Flowering plant genomes lack flagellar and cytoplasmic dyneins as well as the proteins that make up the dynactin complex. The mechanisms for organizing the Golgi apparatus, establishing spindle poles, and moving nuclei, vesicles, and chromosomes in flowering plants must be fundamentally different from those in other systems where these processes are dependent upon dynein and dynactin.Key words: dynein, dynactin, cytoskeleton, motor protein, angiosperm, evolution Received and accepted 7 February 2001One of the major effects of large-scale sequencing and rapid computer-based sequence comparisons has been the recognition that many proteins are evolutionarily conserved among eukaryotes. This seems to be particularly true for proteins involved in intracellular motility. For instance, the cytoskeletal proteins tubulin, actin, myosin, and plus and minus end-directed kinesins are ubiquitous in fungi, animals and plants. We were therefore surprised to find that the genes for cytoplasmic dynein and its partner dynactin, although present in fungi and animals, were not identifiable in higher plant expressed sequence tag (EST) databases or the sequence of the recently published Arabidopsis genome (1).Cytoplasmic dynein is a large protein complex that acts as a microtubule-dependent, minus end-directed motor. It is required for intraflagellar transport (IFT), is involved in organizing the Golgi apparatus and spindle poles, and has roles in moving nuclei, vesicles, pigment granules, and chromosomes (2, 3). Dynein is composed of heavy chains, intermediate chains, a family of light intermediate chains, and several different light chains. It is activated by dynactin, another large protein complex that is believed to couple dynein to its cargoes. Ten genes encode the subunits of the dynactin complex: p24, p25, p27, p32, p37, p62, Arp1, Arp11, dynami-362 tin, and p150 Glued . We found that of all the dynein and dynactin subunits, only dynein light chain LC8, which interacts with a number of unrelated enzymes (2), is represented in the angiosperm sequences present in GenBank.
BackgroundRecent evidence identifies the hippocampus, a brain structure commonly associated with learning and memory, as key to the regulation of food intake and the development and consequences of obesity. Intake of a high fat diet (HFD) results in altered consumptive behavior, hippocampal damage, and cognitive deficits. While many studies report the effects of HFD after chronic consumption and in the instance of obesity, few examine the events that occur following acute HFD consumption. In this study, male rats were fed either a control diet (10% fat by kcal) or HFD (45% fat by kcal) for 72 h. At the end of the 72-h period, serum and tissues were collected and weighed. Brains were rapidly frozen or formalin-fixed in preparation for qRT-PCR or immunohistochemistry, respectively.ResultsAcute intake of HFD resulted in higher serum levels of leptin and cholesterol, with no significant changes in final body weight or adipose tissue mass. In the dorsal hippocampus, transcription of the neuroprotective peptide galanin was significantly upregulated along with a trend for an increase in brain-derived neurotrophic factor and histone deacetylase 2 in the rats fed HFD. In the ventral hippocampus, there was a significant increase in histone deacetylase 4 and a decrease in galanin receptor 1 in this group. Results from immunohistochemistry validate strong presence of the galanin peptide in the CA1/CA2 region of the dorsal hippocampus.ConclusionsThese results provide evidence for a distinct response in specific functional regions of the hippocampus following acute HFD intake.
Introduction Obstructive sleep apnea (OSA) results in chronic intermittent hypoxia leading to systemic inflammation, increases in pro-inflammatory cytokines TNF-Alpha and IL-6, and increased risk for a number of life threatening medical disorders such as cardiovascular and kidney disease. Methods A BioPlex Array was used to examined the serum levels of four cytokines also expressed in endothelial cells and/or macrophages and associated with cardiovascular and kidney disease risk. Results Relative to untreated OSA patients, airways treated OSA patients had a 5.4-fold higher median level of MMP2 (p = 9.1x10 −11 ), a 1.4-fold higher level of TWEAK (p = 1.8x10 −7 ), a 1.7-fold higher level of CD163 (p = 1.4x10 −6 ), but a 2.0-fold lower level of MMP3 (p = 7.9x10 −7 ). Airway treatment resulted in levels more similar to or indistinguishable from control subjects. Both t-SNE or UMAP analysis of the global structure of these multi-dimensional data revealed two data clusters, one populated primarily with data for controls and most airways treated OSA patients and a second populated primarily with data for OSA patients. Discussion We discuss a concept in which the aberrant levels of these cytokines in untreated OSA patients may represent a chronic response after years of experiencing intermittent nightly hypoxia, which attenuated the acute response to hypoxia. A balanced therapeutic correction of the aberrant levels of these cytokines may limit the progression of CVD and kidney disease in OSA patients.
