The cell proliferation antigen Ki-67 organises heterochromatin

Sobecki, Michal; Mrouj, Karim; Camasses, Alain; Parisis, Nikolaos; Nicolas, Emilien; Llères, David; Gerbe, François; Prieto, Susana; Krasińska, Liliana; David, Alexandre; Eguren, Manuel; Birling, Marie‐Christine; Urbach, Serge; Hem, Sonia; Déjardin, Jérôme; Malumbres, Marcos; Jay, Philippe; Dulić, Vjekoslav; Lafontaine, Denis L. J.; Feil, Robert; Fisher, Daniel

doi:10.7554/elife.13722

Cited by 276 publications

(371 citation statements)

References 54 publications

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“…5 and 6). These data are consistent with RNA-seq data sets for HeLa and U2OS cells (12) that did not display a concerted downregulation of DNA replication genes. We concluded that the effects of Ki-67 depletion on RNA levels and cell cycle distribution are cell type dependent.…”

supporting

confidence: 79%

“…hTERT-BJ fibroblasts were sensitive to Ki-67 depletion in our assays; however, a previous study indicated that shRNA-mediated Ki-67 depletion did not affect hTERT-BJ cell cycle reentry after starvation (12). Therefore, not all assays can detect the effects of Ki-67 depletion.…”

Section: Discussionmentioning

confidence: 48%

“…However, recent studies challenged the view that Ki-67 is important for human cell proliferation; for example, depletion of Ki-67 had minimal effects on the cell cycle distribution of tumor-derived HeLa or U2OS cells (12). Because our data indicated that Ki-67 contributes to normal cell cycle progression in hTERT-RPE1 cells, we hypothesized that the contribution of Ki-67 to cell cycle progression would be cell type dependent and may be related to checkpoint function.…”

mentioning

confidence: 99%

“…Ki-67 is required for the normal cellular localization of heterochromatin-associated histone modifications (12) and for the interphase nucleolar association of heterochromatic loci (22). Because the inactive X (Xi) chromosome is a well-studied example of facultative heterochromatin that associates with the nucleoli of female mouse (24) and human (39-41) cells, we tested whether Ki-67 affected characteristics of Xi heterochromatin.…”

mentioning

confidence: 99%

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Ki-67 Contributes to Normal Cell Cycle Progression and Inactive X Heterochromatin in p21 Checkpoint-Proficient Human Cells

Sun

Bizhanova

Matheson

et al. 2017

Molecular and Cellular Biology

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The Ki-67 protein is widely used as a tumor proliferation marker. However, whether Ki-67 affects cell cycle progression has been controversial. Here we demonstrate that depletion of Ki-67 in human hTERT-RPE1, WI-38, IMR90, and hTERT-BJ cell lines and primary fibroblast cells slowed entry into S phase and coordinately downregulated genes related to DNA replication. Some gene expression changes were partially relieved in Ki-67-depleted hTERT-RPE1 cells by codepletion of the Rb checkpoint protein, but more thorough suppression of the transcriptional and cell cycle defects was observed upon depletion of the cell cycle inhibitor p21. Notably, induction of p21 upon depletion of Ki-67 was a consistent hallmark of cell types in which transcription and cell cycle distribution were sensitive to Ki-67; these responses were absent in cells that did not induce p21. Furthermore, upon Ki-67 depletion, a subset of inactive X (Xi) chromosomes in female hTERT-RPE1 cells displayed several features of compromised heterochromatin maintenance, including decreased H3K27me3 and H4K20me1 labeling. These chromatin alterations were limited to Xi chromosomes localized away from the nuclear lamina and were not observed in checkpoint-deficient 293T cells. Altogether, our results indicate that Ki-67 integrates normal S-phase progression and Xi heterochromatin maintenance in p21 checkpoint-proficient human cells.KEYWORDS cell cycle, heterochromatin K i-67 was first identified via an antibody raised against Hodgkin's lymphoma cell nuclei (1). Because Ki-67 is generally expressed strongly in proliferating cells and poorly in quiescent cells (2), anti-Ki-67 antibodies are frequently used to detect proliferative cells in clinical studies (3, 4). In interphase cells, Ki-67 primarily localizes to the nucleolus (5-7), whereas during mitosis, it coats the chromosomes (8-10). In the past few years, several studies have greatly increased our understanding of Ki-67 function. This is particularly true for its mitotic roles. Specifically, Ki-67 is required for formation of the mitotic perichromosomal layer (11, 12), a proteinaceous sheath that coats mitotic chromosomes (13,14). In this layer, Ki-67's large size and highly positively charged amino acid composition keep individual mitotic chromosomes dispersed rather than aggregated upon nuclear envelope disassembly, thereby ensuring normal kinetics of anaphase progression (15). At anaphase onset, Ki-67 binds protein phosphatase 1␥ (PP1␥) to form a holoenzyme (16) important for targeting substrates that must be dephosphorylated during mitotic exit (10). In contrast to its structural role on the

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supporting

confidence: 79%

Section: Discussionmentioning

confidence: 48%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Ki-67 Contributes to Normal Cell Cycle Progression and Inactive X Heterochromatin in p21 Checkpoint-Proficient Human Cells

Sun

Bizhanova

Matheson

et al. 2017

Molecular and Cellular Biology

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“…1C) in the LN renal tissues. As CD68 is typically used as a marker of the macrophage lineage (24), and Ki-67 is established as a marker for cell proliferation (25), these results suggested that macrophage infiltration and cell proliferation were enhanced in the renal cortex of patients with LN.…”

