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https://www.readbyqxmd.com/read/28525301/mood-the-circadian-system-and-melanopsin-retinal-ganglion-cells
#1
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
#2
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
#3
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
#4
Marrit Putker, Priya Crosby, Kevin A Feeney, Nathaniel P Hoyle, Ana S H da Costa, Edoardo Gaude, Christian Frezza, John Stuart 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-hour periodicity is incompletely understood. Reports describing circadian oscillations of over-oxidised peroxiredoxin abundance have suggested 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...
May 15, 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
#5
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...
May 11, 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28496287/a-systems-theoretic-approach-to-analysis-and-control-of-mammalian-circadian-dynamics
#6
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
#7
Yoshiaki Onishi, Tatsunosuke Tomita, Ryoji Kurita
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 hypo-methylated, respectively and that 5-aza-2'-deoxycytidine (aza-dC) not only enhanced PER2 gene expression but also PER2 oscillation within 24 hours in RPMI8402 cells...
May 9, 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
#8
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...
May 1, 2017: Journal of Biological Rhythms
https://www.readbyqxmd.com/read/28466791/computational-modeling-of-the-cell-autonomous-mammalian-circadian-oscillator
#9
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
#10
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
https://www.readbyqxmd.com/read/28463109/the-role-of-pdf-neurons-in-setting-preferred-temperature-before-dawn-in-drosophila
#11
Xin Tang, Sanne Roessingh, Sean E Hayley, Michelle L Chu, Nobuaki K Tanaka, Werner Wolfgang, Seongho Song, Ralf Stanewsky, Fumika N Hamada
Animals have sophisticated homeostatic controls. While mammalian body temperature fluctuates throughout the day, small ectotherms, such as Drosophila, achieve a body temperature rhythm (BTR) through their preference of environmental temperature. Here, we demonstrate that pigment dispersing factor (PDF) neurons play an important role in setting preferred temperature before dawn. We show that small lateral ventral neurons (sLNvs), a subset of PDF neurons, activate the dorsal neurons 2 (DN2s), the main circadian clock cells that regulate temperature preference rhythm (TPR)...
May 2, 2017: ELife
https://www.readbyqxmd.com/read/28456660/assessing-mouse-behaviour-throughout-the-light-dark-cycle-using-automated-in-cage-analysis-tools
#12
Rasneer S Bains, Rowland R Sillito, J Douglas Armstrong, Heather L Cater, Gareth Banks, Patrick M Nolan
An important factor in reducing variability in mouse test outcomes has been to develop assays that can be used for continuous automated home cage assessment. Our experience has shown that this has been most evidenced in long-term assessment of wheel-running activity in mice. Historically, wheel-running in mice and other rodents has been used as a robust assay to determine, with precision, the inherent period of circadian rhythms in mice. Furthermore, this assay has been instrumental in dissecting the molecular genetic basis of mammalian circadian rhythms...
April 26, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28448626/genetic-background-dependent-effects-of-murine-micro-rnas-on-circadian-clock-function
#13
Silke Kiessling, Ahmet Ucar, Kamal Chowdhury, Henrik Oster, Gregor Eichele
MicroRNAs (miRs) are important regulators of a wide range of biological processes. Antagomir studies suggest an implication of miR-132 in the functionality of the mammalian circadian clock. miR-212 and miR-132 are tandemly processed from the same transcript and share the same seed region. We found the clock modulator miR-132 and miR-212 to be expressed rhythmically in the central circadian clock. Consequently, mRNAs implicated in circadian functions may likely be targeted by both miRs. To further characterize the circadian role we generated mice with stable deletion of the miR-132/212 locus and compared the circadian behavior of mutant and wild-type control animals on two genetic backgrounds frequently used in chronobiological research, C57BL/6N and 129/Sv...
2017: PloS One
https://www.readbyqxmd.com/read/28438481/genes-and-neural-circuits-for-sleep-of-the-fruit-fly
#14
REVIEW
Jun Tomita, Gosuke Ban, Kazuhiko Kume
Sleep is a universal physiological state evolutionarily conserved among species, but the molecular basis for its regulation is still largely unknown. Due to its electroencephalogram criteria, sleep has long been investigated and described mostly in mammalian species. The fruit fly, Drosophila melanogaster, has emerged as a genetic model organism for studying sleep. The Drosophila sleep is behaviorally defined, and is tightly regulated by circadian and homeostatic processes, like mammals. Genetic analyses using Drosophila have successfully identified a number of conserved regulatory mechanisms underlying sleep between flies and mammals...
