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ELife Mar 2016Antigen Ki-67 is a nuclear protein expressed in proliferating mammalian cells. It is widely used in cancer histopathology but its functions remain unclear. Here, we show...
Antigen Ki-67 is a nuclear protein expressed in proliferating mammalian cells. It is widely used in cancer histopathology but its functions remain unclear. Here, we show that Ki-67 controls heterochromatin organisation. Altering Ki-67 expression levels did not significantly affect cell proliferation in vivo. Ki-67 mutant mice developed normally and cells lacking Ki-67 proliferated efficiently. Conversely, upregulation of Ki-67 expression in differentiated tissues did not prevent cell cycle arrest. Ki-67 interactors included proteins involved in nucleolar processes and chromatin regulators. Ki-67 depletion disrupted nucleologenesis but did not inhibit pre-rRNA processing. In contrast, it altered gene expression. Ki-67 silencing also had wide-ranging effects on chromatin organisation, disrupting heterochromatin compaction and long-range genomic interactions. Trimethylation of histone H3K9 and H4K20 was relocalised within the nucleus. Finally, overexpression of human or Xenopus Ki-67 induced ectopic heterochromatin formation. Altogether, our results suggest that Ki-67 expression in proliferating cells spatially organises heterochromatin, thereby controlling gene expression.
Topics: Animals; Cell Proliferation; Gene Expression; Gene Knockdown Techniques; Heterochromatin; Humans; Ki-67 Antigen; Mice; Xenopus
PubMed: 26949251
DOI: 10.7554/eLife.13722 -
Journal of Immunology (Baltimore, Md. :... Nov 2016The ability to culture and expand B cells in vitro has become a useful tool for studying human immunity. A limitation of current methods for human B cell culture is the...
The ability to culture and expand B cells in vitro has become a useful tool for studying human immunity. A limitation of current methods for human B cell culture is the capacity to support mature B cell proliferation. We developed a culture method to support the efficient activation and proliferation of naive and memory human B cells. This culture supports extensive B cell proliferation, with ∼10-fold increases following 8 d in culture and 10-fold increases when cultures are split and cultured for 8 more days. In culture, a significant fraction of naive B cells undergo isotype switching and differentiate into plasmacytes. Culture-derived (CD) B cells are readily cryopreserved and, when recovered, retain their ability to proliferate and differentiate. Significantly, proliferating CD B cells express high levels of MHC class II, CD80, and CD86. CD B cells act as APCs and present alloantigens and microbial Ags to T cells. We are able to activate and expand Ag-specific memory B cells; these cultured cells are highly effective in presenting Ag to T cells. We characterized the TCR repertoire of rare Ag-specific CD4 T cells that proliferated in response to tetanus toxoid (TT) presented by autologous CD B cells. TCR Vβ usage by TT-activated CD4 T cells differs from resting and unspecifically activated CD4 T cells. Moreover, we found that TT-specific TCR Vβ usage by CD4 T cells was substantially different between donors. This culture method provides a platform for studying the BCR and TCR repertoires within a single individual.
Topics: Antigen-Presenting Cells; B-Lymphocytes; CD4 Antigens; CD4-Positive T-Lymphocytes; Cell Culture Techniques; Cell Line; Cell Proliferation; Cells, Cultured; Humans; Immunologic Memory; Lymphocyte Activation; Receptors, Antigen, T-Cell; Tetanus Toxoid
PubMed: 27815447
DOI: 10.4049/jimmunol.1502193 -
Nature Immunology May 2023Resident tissue macrophages (RTMs) are differentiated immune cells that populate distinct niches and exert important tissue-supportive functions. RTM maintenance is...
Resident tissue macrophages (RTMs) are differentiated immune cells that populate distinct niches and exert important tissue-supportive functions. RTM maintenance is thought to rely either on differentiation from monocytes or on RTM self-renewal. Here, we used a mouse model of inducible lung interstitial macrophage (IM) niche depletion and refilling to investigate the development of IMs in vivo. Using time-course single-cell RNA-sequencing analyses, bone marrow chimeras and gene targeting, we found that engrafted Ly6C classical monocytes proliferated locally in a Csf1 receptor-dependent manner before differentiating into IMs. The transition from monocyte proliferation toward IM subset specification was controlled by the transcription factor MafB, while c-Maf specifically regulated the identity of the CD206 IM subset. Our data provide evidence that, in the mononuclear phagocyte system, the ability to proliferate is not merely restricted to myeloid progenitor cells and mature RTMs but is also a tightly regulated capability of monocytes developing into RTMs in vivo.
