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https://www.readbyqxmd.com/read/28649427/global-rise-of-potential-health-hazards-caused-by-blue-light-induced-circadian-disruption-in-modern-aging-societies
#1
REVIEW
Megumi Hatori, Claude Gronfier, Russell N Van Gelder, Paul S Bernstein, Josep Carreras, Satchidananda Panda, Frederick Marks, David Sliney, Charles E Hunt, Tsuyoshi Hirota, Toshiharu Furukawa, Kazuo Tsubota
Mammals receive light information through the eyes, which perform two major functions: image forming vision to see objects and non-image forming adaptation of physiology and behavior to light. Cone and rod photoreceptors form images and send the information via retinal ganglion cells to the brain for image reconstruction. In contrast, nonimage-forming photoresponses vary widely from adjustment of pupil diameter to adaptation of the circadian clock. nonimage-forming responses are mediated by retinal ganglion cells expressing the photopigment melanopsin...
2017: NPJ Aging and Mechanisms of Disease
https://www.readbyqxmd.com/read/28637769/potential-contribution-of-tandem-circadian-enhancers-to-nonlinear-oscillations-in-clock-gene-expression
#2
Isao T Tokuda, Akihiko Okamoto, Ritsuko Matsumura, Toru Takumi, Makoto Akashi
Limit cycle oscillations require the presence of nonlinear processes. Although mathematical studies have long suggested that multiple nonlinear processes are required for autonomous circadian oscillation in clock gene expression, the underlying mechanism remains controversial. Here, we experimentally show that cell-autonomous circadian transcription of a mammalian clock gene requires a functionally interdependent tandem E-box motif; the lack of either of the two E-boxes results in arrhythmic transcription. Although previous studies have indicated the role of the tandem motifs in increasing circadian amplitude, enhancing amplitude does not explain the mechanism for limit cycle oscillations in transcription...
June 21, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28625476/feedback-loops-interlocked-at-competitive-binding-sites-amplify-and-facilitate-genetic-oscillations
#3
Koichiro Uriu, Hajime Tei
Positive and negative feedback loops are often present in regulatory networks for genetic oscillations. Relative time scales and integration of these feedback loops are key to robust oscillations in expression levels. Using examples from the circadian clock and synthetic genetic oscillators, we study positive and negative feedback loops interlocked at competitive binding sites. In the mammalian circadian clock, a key clock gene Bmal1 is regulated by the activator ROR and the repressor REV-ERB. Conversely, Bmal1 activates both of them, forming interlocked feedback loops...
June 15, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28622766/translational-contributions-to-tissue-specificity-in-rhythmic-and-constitutive-gene-expression
#4
Violeta Castelo-Szekely, Alaaddin Bulak Arpat, Peggy Janich, David Gatfield
BACKGROUND: The daily gene expression oscillations that underlie mammalian circadian rhythms show striking differences between tissues and involve post-transcriptional regulation. Both aspects remain poorly understood. We have used ribosome profiling to explore the contribution of translation efficiency to temporal gene expression in kidney and contrasted our findings with liver data available from the same mice. RESULTS: Rhythmic translation of constantly abundant messenger RNAs (mRNAs) affects largely non-overlapping transcript sets with distinct phase clustering in the two organs...
June 16, 2017: Genome Biology
https://www.readbyqxmd.com/read/28592378/no-fad-no-cry-redox-and-circadian-rhythms
#5
David Pritchett, Akhilesh B Reddy
There is growing evidence of reciprocal interactions between the endogenous circadian clock and subcellular redox pathways. Recently, researchers at the University of California unearthed another possible link between redox metabolism and the mammalian circadian clock: the redox cofactor FAD stabilises the clock protein cryptochrome (CRY), modifying rhythmic clock gene expression.
June 4, 2017: Trends in Biochemical Sciences
https://www.readbyqxmd.com/read/28591634/a-cell-autonomous-mammalian-12%C3%A2-hr-clock-coordinates-metabolic-and-stress-rhythms
#6
Bokai Zhu, Qiang Zhang, Yinghong Pan, Emily M Mace, Brian York, Athanasios C Antoulas, Clifford C Dacso, Bert W O'Malley
Besides circadian rhythms, oscillations cycling with a 12 hr period exist. However, the prevalence, origin, regulation, and function of mammalian 12 hr rhythms remain elusive. Utilizing an unbiased mathematical approach identifying all superimposed oscillations, we uncovered prevalent 12 hr gene expression and metabolic rhythms in mouse liver, coupled with a physiological 12 hr unfolded protein response oscillation. The mammalian 12 hr rhythm is cell autonomous, driven by a dedicated 12 hr pacemaker distinct from the circadian clock, and can be entrained in vitro by metabolic and ER stress cues...
