scholarly journals A Circadian Clock Entrained by Melatonin Is Ticking in the Rat Fetal Adrenal

Endocrinology ◽  
2011 ◽  
Vol 152 (5) ◽  
pp. 1891-1900 ◽  
Author(s):  
C. Torres-Farfan ◽  
N. Mendez ◽  
L. Abarzua-Catalan ◽  
N. Vilches ◽  
G. J. Valenzuela ◽  
...  
Keyword(s):  
Adrenal Gland ◽  
Circadian Clock ◽  
Clock Genes ◽  
Regulatory Protein ◽  
Fetal Life ◽  
Early Growth Response ◽  
Circadian Expression ◽  
Steroidogenic Acute Regulatory

The adrenal gland in the adult is a peripheral circadian clock involved in the coordination of energy intake and expenditure, required for adaptation to the external environment. During fetal life, a peripheral circadian clock is present in the nonhuman primate adrenal gland. Whether this extends to the fetal adrenal gland like the rat is unknown. Here we explored in vivo and in vitro whether the rat fetal adrenal is a peripheral circadian clock entrained by melatonin. We measured the 24-h changes in adrenal content of corticosterone and in the expression of clock genes Per-2 and Bmal-1 and of steroidogenic acute regulatory protein (StAR), Mt1 melatonin receptor, and early growth response protein 1 (Egr-1) expression. In culture, we explored whether oscillatory expression of these genes persisted during 48 h and the effect of a 4-h melatonin pulse on their expression. In vivo, the rat fetal adrenal gland showed circadian expression of Bmal-1 and Per-2 in antiphase (acrophases at 2200 and 1300 h, respectively) as well as of Mt1 and Egr-1. This was accompanied by circadian rhythms of corticosterone content and of StAR expression both peaking at 0600 h. The 24-h oscillatory expression of Bmal-1, Per-2, StAR, Mt1, and Egr-1 persisted during 48 h in culture; however, the antiphase between Per-2 and Bmal-1 was lost. The pulse of melatonin shifted the acrophases of all the genes studied and restored the antiphase between Per-2 and Bmal-1. Thus, in the rat, the fetal adrenal is a strong peripheral clock potentially amenable to regulation by maternal melatonin.

scholarly journals Cell type resolved co-expression networks of core clock genes in brain development

2021 ◽  
Author(s):  
Surbhi Sharma ◽  
Asgar Hussain Ansari ◽  
Soundhar Ramasamy
Keyword(s):  
Circadian Clock ◽  
Single Cell ◽  
Radial Glia ◽  
Clock Genes ◽  
Neuronal Cell ◽  
Cell Types ◽  
Developing Brain ◽  
Knock Out

AbstractThe circadian clock regulates vital cellular processes by adjusting the physiology of the organism to daily changes in the environment. Rhythmic transcription of core Clock Genes (CGs) and their targets regulate these processes at the cellular level. Circadian clock disruption has been observed in people with neurodegenerative disorders like Alzheimer’s and Parkinson’s. Also, ablation of CGs during development has been shown to affect neurogenesis in both in vivo and in vitro models. Previous studies on the function of CGs in the brain have used knock-out models of a few CGs. However, a complete catalog of CGs in different cell types of the developing brain is not available and it is also tedious to obtain. Recent advancements in single-cell RNA sequencing (scRNA-seq) has revealed novel cell types and elusive dynamic cell states of the developing brain. In this study by using publicly available single-cell transcriptome datasets we systematically explored CGs-coexpressing networks (CGs-CNs) during embryonic and adult neurogenesis. Our meta-analysis reveals CGs-CNs in human embryonic radial glia, neurons and also in lesser studied non-neuronal cell types of the developing brain.

CORTISOL CIRCADIAN RHYTHM AND INSULIN RESISTANCE IN MUSCLE: EFFECT OF DOSING AND TIMING OF HYDROCORTISONE EXPOSURE ON INSULIN SENSITIVITY IN SYNCHRONIZED MUSCLE CELLS.

