scholarly journals Cryptochromes and the Circadian Clock: The Story of a Very Complex Relationship in a Spinning World

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 672
Author(s):  
Loredana Lopez ◽  
Carlo Fasano ◽  
Giorgio Perrella ◽  
Paolo Facella
Keyword(s):  
Circadian Clock ◽  
Cell Cycle Regulation ◽  
Molecular Mechanisms ◽  
Chloroplast Development ◽  
Complex Relationship ◽  
Physiological Processes ◽  
Environmental Light ◽  
Daily Cycles ◽  
Chromatin Organisation ◽  
Cycle Regulation

Cryptochromes are flavin-containing blue light photoreceptors, present in most kingdoms, including archaea, bacteria, plants, animals and fungi. They are structurally similar to photolyases, a class of flavoproteins involved in light-dependent repair of UV-damaged DNA. Cryptochromes were first discovered in Arabidopsis thaliana in which they control many light-regulated physiological processes like seed germination, de-etiolation, photoperiodic control of the flowering time, cotyledon opening and expansion, anthocyanin accumulation, chloroplast development and root growth. They also regulate the entrainment of plant circadian clock to the phase of light–dark daily cycles. Here, we review the molecular mechanisms by which plant cryptochromes control the synchronisation of the clock with the environmental light. Furthermore, we summarise the circadian clock-mediated changes in cell cycle regulation and chromatin organisation and, finally, we discuss a putative role for plant cryptochromes in the epigenetic regulation of genes.

scholarly journals Epigenetic Regulation of Apoptosis and Cell Cycle in Osteosarcoma

Sarcoma ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Krithi Rao-Bindal ◽  
Eugenie S. Kleinerman
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Regulation ◽  
Molecular Mechanisms ◽  
Genetic Mutations ◽  
Epigenetic Mechanisms ◽  
Epigenetic Alterations ◽  
Novel Therapeutic Strategies ◽  
Cycle Regulation ◽  
Insight Into

The role of genetic mutations in the development of osteosarcoma, such as alterations in p53 and Rb, is well understood. However, the significance of epigenetic mechanisms in the progression of osteosarcoma remains unclear and is increasingly being investigated. Recent evidence suggests that epigenetic alterations such as methylation and histone modifications of genes involved in cell cycle regulation and apoptosis may contribute to the pathogenesis of this tumor. Importantly, understanding the molecular mechanisms of regulation of these pathways may give insight into novel therapeutic strategies for patients with osteosarcoma. This paper serves to summarize the described epigenetic mechanisms in the tumorigenesis of osteosarcoma, specifically those pertaining to apoptosis and cell cycle regulation.

Abstract W P198: Sphingomyelin Synthases Regulate Neuronal Cell Proliferation and Cell Cycle Progression

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Umadevi V Wesley ◽  
Daniel Tremmel ◽  
Robert Dempsey
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Regulation ◽  
Cell Cycle Progression ◽  
Molecular Mechanisms ◽  
Neuronal Cell ◽  
Artery Occlusion ◽  
Cycle Progression ◽  
Cycle Arrest ◽  
Cycle Regulation ◽  
Cerebral Artery Occlusion

Introduction: The molecular mechanisms of cerebral ischemia damage and protection are not completely understood, but a number of reports implicate the contribution of lipid metabolism and cell-cycle regulating proteins in stroke out come. We have previously shown that tricyclodecan-9-yl-xanthogenate (D609) resulted in increased ceramide levels after transient middle cerebral artery occlusion (tMCAO) in spontaneously hypertensive rat (SHR). We hypothesized that D609 induced cell cycle arrest probably by inhibiting sphingomyelin synthase (SMS). In this study, we examined the direct effects of SMS on cell cycle progression and proliferation of neuroblast cells. Methods: Ischemia was induced by middle cerebral artery occlusion (MCAO) and reperfusion. Expression levels were measured by western blot analysis, RT-PCR, and Immunofluorescence staining. SMS1 and 2 expressions were silenced by stable transfection with SMS1/2-targeted shRNA. Cell cycle analysis was performed using Flow cytometry. Data were analyzed using MODFIT cell cycle analysis program. Cell proliferation rate was measured by MTT assay. Results: We have identified that the expression of SMS1is significantly up-regulated in the ischemic hemisphere following MCAO. Neuro-2a cells transfected with SMS specific ShRNA acquired more neuronal like phenotype and exhibited decreased proliferation rate. Also, silencing of both SMS1 and 2 induced cell-cycle arrest as shown by significantly increased percentage of cells in G0/G1 and decreased proportion of cells in S-phase as compared to control cells. This was accompanied by up-regulation of cyclin-dependent kinase (Cdk) inhibitors p21 and decreased levels of phophorylated AKT levels. Furthermore, loss of SMS inhibited the migratory potential of Neuro 2a cells. Summary: Up-regulation of SMS under ischemic/reperfusion conditions suggests that this enzyme potentially contributes to cell cycle regulation and may contribute to maintaining neuronal cell population. Further studies may open up a new direction for identifying the molecular mechanisms of cell cycle regulation and protection following ischemic stroke