June 6, 2017: Cell Metabolism
https://www.readbyqxmd.com/read/28585704/the-regulations-and-role-of-circadian-clock-and-melatonin-in-uterine-receptivity-and-pregnancy-an-immunological-perspective
#7
Gene Chi Wai Man, Tao Zhang, Xiaoyan Chen, Jianzhang Wang, Fangrong Wu, Yingyu Liu, Chi Chiu Wang, Ying Cheong, Tin Chiu Li
During normal pregnancy, the mechanism by which the fetus escapes immunological rejection by the maternal womb remains elusive. Given the biological complexities, the immunological mechanism is unlikely to be simply an allograft response in acceptance or rejection of the early pregnancy. Circadian clock responsible for the mammalian circadian rhythm is an endogenously generated rhythm associated with almost all physiological processes including reproduction. There is now growing evidence to suggest that the circadian clocks are intricately linked to the immune system and pregnancy...
June 6, 2017: American Journal of Reproductive Immunology: AJRI
https://www.readbyqxmd.com/read/28583847/timeless-confers-cisplatin-resistance-in-nasopharyngeal-carcinoma-by-activating-the-wnt-%C3%AE-catenin-signaling-pathway-and-promoting-the-epithelial-mesenchymal-transition
#8
Sai-Lan Liu, Huan-Xin Lin, Chu-Yong Lin, Xiao-Qing Sun, Li-Ping Ye, Fang Qiu, Wen Wen, Xin Hua, Xian-Qiu Wu, Jun Li, Li-Bing Song, Ling Guo
This study investigated the expression, clinicopathological significance and mechanism of action of TIMELESS, a mammalian homolog of a Drosophila circadian rhythm gene, in nasopharyngeal carcinoma. Quantitative real-time PCR, western blotting and immunohistochemistry revealed TIMELESS was upregulated in NPC cell lines (n = 8 vs. NP69 cells), and freshly-frozen (n = 6) and paraffin-embedded human NPC specimens (n = 108 vs. normal samples/non-tumor cells). TIMELESS expression was associated with T category (P = 0...
June 3, 2017: Cancer Letters
https://www.readbyqxmd.com/read/28553258/an-overview-of-monthly-rhythms-and-clocks
#9
REVIEW
Florian Raible, Hiroki Takekata, Kristin Tessmar-Raible
Organisms have evolved to cope with geophysical cycles of different period lengths. In this review, we focus on the adaptations of animals to the lunar cycle, specifically, on the occurrence of biological rhythms with monthly (circalunar) or semi-monthly (circasemilunar) period lengths. Systematic experimental investigation, starting in the early twentieth century, has allowed scientists to distinguish between mythological belief and scientific facts concerning the influence of the lunar cycle on animals. These studies revealed that marine animals of various taxa exhibit circalunar or circasemilunar reproductive rhythms...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28532353/ocular-photoreception-for-circadian-rhythm-entrainment-in-mammals
#10
Russell N Van Gelder, Ethan D Buhr
Circadian rhythms are self-sustained, approximately 24-h rhythms of physiology and behavior. These rhythms are entrained to an exactly 24-h period by the daily light-dark cycle. Remarkably, mice lacking all rod and cone photoreceptors still demonstrate photic entrainment, an effect mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells utilize melanopsin (OPN4) as their photopigment. Distinct from the ciliary rod and cone opsins, melanopsin appears to function as a stable photopigment utilizing sequential photon absorption for its photocycle; this photocycle, in turn, confers properties on ipRGCs such as sustained signaling and resistance from photic bleaching critical for an irradiance detection system...