2020 ◽  
Author(s):  
Mariarosaria Negri ◽  
Claudia Pivonello ◽  
Chiara Simeoli ◽  
Gilda Di Gennaro ◽  
Mary Anna Venneri ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Circadian Rhythm ◽  
Insulin Sensitivity ◽  
Circadian Clock ◽  
Insulin Signaling ◽  
Clock Genes ◽  
Muscle Cells ◽  
C2c12 Cells ◽  
Circadian Expression

Introduction/Aim: Circadian rhythm disruption is emerging as a risk factor for metabolic disorders and particularly, alterations in clock genes circadian expression have been shown to influence insulin sensitivity. Recently, the reciprocal interplay between the circadian clock machinery and HPA axis has been largely demonstrated: the circadian clock may control the physiological circadian endogenous glucocorticoids secretion and action; glucocorticoids, in turn, are potent regulator of the circadian clock and their inappropriate replacement has been associated with metabolic impairment. The aim of the current study was to investigate in vitro the interaction between the timing-of-the-day exposure to different hydrocortisone (HC) concentrations on muscle insulin sensitivity. Methods: Serum-shock synchronized mouse skeletal muscle C2C12 cells were exposed to different HC concentrations recapitulating the circulating daily physiological cortisol profile (standard cortisol profile), the circulating daily cortisol profile that reached in adrenal insufficient (AI) patients treated with once-daily MR-HC (flat cortisol profile) and treated with thrice-daily of conventional IR-HC (steep cortisol profile). The 24 hrs spontaneous oscillation of the clock genes in synchronized C2C12 cells was used to align the timing for in vitro HC exposure (Bmal1 acrophase, midphase and bathyphase) with the reference times of cortisol peaks in AI treated with IR-HC (8 am, 1 pm, 6 pm). A panel of 84 insulin sensitivity related genes and intracellular insulin signaling proteins were analyzed by RT-qPCR and western blot, respectively. Results: Only the steep profile, characterized by a higher HC exposure during Bmal1 bathyphase, produced significant downregulation in 21 insulin sensitivity-related genes. Among these, Insr, Irs1, Irs2, Pi3kca and Adipor2 were downregulated when compared the flat to the standard or steep profile. Reduced intracellular IRS1 Tyr608, AKT Ser473, AMPK Thr172 and ACC Ser79 phosphorylations were also observed. Conclusions: The current study demonstrated that is late-in-the-day cortisol exposure that modulates insulin sensitivity-related genes expression and intracellular insulin signaling in skeletal muscle cells.

scholarly journals Gpr19 is a circadian clock-controlled orphan GPCR with a role in modulating free-running period and light resetting capacity of the circadian clock

2021 ◽  
Author(s):  
Yoshiaki Yamaguchi ◽  
Iori Murai ◽  
Kaoru Goto ◽  
Shotaro Doi ◽  
Huihua Zhou ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Clock Genes ◽  
Dorsal Region ◽  
Circadian Expression ◽  
Delayed Initiation ◽  
Free Running ◽  
Responsive Element ◽  
Free Running Period ◽  
Orphan Gpcr

Background and Purpose: Gpr19 encodes an evolutionarily conserved orphan G-protein-coupled receptor (GPCR) with no established physiological function in vivo. The purpose of this study was to determine the role of Gpr19 in the circadian clock system. Experimental Approach: We examined whether and how the master circadian clock neurons in the suprachiasmatic nucleus (SCN) express Gpr19. By analysing Gpr19-deficient (Gpr19−/−) mice, we asked whether Gpr19 has a role in modulating free-running period and light resetting capacity of the circadian clock. Key Results: Compared with the known common core clock genes, Gpr19 was identified to show several distinct yet limited features related to the circadian clock. Gpr19 mRNA was mainly expressed in the middle-to-dorsal region of the SCN. A conserved cAMP-responsive element within the Gpr19 promoter drove the circadian expression of Gpr19. Gpr19−/− mice exhibited a prolonged circadian period and a delayed initiation of daily locomotor activity in a 12-h light/12-h dark cycle. Gpr19 deficiency caused the downregulation of several genes that normally peak during the night, including Bmal1 and Gpr176. Gpr19−/− mice had a reduced capacity for phase shift to early subjective night light. The defect was only observed for phase-delay, but not phase-advance, and accompanied by reduced response of c-Fos expression in the dorsal region of the SCN, while apparently normal in the ventral part of the SCN, in Gpr19−/− mice. Conclusion and Implications: Gpr19 is an SCN-enriched orphan GPCR with a distinct role in circadian regulation and thus may be a potential target for alleviating circadian clock disorders.

