Abstract 20492: Mlf1 Regulates Myocyte Proliferation in Postnatal Hearts

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Shalini Muralidhar ◽  
Feng Xiao ◽  
Suwannee Thet ◽  
Hesham Sadek
Keyword(s):  
Cell Cycle ◽  
Transcription Factors ◽  
Cell Cycle Arrest ◽  
Molecular Mechanisms ◽  
Gene Array ◽  
Bhlh Transcription Factor ◽  
Cardiomyocyte Proliferation ◽  
Regenerative Capacity ◽  
Cycle Arrest ◽  
Endogenous Expression

Lower vertebrates, such as newt and zebrafish, retain a robust cardiac regenerative capacity following injury. Although adult mammals lack this cardiac regenerative potential, there is ample interest in understanding how heart regeneration occurs, and to reawaken this process in adult humans. Recently, we showed that mice are capable of regenerating their hearts shortly after birth following injury. This regenerative response is associated with robust proliferation of cardiomyocytes without significant hypertrophy or fibrosis. However, this regenerative capacity is lost by 7 days postnatally, coinciding with cell cycle arrest. In an effort to determine the mechanism of cardiomyocytes cell cycle arrest after the first week of life, we performed a gene array after cardiac injury at multiple post-natal time points. This enabled us to identify a number of transcription factors that are differentially expressed during this postnatal window. We recently reported that one of these transcription factors Meis1 regulates postnatal cell cycle arrest of cardiomyocytes. Furthermore, Myeloid leukemia factor 1 (Mlf1), a bhlh transcription factor that has not been previously studied in the heart has similar dysregulated pattern following injury. Our preliminary data with in-vitro knockdown of Mlf1 in cardiomyocyte resulted in 2-fold increase in cardiomyocyte proliferation. Furthermore, immunohistochemistry results indicated that the endogenous expression and nuclear localization of Mlf1 in the post-natal cardiomyocytes coincides with cell cycle arrest. To explore this pattern, we generated a cardiomyocyte-specific Mlf1 knockout mouse, and showed that loss of Mlf1 results in robust cardiomyocyte proliferation in postnatal hearts (P14). Additionally, we confirmed previous reports that Mlf1 regulates p53 and induces cell cycle arrest by induction of CDK inhibitors like p21 and p57 in these Mlf1 KO mice. This suggests a role of Mlf1 in promoting reactivation of injured myocardium through induction of cardiomyocyte proliferation. These findings will further provide evidences of molecular mechanisms involved in the dormant regenerative capacity in adult mammals that can be a potential target of therapeutic approaches.

Abstract 64: Meis1 Is a Key Regulator of Postnatal Cardiomyocyte Cell Cycle Arrest

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Fatih Kocabas ◽  
Ahmed I Mahmoud ◽  
Shalini Muralidhar ◽  
Enzo Porrello ◽  
Eric Olson ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Transcriptional Activation ◽  
Gene Array ◽  
Mouse Heart ◽  
Cardiomyocyte Proliferation ◽  
Mammalian Heart ◽  
Cycle Arrest ◽  
Complete Regeneration

Heart failure is a costly and deadly disease affecting over 5 million Americans. The inability of the adult mammalian heart to regenerate following injury lies at core of the pathophysiology of heart failure. We recently showed that the neonatal mammalian heart is capable of complete regeneration following resection of the entire ventricular apex. Moreover, our preliminary data indicate that the neonatal mouse heart is also capable of complete regeneration following ischemic myocardial infarction. In both these types of injury, the regenerative response is associated with robust proliferation of cardiomyocytes without significant hypertrophy or fibrosis. Genetic fate mapping studies demonstrated that the majority of newly formed cardiomyocytes originated from pre-existing cardiomyocytes. In an effort to determine the mechanism of cardiomyocytes cell cycle arrest after the first week of life, we performed a gene array after cardiac injury at multiple post-natal timepoints. This enabled us to identify Meis1 as a potential regulator of neonatal cardiomyocyte proliferation. Meis1, which belongs to the TALE family of homeodomain transcription factors, is required for normal hematopoiesis and cardiac development. While Meis1 has been extensively studied in the hematopoietic system, little is known about its role in the heart. Our results indicate that Meis1 expression and nuclear localization in the post-natal cardiomyocytes coincides with cell cycle arrest. To further explore this pattern, we generated a cardiomyocyte-specific Meis1 knockout mouse, and showed that loss of Meis1 results in robust cardiomyocyte proliferation in the adult heart. Moreover, we identified p16 and p21; two synergistic cyclin dependent kinase inhibitors that induce arrest at all three cell cycle checkpoints, as potential targets for transcriptional activation by Meis1. These results identify Meis1 as a key regulator of post-natal cardiomyocyte cell cycle arrest, and a potential therapeutic target for cardiac regeneration.