October 14, 2016: Annual Review of Vision Science
https://www.readbyqxmd.com/read/28525301/mood-the-circadian-system-and-melanopsin-retinal-ganglion-cells
#11
Lorenzo Lazzerini Ospri, Glen Prusky, Samer Hattar
The discovery of a third type of photoreceptors in the mammalian retina, intrinsically photosensitive retinal ganglion cells (ipRGCs), has had a revolutionary impact on chronobiology. We can now properly account for numerous nonvision-related functions of light, including its effect on the circadian system. Here, we give an overview of ipRGCs and their function as it relates specifically to mood and biological rhythms. Although circadian disruptions have been traditionally hypothesized to be the mediators of light's effects on mood, here we present an alternative model that dispenses with assumptions of causality between the two phenomena and explains mood regulation by light via another ipRGC-dependent mechanism...
May 17, 2017: Annual Review of Neuroscience
https://www.readbyqxmd.com/read/28506462/a-slow-conformational-switch-in-the-bmal1-transactivation-domain-modulates-circadian-rhythms
#12
Chelsea L Gustafson, Nicole C Parsley, Hande Asimgil, Hsiau-Wei Lee, Christopher Ahlbach, Alicia K Michael, Haiyan Xu, Owen L Williams, Tara L Davis, Andrew C Liu, Carrie L Partch
The C-terminal transactivation domain (TAD) of BMAL1 (brain and muscle ARNT-like 1) is a regulatory hub for transcriptional coactivators and repressors that compete for binding and, consequently, contributes to period determination of the mammalian circadian clock. Here, we report the discovery of two distinct conformational states that slowly exchange within the dynamic TAD to control timing. This binary switch results from cis/trans isomerization about a highly conserved Trp-Pro imide bond in a region of the TAD that is required for normal circadian timekeeping...
May 18, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28506231/optogenetic-interrogation-reveals-separable-g-protein-dependent-and-independent-signalling-linking-g-protein-coupled-receptors-to-the-circadian-oscillator
#13
Helena J Bailes, Nina Milosavljevic, Ling-Yu Zhuang, Elliot J Gerrard, Tomoki Nishiguchi, Takeaki Ozawa, Robert J Lucas
BACKGROUND: Endogenous circadian oscillators distributed across the mammalian body are synchronised among themselves and with external time via a variety of signalling molecules, some of which interact with G-protein-coupled receptors (GPCRs). GPCRs can regulate cell physiology via pathways originating with heterotrimeric G-proteins or β-arrestins. We applied an optogenetic approach to determine the contribution of these two signalling modes on circadian phase. RESULTS: We employed a photopigment (JellyOp) that activates Gαs signalling with better selectivity and higher sensitivity than available alternatives, and a point mutant of this pigment (F112A) biased towards β-arrestin signalling...
May 15, 2017: BMC Biology
https://www.readbyqxmd.com/read/28506121/mammalian-circadian-period-but-not-phase-and-amplitude-is-robust-against-redox-and-metabolic-perturbations
#14
Marrit Putker, Priya Crosby, Kevin A Feeney, Nathaniel P Hoyle, Ana S H Costa, Edoardo Gaude, Christian Frezza, John S O'Neill
AIMS: Circadian rhythms permeate all levels of biology to temporally regulate cell and whole-body physiology, although the cell-autonomous mechanism that confers ∼24-h periodicity is incompletely understood. Reports describing circadian oscillations of over-oxidized peroxiredoxin abundance have suggested that redox signaling plays an important role in the timekeeping mechanism. Here, we tested the functional contribution that redox state and primary metabolism make to mammalian cellular timekeeping...
June 26, 2017: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/28498398/per2-is-downregulated-by-the-lps-induced-inflammatory-response-in-synoviocytes-in-rheumatoid-arthritis-and-is-implicated-in-disease-susceptibility
#15
Hwayoung Lee, Seong-Su Nah, Sung-Hae Chang, Hyung-Ki Kim, Jun-Tack Kwon, Sanghyun Lee, Ik-Hyun Cho, Sang Won Lee, Young Ock Kim, Seung-Jae Hong, Hak-Jae Kim
The clinical symptoms of rheumatoid arthritis (RA) present with circadian variation, with joint stiffness and pain more prominent in the early morning. The mammalian clock genes, which include circadian locomotor output cycles kaput, brain and muscle Arnt-like protein 1, period and cryptochrome, regulate circadian rhythms. In order to identify the association between genetic polymorphisms in the circadian clock gene period 2 (PER2) and RA, the present study genotyped three PER2 single nucleotide polymorphisms (SNPs), rs934945, rs6754875, and rs2304674, using genetic information from 256 RA patients and 499 control subjects...
