Monitoring of compound resting membrane potentials of cell cultures with ratiometric genetically encoded voltage indicators

AbstractThe cellular resting membrane potential (Vm) not only determines electrical responsiveness of excitable cells but also plays pivotal roles in non-excitable cells, mediating membrane transport, cell-cycle progression, and tumorigenesis. Studying these processes requires estimation of Vm, ideally over long periods of time. Here, we introduce two ratiometric genetically encoded Vm indicators, rArc and rASAP, and imaging and analysis procedures for measuring differences in average resting Vm between cell groups. We investigated the influence of ectopic expression of K+ channels and their disease-causing mutations involved in Andersen-Tawil (Kir2.1) and Temple-Baraitser (KV10.1) syndrome on median resting Vm of HEK293T cells. Real-time long-term monitoring of Vm changes allowed to estimate a 40–50 min latency from induction of transcription to functional Kir2.1 channels in HEK293T cells. The presented methodology is readily implemented with standard fluorescence microscopes and offers deeper insights into the role of the resting Vm in health and disease.

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Targeting NR4A Nuclear Receptors to Control Stromal Cell Inflammation, Metabolism, Angiogenesis, and Tumorigenesis

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.589770 ◽

2021 ◽

Vol 9 ◽

Cited By ~ 1

Author(s):

Daniel Crean ◽

Evelyn P. Murphy

Keyword(s):

Nuclear Receptors ◽

Cell Cycle Progression ◽

Stromal Cell ◽

Immune Cell ◽

Cycle Progression ◽

Cell Responses ◽

Inflammatory Conditions ◽

Health And Disease

The NR4A1–NR4A3 (Nur77, Nurr1, and Nor-1) subfamily of nuclear receptors is a group of immediate early genes induced by a pleiotropy of stimuli including peptide hormones, growth factors, cytokines, inflammatory, and physiological stimuli, and cellular stress. NR4A receptors function as potent sensors of changes in the cellular microenvironment to control physiological and pathological processes through genomic and non-genomic actions. NR4A receptors control metabolism and cardiovascular and neurological functions and mediate immune cell homeostasis in inflammation and cancer. This receptor subfamily is increasingly recognized as an important molecular connection between chronic inflammation, altered immune cell responses, and cancer development. In this review, we examine how transcriptome analysis identified NR4A1/NR4A2 receptors as transcriptional regulators in mesenchymal stromal cell (MSC) migration, cell cycle progression, and cytokine production to control local immune responses. In chronic inflammatory conditions, such as rheumatoid arthritis, NR4A receptors have been shown to modify the activity of MSC and fibroblast-like stromal cells to regulate synovial tissue hyperplasia, pathological angiogenesis, and cartilage turnover in vivo. Additionally, as NR4A1 has been observed as a major transcriptional regulator in tumor–stromal communication controlling tumorigenesis, we discuss how advances in the pharmacological control of these receptors lead to important new mechanistic insights into understanding the role of the tumor microenvironment in health and disease.

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Cdkn3 Knockout Mice Develop Hematopoietic Malignancies

Blood ◽

10.1182/blood.v128.22.1537.1537 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1537-1537 ◽

Cited By ~ 1

Author(s):

Zejin Sun ◽

Donna Cerabona ◽

Ying He ◽

Grzegorz Nalepa

Keyword(s):

Cell Cycle ◽

Tumor Suppressor ◽

Cell Cycle Progression ◽

Conditional Knockout ◽

Cycle Progression ◽

Mitotic Kinase ◽

Risk Of Death

Abstract Cyclin dependent kinase inhibitor 3 (CDKN3) is a dual-specificity cell cycle regulatory phosphatase. In interphase, CDKN3 prevents premature G1/S transition by dephosphorylating interphase cyclin-dependent kinases (CDKs) to prevent premature inactivation of the RB pathway. During cell division, CDKN3 dephosphorylates the key mitotic kinase CDK1 at threonine-161 to extinguish CDK1 activity at the exit from mitosis. CDKN3 knockdown in cultured cells impairs the spindle assembly checkpoint (SAC), accelerates cell cycle progression and causes chromosomal instability, suggesting that it may function as a tumor suppressor. However, since CDKN3 has been reported as overexpressed in some malignancies and mutated or silenced in others, it is unclear whether it functions as an oncogene or a tumor suppressor. To understand the in vivo role of CDKN3 in carcinogenesis, we generated the first Cdkn3 conditional knockout mouse model. We found that Cdkn3-/- mice were viable, non-dysmorphic and born at expected Mendelian ratios, indicating that this gene is dispensable for normal embryonic development. In agreement with the postulated role of this phosphatase in cell cycle progression and regulation of CDKs, we found that Cdkn3-/- cells had increased CDK1, CDK2 and CDK4 activity; increased inhibitory phosphorylation of Rb; increased DNA replication and proliferation; and impaired SAC. Increased CDK activity and accelerated cell cycle progression caused genomic instability reflected by increased frequency of in vivo micronucleation during hematopoiesis as well as higher frequency of aneuploidy and multinucleation and accumulation of supernumerary centrosomes in Cdkn3-/- cells cultured ex vivo. Cdkn3-/- mice had increased myeloid colony-forming units in progenitor assays. Long-term observation of Cdkn3-/- mice revealed an increased risk of death from a variety of hematopoietic (leukemia and lymphoma) and non-hematopoietic (lung, prostate and ovarian) malignancies. Our findings establish Cdkn3 as an in vivo tumor suppressor in bone marrow and a variety of other tissues. In the long term, Cdkn3-/- mice will serve as a tool to dissect the function of this phosphatase in cell cycle control in more detail, and may prove useful in preclinical studies of chemotherapy of CDK-hyperactive, genomically unstable leukemia and lymphoma. Disclosures No relevant conflicts of interest to declare.

