measurement of DNA content. We applied this method to lymphocytes from 113 individuals, to evaluate lymphocyte proliferation after stimulationin vitroby a mitogen (phytohaemagglutinin, PHA) or a recall antigen (tetanus toxoid), using a kinetic approach with four points sequential measurements of the S and G2 phases over six days of culture. The proportion of cells in S phase after PHA stimulation was significantly higher than in controls overall and as early as on day three of the culture. Activation with a recall antigen significantly induced increasing S phase cell proportions up to day six. These data suggest that flow cytometric assessment of the S phase could be a useful alternative to isotopic methods measuring lymphocyte reactivityin vitro.

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