July 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28496287/a-systems-theoretic-approach-to-analysis-and-control-of-mammalian-circadian-dynamics
#16
John H Abel, Francis J Doyle
The mammalian circadian clock is a complex multi-scale, multivariable biological control system. In the past two decades, methods from systems engineering have led to numerous insights into the architecture and functionality of this system. In this review, we examine the mammalian circadian system through a process systems lens. We present a mathematical framework for examining the cellular circadian oscillator, and show recent extensions for understanding population-scale dynamics. We provide an overview of the routes by which the circadian system can be systemically manipulated, and present in silico proof of concept results for phase resetting of the clock via model predictive control...
December 2016: Chemical Engineering Research & Design: Transactions of the Institution of Chemical Engineers
https://www.readbyqxmd.com/read/28487473/epigenetic-regulation-of-the-circadian-clock-role-of-5-aza-2-deoxycytidine
#17
Tatsunosuke Tomita, Ryoji Kurita, Yoshiaki Onishi
We have been investigating transcriptional regulation of the BMAL1 gene, a critical component of the mammalian clock system including DNA methylation. Here, a more detailed analysis of the regulation of DNA methylation of BMAL1 proceeded in RPMI8402 lymphoma cells. We found that CpG islands in the BMAL1 and the PER2 promoters were hyper- and hypomethylated, respectively and that 5-aza-2'-deoxycytidine (aza-dC) not only enhanced PER2 gene expression but also PER2 oscillation within 24 h in RPMI8402 cells. That is, such hypermethylation of CpG islands in the BMAL1 promoter restricted PER2 expression which was recovered by aza-dC within 1 day in these cells...
June 30, 2017: Bioscience Reports
https://www.readbyqxmd.com/read/28480817/plasticity-in-the-period-of-the-circadian-pacemaker-induced-by-phase-dispersion-of-its-constituent-cellular-clocks
#18
Domien G M Beersma, Kim A Gargar, Serge Daan
The mammalian circadian pacemaker is commonly thought to be a rigid oscillator that generates output under a variety of circumstances that differ only in phase, period, and/or amplitude. Yet the pacemaker is composed of many cells that each can respond to varying circumstances in different ways. Computer simulations demonstrate that networks of such pacemaker cells behave differently under a light-dark cycle compared with constant darkness. The differences demonstrate that the circadian pacemaker is plastic: The pacemaker shapes its properties in response to the circumstances...
June 2017: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28466791/computational-modeling-of-the-cell-autonomous-mammalian-circadian-oscillator
#19
Olga A Podkolodnaya, Natalya N Tverdokhleb, Nikolay L Podkolodnyy
This review summarizes various mathematical models of cell-autonomous mammalian circadian clock. We present the basics necessary for understanding of the cell-autonomous mammalian circadian oscillator, modern experimental data essential for its reconstruction and some special problems related to the validation of mathematical circadian oscillator models. This work compares existing mathematical models of circadian oscillator and the results of the computational studies of the oscillating systems. Finally, we discuss applications of the mathematical models of mammalian circadian oscillator for solving specific problems in circadian rhythm biology...
February 24, 2017: BMC Systems Biology
https://www.readbyqxmd.com/read/28466226/analysis-of-dna-damage-response-to-ionizing-radiation-in-serum-shock-synchronized-human-fibroblasts
#20
Samantha Corrà, Riccardo Salvadori, Leonardo Bee, Vito Barbieri, Maddalena Mognato
Many aspects of cellular physiology, including cellular response to genotoxic stress, are related to the circadian rhythmicity induced by the molecular clock. The current study investigated if the cellular response to DNA damage is in relation to endogenous expression levels of the PER2 protein, a key component of the molecular regulatory system that confers rhythmicity in mammalian cells. Human normal fibroblasts (CCD-34Lu) were subjected to serum shock to induce circadian oscillations of the PER2 protein and then irradiated with γ- rays at times corresponding to the trough and peak expression of the PER2 protein...
May 3, 2017: Cell Biology and Toxicology
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