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Phase-response curves for the pulse application of SB203580. The phase shift was calculated from the difference in phase angle of the melatonin rhythm between the untreated and treated cell culture, which was exposed to 0.1% Me 2 SO (open circles) and 10 or 30 M SB203580 in 0.1% Me 2 SO (solid triangles or squares, respectively) for 4 h from the indicated time point. Each value is mean S.E. of three replicate culture wells. The magnitudes of the phase advance or delay are shown as positive or negative values, respectively. Significance of the difference in magnitude of the phase shift between SB203580- treated cells and Me 2 SO-treated cells at each time point was determined by using two-way analysis of variance followed by Bonferroni's post hoc test. (*, p 0.01; **, p 0.001).
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Extracellular signal-regulated kinase (ERK) and p38 are members of the mitogen-activated protein kinase (MAPK) family, and in some cases these kinases serve for closely related cellular functions within a cell. In a wide range of animal clock structures, ERK plays an important role in the circadian time-keeping mechanism. Here we found that immunor...
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Melatonin, a small organic molecule synthesized by the pineal gland and the retina, has a variety of physiologic functions such as circadian clock pacemaker and antioxidant. Retinal melatonin is down-regulated by light and is barely detectable during the day. The absence of melatonin in the retina during prolonged light exposure may contribute to l...
Rheumatoid arthritis (RA) and osteoarthritis (OA) are the two most prevalent joint diseases. A such, they are important causes of pain and disability in a substantial proportion of the human population. A common characteristic of these diseases is the erosion of articular cartilage and consequently joint dysfunction. Melatonin has been proposed as...
The circadian clock is a regulatory system, with a periodicity of approximately 24 h, that generates rhythmic changes in many physiological processes. Increasing evidence links chronodisruption with aberrant functionality in clock gene expression, resulting in multiple diseases, including cancer. In this context, tumor cells have an altered circadi...
Melatonin or N-acetyl-5-methoxytryptamine, is a compound derived from tryptophan that is found in all organisms from single cells to vertebrates and the human. It is one of the most evolutionarily conserved and pleiotropic hormone still active in humans and has been implicated in vital skin functions such as hair growth, fur pigmentation as well as...
Citations
... 114 p38 MAPK has been demonstrated to be the target for circadian clock regulation in both chickens and Drosophila. 115 These results suggest that natural chronobiotics affect AMPK-dependent degradation. Phytochemically induced degradation can replace light-induced degradation as a clock resetting signal when light is unavailable. ...
The internal circadian clock in mammals drives whole-body biological activity rhythms. The clock reflects changes in external signals by controlling enzyme functions and the release of hormones involved in metabolic processes. Thus, misalignments between the circadian clock and an individual's daily schedule are recognized to be related to various metabolic diseases, such as obesity and diabetes. Although evidence has shown the existence of a complex relationship between circadian clock regulation and daily food intake, the regulatory effects of phytochemicals on the circadian clock remain unclarified. To better elucidate these relationships/effects, the circadian system components in mammals, circadian misalignment-related metabolic diseases, circadian rhythm-adjusting phytochemicals (including the heterocycles, acids, flavonoids and others) and the potential mechanisms (including the regulation of clock genes/proteins, metabolites of gut microbiota and secondary metabolites) are reviewed here. The bioactive components of functional foods discussed in this review could be considered potentially effective factors for the prevention and treatment of metabolic disorders related to circadian misalignment.
... p38b controls period gene expression programs in clock neurons through downstream transcription factor Mef2 -an established nuclear target of p38 (Zhao et al., 1999) -and kinase MNK (Dusik et al., 2014;Vrailas-Mortimer et al., 2014). In vertebrates, active p38 was detected in pineal gland neurons, suggesting p38 kinases are involved in circadian periodicity (Hayashi et al., 2003). It is unclear how p38 kinases are involved in neurons in controlling the circadian rhythm in the mammalian brain. ...
Mitogen-activated protein (MAP) kinases are a central component in signaling networks in a multitude of mammalian cell types. This review covers recent advances on specific functions of p38 MAP kinases in cells of the central nervous system. Unique and specific functions of the four mammalian p38 kinases are found in all major cell types in the brain. Mechanisms of p38 activation and downstream phosphorylation substrates in these different contexts are outlined and how they contribute to functions of p38 in physiological and under disease conditions. Results in different model organisms demonstrated that p38 kinases are involved in cognitive functions, including functions related to anxiety, addiction behavior, neurotoxicity, neurodegeneration, and decision making. Finally, the role of p38 kinases in psychiatric and neurological conditions and the current progress on therapeutic inhibitors targeting p38 kinases are covered and implicate p38 kinases in a multitude of CNS-related physiological and disease states.
