Lamina-associated polypeptide 2α regulates cell cycle progression and differentiation via the retinoblastoma–E2F pathway

Lamina-associated polypeptide (LAP) 2α is a nonmembrane-bound LAP2 isoform that forms complexes with nucleoplasmic A-type lamins. In this study, we show that the overexpression of LAP2α in fibroblasts reduced proliferation and delayed entry into the cell cycle from a G0 arrest. In contrast, stable down-regulation of LAP2α by RNA interference accelerated proliferation and interfered with cell cycle exit upon serum starvation. The LAP2α-linked cell cycle phenotype is mediated by the retinoblastoma (Rb) protein because the LAP2α COOH terminus directly bound Rb, and overexpressed LAP2α inhibited E2F/Rb-dependent reporter gene activity in G1 phase in an Rb-dependent manner. Furthermore, LAP2α associated with promoter sequences in endogenous E2F/Rb-dependent target genes in vivo and negatively affected their expression. In addition, the expression of LAP2α in proliferating preadipocytes caused the accumulation of hypophosphorylated Rb, which is reminiscent of noncycling cells, and initiated partial differentiation into adipocytes. The effects of LAP2α on cell cycle progression and differentiation may be highly relevant for the cell- and tissue-specific phenotypes observed in laminopathic diseases.

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Hippo signaling is intrinsically regulated during cell cycle progression by APC/CCdh1

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1821370116 ◽

2019 ◽

Vol 116 (19) ◽

pp. 9423-9432 ◽

Cited By ~ 10

Author(s):

Wantae Kim ◽

Yong Suk Cho ◽

Xiaohui Wang ◽

Ogyi Park ◽

Xueyan Ma ◽

...

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Molecular Mechanisms ◽

Mitotic Cell ◽

Hippo Signaling ◽

Dependent Manner ◽

Large Tumor ◽

Cycle Progression ◽

Signaling Regulation

The Hippo-YAP/TAZ signaling pathway plays a pivotal role in growth control during development and regeneration and its dysregulation is widely implicated in various cancers. To further understand the cellular and molecular mechanisms underlying Hippo signaling regulation, we have found that activities of core Hippo signaling components, large tumor suppressor (LATS) kinases and YAP/TAZ transcription factors, oscillate during mitotic cell cycle. We further identified that the anaphase-promoting complex/cyclosome (APC/C)Cdh1 E3 ubiquitin ligase complex, which plays a key role governing eukaryotic cell cycle progression, intrinsically regulates Hippo signaling activities. CDH1 recognizes LATS kinases to promote their degradation and, hence, YAP/TAZ regulation by LATS phosphorylation is under cell cycle control. As a result, YAP/TAZ activities peak in G1 phase. Furthermore, we show in Drosophila eye and wing development that Cdh1 is required in vivo to regulate the LATS homolog Warts with a conserved mechanism. Cdh1 reduction increased Warts levels, which resulted in reduction of the eye and wing sizes in a Yorkie dependent manner. Therefore, LATS degradation by APC/CCdh1 represents a previously unappreciated and evolutionarily conserved layer of Hippo signaling regulation.

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Blocking the transcription factor E2F/DP by dominant-negative mutants in a normal breast epithelial cell line efficiently inhibits apoptosis and induces tumor growth in SCID mice.

Journal of Experimental Medicine ◽

10.1084/jem.183.3.1205 ◽

1996 ◽

Vol 183 (3) ◽

pp. 1205-1213 ◽

Cited By ~ 22

Author(s):

R C Bargou ◽

C Wagener ◽

K Bommert ◽

W Arnold ◽

P T Daniel ◽

...

