Circadian regulation of cell cycle and apoptosis proteins in mouse bone marrow and tumor

Haukeland University Hospital, Bergen, Hordaland, Norway
The FASEB Journal (Impact Factor: 5.04). 02/2005; 19(2):304-6. DOI: 10.1096/fj.04-2665fje
Source: PubMed


Proapoptotic drugs such as docetaxel displayed least toxicity and highest antitumor efficacy following dosing during the circadian rest phase in mice, suggesting that cell cycle and apoptotic processes could be regulated by the circadian clock. In study 1, mouse bone marrow and/or tumor were obtained every 4 h for 24 h in C3H/HeN mice with or without MA13/C mammary adenocarcinoma in order to determine the circadian patterns in cell-cycle phase distribution and BCL-2 anti-apoptotic protein expression. In study 2, mouse bone marrow from B6D2F1 mice was sampled every 3 h for 24 h in order to confirm the BCL-2 rhythm and to study its relation with 24 h changes in the expression of proapoptotic BCL-2-associated X protein (BAX) protein and clock genes mPer2, mBmal1, mClock, and mTim mRNAs. The rhythms in G1-, S- or G2/M-phase cells were shifted in tumor compared with bone marrow. In the tumor, the mean proportion of G2/M-phase cells increased by 75% from late rest to late activity span (P from cosinor = 0.001). No 24 h rhythm was found for BCL-2 in tumors. In contrast to this, in the bone marrow, mean BCL-2 expression varied 2.8-fold in B6D2F1 mice (P=0.025) and 3- or 4.5-fold in tumor-bearing and nontumor-bearing C3H/HeN mice, with a peak during the early rest span (P=0.024 and P<0.001, respectively). BAX varied fivefold during the 24 h span with a major peak occurring near mid-activity (P=0.007). The mean mRNAs of mPer2, mClock, and mBmal1 varied twofold to threefold over the 24 h, with high values during the activity span (P<0.05). In the tumor, the circadian organization in cell-cycle phase distribution was shifted and BCL2 rhythm was ablated. Conversely, a molecular circadian clock likely regulated BCL-2 and BAX expression in the bone marrow, increasing cellular protection against apoptosis during the rest span.