Section: Tweak Protein Expression Inflammatory Cell Infiltration Andmentioning

confidence: 64%

Involvement of TWEAK and the NF-κB signaling pathway in lupus nephritis

Sun

Teng

et al. 2018

Exp Ther Med

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Abstract. Previous findings have identified that tumor necrosis factor-related weak inducer of apoptosis (TWEAK) is associated with lupus nephritis (LN) activity status; however, the mechanism involved remains unclear. The present study aimed to investigate the roles of TWEAK and the nuclear factor (NF)-κB signaling pathway in LN. TWEAK levels in the blood and urine of patients with LN or non-LN systemic lupus erythematosus were measured by ELISA and compared with those in healthy controls. TWEAK expression and NF-κB transcriptional activity in the kidney were detected by western blotting, and Ki-67 and cluster of differentiation (CD) 68 expression were assessed using immunofluorescence. Additionally, human mesangial cells (HMCs) were cultured in vitro and divided into five groups: Normal control, TWEAK stimulus group, TWEAK + TWEAK blocking antibody, TWEAK + NF-κB inhibitor (BAY 11-7082) and TWEAK + combined (blocking antibody + BAY 11-7082). Cell cycle activity and Ki-67 expression in the HMCs were evaluated using flow cytometry, and cell induction of macrophage chemotaxis was determined by a Transwell assay. Levels of the inflammation-associated factors interleukin (IL)-6, monocyte chemotactic protein 1 (MCP-1), chemokine ligand 5 (CCL5), IL-8 and IL-10 were also detected by reverse transcription-quantitative polymerase chain reaction. It was observed that the urine levels of TWEAK in patients with LN were significantly elevated compared with those in the other groups (P<0.05). LN kidneys exhibited markedly increased cell proliferative ability, macrophage infiltration, TWEAK expression and NF-κB transcriptional activity compared with normal kidneys. Furthermore, the results indicated that treatment with recombinant TWEAK notably enhanced NF-κB transcriptional activity and significantly promoted cell proliferation and cell cycle activity (P<0.05), induced macrophage chemotaxis (P<0.05), significantly increased the expression of the chemotactic factors IL-6, IL-8, MCP-1 and CCL5 (P<0.05), and significantly reduced anti-inflammatory cytokine IL-10 mRNA expression in HMCs (P<0.05), relative to normal controls. Accordingly, blocking TWEAK function or inhibiting NF-κB activity reversed these effects. Collectively these data indicate that urine TWEAK may be considered as a novel biomarker of LN activity, and that blocking TWEAK function or NF-κB activity may effectively alleviate glomerular mesangial cell proliferation and macrophage chemotaxis.

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Role of TGF‐β1/miR‐382‐5p/SOD2 axis in the induction of oxidative stress in CD34+ cells from primary myelofibrosis

et al. 2018

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Primary myelofibrosis (PMF) is a myeloproliferative neoplasm characterized by an excessive production of pro‐inflammatory cytokines resulting in chronic inflammation and genomic instability. Besides the driver mutations in JAK2,MPL, and CALR genes, the deregulation of miRNA expression may also contribute to the pathogenesis of PMF. To this end, we recently reported the upregulation of miR‐382‐5p in PMF CD34+ cells. In order to unveil the mechanistic details of the role of miR‐382‐5p in pathogenesis of PMF, we performed gene expression profiling of CD34+ cells overexpressing miR‐382‐5p. Among the downregulated genes, we identified superoxide dismutase 2 (SOD2), which is a predicted target of miR‐382‐5p. Subsequently, we confirmed miR‐382‐5p/SOD2 interaction by luciferase assay and we showed that miR‐382‐5p overexpression in CD34+ cells causes the decrease in SOD2 activity leading to reactive oxygen species (ROS) accumulation and oxidative DNA damage. In addition, our data indicate that inhibition of miR‐382‐5p in PMF CD34+ cells restores SOD2 function, induces ROS disposal, and reduces DNA oxidation. Since the pro‐inflammatory cytokine transforming growth factor‐β1 (TGF‐β1) is a key player in PMF pathogenesis, we further investigated the effect of TGF‐β1 on ROS and miR‐382‐5p levels. Our data showed that TGF‐β1 treatment enhances miR‐382‐5p expression and reduces SOD2 activity leading to ROS accumulation. Finally, inhibition of TGF‐β1 signaling in PMF CD34+ cells by galunisertib significantly reduced miR‐382‐5p expression and ROS accumulation and restored SOD2 activity. As a whole, this study reports that TGF‐β1/miR‐382‐5p/SOD2 axis deregulation in PMF cells is linked to ROS overproduction that may contribute to enhanced oxidative stress and inflammation. Our results suggest that galunisertib may represent an effective drug reducing abnormal oxidative stress induced by TGF‐β1 in PMF patients.Database linkingGEO: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE103464.

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The cell proliferation antigen Ki-67 organises heterochromatin

Cited by 276 publications

References 54 publications

Ki-67 Contributes to Normal Cell Cycle Progression and Inactive X Heterochromatin in p21 Checkpoint-Proficient Human Cells

Ki-67 Contributes to Normal Cell Cycle Progression and Inactive X Heterochromatin in p21 Checkpoint-Proficient Human Cells

Involvement of TWEAK and the NF-κB signaling pathway in lupus nephritis

Role of TGF‐β1/miR‐382‐5p/SOD2 axis in the induction of oxidative stress in CD34+ cells from primary myelofibrosis

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