Keyword(s):

Cell Cycle ◽

Transcription Factor ◽

Tumor Growth ◽

Cell Cycle Progression ◽

S Phase ◽

Dominant Negative ◽

Serum Starvation ◽

Cycle Progression ◽

Transcription Factor E2f

The transcription factor E2F is regulated during the cell cycle through interactions with the product of the retinoblastoma susceptibility gene and related proteins. It is thought that E2F-mediated gene regulation at the G1/S boundary and during S phase may be one of the rate-limiting steps in cell proliferation. It was reported that in vivo overexpression of E2F-1 in fibroblasts induces S phase entry and leads to apoptosis. This observation suggests that E2F plays a role in both cell cycle regulation and apoptosis. To further understand the role of E2F in cell cycle progression, cell death, and tumor development, we have blocked endogenous E2F activity in HBL-100 cells, derived from nonmalignant human breast epithelium, using dominant-negative mutants under the control of a tetracycline-dependent expression system. We have shown here that induction of dominant-negative mutants led to strong downregulation of transiently transfected E2F-dependent chloramphenicol acetyl transferase reporter constructs and of endogenous c-myc, which has been described as a target gene of the transcription factor E2F/DP. In addition, we have shown that blocking of E2F could efficiently protect from apoptosis induced by serum starvation within a period of 10 d, whereas control cells started to die after 24 h. Surprisingly, blocking of E2F did not alter the rate of proliferation or of DNA synthesis of these cells; this finding indicates that cell-cycle progression could be driven in an E2F-independent manner. In addition, we have been able to show that blocking of endogenous E2F in HBL-100 cells led to rapid induction of tumor growth in severe combined immunodeficiency mice. No tumor growth could be observed in mice that received mock-transfected clones or tetracycline to block expression of the E2F mutant constructs in vivo. Thus, it appears that E2F has a potential tumor-suppressive function under certain circumstances. Furthermore, we provide evidence that dysregulation of apoptosis may be an important step in tumorigenesis.

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Caveolin-1 Expression Negatively Regulates Cell Cycle Progression by Inducing G0/G1 Arrest via a p53/p21WAF1/Cip1-dependent Mechanism

Molecular Biology of the Cell ◽

10.1091/mbc.12.8.2229 ◽

2001 ◽

Vol 12 (8) ◽

pp. 2229-2244 ◽

Cited By ~ 190

Author(s):

Ferruccio Galbiati ◽

Daniela Volonte' ◽

Jun Liu ◽

Franco Capozza ◽

Philippe G. Frank ◽

...

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Recombinant Expression ◽

Critical Role ◽

Primary Cultures ◽

Serum Starvation ◽

G1 Arrest ◽

Cycle Progression ◽

Caveolin 1

Caveolin-1 is a principal component of caveolae membranes in vivo. Caveolin-1 mRNA and protein expression are lost or reduced during cell transformation by activated oncogenes. Interestingly, the human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). However, it remains unknown whether caveolin-1 plays any role in regulating cell cycle progression. Here, we directly demonstrate that caveolin-1 expression arrests cells in the G0/G1 phase of the cell cycle. We show that serum starvation induces up-regulation of endogenous caveolin-1 and arrests cells in the G0/G1 phase of the cell cycle. Moreover, targeted down-regulation of caveolin-1 induces cells to exit the G0/G1 phase. Next, we constructed a green fluorescent protein-tagged caveolin-1 (Cav-1-GFP) to examine the effect of caveolin-1 expression on cell cycle regulation. We directly demonstrate that recombinant expression of Cav-1-GFP induces arrest in the G0/G1 phase of the cell cycle. To examine whether caveolin-1 expression is important for modulating cell cycle progression in vivo, we expressed wild-type caveolin-1 as a transgene in mice. Analysis of primary cultures of mouse embryonic fibroblasts from caveolin-1 transgenic mice reveals that caveolin-1 induces 1) cells to exit the S phase of the cell cycle with a concomitant increase in the G0/G1 population, 2) a reduction in cellular proliferation, and 3) a reduction in the DNA replication rate. Finally, we demonstrate that caveolin-1-mediated cell cycle arrest occurs through a p53/p21-dependent pathway. Taken together, our results provide the first evidence that caveolin-1 expression plays a critical role in the modulation of cell cycle progression in vivo.