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Available from: Rune Smaaland, Jun 18, 2014
    • "In the midgut epithelium of invertebrates, cells that have phagocytic abilities do not appear and therefore, another mechanism is created—apoptotic cells or apoptotic bodies are discharged into the gut lumen where they are digested (Rost-Roszkowska et al. 2008, 2010, 2015b). To date, the dependence between apoptosis and circadian rhythms has been described in vertebrates (Ijiri and Potten 1988, 1990; Granda et al. 2005; Lee and Sankar 2011a, 2011b), while no information can be found in the literature about these processes in the gut epithelium of invertebrates. Thus, the aims of this study were (1) to answer the question of whether apoptosis and/or necrosis in two centipede species, S. cingulata and L. forficatus, depend on the circadian cycle; (2) to determine whether apoptosis and necrosis concern all types of midgut epithelial cells, i.e., digestive, secretory, and regenerative cells; (3) to describe apoptosis and necrosis in the midgut epithelium at the ultrastructural level in both males and females ; and (4) to describe the role of these processes in the proper functioning of the midgut. "
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    ABSTRACT: Three types of cells have been distinguished in the midgut epithelium of two centipedes, Lithobius forficatus and Scolopendra cingulata: digestive, secretory, and regenerative cells. According to the results of our previous studies, we decided to analyze the relationship between apoptosis and necrosis in their midgut epithelium and circadian rhythms. Ultrastructural analysis showed that these processes proceed in a continuous manner that is independent of the circadian rhythm in L. forficatus, while in S. cingulata necrosis is activated at midnight. Additionally, the description of apoptosis and necrosis showed no differences between males and females of both species analyzed. At the beginning of apoptosis, the cell cytoplasm becomes electron-dense, apparently in response to shrinkage of the cell. Organelles such as the mitochondria, cisterns of endoplasmic reticulum transform and degenerate. Nuclei gradually assume lobular shapes before the apoptotic cell is discharged into the midgut lumen. During necrosis, however, the cytoplasm of the cell becomes electron-lucent, and the number of organelles decreases. While the digestive cells of about 10 % of L. forficatus contain rickettsia-like pathogens, the corresponding cells in S. cingulata are free of rickettsia. As a result, we can state that apoptosis in L. forficatus is presumably responsible for protecting the organism against infections, while in S. cingulata apoptosis is not associated with the elimination of pathogens. Necrosis is attributed to mechanical damage, and the activation of this process coincides with proliferation of the midgut regenerative cells at midnight in S. cingulata.
    Protoplasma 08/2015; DOI:10.1007/s00709-015-0864-8 · 2.65 Impact Factor
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    • "In support of that hypothesis, Schneider et al. [20] recently found Clock, Bmal1, Per2, and Per3 oscillating in phase in the retina of rats kept in constant darkness. Similar coincidental phase patterns of clock gene expression were reported in the retina of a diurnal mammal [13], in mouse retinal cones [33] as well as in more peripheral oscillators such as human blood mononuclear cells [36] and mouse bone marrow [37]. Conversely, we cannot exclude that some of the observed oscillations might be relevant to a transitory stage preceding the final oscillatory mechanism of the clock in explants, which might be set later than the third day. "
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    ABSTRACT: Purpose Circadian rhythms are central to vision and retinal physiology. A circadian clock located within the retina controls various rhythmic processes including melatonin synthesis in photoreceptors. In the present study, we evaluated the rhythmic expression of clock genes and clock output genes in retinal explants maintained for several days in darkness. Methods Retinas were dissected from Wistar rats, either wild-type or from the Per1-luciferase transgenic line housed under a daily 12 h:12 h light-dark cycle (LD12/12), and put in culture at zeitgeber time (ZT) 12 on semipermeable membranes. Explants from wild-type rats were collected every 4 h over 3 days, and total RNA was extracted, quantified, and reverse transcribed. Gene expression was assessed with quantitative PCR, and the periodicity of the relative mRNA amounts was assessed with nonlinear least squares fitting to sine wave functions. Bioluminescence in explants from Per1-luciferase rats was monitored for several days under three different culture protocols. Results Rhythmic expression was found for all studied clock genes and for clock downstream targets such as c-fos and arylalkylamine N-acetyltransferase (Aanat) genes. Clock and output genes cycled with relatively similar periods and acrophases (peaks of expression during subjective night, except c-fos, which peaked around the end of the subjective day). Data for Per1 were confirmed with bioluminescence monitoring, which also permitted culture conditions to be optimized to study the retina clock. Conclusions Our work shows the free-running expression profile of multiple clock genes and potential clock targets in mammalian retinal explants. This research further strengthens the notion that the retina contains a self-sustained oscillator that can be functionally characterized in organotypic culture.
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    • "The circadian rhythm is generated by a set of interacting genes and proteins (see Additional file 3: Figure S2). For example in mammals, the protein products of the clock and Bmal1 genes act together to induce the expression of other clock genes including period (PER) [41]. The up-regulation of period homolog transcripts (PER1, ID 395923, and PER2, ID 392428) in vitamin B6- compared to placebo-treated rats suggests an involvement of the circadian rhythm in the regulation of apoptotic processes (Figure 4B). "
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    ABSTRACT: Bacterial meningitis caused by Streptococcus pneumoniae leads to death in up to 30% of patients and leaves up to half of the survivors with neurological sequelae. The inflammatory host reaction initiates the induction of the kynurenine pathway and contributes to hippocampal apoptosis, a form of brain damage that is associated with learning and memory deficits in experimental paradigms. Vitamin B6 is an enzymatic cofactor in the kynurenine pathway and may thus limit the accumulation of neurotoxic metabolites and preserve the cellular energy status.The aim of this study in a pneumococcal meningitis model was to investigate the effect of vitamin B6 on hippocampal apoptosis by histomorphology, by transcriptomics and by measurement of cellular nicotine amide adenine dinucleotide content.Methods and results: Eleven day old Wistar rats were infected with 1x106 cfu/ml of S. pneumoniae and randomized for treatment with vitamin B6 or saline as controls. Vitamin B6 led to a significant (p > 0.02) reduction of hippocampal apoptosis. According to functional annotation based clustering, vitamin B6 led to down-regulation of genes involved in processes of inflammatory response, while genes encoding for processes related to circadian rhythm, neuronal signaling and apoptotic cell death were mostly up-regulated. Our results provide evidence that attenuation of apoptosis by vitamin B6 is multi-factorial including down-modulation of inflammation, up-regulation of the neuroprotective brain-derived neurotrophic factor and prevention of the exhaustion of cellular energy stores. The neuroprotective effect identifies vitamin B6 as a potential target for the development of strategies to attenuate brain injury in bacterial meningitis.
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