Pisosterol Induces G2/M Cell Cycle Arrest and Apoptosis via the ATM/ATR Signaling Pathway in Human Glioma Cells

2020 ◽  
Vol 20 (6) ◽  
pp. 734-750
Author(s):  
Wallax A.S. Ferreira ◽  
Rommel R. Burbano ◽  
Claudia do Ó. Pessoa ◽  
Maria L. Harada ◽  
Bárbara do Nascimento Borges ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Signaling Pathway ◽  
Glioma Cell ◽  
Molecular Mechanisms ◽  
Glioma Cells ◽  
Dependent Manner ◽  
M Cell ◽  
Trypan Blue Exclusion ◽  
Cycle Arrest

Background: Pisosterol, a triterpene derived from Pisolithus tinctorius, exhibits potential antitumor activity in various malignancies. However, the molecular mechanisms that mediate the pisosterol-specific effects on glioma cells remain unknown. Objective: This study aimed to evaluate the antitumoral effects of pisosterol on glioma cell lines. Methods: The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and trypan blue exclusion assays were used to evaluate the effect of pisosterol on cell proliferation and viability in glioma cells. The effect of pisosterol on the distribution of the cells in the cell cycle was performed by flow cytometry. The expression and methylation pattern of the promoter region of MYC, ATM, BCL2, BMI1, CASP3, CDK1, CDKN1A, CDKN2A, CDKN2B, CHEK1, MDM2, p14ARF and TP53 was analyzed by RT-qPCR, western blotting and bisulfite sequencing PCR (BSP-PCR). Results: Here, it has been reported that pisosterol markedly induced G2/M arrest and apoptosis and decreased the cell viability and proliferation potential of glioma cells in a dose-dependent manner by increasing the expression of ATM, CASP3, CDK1, CDKN1A, CDKN2A, CDKN2B, CHEK1, p14ARF and TP53 and decreasing the expression of MYC, BCL2, BMI1 and MDM2. Pisosterol also triggered both caspase-independent and caspase-dependent apoptotic pathways by regulating the expression of Bcl-2 and activating caspase-3 and p53. Conclusions: It has been, for the first time, confirmed that the ATM/ATR signaling pathway is a critical mechanism for G2/M arrest in pisosterol-induced glioma cell cycle arrest and suggests that this compound might be a promising anticancer candidate for further investigation.

scholarly journals Molecular mechanisms of LKB1 induced cell cycle arrest

2013 ◽  
Vol 4 (3) ◽  
pp. 229-233 ◽  
Author(s):  
Dian-sheng Zhong ◽  
Lin-lin Sun ◽  
Li-xia Dong
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Molecular Mechanisms ◽  
Cycle Arrest

MicroRNA-1225-5p acts as a tumor-suppressor in laryngeal cancer via targeting CDC14B

2019 ◽  
Vol 400 (2) ◽  
pp. 237-246 ◽  
Author(s):  
Peng Sun ◽  
Dan Zhang ◽  
Haiping Huang ◽  
Yafeng Yu ◽  
Zhendong Yang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Cell Division ◽  
Cell Cycle Arrest ◽  
Molecular Mechanisms ◽  
Normal Tissues ◽  
Cycle Arrest ◽  
Enhanced Expression ◽  
Insight Into

Abstract This study aimed to investigate the role of miRNA-1225-5p (miR-1225) in laryngeal carcinoma (LC). We found that the expression of miR-1225 was suppressed in human LC samples, while CDC14B (cell division cycle 14B) expression was reinforced in comparison with surrounding normal tissues. We also demonstrated that enhanced expression of miR-1225 impaired the proliferation and survival of LC cells, and resulted in G1/S cell cycle arrest. In contrast, reduced expression of miR-1225 promoted cell survival. Moreover, miR-1225 resulted in G1/S cell cycle arrest and enhanced cell death. Further, miR-1225 targets CDC14B 3′-UTR and recovery of CDC14B expression counteracted the suppressive influence of miR-1225 on LC cells. Thus, these findings offer insight into the biological and molecular mechanisms behind the development of LC.