... 2D, S2A and S2D). Fourth, inhibition of mitogen-activated protein kinases (MAPKs) increases period length in cultured chick pineal cells 33 and mammalian cells 2 , and we identified a p38 MAPK inhibitor that increased period Progeny from a homozygous Tg(per3:luc) to WT mating were raised for 6 days at 22 °C in 14:10 hour LD. Individual larvae were then added to each well of a 96-well plate, drugs or DMSO vehicle control was added to the water, and luminescence was monitored for 72 hours in DD. ...
The circadian clock ensures that behavioral and physiological processes occur at appropriate times during the 24-hour day/night cycle, and is regulated at both the cellular and organismal levels. To identify pathways acting on intact animals, we performed a small molecule screen using a luminescent reporter of molecular circadian rhythms in zebrafish larvae. We identified both known and novel pathways that affect circadian period, amplitude and phase. Several drugs identified in the screen did not affect circadian rhythms in cultured cells derived from luminescent reporter embryos or in established zebrafish and mammalian cell lines, suggesting they act via mechanisms absent in cell culture. Strikingly, using drugs that promote or inhibit inflammation, as well as a mutant that lacks microglia, we found that inflammatory state affects circadian amplitude. These results demonstrate a benefit of performing drug screens using intact animals and provide novel targets for treating circadian rhythm disorders.
... Studies conducted in rodents have shown that p38 MAPK pathway plays a crucial role in the response to light in the SCN. In addition to the rodents, it has also been shown that p38 MAPK activity was necessary for photic resetting of clock rhythm in the chick pineal gland and as well as in the cultured Xenopus retina [97][98][99][100]. Although the involvement of p38 activity in photic resetting is essential, it is unclear whether TNFα is also required for this. ...
... In N. crassa, the p38 MAPK OS-2 is rhythmically activated and functions as an output of the clock to prepare the organism for daily changes in osmotic stress [9,15,16]. In the chick pineal, p38 MAPK functions in circadian input to the clock [17]. Finally, p38 MAPK activity displays a circadian oscillation in the hamster SCN [9], and in 24 h light:dark cycles, rhythms of p38 MAPK activation in the chick pineal gland and mouse heart have been reported [18,19]. ...
... In addition to being regulated by the clock, previous studies have supported that p38 MAPK alters the properties of the molecular clock. For example, chronic inhibition of p38 MAPK with SB203580 in culture chick pineal cells lengthened the period of the clock, and a pulse of inhibitor during the day led to a phase delay of the rhythm in melatonin [17]. Similarly, in rat-1 fibroblast and C6 glioma cells, inhibition of p38 MAPK with SB203580 lengthened the period of the PER2::LUC reporter [41], and inhibition of U2OS cells with SB202190 lengthened the period of a Bmal1-dLuc reporter [53]. ...
Background:
The circadian clock is the basis for biological time keeping in eukaryotic organisms. The clock mechanism relies on biochemical signaling pathways to detect environmental stimuli and to regulate the expression of clock-controlled genes throughout the body. MAPK signaling pathways function in both circadian input and output pathways in mammals depending on the tissue; however, little is known about the role of p38 MAPK, an established tumor suppressor, in the mammalian circadian system. Increased expression and activity of p38 MAPK is correlated with poor prognosis in cancer, including glioblastoma multiforme; however, the toxicity of p38 MAPK inhibitors limits their clinical use. Here, we test if timed application of the specific p38 MAPK inhibitor VX-745 reduces glioma cell invasive properties in vitro.
Methods:
The levels and rhythmic accumulation of active phosphorylated p38 MAPK in different cell lines were determined by western blots. Rhythmic luciferase activity from clock gene luciferase reporter cells lines was used to test the effect of p38 MAPK inhibition on clock properties as determined using the damped sine fit and Levenberg-Marquardt algorithm. Nonlinear regression and Akaike's information criteria were used to establish rhythmicity. Boyden chamber assays were used to measure glioma cell invasiveness following time-of-day-specific treatment with VX-745. Significant differences were established using t-tests.
Results:
We demonstrate the activity of p38 MAPK cycles under control of the clock in mouse fibroblast and SCN cell lines. The levels of phosphorylated p38 MAPK were significantly reduced in clock-deficient cells, indicating that the circadian clock plays an important role in activation of this pathway. Inhibition of p38 MAPK activity with VX-745 led to cell-type-specific period changes in the molecular clock. In addition, phosphorylated p38 MAPK levels were rhythmic in HA glial cells, and high and arrhythmic in invasive IM3 glioma cells. We show that inhibition of p38 MAPK activity in IM3 cells at the time of day when the levels are normally low in HA cells under control of the circadian clock, significantly reduced IM3 invasiveness.