scholarly journals Cancer clocks in tumourigenesis: the p53 pathway and beyond

2021 ◽  
Vol 28 (4) ◽  
pp. R95-R110
Author(s):  
Ewan M Stephenson ◽  
Laura E J Usselmann ◽  
Vinay Tergaonkar ◽  
David M Virshup ◽  
Robert Dallmann
Keyword(s):  
Circadian Rhythms ◽  
Circadian Clock ◽  
Cancer Biology ◽  
Cell Cycle Progression ◽  
Clock Genes ◽  
Human Cancer ◽  
Epidemiologic Studies ◽  
Current Evidence

Circadian rhythms regulate a vast array of physiological and cellular processes, as well as the hormonal milieu, to keep our cells synchronised to the light–darkness cycle. Epidemiologic studies have implicated circadian disruption in the development of breast and other cancers, and numerous clock genes are dysregulated in human tumours. Here we review the evidence that circadian rhythms, when altered at the molecular level, influence cancer growth. We also note some common pitfalls in circadian-cancer research and how they might be avoided to maximise comparable results and minimise misleading data. Studies of circadian gene mutant mice, and human cancer models in vitro and in vivo, demonstrate that clock genes can impact tumourigenesis. Clock genes influence important cancer-related pathways, ranging from p53-mediated apoptosis to cell cycle progression. Confusingly, clock dysfunction can be both pro- or anti-tumourigenic in a model and cell type-specific manner. Due to this duality, there is no canonical mechanism for clock interaction with tumourigenic pathways. To understand the role of the circadian clock in patients’ tumours requires analysis of the molecular clock status compared to healthy tissue. Novel mathematical approaches are under development, but this remains largely aspirational, and is hampered by a lack of temporal information in publicly available datasets. Current evidence broadly supports the notion that the circadian clock is important for cancer biology. More work is necessary to develop an overarching model of this connection. Future studies would do well to analyse the clock network in addition to alterations in single clock genes.

scholarly journals DAPL1 is a novel regulator of testosterone production in Leydig cells of mouse testis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hong-bin Chen ◽  
Jorge Carlos Pineda Garcia ◽  
Shinako Arizono ◽  
Tomoki Takeda ◽  
Ren-shi Li ◽  
...  
Keyword(s):  
Leydig Cells ◽  
Regulatory Protein ◽  
Serum Testosterone ◽  
Mouse Testis ◽  
Testosterone Levels ◽  
Steroidogenic Acute Regulatory ◽  
Sexually Mature ◽  
In Vitro Data

AbstractLeydig cells in the testes produce testosterone in the presence of gonadotropins. Therefore, male testosterone levels must oscillate within a healthy spectrum, given that elevated testosterone levels augment the risk of cardiovascular disorders. We observed that the expression of death-associated protein-like 1 (DAPL1), which is involved in the early stages of epithelial differentiation and apoptosis, is considerably higher in the testes of sexually mature mice than in other tissues. Accordingly, Dapl1-null mice were constructed to evaluate this variation. Notably, in these mice, the testicular levels of steroidogenic acute regulatory protein (StAR) and serum testosterone levels were significantly elevated on postnatal day 49. The findings were confirmed in vitro using I-10 mouse testis-derived tumor cells. The in vivo and in vitro data revealed the DAPL1-regulated the expression of StAR involving altered transcription of critical proteins in the protein kinase A and CREB/CREM pathways in Leydig cells. The collective findings implicate DAPL1 as an important factor for steroidogenesis regulation, and DAPL1 deregulation may be related to high endogenous levels of testosterone.

