Macrophages kill capillary cells in G1 phase of the cell cycle during programmed vascular regression

Development ◽  
1999 ◽  
Vol 126 (10) ◽  
pp. 2141-2147 ◽  
Author(s):  
G. Diez-Roux ◽  
M. Argilla ◽  
H. Makarenkova ◽  
K. Ko ◽  
R.A. Lang

Programmed capillary regression occurs during normal development of the eye and serves as a useful model for assessing the forces that drive vascular involution. Using a combination of S-phase labeling and liposome-mediated macrophage elimination, we show that during regression, macrophages induce apoptosis of both pericytes and endothelial cells in a cell cycle stage-dependent manner. Target cells are signaled to die by macrophages approximately 15 hours after S-phase labeling and this corresponds to a point in mid-G1 phase of the cell cycle. The tight correlation between the restriction point of the cell cycle and the point where the macrophage death signal is received suggests that the mitogen, matrix and cytoskeletal signals essential for cell-cycle progression may be inhibited by macrophages as a means of inducing cell death. Furthermore, these experiments show that cells from two distinct lineages are induced to die as a consequence of macrophage action, and this provides evidence that macrophage-induced cell death may be a general phenomenon during development and homeostasis.

1994 ◽  
Vol 14 (12) ◽  
pp. 8166-8173 ◽  
Author(s):  
B Shan ◽  
W H Lee

E2F-1, the first gene product identified among a family of E2F transcription factors, is thought to play a critical role in G1/S progression of the cell cycle. Transcriptional activities of E2F are modulated during the cell cycle, mainly by the formation of complexes between E2F and several key regulators of cell cycle such as the retinoblastoma protein and related proteins. To further understand the roles of E2F in the cell cycle progression, we have overexpressed exogenous E2F-1 by using a tetracycline-controlled expression system. We have found that the induced expression of E2F-1 in Rat-2 fibroblasts promotes S-phase entry and subsequently leads to apoptosis. The apoptosis occurs in an E2F-1 dose-dependent manner. Cells resistant to the induction of apoptosis have lost the ability to express exogenous E2F-1. Cells growing in low serum are more sensitive to the E2F-1-mediated cell death. Overexpression of E2F-1 mutants that impair DNA binding or transactivation does not alter cell cycle progression or induce apoptosis. These results define a novel pathway to apoptosis and demonstrate that premature S-phase entry is associated with apoptotic cell death.


1994 ◽  
Vol 14 (12) ◽  
pp. 8166-8173 ◽  
Author(s):  
B Shan ◽  
W H Lee

E2F-1, the first gene product identified among a family of E2F transcription factors, is thought to play a critical role in G1/S progression of the cell cycle. Transcriptional activities of E2F are modulated during the cell cycle, mainly by the formation of complexes between E2F and several key regulators of cell cycle such as the retinoblastoma protein and related proteins. To further understand the roles of E2F in the cell cycle progression, we have overexpressed exogenous E2F-1 by using a tetracycline-controlled expression system. We have found that the induced expression of E2F-1 in Rat-2 fibroblasts promotes S-phase entry and subsequently leads to apoptosis. The apoptosis occurs in an E2F-1 dose-dependent manner. Cells resistant to the induction of apoptosis have lost the ability to express exogenous E2F-1. Cells growing in low serum are more sensitive to the E2F-1-mediated cell death. Overexpression of E2F-1 mutants that impair DNA binding or transactivation does not alter cell cycle progression or induce apoptosis. These results define a novel pathway to apoptosis and demonstrate that premature S-phase entry is associated with apoptotic cell death.


2014 ◽  
Vol 33 (1) ◽  
pp. 103-110 ◽  
Author(s):  
JIAN ZHANG ◽  
WEI WEI ◽  
HUI-CHENG JIN ◽  
RONG-CHAO YING ◽  
A-KAO ZHU ◽  
...  

1993 ◽  
Vol 13 (6) ◽  
pp. 3577-3587 ◽  
Author(s):  
E A Musgrove ◽  
J A Hamilton ◽  
C S Lee ◽  
K J Sweeney ◽  
C K Watts ◽  
...  

Cyclins and proto-oncogenes including c-myc have been implicated in eukaryotic cell cycle control. The role of cyclins in steroidal regulation of cell proliferation is unknown, but a role for c-myc has been suggested. This study investigated the relationship between regulation of T-47D breast cancer cell cycle progression, particularly by steroids and their antagonists, and changes in the levels of expression of these genes. Sequential induction of cyclins D1 (early G1 phase), D3, E, A (late G1-early S phase), and B1 (G2 phase) was observed following insulin stimulation of cell cycle progression in serum-free medium. Transient acceleration of G1-phase cells by progestin was also accompanied by rapid induction of cyclin D1, apparent within 2 h. This early induction of cyclin D1 and the ability of delayed administration of antiprogestin to antagonize progestin-induced increases in both cyclin D1 mRNA and the proportion of cells in S phase support a central role for cyclin D1 in mediating the mitogenic response in T-47D cells. Compatible with this hypothesis, antiestrogen treatment reduced the expression of cyclin D1 approximately 8 h before changes in cell cycle phase distribution accompanying growth inhibition. In the absence of progestin, antiprogestin treatment inhibited T-47D cell cycle progression but in contrast did not decrease cyclin D1 expression. Thus, changes in cyclin D1 gene expression are often, but not invariably, associated with changes in the rate of T-47D breast cancer cell cycle progression. However, both antiestrogen and antiprogestin depleted c-myc mRNA by > 80% within 2 h. These data suggest the involvement of both cyclin D1 and c-myc in the steroidal control of breast cancer cell cycle progression.