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Dp1 Is Largely Dispensable for Embryonic Development

Molecular and Cellular Biology ◽

10.1128/mcb.24.16.7197-7205.2004 ◽

2004 ◽

Vol 24 (16) ◽

pp. 7197-7205 ◽

Cited By ~ 20

Author(s):

Matthew J. Kohn ◽

Sandra W. Leung ◽

Vittoria Criniti ◽

Monica Agromayor ◽

Lili Yamasaki

Keyword(s):

Cell Cycle ◽

Embryonic Development ◽

Cell Cycle Progression ◽

Target Genes ◽

Es Cells ◽

Embryonic Stem ◽

Wild Type ◽

Cycle Progression ◽

Cell Cycle Genes

ABSTRACT E2F/DP complexes activate or repress the transcription of E2F target genes, depending on the association of a pRB family member, thereby regulating cell cycle progression. Whereas the E2F family consists of seven members, the DP family contains only two (Dp1 and Dp2), Dp1 being the more highly expressed member. In contrast to the inactivation of individual E2F family members, we have recently demonstrated that loss of Dp1 results in embryonic lethality by embryonic day 12.5 (E12.5) due to the failure of extraembryonic lineages to develop and replicate DNA properly. To bypass this placental requirement and search for roles of Dp1 in the embryo proper, we generated Dp1-deficient embryonic stem (ES) cells that carry the ROSA26-LacZ marker and injected them into wild-type blastocysts to construct Dp1-deficient chimeras. Surprisingly, we recovered mid- to late gestational embryos (E12.5 to E17.5), in which the Dp1-deficient ES cells contributed strongly to most chimeric tissues as judged by X-Gal (5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside) staining and Western blotting. Importantly, the abundance of DP2 protein does not increase and the expression of an array of cell cycle genes is virtually unchanged in Dp1-deficient ES cells or chimeric E15.5 tissues with the absence of Dp1. Thus, Dp1 is largely dispensable for embryonic development, despite the absolute extraembryonic requirement for Dp1, which is highly reminiscent of the restricted roles for Rb and cyclins E1/E2 in vivo.

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Epigenetic Regulation of Cell Cycle-Promoting Genes By Ikaros and HDAC1 in Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood.v124.21.3571.3571 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3571-3571

Author(s):

Sunil Muthusami ◽

Chunhua Song ◽

Xiaokang Pan ◽

Chandrika S. Gowda ◽

Kimberly J Payne ◽

...

Keyword(s):