Conclusions:
Glioma treatment with p38 MAPK inhibitors may be more effective and less toxic if administered at the appropriate time of the day.
... These data suggest that the p38 MAPK signaling pathway may be involved in AHE-induced AQP3 expression in HaCaT keratinocytes. The role of p38 MAPK in regulating circadian rhythms in chicken 39 and fruit fly 40 has been demonstrated. The p38 MAPK pathway is also involved in TGFβ1-induced AQP3 up-regulation in human peritoneal mesothelial cells 41 . ...
The juice of Ageratum houstonianum is used in folk medicine as an external wound healing aid for skin injuries. However, the active component of A. houstonianum and its mode of action in skin wound healing has not been investigated. This study was conducted to investigate the effect of A. houstonianum ethanolnolic extract (AHE) on the expression of aquaporin-3 (AQP3), an integral membrane protein for water and glycerol transport in keratinocytes, and to identify the structure of the A. houstonianum bioactive compound. Here, we show that AHE increased AQP3 gene expression at the transcriptional level through the p38 MAPK pathway in HaCaT cells. Furthermore, AHE ameliorated suppression of AQP3 expression caused by ultraviolet B (UVB) irradiation. Agerarin (6,7-dimethoxy-2,2-dimethyl-2H-chromene) was identified as the bioactive compound responsible for the up-regulation of AQP3 expression by enhancing the expression of the transcription factor circadian locomotor output cycles kaput (CLOCK). In conclusion, agerarin is a bioactive compound in AHE responsible for CLOCK-mediated AQP3 expression in keratinocytes.
... However, because low levels of P-eEF-2 were observed in Δrck-2, Δos-2, and Δrck-2, Δos-2 double mutants following osmotic stress ( Fig. 2C and Fig. S3), it appears that RCK-2 is the major pathway leading to phosphorylation of eEF-2, although other kinases, such as AMPK, PKA, and/or TOR pathway-directed kinases, may also have minor roles. Importantly, p38, as well as TOR, AMPK activity, and cAMP levels, are clock-controlled in higher eukaryotes (49)(50)(51)(52)(53)(54), suggesting that clock control of translation elongation through rhythmic eEF-2 phosphorylation may be conserved. Furthermore, recent studies have shown that eEF-2 levels cycle in abundance in mouse liver (55,56); however, it remains to be determined if rhythms in mammalian eEF-2 levels affect its activity. ...
Significance
The circadian clock controls daily rhythms in genes involved in a wide range of biological processes, including signal transduction, cell division, metabolism, and behavior. The primary focus on understanding clock control of gene expression has been at the level of transcription. However, in many systems, there are examples of proteins that accumulate rhythmically from transcripts that are constitutively expressed. These data suggested that the clock regulates translation, but the underlying mechanisms were largely unknown. We show that the clock in Neurospora crassa controls the activity of translation elongation factor-2 (eEF-2) and that regulation of translation elongation leads to rhythmic translation in vitro and in vivo. These studies uncover a mechanism for controlling rhythmic protein accumulation.
... However, a few recent studies conducted in chickens have confirmed the involvement of clock genes in the regulation of Aanat transcription via suppressing its transcription using Bmal1 antisense oligonucleotides (36) and through RNA interference (RNAi)-mediated knockdown of CLOCK and NPAS2 (37). Involvement of MAP kinases and cFos/Jun in the rhythmicity of pineal MEL biosynthesis in birds has also been noted, but the relevant results have not been consistent (38,39). ...
Our recent research on the pineal gland of young chickens confirmed that three genes encoding enzymes involved in pineal melatonin biosynthesis,tryptophan hydroxylase 1 (Tph1),arylalkylamine-N-acetyltransferase (Aanat) and acetylserotonin O-methyltransferase (Asmt),are transcribed rhythmically under light:dark (L:D) 12:12 conditions in vivo. Additionally,in the pineal gland of maturing chickens,the dopa decarboxylase (Ddc) gene is transcribed rhythmically at a specific stage of the developmental process. Therefore,the aim of the present study was to verify whether all of these genes are transcribed rhythmically in vivo under constant darkness (D:D) and in pinealocyte cultures under both L:D and D:D. Experiments were performed on chickens maintained under L:D 12:12 conditions. Chickens at 15 days of age were divided into two groups; chickens from the first group remained under the same conditions,whereas those from the second group were kept in darkness. Subsequently,16-day-old animals were sacrificed every 2 hours over a 24-h period. For the in vitro experiments,16-day-old chickens were sacrificed at ZT 6,and their pineal glands were isolated. Pineal cultures were maintained for up to two days in L:D conditions. Then,the pinealocyte cultures were divided into two groups: the first remained under L:D conditions,whereas the second was transferred to D:D conditions. Pinealocytes were subsequently collected every 2 hours over a 24-h period. Transcription was evaluated using the RT-qPCR method,and the rhythm percentage was calculated through Cosinor analysis. The mRNA levels of all genes examined were rhythmic under all conditions. Moreover,in silico analysis of the promoters of all of the genes examined revealed the presence of enhancer box sequences in all of the promoters as well as DBP/E4BP4 binding elements in the promoters of Tph1 and Asmt. This suggests that these genes may all be regulated transcriptionally by the molecular clock mechanism and may be considered clock as controlled genes.