Topics: Animals; Mice; Monocytes; Macrophages; Cell Differentiation; Lung; Cell Proliferation; MafB Transcription Factor
PubMed: 36928411
DOI: 10.1038/s41590-023-01468-3 -
Environmental Microbiology Nov 2022Methanonatronarchaeia represents a deep-branching phylogenetic lineage of extremely halo(alkali)philic and moderately thermophilic methyl-reducing methanogens belonging...
Methanonatronarchaeia represents a deep-branching phylogenetic lineage of extremely halo(alkali)philic and moderately thermophilic methyl-reducing methanogens belonging to the phylum Halobacteriota. It includes two genera, the alkaliphilic Methanonatronarchaeum and the neutrophilic Ca. Methanohalarchaeum. The former is represented by multiple closely related pure culture isolates from hypersaline soda lakes, while the knowledge about the latter is limited to a few mixed cultures with anaerobic haloarchaea. To get more insight into the distribution and ecophysiology of this enigmatic group of extremophilic methanogens, potential activity tests and enrichment cultivation with different substrates and at different conditions were performed with anaerobic sediment slurries from various hypersaline lakes in Russia. Methanonatronarchaeum proliferated exclusively in hypersaline soda lake samples mostly at elevated temperature, while at mesophilic conditions it coexisted with the extremely salt-tolerant methylotroph Methanosalsum natronophilum. Methanonatronarchaeum was also able to serve as a methylotrophic or hydrogenotrophic partner in several thermophilic enrichment cultures with fermentative bacteria. Ca. Methanohalarchaeum did not proliferate at mesophilic conditions and at thermophilic conditions it competed with extremely halophilic and moderately thermophilic methylotroph Methanohalobium, which it outcompeted at a combination of elevated temperature and methyl-reducing conditions. Overall, the results demonstrated that Methanonatronarchaeia are specialized extremophiles specifically proliferating in conditions of elevated temperature coupled with extreme salinity and simultaneous availability of a wide range of C -methylated compounds and H /formate.
Topics: Phylogeny; Euryarchaeota; Methanosarcinaceae; Lakes; Salinity; RNA, Ribosomal, 16S
PubMed: 35726892
DOI: 10.1111/1462-2920.16108 -
Modern Pathology : An Official Journal... Feb 2016Plasmacytoid dendritic cell neoplasms manifest in two clinically and pathologically distinct forms. The first variant is represented by nodular aggregates of clonally... (Review)
Review
Plasmacytoid dendritic cell neoplasms manifest in two clinically and pathologically distinct forms. The first variant is represented by nodular aggregates of clonally expanded plasmacytoid dendritic cells found in lymph nodes, skin, and bone marrow ('Mature plasmacytoid dendritic cells proliferation associated with myeloid neoplasms'). This entity is rare, although likely underestimated in incidence, and affects predominantly males. Almost invariably, it is associated with a myeloid neoplasm such as chronic myelomonocytic leukemia or other myeloid proliferations with monocytic differentiation. The concurrent myeloid neoplasm dominates the clinical pictures and guides treatment. The prognosis is usually dismal, but reflects the evolution of the associated myeloid leukemia rather than progressive expansion of plasmacytoid dendritic cells. A second form of plasmacytoid dendritic cells tumor has been recently reported and described as 'blastic plasmacytoid dendritic cell neoplasm'. In this tumor, which is characterized by a distinctive cutaneous and bone marrow tropism, proliferating cells derive from immediate CD4(+)CD56(+) precursors of plasmacytoid dendritic cells. The diagnosis of this form can be easily accomplished by immunohistochemistry, using a panel of plasmacytoid dendritic cells markers. The clinical course of blastic plasmacytoid dendritic cell neoplasm is characterized by a rapid progression to systemic disease via hematogenous dissemination. The genomic landscape of this entity is currently under intense investigation. Recurrent somatic mutations have been uncovered in different genes, a finding that may open important perspectives for precision medicine also for this rare, but highly aggressive leukemia.