2003 ◽  
Vol 23 (22) ◽  
pp. 8110-8123 ◽  
Author(s):  
Partha Mitra ◽  
Rong-Lin Xie ◽  
Ricardo Medina ◽  
Hayk Hovhannisyan ◽  
S. Kaleem Zaidi ◽  
...  

ABSTRACT At the G1/S phase cell cycle transition, multiple histone genes are expressed to ensure that newly synthesized DNA is immediately packaged as chromatin. Here we have purified and functionally characterized the critical transcription factor HiNF-P, which is required for E2F-independent activation of the histone H4 multigene family. Using chromatin immunoprecipitation analysis and ligation-mediated PCR-assisted genomic sequencing, we show that HiNF-P interacts with conserved H4 cell cycle regulatory sequences in vivo. Antisense inhibition of HiNF-P reduces endogenous histone H4 gene expression. Furthermore, we find that HiNF-P utilizes NPAT/p220, a substrate of the cyclin E/cyclin-dependent kinase 2 (CDK2) kinase complex, as a key coactivator to enhance histone H4 gene transcription. The biological role of HiNF-P is reflected by impeded cell cycle progression into S phase upon antisense-mediated reduction of HiNF-P levels. Our results establish that HiNF-P is the ultimate link in a linear signaling pathway that is initiated with the growth factor-dependent induction of cyclin E/CDK2 kinase activity at the restriction point and culminates in the activation of histone H4 genes through HiNF-P at the G1/S phase transition.


2003 ◽  
Vol 77 (6) ◽  
pp. 3451-3459 ◽  
Author(s):  
Robert F. Kalejta ◽  
Thomas Shenk

ABSTRACT As viruses are reliant upon their host cell to serve as proper environments for their replication, many have evolved mechanisms to alter intracellular conditions to suit their own needs. For example, human cytomegalovirus induces quiescent cells to enter the cell cycle and then arrests them in late G1, before they enter the S phase, a cell cycle compartment that is presumably favorable for viral replication. Here we show that the protein product of the human cytomegalovirus UL82 gene, pp71, can accelerate the movement of cells through the G1 phase of the cell cycle. This activity would help infected cells reach the late G1 arrest point sooner and thus may stimulate the infectious cycle. pp71 also induces DNA synthesis in quiescent cells, but a pp71 mutant protein that is unable to induce quiescent cells to enter the cell cycle still retains the ability to accelerate the G1 phase. Thus, the mechanism through which pp71 accelerates G1 cell cycle progression appears to be distinct from the one that it employs to induce quiescent cells to exit G0 and subsequently enter the S phase.


2022 ◽  
Author(s):  
Miji Jeon ◽  
Danielle L Schmitt ◽  
Minjoung Kyoung ◽  
Songon An

Glucose metabolism has been studied extensively to understand functional interplays between metabolism and a cell cycle. However, our understanding of cell cycle-dependent metabolic adaptation particularly in human cells remains largely elusive. Meanwhile, human enzymes in glucose metabolism are shown to functionally organize into three different sizes of a multienzyme metabolic assembly, the glucosome, to regulate glucose flux in a size-dependent manner. Here, using fluorescence single-cell imaging techniques, we discover that glucosomes spatiotemporally oscillate during a cell cycle in an assembly size-dependent manner. Importantly, their oscillation at single-cell levels is in accordance with functional contributions of glucose metabolism to cell cycle progression at a population level. Collectively, we demonstrate functional oscillation of glucosomes during cell cycle progression and thus their biological significance to human cell biology.


1994 ◽  
Vol 107 (1) ◽  
pp. 241-252 ◽  
Author(s):  
C. Burger ◽  
M. Wick ◽  
S. Brusselbach ◽  
R. Muller

Mitogenic stimulation of quiescent cells not only triggers the cell division cycle but also induces an increase in cell volume, associated with an activation of cellular metabolism. It is therefore likely that genes encoding enzymes and other proteins involved in energy metabolism and biosynthetic pathways represent a major class of mitogen-induced genes. In the present study, we investigated in the non-established human fibroblast line WI-38 the induction by mitogens of 17 genes whose products play a role in different metabolic processes. We show that these genes fall into 4 different categories, i.e. non-induced genes, immediate early (IE) primary genes, delayed early (DE) secondary genes and late genes reaching peak levels in S-phase. In addition, we have analysed the regulation of these genes during normal cell cycle progression, using HL-60 cells separated by counterflow elutriation. A clear cell cycle regulation was seen with those genes that are induced in S-phase, i.e. thymidine kinase, thymidylate synthase and dihydrofolate reductase. In addition, two DE genes showed a cell cycle dependent expression. Ornithine decarboxylase mRNA increased around mid-G1, reaching maximum levels in S/G2, while hexokinase mRNA expression was highest in early G1. In contrast, the expression of other DE and IE genes did not fluctuate during the cell cycle, a result that was confirmed with elutriated WI-38 and serum-stimulated HL-60 cells. These observations suggest that G0-->S and G1-->S transition are distinct processes, exhibiting characteristic programmes of gene regulation, and merging around S-phase entry.