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PTTG has a Dual Role of Promotion-Inhibition in the Development of Pituitary Adenomas

Protein and Peptide Letters ◽

10.2174/0929866526666190722145449 ◽

2019 ◽

Vol 26 (11) ◽

pp. 800-818

Author(s):

Zujian Xiong ◽

Xuejun Li ◽

Qi Yang

Keyword(s):

Cell Cycle ◽

Pituitary Adenoma ◽

Pituitary Adenomas ◽

Cell Cycle Progression ◽

Key Factors ◽

Cycle Progression ◽

Sister Chromatids ◽

Regulation Of Cell Cycle ◽

Late Stages

Pituitary Tumor Transforming Gene (PTTG) of human is known as a checkpoint gene in the middle and late stages of mitosis, and is also a proto-oncogene that promotes cell cycle progression. In the nucleus, PTTG works as securin in controlling the mid-term segregation of sister chromatids. Overexpression of PTTG, entering the nucleus with the help of PBF in pituitary adenomas, participates in the regulation of cell cycle, interferes with DNA repair, induces genetic instability, transactivates FGF-2 and VEGF and promotes angiogenesis and tumor invasion. Simultaneously, overexpression of PTTG induces tumor cell senescence through the DNA damage pathway, making pituitary adenoma possessing the potential self-limiting ability. To elucidate the mechanism of PTTG in the regulation of pituitary adenomas, we focus on both the positive and negative function of PTTG and find out key factors interacted with PTTG in pituitary adenomas. Furthermore, we discuss other possible mechanisms correlate with PTTG in pituitary adenoma initiation and development and the potential value of PTTG in clinical treatment.

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The Role of Cell Metabolism in Innate Immune Memory

Journal of Innate Immunity ◽

10.1159/000512280 ◽

2020 ◽

pp. 1-9

Author(s):

Anaisa Valido Ferreira ◽

Jorge Domiguéz-Andrés ◽

Mihai Gheorghe Netea

Keyword(s):

Metabolic Pathways ◽

Tricarboxylic Acid Cycle ◽

Cell Metabolism ◽

Innate Immune ◽

Immune Memory ◽

Functional Changes ◽

Trained Immunity ◽

Health And Disease

Immunological memory is classically attributed to adaptive immune responses, but recent studies have shown that challenged innate immune cells can display long-term functional changes that increase nonspecific responsiveness to subsequent infections. This phenomenon, coined <i>trained immunity</i> or <i>innate immune memory</i>, is based on the epigenetic reprogramming and the rewiring of intracellular metabolic pathways. Here, we review the different metabolic pathways that are modulated in trained immunity. Glycolysis, oxidative phosphorylation, the tricarboxylic acid cycle, amino acid, and lipid metabolism are interplaying pathways that are crucial for the establishment of innate immune memory. Unraveling this metabolic wiring allows for a better understanding of innate immune contribution to health and disease. These insights may open avenues for the development of future therapies that aim to harness or dampen the power of the innate immune response.

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Phosphorylation of RCC1 on Serine 11 Facilitates G1/S Transition in HPV E7-Expressing Cells

Biomolecules ◽

10.3390/biom11070995 ◽

2021 ◽

Vol 11 (7) ◽

pp. 995

Author(s):

Xiaoyan Hou ◽

Lijun Qiao ◽

Ruijuan Liu ◽

Xuechao Han ◽

Weifang Zhang

Keyword(s):