Cell Cycle ◽

Chromatin Remodeling ◽

Transcriptional Repression ◽

Cell Cycle Progression ◽

Target Genes ◽

Lymphoblastic Leukemia ◽

Promoter Regions ◽

Cycle Progression ◽

Repressive Chromatin

Abstract B-cell acute lymphoblastic leukemia (B-ALL) is the most common childhood leukemia. Expression profiling has identified IKZF1 (Ikaros) as a major tumor suppressor in B-ALL and established reduced Ikaros function as a poor prognostic marker for this disease. Ikaros regulates expression of its target genes via chromatin remodeling. In vivo, Ikaros can form a complex with histone deacetylases HDAC1 and/or HDAC2 as well as the NuRD chromatin remodeling complex. The mechanisms by which Ikaros exerts its tumor suppressor function and regulates gene expression in B-ALL are unknown. Here we report the use of chromatin immunoprecipitation coupled with next generation sequencing (ChIP-SEQ) to identify genes that are regulated by Ikaros in vivo and to determine the role of Ikaros in chromatin remodeling in B-ALL. Results reveal that Ikaros binds to the promoter regions of a large number of genes that are critical for cell cycle progression. These include CDC2, CDC16, CDC25A, ANAPC1, and ANAPC7. Overexpression of Ikaros in leukemia cells resulted in transcriptional repression of Ikaros target genes. Results from luciferase reporter assays performed using the respective promoters of Ikaros target genes support a role for Ikaros as a transcriptional repressor of these genes. Downregulation of Ikaros by siRNA resulted in increased expression of Ikaros target genes that control cell cycle progression. These results suggest that Ikaros functions as a negative regulator of cell cycle progression by repressing transcription of cell cycle-promoting genes. Next, we studied how Ikaros binding affects the epigenetic signature at promoters of Ikaros target genes. Global epigenetic mapping showed that Ikaros binding at the promoter region of cell cycle-promoting genes is associated with the formation of one of two types of repressive epigenetic marks – either H3K27me3 or H3K9me3. While these epigenetic marks were mutually exclusive, they were both associated with the loss of H3K9 acetylation and transcriptional repression. Serial qChIP assays spanning promoters of the Ikaros target genes revealed that the presence of H3K27me3 is associated with Ikaros and HDAC1 binding, while the H3K9me3 modification is associated with Ikaros binding and the absence of HDAC1. ChIP-SEQ analysis of HDAC1 global genomic binding demonstrated that over 80% of H3K27me3 modifications at promoter regions are associated with HDAC1 binding at surrounding sites. The treatment of leukemia cells with the histone deacetylase inhibitor – trichostatin (TSA) resulted in a severe reduction of global levels of H3K27me3, as evidenced by Wesern blot. These data suggest that HDAC1 activity in leukemia is essential for the formation of repressive chromatin that is characterized by the presence of H3K27me3. Our data suggest that Ikaros binding at the promoters of its target genes can result in the formation of repressive chromatin by two distinct mechanisms: 1) direct Ikaros binding resulting in increased H3K9me3 or 2) Ikaros recruitment of HDAC1 with increased H3K27me3 modifications. These data suggest distinct mechanisms for the regulation of chromatin remodeling and target gene expression by Ikaros alone, and Ikaros in complex with HDAC1. In conclusion, the presented data suggest that HDAC1 has a key role in regulating cell cycle progression and proliferation in B-ALL. Our results identify novel, Ikaros-mediated mechanisms of epigenetic regulation that contribute to tumor suppression in leukemia. Supported by National Institutes of Health R01 HL095120, and the Four Diamonds Fund Endowment. Disclosures No relevant conflicts of interest to declare.

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The THAP–zinc finger protein THAP1 regulates endothelial cell proliferation through modulation of pRB/E2F cell-cycle target genes

Blood ◽

10.1182/blood-2006-03-012013 ◽

2006 ◽

Vol 109 (2) ◽

pp. 584-594 ◽

Cited By ~ 83

Author(s):

Corinne Cayrol ◽

Chrystelle Lacroix ◽

Catherine Mathe ◽

Vincent Ecochard ◽

Michele Ceribelli ◽

...

Keyword(s):

Cell Cycle ◽

Cell Proliferation ◽

Large Scale ◽

Cell Cycle Progression ◽

Target Genes ◽

Zinc Finger Protein ◽

Endothelial Cell Proliferation ◽

Cycle Progression ◽

Transcriptional Target

Abstract We recently cloned a novel human nuclear factor (designated THAP1) from postcapillary venule endothelial cells (ECs) that contains a DNA-binding THAP domain, shared with zebrafish E2F6 and several Caenorhabditis elegans proteins interacting genetically with retinoblastoma gene product (pRB). Here, we show that THAP1 is a physiologic regulator of EC proliferation and cell-cycle progression, 2 essential processes for angiogenesis. Retroviral-mediated gene transfer of THAP1 into primary human ECs inhibited proliferation, and large-scale expression profiling with microarrays revealed that THAP1-mediated growth inhibition is due to coordinated repression of pRB/E2F cell-cycle target genes. Silencing of endogenous THAP1 through RNA interference similarly inhibited EC proliferation and G1/S cell-cycle progression, and resulted in down-regulation of several pRB/E2F cell-cycle target genes, including RRM1, a gene required for S-phase DNA synthesis. Chromatin immunoprecipitation assays in proliferating ECs showed that endogenous THAP1 associates in vivo with a consensus THAP1-binding site found in the RRM1 promoter, indicating that RRM1 is a direct transcriptional target of THAP1. The similar phenotypes observed after THAP1 overexpression and silencing suggest that an optimal range of THAP1 expression is essential for EC proliferation. Together, these data provide the first links in mammals among THAP proteins, cell proliferation, and pRB/E2F cell-cycle pathways.

