scholarly journals Minireview: Entrainment of the Suprachiasmatic Clockwork in Diurnal and Nocturnal Mammals

Endocrinology ◽  
2007 ◽  
Vol 148 (12) ◽  
pp. 5648-5655 ◽  
Author(s):  
Etienne Challet
Keyword(s):  
Activity Pattern ◽  
Molecular Mechanisms ◽  
Clock Genes ◽  
Light Exposure ◽  
Hormone Secretion ◽  
Receptor Activation ◽  
Active Species ◽  
Voluntary Exercise ◽  
Nocturnal Species ◽  
Master Clock

Daily rhythmicity, including timing of wakefulness and hormone secretion, is mainly controlled by a master clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN clockwork involves various clock genes, with specific temporal patterns of expression that are similar in nocturnal and diurnal species (e.g. the clock gene Per1 in the SCN peaks at midday in both categories). Timing of sensitivity to light is roughly similar, during nighttime, in diurnal and nocturnal species. Molecular mechanisms of photic resetting are also comparable in both species categories. By contrast, in animals housed in constant light, exposure to darkness can reset the SCN clock, mostly during the resting period, i.e. at opposite circadian times between diurnal and nocturnal species. Nonphotic stimuli, such as scheduled voluntary exercise, food shortage, exogenous melatonin, or serotonergic receptor activation, are also capable of shifting the master clock and/or modulating photic synchronization. Comparison between day- and night-active species allows classifications of nonphotic cues in two, arousal-independent and arousal-dependent, families of factors. Arousal-independent factors, such as melatonin (always secreted during nighttime, independently of daily activity pattern) or γ-aminobutyric acid (GABA), have shifting effects at the same circadian times in both nocturnal and diurnal rodents. By contrast, arousal-dependent factors, such as serotonin (its cerebral levels follow activity pattern), induce phase shifts only during resting and have opposite modulating effects on photic resetting between diurnal and nocturnal species. Contrary to light and arousal-independent nonphotic cues, arousal-dependent nonphotic stimuli provide synchronizing feedback signals to the SCN clock in circadian antiphase between nocturnal and diurnal animals.

scholarly journals Bright Light Therapy’s Effect on Night Shift Health Care Workers Who Suffer from Light Induced Misalignment of Circadian Rhythms

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Mackenzie Peed
Keyword(s):  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Cell Cycle Progression ◽  
Clock Genes ◽  
Light Exposure ◽  
Night Shift ◽  
Hormone Secretion ◽  
Bright Light ◽  
The United States ◽  
Sleep Cycle

Modern-day society is based on a high pace lifestyle that people are constantly attempting to keep up with. The invention of the light completely changed society, allowing people to work outside of daylight hours. As countries become more and more industrialized, the need for 24/7 productivity becomes more and more common. From transportation to mining to medicine, individuals willing to work unconventional hours are necessary for the sustainability of the industry. This group of people, working outside “normal” work hours such as between 7 a.m. and 6 p.m. or shifts longer than eight hours, are known as shift workers. They make up about 26.5 million people in the employed population in the United States and about 100 million around the world (Moore-Ede & Platika, 2018). Shift work affects a person’s circadian rhythm, causing issues. “Circadian rhythm mainly controls the daily wake and sleep cycle and regulates physiological processes including hormone secretion, body temperature, feeding behavior, cell cycle progression, and drug, glucose, and xenobiotic metabolism” (Khan et al., 2018, p.2). This circadian rhythm is controlled by the circadian clock and is regulated through clock genes. Light exposure greatly influences circadian rhythms and specifically affects the release of the hormone melatonin which activates specific receptors MTI and MT2 that mediate sleep-promoting effects.

Organization of endogenous clocks in insects

2005 ◽  
Vol 33 (5) ◽  
pp. 957-961 ◽  
Author(s):  
C. Helfrich-Förster
Keyword(s):  
Drosophila Melanogaster ◽  
Molecular Mechanisms ◽  
Clock Genes ◽  
Fruit Fly ◽  
Circadian Clocks ◽  
Rhythm Generation ◽  
Similarities And Differences ◽  
The Brain ◽  
Master Clock

Insect and mammalian circadian clocks show striking similarities. They utilize homologous clock genes, generating self-sustained circadian oscillations in distinct master clocks of the brain, which then control rhythmic behaviour. The molecular mechanisms of rhythm generation were first uncovered in the fruit fly Drosophila melanogaster, whereas cockroaches were among the first animals where the brain master clock was localized. Despite many similarities, there exist obvious differences in the organization and functioning of insect master clocks. These similarities and differences are reviewed on a molecular and anatomical level.