scholarly journals Single adeno-associated virus-based multiplexed CRISPR-Cas9 system to nullify core components of the mammalian molecular clock

2020 ◽  
Author(s):  
Boil Kim ◽  
Jihoon Kim ◽  
Minjeong Chun ◽  
Inah Park ◽  
Mijung Choi ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Molecular Clock ◽  
Viral Vectors ◽  
Clock Genes ◽  
Ex Vivo ◽  
Physiological Role ◽  
Guide Rnas ◽  
Multiple Genes

ABSTRACTThe mammalian molecular clock is based on a transcription-translation feedback loop (TTFL) containing Period1, 2 (Per1, 2), Cryptochrome1, 2 (Cry1, 2), and Brain and Muscle ARNT-Like 1 (Bmal1). TTFL robustness is endowed by genetic complementation between these components; therefore, multiple genes must be knocked out to physiologically investigate the molecular clock, which requires extensive research resources. To facilitate molecular clock disruption, we developed a CRISPR-Cas9-based single adeno-associated viral (AAV) system targeting the circadian clock (CSAC) for Pers, Crys, or Bmal1. First, we designed single guide RNAs (sgRNAs) targeting individual clock genes using an in silico approach and validated their efficiency in Neuro2a cells. To target multiple genes, multiplex sgRNA plasmids were constructed using Golden Gate assembly and expressed in viral vectors. CSAC efficiency was demonstrated by decreased protein expression in vitro and ablated molecular oscillation ex vivo. We also measured locomotor activity and body temperature in Cas9-expressing mice injected with CSAC at the suprachiasmatic nucleus. Circadian rhythm disruption was observed under free-running conditions, indicating that CSAC can efficiently and robustly disrupt molecular circadian clock. Thus, CSAC is a simple and powerful tool for investigating the physiological role of the molecular clock in vivo.

scholarly journals The Core-Clock Gene NR1D1 Impacts Cell Motility In Vitro and Invasiveness in a Zebrafish Xenograft Colon Cancer Model

Cancers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 853 ◽  
Author(s):  
Alireza Basti ◽  
Rita Fior ◽  
Müge Yalҫin ◽  
Vanda Póvoa ◽  
Rosario Astaburuaga ◽  
...  
Keyword(s):  
Cell Migration ◽  
Circadian Clock ◽  
Cell Motility ◽  
Clock Genes ◽  
Xenograft Model ◽  
Migration And Invasion ◽  
Altered Expression ◽  
The Core

Malfunctions of circadian clock trigger abnormal cellular processes and influence tumorigenesis. Using an in vitro and in vivo xenograft model, we show that circadian clock disruption via the downregulation of the core-clock genes BMAL1, PER2, and NR1D1 impacts the circadian phenotype of MYC, WEE1, and TP53, and affects proliferation, apoptosis, and cell migration. In particular, both our in vitro and in vivo results suggest an impairment of cell motility and a reduction in micrometastasis formation upon knockdown of NR1D1, accompanied by altered expression levels of SNAI1 and CD44. Interestingly we show that differential proliferation and reduced tumour growth in vivo may be due to the additional influence of the host-clock and/or to the 3D tumour architecture. Our results raise new questions concerning host–tumour interaction and show that core-clock genes are involved in key cancer properties, including the regulation of cell migration and invasion by NR1D1 in zebrafish xenografts.

scholarly journals Cellular Senescence Impairs Circadian Expression of Clock Genes In Vitro and In Vivo