Achilles-Mediated and Sex-Specific Regulation of Circadian mRNA Rhythms in Drosophila

2019 ◽  
Vol 34 (2) ◽  
pp. 131-143 ◽  
Author(s):  
Jiajia Li ◽  
Renee Yin Yu ◽  
Farida Emran ◽  
Brian E. Chen ◽  
Michael E. Hughes
Keyword(s):  
Circadian Clock ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Clock Genes ◽  
Peripheral Tissues ◽  
Knock Down ◽  
Rhythmic Expression ◽  
The Core ◽  
Physiological Processes ◽  
Specific Regulation

The circadian clock is an evolutionarily conserved mechanism that generates the rhythmic expression of downstream genes. The core circadian clock drives the expression of clock-controlled genes, which in turn play critical roles in carrying out many rhythmic physiological processes. Nevertheless, the molecular mechanisms by which clock output genes orchestrate rhythmic signals from the brain to peripheral tissues are largely unknown. Here we explored the role of one rhythmic gene, Achilles, in regulating the rhythmic transcriptome in the fly head. Achilles is a clock-controlled gene in Drosophila that encodes a putative RNA-binding protein. Achilles expression is found in neurons throughout the fly brain using fluorescence in situ hybridization (FISH), and legacy data suggest it is not expressed in core clock neurons. Together, these observations argue against a role for Achilles in regulating the core clock. To assess its impact on circadian mRNA rhythms, we performed RNA sequencing (RNAseq) to compare the rhythmic transcriptomes of control flies and those with diminished Achilles expression in all neurons. Consistent with previous studies, we observe dramatic upregulation of immune response genes upon knock-down of Achilles. Furthermore, many circadian mRNAs lose their rhythmicity in Achilles knock-down flies, suggesting that a subset of the rhythmic transcriptome is regulated either directly or indirectly by Achilles. These Achilles-mediated rhythms are observed in genes involved in immune function and in neuronal signaling, including Prosap, Nemy and Jhl-21. A comparison of RNAseq data from control flies reveals that only 42.7% of clock-controlled genes in the fly brain are rhythmic in both males and females. As mRNA rhythms of core clock genes are largely invariant between the sexes, this observation suggests that sex-specific mechanisms are an important, and heretofore under-appreciated, regulator of the rhythmic transcriptome.

The emerging importance of cyclin-dependent kinase inhibitors in the regulation of the plant cell cycle and related processesThis review is one of a selection of papers published in the Special Issue on Plant Cell Biology.

2006 ◽  
Vol 84 (4) ◽  
pp. 640-650 ◽  
Author(s):  
Hong Wang ◽  
Yongming Zhou ◽  
Larry C. Fowke
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Plant Cell ◽  
Cell Biology ◽  
Cell Cycle Regulation ◽  
Cellular Localization ◽  
Molecular Mechanisms ◽  
Cdk Inhibitors ◽  
Cyclin Dependent Kinase ◽  
Cycle Regulation