Effect of cortisol on neurophysin I/oxytocin and peptidyl glycine-α-amidating mono-oxygenase mRNA expression in bovine luteal and granulosa cells

2013 ◽  
Vol 16 (2) ◽  
pp. 231-239
Author(s):  
A. Ziolkowska ◽  
J. Mlynarczuk ◽  
J. Kotwica
Keyword(s):  
Mrna Expression ◽  
Granulosa Cells ◽  
Molecular Mechanisms ◽  
Hormone Secretion ◽  
Oestrous Cycle ◽  
Luteal Cells ◽  
Ru 486 ◽  
Ovarian Cells ◽  
Key Genes ◽  
Ovary Function

Abstract Cortisol stimulates the synthesis and secretion of oxytocin (OT) from bovine granulosa and luteal cells, but the molecular mechanisms of cortisol action remain unknown. In this study, granulosa cells or luteal cells from days 1-5 and 11-15 of the oestrous cycle were incubated for 4 or 8 h with cortisol (1x10-5, 1x10-7 M). After testing cell viability and hormone secretion (OT, progesterone, estradiol), we studied the effect of cortisol on mRNA expression for precursor of OT (NP-I/OT) and peptidyl glycine-α-amidating mono-oxygenase (PGA). The influence of RU 486 (1x10-5 M), a progesterone receptor blocker and inhibitor of the glucocorticosteroid receptor (GR), on the expression for both genes was tested. Cortisol increased the mRNA expression for NP-I/OT and PGA in granulosa cells and stimulated the expression for NP-I/OT mRNA in luteal cells obtained from days 1-5 and days 11-15 of the oestrous cycle. Expression for PGA mRNA was increased only in luteal cells from days 11-15 of the oestrous cycle. In addition, RU 486 blocked the cortisol-stimulated mRNA expression for NP-I/OT and PGA in both types of cells. These data suggest that cortisol affects OT synthesis and secretion in bovine ovarian cells, by acting on the expression of key genes, that may impair ovary function.

scholarly journals Revising Endosomal Trafficking under Insulin Receptor Activation

2021 ◽  
Vol 22 (13) ◽  
pp. 6978
Author(s):  
Maria J. Iraburu ◽  
Tommy Garner ◽  
Cristina Montiel-Duarte
Keyword(s):  
Plasma Membrane ◽  
Tyrosine Kinase ◽  
Insulin Receptor ◽  
Molecular Mechanisms ◽  
Receptor Activation ◽  
Small Gtpases ◽  
Early Endosome ◽  
Tyrosine Kinase Receptors ◽  
Endosomal Trafficking ◽  
Cell Functions

The endocytosis of ligand-bound receptors and their eventual recycling to the plasma membrane (PM) are processes that have an influence on signalling activity and therefore on many cell functions, including migration and proliferation. Like other tyrosine kinase receptors (TKR), the insulin receptor (INSR) has been shown to be endocytosed by clathrin-dependent and -independent mechanisms. Once at the early endosome (EE), the sorting of the receptor, either to the late endosome (LE) for degradation or back to the PM through slow or fast recycling pathways, will determine the intensity and duration of insulin effects. Both the endocytic and the endosomic pathways are regulated by many proteins, the Arf and Rab families of small GTPases being some of the most relevant. Here, we argue for a specific role for the slow recycling route, whilst we review the main molecular mechanisms involved in INSR endocytosis, sorting and recycling, as well as their possible role in cell functions.

scholarly journals Advances in the Regulation of Mammalian Follicle-Stimulating Hormone Secretion

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1134
Author(s):  
Hao-Qi Wang ◽  
Wei-Di Zhang ◽  
Bao Yuan ◽  
Jia-Bao Zhang
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Follicle Stimulating Hormone ◽  
Hormone Secretion ◽  
Β Subunit ◽  
Glycoprotein Hormone ◽  
Livestock Breeding ◽  
Biological Specificity ◽  
Therapeutic Development ◽  
Stimulating Hormone

Mammalian reproduction is mainly driven and regulated by the hypothalamic-pituitary-gonadal (HPG) axis. Follicle-stimulating hormone (FSH), which is synthesized and secreted by the anterior pituitary gland, is a key regulator that ultimately affects animal fertility. As a dimeric glycoprotein hormone, the biological specificity of FSH is mainly determined by the β subunit. As research techniques are being continuously innovated, studies are exploring the underlying molecular mechanism regulating the secretion of mammalian FSH. This article will review the current knowledge on the molecular mechanisms and signaling pathways systematically regulating FSH synthesis and will present the latest hypothesis about the nuclear cross-talk among the various endocrine-induced pathways for transcriptional regulation of the FSH β subunit. This article will provide novel ideas and potential targets for the improved use of FSH in livestock breeding and therapeutic development.