Topics: Biomarkers, Tumor; Biopsy; Cell Differentiation; Cell Lineage; Cell Proliferation; Dendritic Cells; Genetic Predisposition to Disease; Hematologic Neoplasms; Humans; Immunohistochemistry; Immunophenotyping; Mutation; Phenotype; Predictive Value of Tests; Prognosis; Skin Neoplasms
PubMed: 26743477
DOI: 10.1038/modpathol.2015.145 -
Neural Plasticity 2016Regeneration in the animal kingdom is one of the most fascinating problems that have allowed scientists to address many issues of fundamental importance in basic... (Review)
Review
Regeneration in the animal kingdom is one of the most fascinating problems that have allowed scientists to address many issues of fundamental importance in basic biology. However, we came to know that the regenerative capability may vary across different species. Among vertebrates, fish and amphibians are capable of regenerating a variety of complex organs through epimorphosis. Zebrafish is an excellent animal model, which can repair several organs like damaged retina, severed spinal cord, injured brain and heart, and amputated fins. The focus of the present paper is on spinal cord regeneration in adult zebrafish. We intend to discuss our current understanding of the cellular and molecular mechanism(s) that allows formation of proliferating progenitors and controls neurogenesis, which involve changes in epigenetic and transcription programs. Unlike mammals, zebrafish retains radial glia, a nonneuronal cell type in their adult central nervous system. Injury induced proliferation involves radial glia which proliferate, transcribe embryonic genes, and can give rise to new neurons. Recent technological development of exquisite molecular tools in zebrafish, such as cell ablation, lineage analysis, and novel and substantial microarray, together with advancement in stem cell biology, allowed us to investigate how progenitor cells contribute to the generation of appropriate structures and various underlying mechanisms like reprogramming.
Topics: Age Factors; Animals; Central Nervous System; Nerve Regeneration; Neurogenesis; Spinal Cord; Spinal Cord Injuries; Zebrafish; Zebrafish Proteins
PubMed: 27382491
DOI: 10.1155/2016/5815439 -
Viruses Jan 2020Human immunodeficiency virus (HIV) is a chronic infection that destroys the immune system in infected individuals. Although antiretroviral therapy is effective at... (Review)
Review
Human immunodeficiency virus (HIV) is a chronic infection that destroys the immune system in infected individuals. Although antiretroviral therapy is effective at preventing infection of new cells, it is not curative. The inability to clear infection is due to the presence of a rare, but long-lasting latent cellular reservoir. These cells harboring silent integrated proviral genomes have the potential to become activated at any moment, making therapy necessary for life. Latently-infected cells can also proliferate and expand the viral reservoir through several methods including homeostatic proliferation and differentiation. The chromosomal location of HIV proviruses within cells influences the survival and proliferative potential of host cells. Proliferating, latently-infected cells can harbor proviruses that are both replication-competent and defective. Replication-competent proviral genomes contribute to viral rebound in an infected individual. The majority of available techniques can only assess the integration site or the proviral genome, but not both, preventing reliable evaluation of HIV reservoirs.
Topics: CD4-Positive T-Lymphocytes; Cell Proliferation; HIV Infections; HIV-1; Hematopoietic Stem Cells; Host Microbial Interactions; Humans; Proviruses; Viral Load; Virus Latency; Virus Replication
PubMed: 31973022
DOI: 10.3390/v12020127 -
Journal of Applied Physiology... Oct 2018In asthma, it is unclear if the airway smooth muscle cells proliferate more or are increased at the onset of asthma and remain stable. This study aimed to compare smooth...
In asthma, it is unclear if the airway smooth muscle cells proliferate more or are increased at the onset of asthma and remain stable. This study aimed to compare smooth muscle cell proliferation in individuals with and without asthma and correlate proliferation rates with cell size and number and with granulocytic airway inflammation. Postmortem airway sections were labeled with proliferating cell nuclear antigen (PCNA) and percent positive muscle cells calculated. On the same sections, smooth muscle cell size and number and the number of eosinophils and neutrophils were estimated and compared in cases of nonfatal ( n = 15) and fatal ( n = 15) asthma and control subjects ( n = 15). The %PCNA muscle cells was not significantly different in fatal (29.4 ± 7.7%, mean ± SD), nonfatal asthma (28.6 ± 8.3%), or control subjects (24.6 ± 6.7%) and not related to mean muscle cell size ( r = 0.09), number ( r = 0.36), thickness of the muscle layer ( r = 0.05), or eosinophil numbers ( r = 0.04) in the asthma cases. These data support the hypothesis that in asthma the increased thickness of the smooth muscle layer may be present before or at the onset of asthma and independent of concurrent granulocytic inflammation or exacerbation. NEW & NOTEWORTHY There is debate regarding the origins of the increased airway smooth muscle in asthma. It may be independent of inflammation or arise as a proliferative response to inflammation. The present study found no increase in the proportion of proliferating smooth muscle cells in asthma and no relation of proliferation to numbers of airway smooth muscle cells or inflammation. These results support a stable increase in smooth muscle in asthma that is independent of airway inflammation.
