Diversification of CpG-Island Promoters Revealed by Comparative Analysis Between Human and Rhesus Monkey Genomes

Mammalian Genome - While CpG dinucleotides are significantly reduced compared to other dinucleotides in mammalian genomes, they can congregate and form CpG islands, which localize around...     

Novel (p)ppGpp0 suppressor mutations reveal an unexpected link between methionine catabolism and GTP synthesis in Bacillus subtilis

In bacteria, guanosine (penta)tetra-phosphate ([p]ppGpp) is essential for controlling intracellular metabolism that is needed to adapt to environmental changes, such as amino acid starvation. The (p)ppGpp⁰ strain of Bacillus subtilis, which lacks (p)ppGpp synthetase, is unable to form colonies on minimal medium. Here, we found suppressor mutations in the (p)ppGpp⁰ strain, in the purine nucleotide biosynthesis genes, prs, purF and rpoB/C, which encode RNA polymerase core enzymes. In comparing our work with prior studies of ppGpp⁰ suppressors, we discovered that methionine addition masks the suppression on minimal medium, especially of rpoB/C mutations. Furthermore, methionine addition increases intracellular GTP in rpoB suppressor and this effect is decreased by inhibiting GTP biosynthesis, indicating that methionine addition activated GTP biosynthesis and inhibited growth under amino acid starvation conditions in (p)ppGpp⁰ backgrounds. Furthermore, we propose that the increase in intracellular GTP levels induced by methionine is due to methionine derivatives that increase the activity of the de novo GTP biosynthesis enzyme, GuaB. Our study sheds light on the potential relationship between GTP homeostasis and methionine metabolism, which may be the key to adapting to environmental changes.     

Safety and immunomodulatory effects of allogeneic canine adipose-derived mesenchymal stromal cells transplanted into the region of the lacrimal gland,the gland of the third eyelid and the knee joint

Background aimsMesenchymal stromal cells (MSCs) have been extensively studied as a cellular therapeutic for various pathologic conditions. However, there remains a paucity of data regarding regional and systemic safety of MSC transplantations, particularly with multiple deliveries of allogeneic cells. The purpose of this study was to investigate the safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs into the region of the lacrimal gland, the gland of the third eyelid and the knee joint in dogs.MethodsAllogeneic adipose tissue-derived canine MSCs were delivered to the regions of the lacrimal gland and the third eyelid gland as well as in the knee joints of six healthy laboratory beagles as follows: six times with 1-week intervals for delivery to the lacrimal gland and the third eyelid gland regions and three to four times with 1- to 2-week intervals for intra-articular transplantations. Dogs were sequentially evaluated by clinical examination. At the conclusion of the study, dogs were humanely euthanized, and a complete gross and histopathologic examination of all organ systems was performed. Mixed leukocyte reactions were also performed before the first transplantation and after the final transplantation.ResultsClinical and pathologic examinations found no severe consequences after repeated MSC transplantations. Results of mixed leukocyte reactions demonstrated suppression of T-cell proliferation after MSC transplantations.ConclusionsThis is the first study to demonstrate regional and systemic safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs in vivo.     

Protein N-Myristoylation Plays a Critical Role in the Endoplasmic Reticulum Morphological Change Induced by Overexpression of Protein Lunapark,an Integral Membrane Protein of the Endoplasmic Reticulum