G-protein-coupled receptors signalling at the cell nucleus: an emerging paradigmThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 287-297 ◽  
Author(s):  
Fernand Gobeil ◽  
Audrey Fortier ◽  
Tang Zhu ◽  
Michela Bossolasco ◽  
Martin Leduc ◽  
...  
Keyword(s):  
G Protein ◽  
Cell Nucleus ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Cell Metabolism ◽  
Hormone Secretion ◽  
G Protein Coupled Receptors ◽  
A Cell ◽  
G Protein Coupled

G-protein-coupled receptors (GPCRs) comprise a wide family of monomeric heptahelical glycoproteins that recognize a broad array of extracellular mediators including cationic amines, lipids, peptides, proteins, and sensory agents. Thus far, much attention has been given towards the comprehension of intracellular signaling mechanisms activated by cell membrane GPCRs, which convert extracellular hormonal stimuli into acute, non-genomic (e.g., hormone secretion, muscle contraction, and cell metabolism) and delayed, genomic biological responses (e.g., cell division, proliferation, and apoptosis). However, with respect to the latter response, there is compelling evidence for a novel intracrine mode of genomic regulation by GPCRs that implies either the endocytosis and nuclear translocation of peripheral-liganded GPCR and (or) the activation of nuclearly located GPCR by endogenously produced, nonsecreted ligands. A noteworthy example of the last scenario is given by heptahelical receptors that are activated by bioactive lipoids (e.g., PGE2 and PAF), many of which may be formed from bilayer membranes including those of the nucleus. The experimental evidence for the nuclear localization and signalling of GPCRs will be reviewed. We will also discuss possible molecular mechanisms responsible for the atypical compartmentalization of GPCRs at the cell nucleus, along with their role in gene expression.

scholarly journals Identification of Differentially Expressed Genes in Porcine Ovaries at Proestrus and Estrus Stages Using RNA-Seq Technique

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Songbai Yang ◽  
Xiaolong Zhou ◽  
Yue Pei ◽  
Han Wang ◽  
Ke He ◽  
...  
Keyword(s):  
Differentially Expressed Genes ◽  
Molecular Mechanisms ◽  
Expression Patterns ◽  
Hormone Secretion ◽  
Differentially Expressed ◽  
Receptor Interaction ◽  
The Novel ◽  
Kegg Pathways ◽  
Go Enrichment ◽  
Single Organism

Estrus is an important factor for the fecundity of sows, and it is involved in ovulation and hormone secretion in ovaries. To better understand the molecular mechanisms of porcine estrus, the expression patterns of ovarian mRNA at proestrus and estrus stages were analyzed using RNA sequencing technology. A total of 2,167 differentially expressed genes (DEGs) were identified (P≤0.05, log2  Ratio≥1), of which 784 were upregulated and 1,383 were downregulated in the estrus compared with the proestrus group. Gene Ontology (GO) enrichment indicated that these DEGs were mainly involved in the cellular process, single-organism process, cell and cell part, and binding and metabolic process. In addition, a pathway analysis showed that these DEGs were significantly enriched in 33 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including cell adhesion molecules, ECM-receptor interaction, and cytokine-cytokine receptor interaction. Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) confirmed the differential expression of 10 selected DEGs. Many of the novel candidate genes identified in this study will be valuable for understanding the molecular mechanisms of the sow estrous cycle.

scholarly journals The Complexities of Organ Crosstalk in Phosphate Homeostasis: Time to Put Phosphate Sensing Back in the Limelight

2021 ◽  
Vol 22 (11) ◽  
pp. 5701
Author(s):  
Lucile Figueres ◽  
Sarah Beck-Cormier ◽  
Laurent Beck ◽  
Joanne Marks
Keyword(s):  
Molecular Mechanisms ◽  
Dominant Role ◽  
Fibroblast Growth Factor 23 ◽  
Hormone Secretion ◽  
Phosphate Transport ◽  
Phosphate Homeostasis ◽  
Cellular Mechanisms ◽  
Exact Function ◽  
Phosphate Sensing ◽  
Significant Research

Phosphate homeostasis is essential for health and is achieved via interaction between the bone, kidney, small intestine, and parathyroid glands and via intricate processes involving phosphate transporters, phosphate sensors, and circulating hormones. Numerous genetic and acquired disorders are associated with disruption in these processes and can lead to significant morbidity and mortality. The role of the kidney in phosphate homeostasis is well known, although it is recognized that the cellular mechanisms in murine models and humans are different. Intestinal phosphate transport also appears to differ in humans and rodents, with recent studies demonstrating a dominant role for the paracellular pathway. The existence of phosphate sensing has been acknowledged for decades; however, the underlying molecular mechanisms are poorly understood. At least three phosphate sensors have emerged. PiT2 and FGFR1c both act as phosphate sensors controlling Fibroblast Growth Factor 23 secretion in bone, whereas the calcium-sensing receptor controls parathyroid hormone secretion in response to extracellular phosphate. All three of the proposed sensors are expressed in the kidney and intestine but their exact function in these organs is unknown. Understanding organ interactions and the mechanisms involved in phosphate sensing requires significant research to develop novel approaches for the treatment of phosphate homeostasis disorders.

