Increase in non-professional phagocytosis during the progression of cell cycle

Homotypic or heterotypic internalization of another, either living or necrotic cell is currently in the center of research interest. The active invasion of a living cell called entosis and cannibalism of cells by rapidly proliferating cancers are prominent examples. Additionally, normal healthy tissue cells are capable of non-professional phagocytosis. This project studied the relationship between non-professional phagocytosis, individual proliferation and cell cycle progression. Three mesenchymal and two epithelial normal tissue cell lines were studied for homotypic non-professional phagocytosis. Homotypic dead cells were co-incubated with adherent growing living cell layers. Living cells were synchronized by mitotic shake-off as well as Aphidicolin-treatment and phagocytotic activity was analyzed by immunostaining. Cell cycle phases were evaluated by flow cytometry. Mesenchymal and epithelial normal tissue cells were capable of internalizing dead cells. Epithelial cells had much higher non-professional phagocytotic rates than mesenchymal cells. Cells throughout the entire cell cycle were able to phagocytose. The phagocytotic rate significantly increased with progressing cell cycle phases. Mitotic cells regularly phagocytosed dead cells, this was verified by Nocodazole and Colcemid treatment. Taken together, our findings indicate the ability of human tissue cells to phagocytose necrotic neighboring cells in confluent cell layers. The origin of the cell line influences the rate of cell-in-cell structure formation. The higher cell-in-cell structure rates during cell cycle progression might be influenced by cytoskeletal reorganization during this period or indicate an evolutionary anchorage of the process. Recycling of nutrients during cell growth might also be an explanation.

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Prognostication by multigene proliferative marker panel compared with Ki-67 in small-intestinal NENs.

Journal of Clinical Oncology ◽

10.1200/jco.2012.30.4_suppl.242 ◽

2012 ◽

Vol 30 (4_suppl) ◽

pp. 242-242

Author(s):

Ben Lawrence ◽

Simon Schimmack ◽

Bernhard Svejda ◽

Ignat Drozdov ◽

Daniele Alaimo ◽

...

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Ki 67 ◽

Cycle Progression ◽

Qrt Pcr ◽

Proliferative Markers ◽

Cell Cycle Phases ◽

Proliferative Marker ◽

Proliferating Cell

242 Background: Ki-67 is the major proliferative marker in clinical use to determine neuroendocrine neoplasm (NEN) prognosis. Ki-67 is unable to predict the outcome of SI-NENs, as the majority have a low (≤2) Ki-67%. Therefore, we aimed to identify a sensitive panel of proliferative markers using qRT-PCR to more accurately define the proliferation of these slow growing tumors. Methods: We identified genes with a mechanistic function in cell cycle progression that were over-expressed in RNA microarrays of SI-NENs (n=8) compared to adjacent normal tissue (n=4) (dCHIP, annotation databases). Timing of marker gene expression (qRT-PCR) in proliferating cell-cycle phases (S, G2, M) was determined in flow-sorted SI-NEN cell lines (KRJ-1, H-STS) after propidium iodide staining. RNA expression of candidate proliferative markers was then investigated using an in vivo model and two independent tumor datasets, and transcript level compared to Ki-67% protein expression (immunohistochemical staining). Results: Twenty genes with a mechanistic role in proliferation were identified and 17 confirmed to be expressed in proliferating cell cycle phases. Each tumor expressed a unique profile of the 17 proliferative markers. Both Ki-67 protein and Ki-67 RNA transcript levels failed to differentiate in vivo SI-NEN models or patient samples despite variable proliferative capacity (e.g., WDNETs versus WDNECs). Although most tumors showed low levels of Ki-67 expression, the tumors expressed high levels of select alternative proliferative markers. Hierarchical clustering provided a novel and clinically meaningful prognostic classification. Conclusions: Proliferation of individual SI-NENs is regulated by unique combinations of multiple genes with a mechanistic role in cell-cycle progression. Regulation of proliferation in SI-NENs is therefore complex and cannot accurately be defined by Ki-67 as a single marker. A panel of proliferative RNA markers has potential to significantly improve prognostication in patients with SI-NENs.