Topics: Adolescent; Adult; Asthma; Bronchi; Case-Control Studies; Cell Proliferation; Female; Humans; Inflammation; Male; Muscle, Smooth; Myocytes, Smooth Muscle; Young Adult
PubMed: 30024335
DOI: 10.1152/japplphysiol.00342.2018 -
Veterinary Immunology and... May 2020CellTrace Violet™ is a commonly used fluorescent dye used with flow cytometry to identify cell proliferation. Activated equine lymphocytes were examined using flow...
CellTrace Violet™ is a commonly used fluorescent dye used with flow cytometry to identify cell proliferation. Activated equine lymphocytes were examined using flow cytometry, microscopy and tritiated thymidine proliferation assays. CellTrace Violet™ was incorporated into the equine lymphocytes effectively. Equine lymphocytes proliferated when activated with pokeweed mitogen, but did not proliferate when previously stained with CellTrace Violet™. Serial dilutions of CellTrace Violet™ did not eliminate the inhibition of activated lymphocytes. Equine lymphocyte viability was greater than 90 % for both stained and unstained cells. Based on these data, CellTrace Violet™ is not recommended for the assessment of lymphocyte proliferation in equine cells. The mechanism of inhibition of equine lymphocyte proliferation by CellTrace Violet™ is unknown.
Topics: Animals; Cell Proliferation; Cell Survival; Concanavalin A; Flow Cytometry; Fluorescent Dyes; Horses; Lymphocyte Activation; Lymphocytes; Pokeweed Mitogens
PubMed: 32229340
DOI: 10.1016/j.vetimm.2020.110037 -
Medical Archives (Sarajevo, Bosnia and... Aug 2021Recent advances in stem cell technologies have rekindled an interest in the use of cell therapies to treat patients with Parkinson's disease. Although the...
BACKGROUND
Recent advances in stem cell technologies have rekindled an interest in the use of cell therapies to treat patients with Parkinson's disease. Although the transplantation of dopaminergic mesencephalic human fetal brain tissue has previously been reported in the treatment of patients with Parkinson's disease, this method is limited by the availability of tissue obtained from each human embryo.
OBJECTIVE
Our study aimed to isolate, culture, proliferate, and differentiate dopaminergic neurons from human neuroepithelial stem cells obtained from embryo reduction procedures performed in multifetal pregnancies following in vitro fertilization.
MATERIALS AND METHODS
A total of 201 human embryos were dissected for isolation and culture of neuroepithelial stem cells for proliferation and differentiation into dopaminergic neurons. All embryos were obtained from embryo reduction procedures performed in multifetal pregnancies after in vitro fertilization treatments.
RESULTS
Human neuroepithelial stem cells were isolated and cultured from embryos from 6.0 to 8.0 weeks. Neuroepithelial stem cells were successfully isolated, proliferated, and differentiated into dopaminergic neurons. The cells adhered to the surfaces of cell culture plates after 2 days and could be proliferated and differentiated into neurons within 4 days. Cultured cells expressed the dopaminergic marker tyrosine hydroxylase after 6 days, suggesting that these cells were successfully differentiated into dopaminergic neurons.
CONCLUSION
The successful isolation, culture, proliferation, and differentiation of human dopaminergic neurons from embryo reductions performed for multifetal pregnancies after in vitro fertilization suggests that this pathway may serve as a potential source of cell therapy materials for use in the treatment of Parkinson's disease.
Topics: Cell Differentiation; Cell Proliferation; Cells, Cultured; Dopaminergic Neurons; Female; Fertilization in Vitro; Humans; Pregnancy; Pregnancy Reduction, Multifetal; Stem Cells
PubMed: 34759448
DOI: 10.5455/medarh.2021.75.280-285