scholarly journals Context-dependent expression of the foraging gene in field colonies of ants: the interacting roles of age, environment and task

2016 ◽  
Vol 283 (1837) ◽  
pp. 20160841 ◽  
Author(s):  
Krista K. Ingram ◽  
Deborah M. Gordon ◽  
Daniel A. Friedman ◽  
Michael Greene ◽  
John Kahler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Task Allocation ◽  
Molecular Mechanisms ◽  
Light Exposure ◽  
Genetic Regulation ◽  
Behavioural Plasticity ◽  
Harvester Ants ◽  
Ontogenetic Changes ◽  
Context Dependent ◽  
And Task

Task allocation among social insect workers is an ideal framework for studying the molecular mechanisms underlying behavioural plasticity because workers of similar genotype adopt different behavioural phenotypes. Elegant laboratory studies have pioneered this effort, but field studies involving the genetic regulation of task allocation are rare. Here, we investigate the expression of the foraging gene in harvester ant workers from five age- and task-related groups in a natural population, and we experimentally test how exposure to light affects foraging expression in brood workers and foragers. Results from our field study show that the regulation of the foraging gene in harvester ants occurs at two time scales: levels of foraging mRNA are associated with ontogenetic changes over weeks in worker age, location and task, and there are significant daily oscillations in foraging expression in foragers. The temporal dissection of foraging expression reveals that gene expression changes in foragers occur across a scale of hours and the level of expression is predicted by activity rhythms: foragers have high levels of foraging mRNA during daylight hours when they are most active outside the nests. In the experimental study, we find complex interactions in foraging expression between task behaviour and light exposure. Oscillations occur in foragers following experimental exposure to 13 L : 11 D (LD) conditions, but not in brood workers under similar conditions. No significant differences were seen in foraging expression over time in either task in 24 h dark (DD) conditions. Interestingly, the expression of foraging in both undisturbed field and experimentally treated foragers is also significantly correlated with the expression of the circadian clock gene, cycle . Our results provide evidence that the regulation of this gene is context-dependent and associated with both ontogenetic and daily behavioural plasticity in field colonies of harvester ants. Our results underscore the importance of assaying temporal patterns in behavioural gene expression and suggest that gene regulation is an integral mechanism associated with behavioural plasticity in harvester ants.

scholarly journals Transformation of postingestive glucose responses after deletion of sweet taste receptor subunits or gastric bypass surgery

2012 ◽  
Vol 303 (4) ◽  
pp. E464-E474 ◽  
Author(s):  
Maartje C. P. Geraedts ◽  
Tatsuyuki Takahashi ◽  
Stephan Vigues ◽  
Michele L. Markwardt ◽  
Andongfac Nkobena ◽  
...  
Keyword(s):  
Gastric Bypass ◽  
Glycemic Control ◽  
Large Intestine ◽  
Molecular Mechanisms ◽  
Hormone Secretion ◽  
Taste Receptor ◽  
Sweet Taste ◽  
Oral Glucose ◽  
Isolated Pancreatic Islets ◽  
Sweet Taste Receptor

The glucose-dependent secretion of the insulinotropic hormone glucagon-like peptide-1 (GLP-1) is a critical step in the regulation of glucose homeostasis. Two molecular mechanisms have separately been suggested as the primary mediator of intestinal glucose-stimulated GLP-1 secretion (GSGS): one is a metabotropic mechanism requiring the sweet taste receptor type 2 (T1R2) + type 3 (T1R3) while the second is a metabolic mechanism requiring ATP-sensitive K+(KATP) channels. By quantifying sugar-stimulated hormone secretion in receptor knockout mice and in rats receiving Roux-en-Y gastric bypass (RYGB), we found that both of these mechanisms contribute to GSGS; however, the mechanisms exhibit different selectivity, regulation, and localization. T1R3−/−mice showed impaired glucose and insulin homeostasis during an oral glucose challenge as well as slowed insulin granule exocytosis from isolated pancreatic islets. Glucose, fructose, and sucralose evoked GLP-1 secretion from T1R3+/+, but not T1R3−/−, ileum explants; this secretion was not mimicked by the KATPchannel blocker glibenclamide. T1R2−/−mice showed normal glycemic control and partial small intestine GSGS, suggesting that T1R3 can mediate GSGS without T1R2. Robust GSGS that was KATPchannel-dependent and glucose-specific emerged in the large intestine of T1R3−/−mice and RYGB rats in association with elevated fecal carbohydrate throughout the distal gut. Our results demonstrate that the small and large intestines utilize distinct mechanisms for GSGS and suggest novel large intestine targets that could mimic the improved glycemic control seen after RYGB.

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