Cell Cycle ◽

Cervical Cancer ◽

Cell Cycle Regulation ◽

Cell Cycle Progression ◽

Mtor Pathway ◽

Cycle Progression ◽

Post Translational Modifications ◽

Hpv E7 ◽

Cycle Regulation

Persistent infection of high-risk human papillomavirus (HR-HPV) plays a causal role in cervical cancer. Regulator of chromosome condensation 1 (RCC1) is a critical cell cycle regulator, which undergoes a few post-translational modifications including phosphorylation. Here, we showed that serine 11 (S11) of RCC1 was phosphorylated in HPV E7-expressing cells. However, S11 phosphorylation was not up-regulated by CDK1 in E7-expressing cells; instead, the PI3K/AKT/mTOR pathway promoted S11 phosphorylation. Knockdown of AKT or inhibition of the PI3K/AKT/mTOR pathway down-regulated phosphorylation of RCC1 S11. Furthermore, S11 phosphorylation occurred throughout the cell cycle, and reached its peak during the mitosis phase. Our previous data proved that RCC1 was necessary for the G1/S cell cycle progression, and in the present study we showed that the RCC1 mutant, in which S11 was mutated to alanine (S11A) to mimic non-phosphorylation status, lost the ability to facilitate G1/S transition in E7-expressing cells. Moreover, RCC1 S11 was phosphorylated by the PI3K/AKT/mTOR pathway in HPV-positive cervical cancer SiHa and HeLa cells. We conclude that S11 of RCC1 is phosphorylated by the PI3K/AKT/mTOR pathway and phosphorylation of RCC1 S11 facilitates the abrogation of G1 checkpoint in HPV E7-expressing cells. In short, our study explores a new role of RCC1 S11 phosphorylation in cell cycle regulation.

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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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The nucleoplasmic interactions among Lamin A/C-pRB-LAP2α-E2F1 are modulated by dexamethasone

Scientific Reports ◽

10.1038/s41598-021-89608-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Anastasia Ricci ◽

Sara Orazi ◽

Federica Biancucci ◽

Mauro Magnani ◽

Michele Menotta

Keyword(s):

Gene Expression ◽

Cell Cycle Progression ◽

Regulation Of Gene Expression ◽

Lamin A ◽

Wild Type ◽

Cycle Progression ◽

C Dynamics ◽

E2f Transcription Factor ◽

Transcription Factor 1

AbstractAtaxia telangiectasia (AT) is a rare genetic neurodegenerative disease. To date, there is no available cure for the illness, but the use of glucocorticoids has been shown to alleviate the neurological symptoms associated with AT. While studying the effects of dexamethasone (dex) in AT fibroblasts, by chance we observed that the nucleoplasmic Lamin A/C was affected by the drug. In addition to the structural roles of A-type lamins, Lamin A/C has been shown to play a role in the regulation of gene expression and cell cycle progression, and alterations in the LMNA gene is cause of human diseases called laminopathies. Dex was found to improve the nucleoplasmic accumulation of soluble Lamin A/C and was capable of managing the large chromatin Lamin A/C scaffolds contained complex, thus regulating epigenetics in treated cells. In addition, dex modified the interactions of Lamin A/C with its direct partners lamin associated polypeptide (LAP) 2a, Retinoblastoma 1 (pRB) and E2F Transcription Factor 1 (E2F1), regulating local gene expression dependent on E2F1. These effects were differentially observed in both AT and wild type (WT) cells. To our knowledge, this is the first reported evidence of the role of dex in Lamin A/C dynamics in AT cells, and may represent a new area of research regarding the effects of glucocorticoids on AT. Moreover, future investigations could also be extended to healthy subjects or to other pathologies such as laminopathies since glucocorticoids may have other important effects in these contexts as well.

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Mutations at sites involved in Suc1 binding inactivate Cdc2

Molecular and Cellular Biology ◽

10.1128/mcb.11.12.6177-6184.1991 ◽

1991 ◽

Vol 11 (12) ◽

pp. 6177-6184

Author(s):

B Ducommun ◽

P Brambilla ◽

G Draetta

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Specific Interaction ◽

Physiological Role ◽

Negative Effects ◽

Alanine Scanning Mutagenesis ◽

Cycle Progression ◽

Mutant Proteins ◽

Additional Protein

suc1+ encodes an essential cell cycle regulator of the fission yeast Schizosaccharomyces pombe. Its product, a 13-kDa protein, interacts with the Cdc2 protein kinase. Both positive and negative effects on cell cycle progression have been attributed to Suc1. To date, the exact mechanisms and the physiological role of the interaction between Suc1 and Cdc2 remain unclear. Here we have studied the molecular basis of this association. We show that Cdc2 can bind Suc1 or its mammalian homolog directly in the absence of any additional protein component. Using an alanine scanning mutagenesis method, we analyzed the interaction between Cdc2 and Suc1. We show that the integrity of several domains on the Cdc2 protein, including sites directly involved in catalytic activity, is required for binding to Suc1. Furthermore, Cdc2 mutant proteins unable to bind Suc1 (but able to bind cyclins) are nonfunctional when overexpressed in S. pombe, indicating that a specific interaction with Suc1 is required for Cdc2 function.

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