2006 ◽  
Vol 98 (4) ◽  
pp. 532-539 ◽  
Author(s):  
Takeshige Kunieda ◽  
Tohru Minamino ◽  
Taro Katsuno ◽  
Kaoru Tateno ◽  
Jun-ichiro Nishi ◽  
...  
Keyword(s):  
Cellular Senescence ◽  
Clock Genes ◽  
Circadian Expression

scholarly journals The Contribution of Serine 194 Phosphorylation to Steroidogenic Acute Regulatory Protein Function

2014 ◽  
Vol 28 (7) ◽  
pp. 1088-1096 ◽  
Author(s):  
Goro Sasaki ◽  
Mohamad Zubair ◽  
Tomohiro Ishii ◽  
Toshikatsu Mitsui ◽  
Tomonobu Hasegawa ◽  
...  
Keyword(s):  
Adrenal Cortex ◽  
Protein Function ◽  
Regulatory Protein ◽  
Initial Step ◽  
Artificial Chromosome ◽  
Steroidogenic Acute Regulatory Protein ◽  
Inner Mitochondrial Membrane ◽  
Steroidogenic Acute Regulatory

The steroidogenic acute regulatory protein (StAR) facilitates the delivery of cholesterol to the inner mitochondrial membrane, where the cholesterol side-chain cleavage enzyme catalyzes the initial step of steroid hormone biosynthesis. StAR was initially identified in adrenocortical cells as a phosphoprotein, the expression and phosphorylation of which were stimulated by corticotropin. A number of in vitro studies have implicated cAMP-dependent phosphorylation at serine 194 (S194, S195 in human StAR) as an important residue for StAR activity. To explore the importance of S194 phosphorylation in StAR function in vivo, we developed a transgenic model using a bacterial artificial chromosome expressing either wild-type (WT) StAR or StAR mutation S194A to rescue StAR knockout (KO) mice. Despite StAR protein expression comparable to or higher than amounts seen with control animals or rescue with WT StAR, S194A StAR did not rescue the neonatal lethality and only partially rescued the sex reversal in male mice observed uniformly in StAR KO mice. Like the StAR KO mice, the adrenal cortex and testicular Leydig cells contained abundant lipid deposits when stained with oil red O. Adrenal StAR from S194A rescue animals lacks an acidic species, which appears upon corticotropin stimulation in animals rescued with WT StAR, consistent with defective StAR phosphorylation. These findings demonstrate that S194 is an essential residue for normal StAR function in the adrenal cortex and testes of mice.

scholarly journals Clock Genes, Inflammation and the Immune System—Implications for Diabetes, Obesity and Neurodegenerative Diseases

2020 ◽  
Vol 21 (24) ◽  
pp. 9743
Author(s):  
Elaine Vieira ◽  
Gerardo Gabriel Mirizio ◽  
Geovana Reichert Barin ◽  
Rosângela Vieira de Andrade ◽  
Nidah Fawzi Said Nimer ◽  
...  
Keyword(s):  
Immune System ◽  
Neurodegenerative Diseases ◽  
Circadian Clock ◽  
Inflammatory Cytokines ◽  
Clock Genes ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Obesity And Diabetes

Inflammation is a common feature of several diseases, including obesity, diabetes and neurodegenerative disorders. Circadian clock genes are expressed and oscillate in many cell types such as macrophages, neurons and pancreatic β cells. During inflammation, these endogenous clocks control the temporal gating of cytokine production, the antioxidant response, chemokine attraction and insulin secretion, among other processes. Deletion of clock genes in macrophages or brain-resident cells induces a higher production of inflammatory cytokines and chemokines, and this is often accompanied by an increased oxidative stress. In the context of obesity and diabetes, a high-fat diet disrupts the function of clock genes in macrophages and in pancreatic β cells, contributing to inflammation and systemic insulin resistance. Recently, it has been shown that the administration of natural and synthetic ligands or pharmacological enhancers of the circadian clock function can selectively regulate the production and release of pro-inflammatory cytokines and improve the metabolic function in vitro and in vivo. Thus, a better understanding of the circadian regulation of the immune system could have important implications for the management of metabolic and neurodegenerative diseases.

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