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Targeting Casein Kinase II Exerts a Therapeutic Effect in Pediatric High Risk Leukemia Via Inhibition of Cell Cycle Progression and the PI3K Pathway

Blood ◽

10.1182/blood.v126.23.4800.4800 ◽

2015 ◽

Vol 126 (23) ◽

pp. 4800-4800

Author(s):

Chandrika S. Gowda ◽

Chunhua Song ◽

Yali Ding ◽

Sunil Muthusami ◽

Kimberly Payne ◽

...

Keyword(s):

Cell Cycle ◽

High Risk ◽

Tumor Suppressor ◽

Therapeutic Effect ◽

Cell Cycle Progression ◽

Target Genes ◽

Transcriptional Regulator ◽

Pi3k Pathway ◽

Cycle Progression

Abstract IKZF1 (Ikaros) encodes a DNA-binding protein that acts as a tumor suppressor in acute lymphoblastic leukemia. Deletion of one Ikaros allele results in the development of high-risk B-cell acute lymphoblastic leukemia (B-ALL) with a high incidence of relapse and poor prognosis. The mechanisms through which Ikaros suppresses leukemogenesis and that regulate Ikaros tumor suppressor activity in leukemia are unknown. Using a systems biology approach, we determined that Ikaros regulates transcription of genes that control two pathways that are crucial in leukemia cell proliferation: 1) cell cycle progression and 2) the phosphatidylinositol 3-kinase (PI3K) pathway. Gain- and loss-of-function experiments demonstrate that Ikaros represses the transcription of genes that promote cell cycle progression and the PI3K pathway and activates transcription of a gene that suppresses the PI3K pathway. We show that in high-risk B-ALL with deletion of one Ikaros allele, the function of Ikaros as a transcriptional regulator is impaired due to reduced DNA-binding affinity for promoters of its target genes. It has been shown that Ikaros DNA-binding affinity is regulated via direct phosphorylation by pro-oncogenic Casein Kinase II (CK2). CK2 is overexpressed in high-risk B-ALL as compared to normal B-cell precursors, which further reduces Ikaros function in high-risk B-ALL. Treatment of primary high-risk B-ALL (with deletion of one Ikaros allele) using the CK2 specific inhibitor, CX-4945, restored Ikaros function as a transcriptional regulator of the genes that regulate cell cycle progression and the PI3K pathway, and was associated with cell cycle arrest and loss of phosphorylation of the AKT kinase - a downstream target of the PI3K pathway. The use of serial quantitative chromatin immunoprecipitation (qChIP) analyses spanning the promoters of Ikaros target genes demonstrated that Ikaros can repress transcription of its target genes by two different mechanisms: 1) via recruitment of histone deacetylase 1 (HDAC1), which is associated with the formation of repressive chromatin characterized by H3K27me3 and loss of H3K9ac; and 2) via an HDAC1-independent mechanism which is associated with the formation of repressive chromatin characterized by H3K9me3, along with the loss of H3K9ac. The therapeutic effect of CK2 inhibition by CX-4945 on high-risk B-ALL was demonstrated in vivo using 4 different xenografts: 3 different high-risk primary pre-B-ALL xenografts and Nalm6 xenografts. Treatment with CX-4945 showed a strong therapeutic effect in all 4 xenografts, as evidence by reduced leukemia cell number in bone marrow and in spleen, along with prolonged survival of all xenografts. Expression analysis of Ikaros target genes that regulate cell cycle progression and the PI3K pathway in leukemia cells treated in vivo with CX-4945 revealed an expression pattern that was highly similar to that observed with Ikaros overexpression. This suggests that CK2 inhibition in vivo exerts its therapeutic effect on high-risk B-ALL via restoration of Ikaros function as transcriptional regulator of genes that promote cell cycle progression and the PI3K pathway. In summary, our results reveal that: 1) Ikaros functions as a tumor suppressor by suppressing cell cycle progression and the PI3K pathway; 2) Ikaros regulates transcription by inducing two distinct epigenetic alterations at promoters of its target genes and 3) CK2 inhibition with CX-4945 restores Ikaros function as a transcriptional regulator in vivo, and has a strong therapeutic effect in primary xenografts of high-risk B-ALL. These results provide support for the use of CK2 inhibitors in clinical trials for high-risk B-ALL. Supported by the National Institutes of Health R01 HL095120, and the Four Diamonds Fund Endowment. Disclosures No relevant conflicts of interest to declare.