April 21, 2017: Neuroscience Research
https://www.readbyqxmd.com/read/28412365/vaccinia-related-kinase-3-vrk3-sets-the-circadian-period-and-amplitude-by-affecting-the-subcellular-localization-of-clock-proteins-in-mammalian-cells
#15
Nayoung Park, Jieun Song, Seongsu Jeong, Thanh Thi Tran, Hyuk Wan Ko, Eun Young Kim
In the eukaryotic circadian clock machinery, negative feedback repression of CLOCK (CLK) and BMAL1 transcriptional activity by PERIOD (PER) and CRYPTOCHROME (CRY) underlies the basis for 24 h rhythmic gene expression. Thus, precise regulation of the time-dependent nuclear entry of circadian repressors is crucial to generating normal circadian rhythms. Here, we sought to identify novel kinase(s) that regulate nuclear entry of mammalian CRY1 (mCRY1) with an unbiased screening using red fluorescent protein (RFP)-tagged human kinome expression plasmids in mammalian cells...
April 13, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28405468/cryptochrome-genes-form-an-oscillatory-loop-independent-of-the-per-tim-loop-in-the-circadian-clockwork-of-the-cricket-gryllus-bimaculatus
#16
Atsushi Tokuoka, Taichi Q Itoh, Shinryo Hori, Outa Uryu, Yoshiki Danbara, Motoki Nose, Tetsuya Bando, Teiichi Tanimura, Kenji Tomioka
BACKGROUND: Animals exhibit circadian rhythms with a period of approximately 24 h in various physiological functions, including locomotor activity. This rhythm is controlled by an endogenous oscillatory mechanism, or circadian clock, which consists of cyclically expressed clock genes and their product proteins. cryptochrome (cry) genes are thought to be involved in the clock mechanism, and their functions have been examined extensively in holometabolous insects, but in hemimetabolous insects their role is less well understood...
2017: Zoological Letters
https://www.readbyqxmd.com/read/28401917/cooperative-roles-of-the-suprachiasmatic-nucleus-central-clock-and-the-adrenal-clock-in-controlling-circadian-glucocorticoid-rhythm
#17
Sooyoung Chung, Eun Jeong Lee, Hyo Kyeong Cha, Jeongah Kim, Doyeon Kim, Gi Hoon Son, Kyungjin Kim
The mammalian circadian timing system consists of the central clock in the hypothalamic suprachiasmatic nucleus (SCN) and subsidiary peripheral clocks in other tissues. Glucocorticoids (GCs) are adrenal steroid hormones with widespread physiological effects that undergo daily oscillations. We previously demonstrated that the adrenal peripheral clock plays a pivotal role in circadian GC rhythm by driving cyclic GC biosynthesis. Here, we show that the daily rhythm in circulating GC levels is controlled by bimodal actions of central and adrenal clockwork...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28382017/disrupted-ultradian-activity-rhythms-and-differential-expression-of-several-clock-genes-in-interleukin-6-deficient-mice
#18
Francisco J Monje, Ana Cicvaric, Juan Pablo Acevedo Aguilar, Immanuel Elbau, Orsolya Horvath, Weifei Diao, Micaela Glat, Daniela D Pollak
The characteristics of the cycles of activity and rest stand out among the most intensively investigated aspects of circadian rhythmicity in humans and experimental animals. Alterations in the circadian patterns of activity and rest are strongly linked to cognitive and emotional dysfunctions in severe mental illnesses such as Alzheimer's disease (AD) and major depression (MDD). The proinflammatory cytokine interleukin 6 (IL-6) has been prominently associated with the pathogenesis of AD and MDD. However, the potential involvement of IL-6 in the modulation of the diurnal rhythms of activity and rest has not been investigated...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28367335/circadian-plasticity-of-mammalian-inhibitory-interneurons
#19
REVIEW
Malgorzata Jasinska, Elzbieta Pyza
Inhibitory interneurons participate in all neuronal circuits in the mammalian brain, including the circadian clock system, and are indispensable for their effective function. Although the clock neurons have different molecular and electrical properties, their main function is the generation of circadian oscillations. Here we review the circadian plasticity of GABAergic interneurons in several areas of the mammalian brain, suprachiasmatic nucleus, neocortex, hippocampus, olfactory bulb, cerebellum, striatum, and in the retina...
2017: Neural Plasticity
https://www.readbyqxmd.com/read/28363845/the-expression-of-the-clock-gene-cycle-has-rhythmic-pattern-and-is-affected-by-photoperiod-in-the-moth-sesamia-nonagrioides
#20
Dimitrios Kontogiannatos, Theodoros Gkouvitsas, Anna Kourti
To obtain clues to the link between the molecular mechanism of circadian and photoperiod clocks, we have cloned the circadian clock gene cycle (Sncyc) in the corn stalk borer, Sesamia nonagrioides, which undergoes facultative diapause controlled by photoperiod. Sequence analysis revealed a high degree of conservation among insects for this gene. SnCYC consists of 667 amino acids and structural analysis showed that it contains a BCTR domain in its C-terminal in addition to the common domains found in Drosophila CYC, i...
March 29, 2017: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
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