scholarly journals ROS-Mediated Apoptosis and Genotoxicity Induced by Palladium Nanoparticles in Human Skin Malignant Melanoma Cells

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Saud Alarifi ◽  
Daoud Ali ◽  
Saad Alkahtani ◽  
Rafa S. Almeer
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Malignant Melanoma ◽  
Cell Cycle Arrest ◽  
Human Skin ◽  
Palladium Nanoparticles ◽  
Molecular Mechanisms ◽  
Time Dependent ◽  
Cycle Arrest ◽  
A375 Cells

The present work was designed to investigate the effect of palladium nanoparticles (PdNPs) on human skin malignant melanoma (A375) cells, for example, induction of apoptosis, cytotoxicity, and DNA damage. Diseases resulting from dermal exposure may have a significant impact on human health. There is a little study that has been reported on the toxic potential of PdNPs on A375. Cytotoxic potential of PdNPs (0, 5, 10, 20, and 40 μg/ml) was measured by tetrazolium bromide (MTT assay) and NRU assay in A375 cells. PdNPs elicited concentration and time-dependent cytotoxicity, and longer exposure period induced more cytotoxicity as measured by MTT and NRU assay. The molecular mechanisms of cytotoxicity through cell cycle arrest and apoptosis were investigated by AO (acridine orange)/EtBr (ethidium bromide) stain and flow cytometry. PdNPs not only inhibit proliferation of A375 cells in a dose- and time-dependent model but also induce apoptosis and cell cycle arrest at G2/M phase (before 12 h) and S phase (after 24 h). The induction of oxidative stress in A375 cells treated with above concentration PdNPs for 24 and 48 h increased ROS level; on the other hand, glutathione level was declined. Apoptosis and DNA damage was significantly increased after treatment of PdNPs. Considering all results, PdNPs showed cytotoxicity and genotoxic effect in A375 cells.

Molecular mechanisms of G0/G1 cell-cycle arrest and apoptosis induced by terfenadine in human cancer cells

2003 ◽  
Vol 37 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Jean-Dean Liu ◽  
Ying-Jan Wang ◽  
Chien-Ho Chen ◽  
Cheng-Fei Yu ◽  
Li-Ching Chen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Cancer Cells ◽  
Molecular Mechanisms ◽  
Human Cancer ◽  
Human Cancer Cells ◽  
Cycle Arrest ◽  
G1 Cell Cycle Arrest

scholarly journals Vasoactive Intestinal Peptide Induces Cell Cycle Arrest and Regulatory Functions in Human T Cells at Multiple Levels

2010 ◽  
Vol 30 (10) ◽  
pp. 2537-2551 ◽  
Author(s):  
Per Anderson ◽  
Elena Gonzalez-Rey
Keyword(s):  
Cell Cycle ◽  
T Cells ◽  
Cell Cycle Arrest ◽  
Vasoactive Intestinal Peptide ◽  
Molecular Mechanisms ◽  
Cytotoxic T Lymphocyte ◽  
Interleukin 2 ◽  
Experimental Models ◽  
Cycle Arrest ◽  
Human T Cells

ABSTRACT Vasoactive intestinal peptide (VIP) is a potent anti-inflammatory neuropeptide that, by inhibiting Th1-driven responses and inducing the emergence of regulatory T cells (Treg), has been proven successful in the induction of tolerance in various experimental models of autoimmune disorders. Here, we investigate the molecular mechanisms involved in VIP-induced tolerance. VIP treatment in the presence of T-cell receptor (TCR) signaling and CD28 costimulation induced cell cycle arrest in human T cells. VIP blocked G1/S transition and inhibited the synthesis of cyclins D3 and E and the activation of the cyclin-dependent kinases (CDKs) cdk2 and cdk4. This effect was accompanied by maintenance of threshold levels of the CDK inhibitor p27kip1 and impairment of phosphatidylinositol 3-kinase (PI3K)-Akt signaling. Inhibition of interleukin 2 (IL-2) transcription and downregulation of signaling through NFAT, AP-1, and Ras-Raf paralleled the VIP-induced cell cycle arrest. Noteworthy from a functional point of view is the fact that VIP-treated T cells show a regulatory phenotype characterized by high expression of CD25, cytotoxic-T-lymphocyte-associated protein 4 (CTLA4), and Forkhead box protein 3 (FoxP3) and potent suppressive activities against effector T cells. CTLA4 appears to be critically involved in the generation and suppressive activities of VIP-induced Treg. Finally, cyclic AMP (cAMP) and protein kinase A (PKA) activation seems to mediate the VIP-induced cell cycle arrest and Treg generation.