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Sinorhizobium meliloti CtrA Stability Is Regulated in a CbrA-Dependent Manner That Is Influenced by CpdR1

Journal of Bacteriology ◽

10.1128/jb.02593-14 ◽

2015 ◽

Vol 197 (13) ◽

pp. 2139-2149 ◽

Cited By ~ 9

Author(s):

Karla B. Schallies ◽

Craig Sadowski ◽

Julia Meng ◽

Peter Chien ◽

Katherine E. Gibson

Keyword(s):

Cell Cycle ◽

Living Cell ◽

Sinorhizobium Meliloti ◽

Cell Cycle Progression ◽

Caulobacter Crescentus ◽

Ectopic Expression ◽

Dependent Manner ◽

Free Living ◽

Cycle Progression ◽

Content Type

ABSTRACTCbrA is a DivJ/PleC-like histidine kinase of DivK that is required for cell cycle progression and symbiosis in the alphaproteobacteriumSinorhizobium meliloti. Loss ofcbrAresults in increased levels of CtrA as well as its phosphorylation. While many of the knownCaulobacter crescentusregulators of CtrA phosphorylation and proteolysis are phylogenetically conserved withinS. meliloti, the latter lacks the PopA regulator that is required for CtrA degradation inC. crescentus. In order to investigate whether CtrA proteolysis occurs inS. meliloti, CtrA stability was assessed. During exponential growth, CtrA is unstable and therefore likely to be degraded in a cell cycle-regulated manner. Loss ofcbrAsignificantly increases CtrA stability, but this phenotype is restored to that of the wild type by constitutive ectopic expression of a CpdR1 variant that cannot be phosphorylated (CpdR1D53A). Addition of CpdR1D53Afully suppressescbrAmutant cell cycle defects, consistent with regulation of CtrA stability playing a key role in mediating proper cell cycle progression inS. meliloti. Importantly, thecbrAmutant symbiosis defect is also suppressed in the presence of CpdR1D53A. Thus, regulation of CtrA stability by CbrA and CpdR1 is associated with free-living cell cycle outcomes and symbiosis.IMPORTANCEThe cell cycle is a fundamental process required for bacterial growth, reproduction, and developmental differentiation. Our objective is to understand how a two-component signal transduction network directs cell cycle events during free-living growth and host colonization. TheSinorhizobium melilotinitrogen-fixing symbiosis with plants is associated with novel cell cycle events. This study identifies a link between the regulated stability of an essential response regulator, free-living cell cycle progression, and symbiosis.

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Mapping metabolic oscillations during cell cycle progression

10.1101/2020.01.31.928267 ◽

2020 ◽

Author(s):

Irena Roci ◽

Jeramie D. Watrous ◽

Kim A. Lagerborg ◽

Mohit Jain ◽

Roland Nilsson

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

High Resolution Mass Spectrometry ◽

Energy Charge ◽

Membrane Lipid ◽

M Cell ◽

Proliferating Cells ◽

Cycle Progression ◽

Metabolic Remodeling ◽

Cell Cycle Phases

AbstractProliferating cells must synthesize a wide variety of macromolecules while progressing through the cell cycle, but the coordination between cell cycle progression and cellular metabolism is still poorly understood. To identify metabolic processes that oscillate over the cell cycle, we performed comprehensive, non-targeted liquid chromatography-high resolution mass spectrometry (LC-HRMS) based metabolomics of HeLa cells isolated in the G1 and SG2M cell cycle phases, capturing thousands of diverse metabolite ions. When accounting for increased total metabolite abundance due to cell growth throughout the cell cycle, 18% of the observed LC-HRMS peaks were at least 2-fold different between the stages, consistent with broad metabolic remodeling throughout the cell cycle. While most amino acids, phospholipids, and total ribonucleotides were constant across cell cycle phases, consistent with the view that total macromolecule synthesis does not vary across the cell cycle, certain metabolites were oscillating. For example, ribonucleotides were highly phosphorylated in SG2M, indicating an increase in energy charge, and several phosphatidylinositols were more abundant in G1, possibly indicating altered membrane lipid signaling. Within carbohydrate metabolism, pentose phosphates and methylglyoxal metabolites were associated with the cycle. Interestingly, hundreds of yet uncharacterized metabolites similarly oscillated between cell cycle phases, suggesting previously unknown metabolic activities that may be synchronized with cell cycle progression, providing an important resource for future studies.

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