... 7,10,15,18,19 The present study revealed that the period of the cellular clock was lengthened by SB203580, SP600125, IC261 and Roscovitine, consistent with the previous studies. [3][4][5][6][7][8][9][10][11][12][13] On the other hand, the period was shortened by SB216763 or KN93. We recently reported the roles of CaMKII in regulation of the circadian clock at multiple levels. ...
Molecular oscillation of the circadian clock is based on E-box-mediated transcriptional feedback loop formed with clock genes and their encoding products, clock proteins. The clock proteins are regulated by post-translational modifications such as phosphorylation. We investigated the effects of a series of kinase inhibitors on gene expression rhythms in Rat-1 fibroblasts. The period of the cellular circadian rhythm in culture was lengthened by treatment with SB203580 (p38 MAPK inhibitor), SP600125 (JNK inhibitor), IC261 (CKI inhibitor) and Roscovitine (CDK inhibitor). On the other hand, the period was shortened by SB216763 (GSK-3 inhibitor) or KN93 (CaMKII inhibitor) treatment. Application of 20 μM KN93 completely abolished the rhythmic gene expression. The activity of CaMKII exhibited circadian variation in a phase close to the E-box-mediated transcriptional rhythms. In vitro kinase assay revealed that CaMKII directly phosphorylates N-terminal and Ser/Pro-rich domains of CLOCK, an activator of E-box-mediated transcription. These results indicate a phosphorylation-dependent tuning of the period length by a regulatory network of multiple kinases and reveal an essential role of CaMKII in the cellular oscillation mechanism.
... We have recently found that the stress response protein kinase p38 MAP Kinase (p38K) is a regulator of lifespan and aging in the fly (Vrailas- Mortimer et al., 2011). The activity of p38K is regulated by dual phosphorylation of the TGY motif, and in a variety of organisms the phosphorylation state of p38K cycles throughout the 24-h day (Chik et al., 2004;Hayashi et al., 2003;Pizzio et al., 2003;Vitalini et al., 2007). In Neurospora, p38K phosphorylation cycles through the day with peak levels in the early morning (Vitalini et al., 2007). ...
... However, in hamster suprachiasmatic nuclei, p38K phosphorylation increases during the day, and light exposure during the dark induces phosphorylation (Pizzio et al., 2003). In contrast, phospho-p38K in the chick pineal gland doesn't cycle; however, inhibition of p38K during the day in the pineal gland leads to a lengthening of the free-running period of the melatonin secretion rhythm (Hayashi et al., 2003). Interestingly, inhibition of per1 in rat spinal cord astrocytes leads to increased p38K phosphorylation (Sugimoto et al., 2014), while loss of per in flies leads to a decrease in p38K mRNA expression (Kula-Eversole et al., 2010). ...
The large repertoire of circadian rhythms in diverse organisms depends on oscillating central clock genes, input pathways for entrainment, and output pathways for controlling rhythmic behaviors. Stress-activated p38 MAP Kinases (p38K), although sparsely investigated in this context, show circadian rhythmicity in mammalian brains and are considered part of the circadian output machinery in Neurospora. We find that Drosophila p38Kb is expressed in clock neurons, and mutants in p38Kb either are arrhythmic or have a longer free-running periodicity, especially as they age. Paradoxically, similar phenotypes are observed through either transgenic inhibition or activation of p38Kb in clock neurons, suggesting a requirement for optimal p38Kb function for normal free-running circadian rhythms. We also find that p38Kb genetically interacts with multiple downstream targets to regulate circadian locomotor rhythms. More specifically, p38Kb interacts with the period gene to regulate period length and the strength of rhythmicity. In addition, we show that p38Kb suppresses the arrhythmic behavior associated with inhibition of a second p38Kb target, the transcription factor Mef2. Finally, we find that manipulating p38K signaling in free-running conditions alters the expression of another downstream target, MNK/Lk6, which has been shown to cycle with the clock and to play a role in regulating circadian rhythms. These data suggest that p38Kb may affect circadian locomotor rhythms through the regulation of multiple downstream pathways.
© 2014 The Author(s).
