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Important Physiological Processes (important + physiological_process)
Selected AbstractsGroup I metabotropic glutamate receptors regulate the frequency,response function of hippocampal CA1 synapses for the induction of LTP and LTDEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2004Els J. M. Van Dam Abstract Synaptically released glutamate binds to ionotropic or metabotropic glutamate receptors. Metabotropic glutamate receptors (mGluRs) are G-protein-coupled receptors and can be divided into three subclasses (Group I,III) depending on their pharmacology and coupling to signal transduction cascades. Group I mGluRs are coupled to phospholipase C and are implicated in several important physiological processes, including activity-dependent synaptic plasticity, but their exact role in synaptic plasticity remains unclear. Synaptic plasticity can manifest itself as an increase or decrease of synaptic efficacy, referred to as long-term potentiation (LTP) and long-term depression (LTD). The likelihood, degree and direction of the change in synaptic efficacy depends on the history of the synapse and is referred to as ,metaplasticity'. We provide direct experimental evidence for an involvement of group I mGluRs in metaplasticity in CA1 hippocampal synapses. Bath application of a low concentration of the specific group I agonist 3,5-dihydroxyphenylglycine (DHPG), which does not affect basal synaptic transmission, resulted in a leftward shift of the frequency,response function for the induction of LTD and LTP in naïve synapses. DHPG resulted in the induction of LTP at frequencies which induced LTD in control slices. These alterations in the induction of LTD and LTP resemble the metaplastic changes observed in previously depressed synapses. In addition, in the presence of DHPG additional potentiation could be induced after LTP had apparently been saturated. These findings provide strong evidence for an involvement of group I mGluRs in the regulation of metaplasticity in the CA1 field of the hippocampus. [source] miR-17, miR-19b, miR-20a, and miR-106a are down-regulated in human agingAGING CELL, Issue 2 2010Matthias Hackl Summary Aging is a multifactorial process where deterioration of body functions is driven by stochastic damage while counteracted by distinct genetically encoded repair systems. To better understand the genetic component of aging, many studies have addressed the gene and protein expression profiles of various aging model systems engaging different organisms from yeast to human. The recently identified small non-coding miRNAs are potent post-transcriptional regulators that can modify the expression of up to several hundred target genes per single miRNA, similar to transcription factors. Increasing evidence shows that miRNAs contribute to the regulation of most if not all important physiological processes, including aging. However, so far the contribution of miRNAs to age-related and senescence-related changes in gene expression remains elusive. To address this question, we have selected four replicative cell aging models including endothelial cells, replicated CD8+ T cells, renal proximal tubular epithelial cells, and skin fibroblasts. Further included were three organismal aging models including foreskin, mesenchymal stem cells, and CD8+ T cell populations from old and young donors. Using locked nucleic acid-based miRNA microarrays, we identified four commonly regulated miRNAs, miR-17 down-regulated in all seven; miR-19b and miR-20a, down-regulated in six models; and miR-106a down-regulated in five models. Decrease in these miRNAs correlated with increased transcript levels of some established target genes, especially the cdk inhibitor p21/CDKN1A. These results establish miRNAs as novel markers of cell aging in humans. [source] Resonance Raman spectra of the neutral and anionic radical semiquinones of flavin adenine dinucleotide in glucose oxidase revisitedJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2006Johannes P. M. Schelvis Abstract Flavin radical semiquinones are intermediates in important physiological processes. Resonance Raman (RR) spectroscopy is an important tool to determine the interactions between these radical intermediates and their protein environment that regulate their reactivity and role in the reaction mechanisms. RR spectra of flavin radical semiquinones have been available for several flavoproteins, and those in the glucose oxidase (GO) seem significantly different from all the other available data. Since GO is often used not only as a standard for flavin-containing proteins but also in biotechnological applications, we decided to reexamine the RR spectra of the neutral and anionic radical semiquinone forms of the flavin adenine dinucleotide (FAD) cofactor in this enzyme. The new data show that the vibrational wavenumbers of the neutral and anionic radical semiquinone forms of FAD in GO are very similar to those in other flavoproteins. The discrepancies that were observed earlier seem related to contributions of the FAD in different redox and protonation states. We also obtained the first RR spectra of the oxidized FAD cofactor in GO. Analysis of the vibrations of the oxidized FAD and its anionic radical semiquinone in GO in H2O and D2O solutions indicates that the subtle differences between these spectra in GO and in other flavoproteins are related to the weak hydrogen-bonding environment of the FAD cofactor in GO. Copyright © 2006 John Wiley & Sons, Ltd. [source] A study of Streptococcus thermophilus proteome by integrated analytical procedures and differential expression investigationsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 1 2006Simona Arena Abstract Streptococcus thermophilus is a Gram-positive bacterium belonging to the group of lactic acid bacteria, among which several genera play an essential role in manufacture of food products. Recently, a genomic consortium sequenced and annotated its entire genome, which has been demonstrated to contain 1900 coding sequences. In this study, we have revealed the expression products of almost 200 different genes using a proteomic strategy combining 2-DE plus MALDI-TOF PMF and differential 1-DE plus ,LC-ESI-IT-MS/MS. Thus, a number of cellular pathways related to important physiological processes were described at the proteomic level. Almost 50 genes were related to multiple electrophoretic species, whose heterogeneity was mainly due to variability in pI values. A 2-DE reference map obtained for lactose-grown cells was compared with those obtained after heat, cold, acid, oxidative and starvation stresses. Protein up/down-regulation measurements demonstrated that adaptation to different environmental challenges may involve the contribution of unique as well as combined physiological mechanisms. Common regulatory sites in the promoter region of genes whose expression was induced after stress were identified. These results provide a better comprehension of biochemical processes related to stress resistance in S. thermophilus, allowing defining the molecular bases of adaptative responses or markers for the identification of strains with potential industrial applications. [source] Crystallization and preliminary X-ray analysis of Escherichia coli RNase GACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2009Pengfei Fang The homologous RNases RNase E and RNase G are widely distributed in bacteria and function in many important physiological processes, including mRNA degradation, rRNA maturation and so on. In this study, the crystallization and preliminary X-ray analysis of RNase G from Escherichia coli is described. Purified recombinant E. coli RNase G, which has 497 amino acids, was crystallized in the cubic space group F432, with unit-cell parameters a = b = c = 219.84,Å. X-ray diffraction data were collected to a resolution of 3.4,Å. [source] | |||||||||||||