N-myristoylation of eukaryotic cellular proteins has been recognized as a modification that occurs mainly on cytoplasmic proteins. In this study, we examined the membrane localization, membrane integration, and intracellular localization of four recently identified human N-myristoylated proteins with predicted transmembrane domains. As a result, it was found that protein Lunapark, the human ortholog of yeast protein Lnp1p that has recently been found to be involved in network formation of the endoplasmic reticulum (ER), is an N-myristoylated polytopic integral membrane protein. Analysis of tumor necrosis factor-fusion proteins with each of the two putative transmembrane domains and their flanking regions of protein Lunapark revealed that transmembrane domain 1 and 2 functioned as type II signal anchor sequence and stop transfer sequence, respectively, and together generated a double-spanning integral membrane protein with an N-/C-terminal cytoplasmic orientation. Immunofluorescence staining of HEK293T cells transfected with a cDNA encoding protein Lunapark tagged with FLAG-tag at its C-terminus revealed that overexpressed protein Lunapark localized mainly to the peripheral ER and induced the formation of large polygonal tubular structures. Morphological changes in the ER induced by overexpressed protein Lunapark were significantly inhibited by the inhibition of protein N-myristoylation by means of replacing Gly2 with Ala. These results indicated that protein N-myristoylation plays a critical role in the ER morphological change induced by overexpression of protein Lunapark.     

Spontaneous Slow Fluctuation of EEG Alpha Rhythm Reflects Activity in Deep-Brain Structures: A Simultaneous EEG-fMRI Study

The emergence of the occipital alpha rhythm on brain electroencephalogram (EEG) is associated with brain activity in the cerebral neocortex and deep brain structures. To further understand the mechanisms of alpha rhythm power fluctuation, we performed simultaneous EEGs and functional magnetic resonance imaging recordings in human subjects during a resting state and explored the dynamic relationship between alpha power fluctuation and blood oxygenation level-dependent (BOLD) signals of the brain. Based on the frequency characteristics of the alpha power time series (APTS) during 20-minute EEG recordings, we divided the APTS into two components: fast fluctuation (0.04–0.167 Hz) and slow fluctuation (0–0.04 Hz). Analysis of the correlation between the MRI signal and each component revealed that the slow fluctuation component of alpha power was positively correlated with BOLD signal changes in the brain stem and the medial part of the thalamus and anterior cingulate cortex, while the fast fluctuation component was correlated with the lateral part of the thalamus and the anterior cingulate cortex, but not the brain stem. In summary, these data suggest that different subcortical structures contribute to slow and fast modulations of alpha spectra on brain EEG.     

Fission yeast TOR signaling is essential for the down-regulation of a hyperactivated stress-response MAP kinase under salt stress

TOR (target of rapamycin) signaling regulates cell growth and division in response to environmental stimuli such as the availability of nutrients and various forms of stress. The vegetative growth of fission yeast cells, unlike other eukaryotic cells, is not inhibited by treatment with rapamycin. We found that certain mutations including pmc1Δ (Ca²⁺-ATPase), cps9-193 (small GTPase, Ryh1) and cps1-12 (1,3-β-d-glucan synthase, Bgs1) confer a rapamycin-sensitive phenotype to cells under salt stress with potassium chloride (>0.5 M). Cytometric analysis revealed that the mutant cells were unable to enter the mitotic cell cycle when treated with the drug under salt stress. Gene cloning and overexpression experiments revealed that the sensitivity to rapamycin was suppressed by the ectopic expression of tyrosine phosphatases, Pyp1 and Pyp2, which are negative regulators of Spc1/Sty1 mitogen-activated protein kinase (MAPK). The level of tyrosine phosphorylation on Spc1 was higher and sustained substantially longer in these mutants than in the wild type under salt stress. The hyperphosphorylation was significantly suppressed by overexpression of pyp1 ⁺ with concomitant resumption of the mutant cells’ growth. In fission yeast, TOR signaling has been thought to stimulate the stress-response pathway, because mutations of TORC2 components such as Tor1, Sin1 and Ste20 result in similar sensitive phenotypes to environmental stress. The present study, however, strongly suggests that TOR signaling is required for the down-regulation of a hyperactivated Spc1 for reentry into the mitotic cell cycle. This finding may shed light on our understanding of a new stress-responsive mechanism in TOR signaling in higher organisms.     

Human cathelicidin antimicrobial peptide LL-37 promotes lymphangiogenesis in lymphatic endothelial cells through the ERK and Akt signaling pathways

Molecular Biology Reports - LL-37, the only member of the cathelicidin family of cationic antimicrobial peptides in humans has been shown to exhibit a wide variety of biological actions in addition...