Purpose Obstructive sleep apnea (OSA) results in systemic intermittent hypoxia. By one model, hypoxic stress signaling in OSA patients alters the levels of inflammatory soluble cytokines TNF and IL6, damages the blood brain barrier, and activates microglial targeting of neuronal cell death to increase the risk of neurodegenerative disorders and other diseases. However, it is not yet clear if OSA significantly alters the levels of the soluble isoforms of TNF receptors TNFR1 and TNFR2 and IL6 receptor (IL6R) and co-receptor gp130, which have the potential to modulate TNF and IL6 signaling. Methods Picogram per milliliter levels of the soluble isoforms of these four cytokine receptors were estimated in OSA patients, in OSA patients receiving airways therapy, and in healthy control subjects. Triplicate samples were examined using Bio-Plex fluorescent bead microfluidic technology. The statistical significance of cytokine data was estimated using the nonparametric Wilcoxon rank-sum test. The clustering of these high-dimensional data was visualized using t-distributed stochastic neighbor embedding (t-SNE). Results OSA patients had significant twofold to sevenfold reductions in the soluble serum isoforms of all four cytokine receptors, gp130, IL6R, TNFR1, and TNFR2, as compared with control individuals (p = 1.8 × 10−13 to 4 × 10−8). Relative to untreated OSA patients, airways therapy of OSA patients had significantly higher levels of gp130 (p = 2.8 × 10−13), IL6R (p = 1.1 × 10−9), TNFR1 (p = 2.5 × 10−10), and TNFR2 (p = 5.7 × 10−9), levels indistinguishable from controls (p = 0.29 to 0.95). The data for most airway-treated patients clustered with healthy controls, but the data for a few airway-treated patients clustered with apneic patients. Conclusions Patients with OSA have aberrantly low levels of four soluble cytokine receptors associated with neurodegenerative disease, gp130, IL6R, TNFR1, and TNFR2. Most OSA patients receiving airways therapy have receptor levels indistinguishable from healthy controls, suggesting a chronic intermittent hypoxia may be one of the factors contributing to low receptor levels in untreated OSA patients.
Folate is a key source of one‐carbon groups for DNA methylation; but studies on DNA methylation response to folic acid (FA) supplementation show inconsistent results. We hypothesize that measuring DNA methylation in whole blood (WB), which contains a mixture of distinct leukocyte cell types, may have confounded the results of previous studies. Therefore, the aim of this pilot study was to determine if a single cell type could serve as a more reliable epigenetic reporter. The study was performed in normal weight (BMI 18.5 – 24.9 kg/m2) women (18 – 35 y; n = 12), with blood samples taken before and after eight weeks of supplementation with 800 ug/day of FA. CD16+ cells (CD16) were isolated using antibody‐bound magnetic beads. DNA methylation patterns from WB and CD16 cells were measured across >485,000 CpG sites using the Infinium Human Methylation450 Bead Chip. For each CpG site, the proportion of DNA methylation that changed over the 8 week intervention was evaluated by fitting a separate linear model. Genome‐wide analysis indicated changes in 7887 vs. 8482 CpG sites in response to supplementation in WB and CD16, respectively; with DNA methylation decreased in 77.2% (WB) or 66.3% (CD16) of these sites. Results suggest that there are differences in methylation response in WB and CD16 after FA supplementation. The implication of these methylation differences are being explored in our on‐going gene enrichment analyses. Grant Funding Source: Funded in part by HATCH #GEO00706, #GEO00707 and the Obesity Initiative at the University of Georgia
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