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Targeting of Casein Kinase II (CK2) Enhances Ikaros-Mediated Control of the Cell Cycle Progression in Pre-Clinical Model of Pre-B-ALL.

Blood ◽

10.1182/blood.v120.21.2431.2431 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2431-2431

Author(s):

Sinsa Dovat ◽

Chunhua Song ◽

Kimberly J Payne ◽

Chandrika S. Gowda

Keyword(s):

Cell Cycle ◽

Tumor Suppressor ◽

Cell Cycle Progression ◽

Target Genes ◽

Signal Transduction Pathway ◽

Preclinical Model ◽

Suppressor Activity ◽

Cycle Progression

Abstract Abstract 2431 The Ikaros (IKZF1) gene encodes a DNA-binding zinc finger protein that functions as a tumor suppressor in leukemia. Defects in the Ikaros gene that lead to its decreased activity are associated with the development of B-cell precursor acute lymphoblastic leukemia (pre-B-ALL). However, the mechanisms by which Ikaros exerts its tumor suppressor activity, as well as the mechanisms that control the tumor suppressor function of Ikaros are poorly understood. Here, we report the identification of two novel Ikaros target genes, as well as a signal transduction pathway that regulates the Ikaros-mediated transcriptional control of these genes in pre-B ALL. We also present evidence that targeting the signal transduction pathway which regulates Ikaros transcriptional control is a potent therapeutic tool for treating pre-B ALL. Analysis of the promoter sequences of the CDC7 and the CDK6 genes revealed multiple evolutionarily-conserved Ikaros consensus binding sites. Using qChIP (quantitative chromatin immunoprecipitation assay) we found that Ikaros binds in vivo to the promoters of the CDC7 and CDK6 genes in the human Nalm6 pre-B ALL cell line, and in primary human pre-B ALL cells. This led to the hypothesis that Ikaros regulates transcription of CDC7 and CDK6 - genes whose expression is essential for cell cycle progression and cellular proliferation. The effect of Ikaros on CDC7 and CDK6 expression was studied using a transient co-transfection assay. Luciferase reporter plasmids containing the CDC7 or CDK6 promoter regions were co-transfected with or without Ikaros into 293T cells. Co-transfection of Ikaros led to decreased luciferase activity, suggesting that Ikaros acts as a repressor of the CDC7 and CDK6 upstream regulatory elements. Increased expression of Ikaros via retroviral transduction in Nalm6 cells resulted in decreased transcription of CDC7 and CDK6. Decreased transcription of these genes was associated with increased binding of Ikaros to their promoter regions as measured by qChIP. These results suggest that Ikaros negatively regulates transcription of CDC7 and CDK6, and thus negatively regulates cell cycle progression in pre-B cell leukemia. We have shown previously that phosphorylation of Ikaros by casein kinase II (CK2) inhibits Ikaros' ability to bind DNA and to regulate transcription of its target genes. CK2 activity is elevated in human leukemia. We tested whether the inhibition of CK2 affects the transcription of CDC7 and CDK6 in pre-B ALL in vitro and in vivo. In vitro treatment of Nalm6 pre-B ALL with TBB, a specific CK2 inhibitor, decreased transcription of CDC7 and CDK6 and was associated with increased binding of Ikaros to the promoters of these genes. Using an in vivo preclinical model of pre-B ALL we tested whether targeting of CK2 would affect transcription of CDC7 and CDK6. In vivo treatment of a human-mouse xenograft model of pre-B ALL with a CK2 inhibitor resulted in decreased transcription of CDC7 and CDK6 and strongly increased Ikaros binding to the promoters of these genes. The in vivo targeting of CK2 provided a strong anti-leukemia effect that resulted in the prolonged survival of treated mice as compared to controls. In summary, our results suggest that Ikaros exerts its tumor suppressor activity in pre-B ALL by repressing transcription of cell cycle-promoting genes. Targeting CK2 in vivo enhances Ikaros-mediated repression of cell cycle progression resulting in an anti-leukemia effect. These data demonstrate the efficacy of CK2 targeting as a treatment for pre-B ALL in a preclinical model. These results provide a mechanistic rationale and support for the use of CK2 inhibitors as a targeted treatment of pre-B ALL in early-stage clinical trials. Supported by National Institutes of Health R01 HL095120 and a St. Baldrick's Foundation Career Development Award (to S.D.). Disclosures: No relevant conflicts of interest to declare.