2000 ◽  
Vol 113 (7) ◽  
pp. 1139-1148 ◽  
Author(s):  
J.M. Frade

During their early postmitotic life, a proportion of the nascent retinal ganglion cells (RGCs) are induced to die as a result of the interaction of nerve growth factor (NGF) with the neurotrophin receptor p75. To analyse the mechanisms by which NGF promotes apoptosis, an in vitro culture system consisting of dissociated E5 retinal cells was established. In this system, NGF-induced apoptosis was only observed in the presence of insulin and neurotrophin-3, conditions that favour the birth of RGCs and other neurones expressing the glycoprotein G4. The pro-apoptotic effect of NGF on the G4-positive neurones was evident after 10 hours in vitro and was preceded by a significant upregulation of cyclin B2, but not cyclin D1, and the presence of mitotic nuclei in these cells. Brain-derived neurotrophic factor prevented both the increase of cyclin B2 expression in the G4-positive neurones and the NGF-induced cell death. Finally, pharmacologically blocking cell-cycle progression using the cyclin-dependent kinase inhibitor roscovitine prevented NGF-induced cell death in a dose-dependent manner. These results strongly suggest that the apoptotic signalling initiated by NGF requires a driving stimulus manifested by the neuronal birth and is preceded by the unscheduled re-entry of postmitotic neurones into the cell cycle.


Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1447-1447
Author(s):  
Shaoyan Hu ◽  
Shui-yan Wu ◽  
Jian-nong Cen ◽  
Jian Pan ◽  
Xiaofei Qi ◽  
...  

Abstract Abstract 1447 Insulin-like growth factor binding protein 7 (IGFBP7) has been ascribed properties of both tumor suppressor and enhancer of cell proliferation. In solid tumors the important role of IGFBP7 as a tumor suppressor was revealed in several studies. In acute T-lymphoblastic leukemia (T-ALL), high IGFBP7 expression is associated with a more immature phenotype of early T-ALL, inferior survival, and predicts primary chemotherapy resistance. In a separate study, IGFBP7 acts as a positive regulator of ALL and bone marrow stromal cells growth, and significantly enhances in-vitro resistance to asparaginase. Higher IGFBP7 mRNA levels were associated with lower leukemia-free survival (P=0.003) in precursor B-cell Ph negative ALL patients (n=147) treated with a contemporary polychemotherapy protocol. In acute myeloid leukemia, the role of IGFBP7 is largely unknown. In our previous published study [Hu et al, 2011], we demonstrated that IGFBP7 overexpressed in majority of childhood AML (n=66) at diagnosis and upon relapsed, but not at remission stage. We now further explore its mechanism in promoting AML cells proliferation. Compared with control, transfection of full length IGFBP7 in K562 cells [V-BP7] resulted in 23% increased of proliferation in 48 hours. Cell cycle analysis by flow cytometry showed decreased G0/G1 phase and increased S phase in V-BP7 comparing with control, suggesting enhanced cell cycle progression. While transfection of IGFPB7 siRNA produced an opposite effect of reducing the cell growth in K562 cells. In consistent with the nature of a secretory protein, the extracellular IGFBP7 level in the condition media from v-BP7 was significantly higher than that from vector control or parental K562 cells measured by ELISA. Incubation parental K562 cells in V-BP7 derived conditioned medium resulted in significant growth enhancement. Gene expression profiling (GEP) was performed on V-BP7 in contrast to parental K562 cells. Genes which were up-regulated or down-regulated more than 2 folds were regarded as significant difference. Among 10 verified genes, AKT3 showed the highest extent of up-regulation and IGFBP7 siRNA transfection reduced its expression. Cyclin D1 (CCND1) expression was also significantly up-regulated and validated by RT-PCR and Western blot. V-BP7 treated with an AKT inhibitor (Triciribine) at 2.5μM for 72 hours showed 50% reduction of cell viability. The cell cycle analysis indicated that triciribine reversed cell cycle progression in V-BP7, by increasing cells in G0/G1 phase and reducing cells in S phase. Western blot demonstrated that both phospho-AKT3 and CCND1 were down regulated after treatment with triciribine. Using real time RT-PCR, we further identified that IGFBP7 and AKT3 expression were significantly correlated (p=0.001; r=0.255) in 39 newly diagnosed childhood AML. Conclusions IGFBP7 aberrantly overexpressed in majority of childhood AML. IGFBP7 promotes proliferation of K562 cells and AML via overexpression/activation of AKT3 and CCND1. Disclosures: No relevant conflicts of interest to declare.


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