scholarly journals The N-Terminal 24 Amino Acids of the p55 Gamma Regulatory Subunit of Phosphoinositide 3-Kinase Binds Rb and Induces Cell Cycle Arrest

2003 ◽  
Vol 23 (5) ◽  
pp. 1717-1725 ◽  
Author(s):  
Xianmin Xia ◽  
Aiwu Cheng ◽  
Damilola Akinmade ◽  
Anne W. Hamburger
Keyword(s):  
Cell Cycle ◽  
Amino Acid ◽  
Cell Cycle Arrest ◽  
Cell Cycle Progression ◽  
Molecular Mechanisms ◽  
Biological Effects ◽  
Cycle Progression ◽  
Regulatory Subunits ◽  
Cycle Arrest ◽  
Phosphoinositide 3 Kinase

ABSTRACT Although phosphoinositide 3-kinase (PI 3-kinase) is essential for cell cycle progression, the molecular mechanisms that regulate its diverse biological effects are poorly understood. We demonstrate here that Rb, a key regulator of cell cycle progression, associates with p55 kDa (p55α and p55γ) regulatory subunits of PI 3-kinase in vivo and in vitro. Both confocal microscopy and biochemical analysis demonstrated the presence of p55γ in the nucleus. The 24-amino-acid N-terminal end of p55γ, which is unique among PI 3-kinase regulatory subunits, was sufficient to bind Rb. Addition of serum or growth factors to quiescent cells triggered the dissociation of Rb from p55. Ectopic expression of the 24-amino-acid N-terminal end of p55γ inhibited cell cycle progression, as evidenced by induction of cell growth arrest at the G0/G1 phase, inhibition of DNA synthesis, inhibition of cyclin D and cyclin E promoter activity, and changes in the expression of cell cycle-related proteins. The inhibitory effects of the N-terminal end of p55γ on cell cycle progression depended on the presence of functional Rb. These data demonstrate for the first time an association of p55γ with Rb and show that modification of this association can lead to cell cycle arrest.

scholarly journals Cell Cycle Inhibition by FoxO Forkhead Transcription Factors Involves Downregulation of Cyclin D

2002 ◽  
Vol 22 (22) ◽  
pp. 7842-7852 ◽  
Author(s):  
Marc Schmidt ◽  
Sylvia Fernandez de Mattos ◽  
Armando van der Horst ◽  
Rob Klompmaker ◽  
Geert J. P. L Kops ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcription Factors ◽  
Protein Expression ◽  
Cell Cycle Arrest ◽  
Cellular Proliferation ◽  
Kinase Inhibitor ◽  
Ectopic Expression ◽  
Forkhead Transcription Factors ◽  
Cycle Arrest ◽  
Cell Cycle Inhibition

ABSTRACT The FoxO forkhead transcription factors FoxO4 (AFX), FoxO3a (FKHR.L1), and FoxO1a (FKHR) represent important physiological targets of phosphatidylinositol-3 kinase (PI3K)/protein kinase B (PKB) signaling. Overexpression or conditional activation of FoxO factors is able to antagonize many responses to constitutive PI3K/PKB activation including its effect on cellular proliferation. It was previously shown that the FoxO-induced cell cycle arrest is partially mediated by enhanced transcription and protein expression of the cyclin-dependent kinase inhibitor p27kip1 (R. H. Medema, G. J. Kops, J. L. Bos, and B. M. Burgering, Nature 404:782-787, 2000). Here we have identified a p27kip1-independent mechanism that plays an important role in the antiproliferative effect of FoxO factors. Forced expression or conditional activation of FoxO factors leads to reduced protein expression of the D-type cyclins D1 and D2 and is associated with an impaired capacity of CDK4 to phosphorylate and inactivate the S-phase repressor pRb. Downregulation of D-type cyclins involves a transcriptional repression mechanism and does not require p27kip1 function. Ectopic expression of cyclin D1 can partially overcome FoxO factor-induced cell cycle arrest, demonstrating that downregulation of D-type cyclins represents a physiologically relevant mechanism of FoxO-induced cell cycle inhibition.

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