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EGFR-ERK induced activation of GRHL1 promotes cell cycle progression by up-regulating cell cycle related genes in lung cancer

Cell Death and Disease ◽

10.1038/s41419-021-03721-9 ◽

2021 ◽

Vol 12 (5) ◽

Author(s):

Yiming He ◽

Mingxi Gan ◽

Yanan Wang ◽

Tong Huang ◽

Jianbin Wang ◽

...

Keyword(s):

Lung Cancer ◽

Cell Cycle ◽

Cell Cycle Progression ◽

Potential Role ◽

Target Genes ◽

Nuclear Translocation ◽

Phosphorylation Site ◽

Promoter Regions ◽

Cycle Progression

AbstractGrainyhead-like 1 (GRHL1) is a transcription factor involved in embryonic development. However, little is known about the biological functions of GRHL1 in cancer. In this study, we found that GRHL1 was upregulated in non-small cell lung cancer (NSCLC) and correlated with poor survival of patients. GRHL1 overexpression promoted the proliferation of NSCLC cells and knocking down GRHL1 inhibited the proliferation. RNA sequencing showed that a series of cell cycle-related genes were altered when knocking down GRHL1. We further demonstrated that GRHL1 could regulate the expression of cell cycle-related genes by binding to the promoter regions and increasing the transcription of the target genes. Besides, we also found that EGF stimulation could activate GRHL1 and promoted its nuclear translocation. We identified the key phosphorylation site at Ser76 on GRHL1 that is regulated by the EGFR-ERK axis. Taken together, these findings elucidate a new function of GRHL1 on regulating the cell cycle progression and point out the potential role of GRHL1 as a drug target in NSCLC.

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To Divide or Not to Divide? How Deuterium Affects Growth and Division of Chlamydomonas reinhardtii

Biomolecules ◽

10.3390/biom11060861 ◽

2021 ◽

Vol 11 (6) ◽

pp. 861

Author(s):

Veronika Kselíková ◽

Vilém Zachleder ◽

Kateřina Bišová

Keyword(s):

Cell Cycle ◽

Chlamydomonas Reinhardtii ◽

Cell Cycle Progression ◽

Model Organism ◽

Cycle Progression ◽

Synchronous Cultures ◽

Multiple Fission ◽

First Choice ◽

High Doses

Extensive in vivo replacement of hydrogen by deuterium, a stable isotope of hydrogen, induces a distinct stress response, reduces cell growth and impairs cell division in various organisms. Microalgae, including Chlamydomonas reinhardtii, a well-established model organism in cell cycle studies, are no exception. Chlamydomonas reinhardtii, a green unicellular alga of the Chlorophyceae class, divides by multiple fission, grows autotrophically and can be synchronized by alternating light/dark regimes; this makes it a model of first choice to discriminate the effect of deuterium on growth and/or division. Here, we investigate the effects of high doses of deuterium on cell cycle progression in C. reinhardtii. Synchronous cultures of C. reinhardtii were cultivated in growth medium containing 70 or 90% D2O. We characterize specific deuterium-induced shifts in attainment of commitment points during growth and/or division of C. reinhardtii, contradicting the role of the “sizer” in regulating the cell cycle. Consequently, impaired cell cycle progression in deuterated cultures causes (over)accumulation of starch and lipids, suggesting a promising potential for microalgae to produce deuterated organic compounds.

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