The cell division cycle in plants as in other eukaryotes is controlled by the cyclin-dependent kinase (CDK). This CDK paradigm determines that developmental cues and environmental signals need to impinge on the CDK complex to affect the cell cycle. An important part of understanding cell cycle regulation is to understand how CDK is regulated by various factors. In addition, there are features that set the cell cycle regulation in plants apart from that in other eukaryotes such as animals. Our knowledge of the molecular mechanisms that underlie the differences is poor. A family of plant CDK inhibitor proteins has been identified. The plant CDK inhibitors share similarity with a family of animal CDK inhibitors in a small region, while most of the sequence and the structural layout of the plant CDK inhibitors are different from the animal counterparts. Studies of plant CDK inhibitors have been performed mostly with the CDK inhibitors from Arabidopsis called ICKs (also referred to as KRPs). ICKs interact with D-type cyclins and A-type CDK. Overexpression of ICKs has been shown to affect cell division, plant growth, and morphogenesis. Studies of ICKs have also provided insightful information on the control of endoreduplication in plants. These aspects as well as cellular localization and protein regulation of ICKs are reviewed.

The molecular mechanisms of vitamin C on cell cycle regulation in B16F10 murine melanoma

2007 ◽  
Vol 102 (4) ◽  
pp. 1002-1010 ◽  
Author(s):  
Eunsil Hahm ◽  
Dong-Hoon Jin ◽  
Jae Seung Kang ◽  
Young-In Kim ◽  
Seung-Woo Hong ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Vitamin C ◽  
Cell Cycle Regulation ◽  
Molecular Mechanisms ◽  
Murine Melanoma ◽  
Cycle Regulation

scholarly journals Slaves to the rhythm: Oscillations, cycling and the pace of life

2004 ◽  
Vol 26 (1) ◽  
pp. 11-13 ◽  
Author(s):  
Fabian Rudolf ◽  
Franziska Wehrle ◽  
Dorothee Staiger
Keyword(s):  
Circadian Clock ◽  
Limited Availability ◽  
Important Resource ◽  
Physiological Processes ◽  
Pace Of Life ◽  
Environmental Light ◽  
Metabolic Reactions ◽  
Sessile Organisms

Plants, as sessile organisms, are forced to take advantage of the limited availability of sunlight, their most important resource. Not surprisingly, many aspects of physiology and development are therefore organized by an endogenous chronometer in plants. This so-called ‘circadian’ clock imposes a 24-hour rhythm on metabolic reactions and physiological processes to optimally align them with the environmental light-dark cycle1.

scholarly journals MECHANISMS OF ENDOCRINOLOGY: Cell cycle regulation in adrenocortical carcinoma

2018 ◽  
Vol 179 (2) ◽  
pp. R95-R110 ◽  
Author(s):  
Sofia S Pereira ◽  
Mariana P Monteiro ◽  
Isabelle Bourdeau ◽  
André Lacroix ◽  
Duarte Pignatelli
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Regulation ◽  
Molecular Mechanisms ◽  
Kinase Inhibitors ◽  
Treatment Options ◽  
Growth Factor Receptor ◽  
Biological Behavior ◽  
Endocrine Tumors ◽  
Breast Cancers ◽  
Cycle Regulation

Adrenocortical carcinomas (ACCs) are rather rare endocrine tumors that often have a poor prognosis. The reduced survival rate associated with these tumors is due to their aggressive biological behavior, combined with the scarcity of effective treatment options that are currently available. The recent identification of the genomic alterations present in ACC have provided further molecular mechanisms to develop consistent strategies for the diagnosis, prevention of progression and treatment of advanced ACCs. Taken together, molecular and genomic advances could be leading the way to develop personalized medicine in ACCs similarly to similar developments in lung or breast cancers. In this review, we focused our attention to systematically compile and summarize the alterations in the cell cycle regulation that were described so far in ACC as they are known to play a crucial role in cell differentiation and growth. We have divided the analysis according to the major transition phases of the cell cycle, G1 to S and G2 to M. We have analyzed the most extensively studied checkpoints: the p53/Rb1 pathway, CDC2/cyclin B and topoisomerases (TOPs). We reached the conclusion that the most important alterations having a potential application in clinical practice are the ones related to p53/Rb1 and TOP 2. We also present a brief description of on-going clinical trials based on molecular alterations in ACC. The drugs have targeted the insulin-like growth factor receptor 1, TOP 2, polo-like kinase1, cyclin-dependent kinase inhibitors, p53 reactivation and CDC25.

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