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Biochemical Machinery (biochemical + machinery)
Selected AbstractsMolecular anatomy of a speckleTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 7 2006Lisa L. Hall Abstract Direct localization of specific genes, RNAs, and proteins has allowed the dissection of individual nuclear speckles in relation to the molecular biology of gene expression. Nuclear speckles (aka SC35 domains) are essentially ubiquitous structures enriched for most pre-mRNA metabolic factors, yet their relationship to gene expression has been poorly understood. Analyses of specific genes and their spliced or mature mRNA strongly support that SC35 domains are hubs of activity, not stores of inert factors detached from gene expression. We propose that SC35 domains are hubs that spatially link expression of specific pre-mRNAs to rapid recycling of copious RNA metabolic complexes, thereby facilitating expression of many highly active genes. In addition to increasing the efficiency of each step, sequential steps in gene expression are structurally integrated at each SC35 domain, consistent with other evidence that the biochemical machineries for transcription, splicing, and mRNA export are coupled. Transcription and splicing are subcompartmentalized at the periphery, with largely spliced mRNA entering the domain prior to export. In addition, new findings presented here begin to illuminate the structural underpinnings of a speckle by defining specific perturbations of phosphorylation that promote disassembly or assembly of an SC35 domain in relation to other components. Results thus far are consistent with the SC35 spliceosome assembly factor as an integral structural component. Conditions that disperse SC35 also disperse poly(A) RNA, whereas the splicing factor ASF/SF2 can be dispersed under conditions in which SC35 or SRm300 remain as intact components of a core domain. Anat Rec Part A, 288A:664,675, 2006. © 2006 Wiley-Liss, Inc. [source] Neurons bearing presenilins: weapons for defense or suicide?JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2000B.O. Popescu Abstract Apoptotic machinery designed for cell's organized self-destruction involve different systems of proteases which cleave vital proteins and disassemble nuclear and cytoplasmic structures, committing the cell to death. The most studied apoptotic proteolytic system is the caspase family, but calpains and the proteasome could play important roles as well. Alzheimer's disease associated presenilins showed to be a substrate for such proteolytic systems, being processed early in several apoptotic models, and recent data suggest that alternative presenilin fragments could regulate cell survival. Mutations in genes encoding presenilins proved to sensitize neurons to apoptosis by different mechanisms e.g. increased caspase-3 activation, oxyradicals production and calcium signaling dysregulation. Here we review the data involving presenilins in apoptosis and discuss a possible role of presenilins in the regulation of apoptotic biochemical machinery. [source] EVIDENCE OF A LATENT OXIDATIVE BURST IN RELATION TO WOUND REPAIR IN THE GIANT UNICELLULAR CHLOROPHYTE DASYCLADUS VERMICULARIS,JOURNAL OF PHYCOLOGY, Issue 3 2005Cliff Ross We investigated the kinetics and composition of the second phase of the wound repair process of Dasycladus vermicularis ([Scropoli] Krasser) using fluorescent probes, chromatography, UV spectroscopy, and histochemistry. Our new evidence supports the hypothesis that the second phase of wound repair (initiated at approximately 35,45 min postinjury) is based on the activation of an oxidative burst that produces micromolar H2O2 levels. These results provide evidence of peroxidase activity at the wound site, real-time measurements of an oxidative burst, and catechol localization in wound plugs. Strong evidence is presented indicating that the biochemical machinery exists for oxidative cross-linking to ensue in the wound-healing process of D. vermicularis. [source] The Ontogenetic Expression Pattern of Type 5 Phosphodiesterase Correlates with Androgen Receptor Expression in Rat Corpora CavernosaTHE JOURNAL OF SEXUAL MEDICINE, Issue 2 2009Eleonora Carosa MD ABSTRACT Introduction., The mechanisms controlling erection in animals and in humans are mainly age-dependent. However, the ontogenesis of the biochemical machinery of erection is largely unknown. Aim., The aim of this article was to study the expression pattern of androgen receptor (AR) and the major cyclic guanosine monophosphate-hydrolyzing enzyme present in the corpora cavernosa, type 5 phosphodiesterase (PDE5), in the rat penis during development. Methods., AR and PDE5 expression was tested on ribonucleic acids (RNAs) and proteins extracted from the whole penis or from primary cultures of smooth muscle cells obtained from the corpora cavernosa of 3- (rCC3), 20- (rCC20), and 60- (rCC60) day-old rats. Rat corpus cavernosum cells were characterized by immunocytochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). Main Outcome Measures., Expression of PDE5 and AR messenger RNA (mRNA) and protein have been measured by RT-PCR and Western blot, respectively. Results., A significant increase in PDE5 mRNA expression was observed with RT-PCR from prepuberty to adulthood (0.5 ± 0.06 vs. 1.6 ± 0.046 arbitrary units [a.u.]P = 0.049). This age-dependent increase was mirrored by the increase in PDE5 protein expression found when comparing neonatal to adult corpus cavernosum smooth muscle cells (1.5 ± 0.26 vs. 4.9 ± 0.59 a.u. P = 0.0038) and the further 1.6-fold increase from rCC20 to rCC60 (4.9 ± 0.59 vs. 8.0 ± 0.8 a.u. P = 0.0024). This is the first demonstration of the ontogenetic profile of PDE5 expression in corpus cavernosum smooth muscle. As it has been demonstrated that androgens control PDE5 expression and that PDE5 inhibitors need an optimal androgenic milieu to act perfectly on erection, the expression of AR protein in rat corpus cavernosum cells was then tested by Western blot. A 7.0-fold increase was observed in primary cultured cells from 3 to 60 days old (1.4 ± 0.38 vs. 9.8 ± 1.3 a.u. P = 0.0052). Conclusion., The increase in ARs during rat penile development parallels that of PDE5 RNA and protein, thus suggesting a positive effect of androgens on PDE5 expression. Carosa E, Rossi S, Giansante N, Gravina GL, Castri A, Dolci S, Botti F, Morelli A, Di Luigi L, Pepe M, Lenzi A, and Jannini EA. The ontogenetic expression pattern of type 5 phosphodiesterase correlates with androgen receptor expression in rat corpora cavernosa. J Sex Med 2009;6:388,396. [source] Expression and modulation of ghrelin O -acyltransferase in cultured chondrocytesARTHRITIS & RHEUMATISM, Issue 6 2009Rodolfo Gómez Objective To use reverse transcription,polymerase chain reaction to detect ghrelin O -acyltransferase (GOAT) transcripts in both murine and human chondrocytes, to evaluate the effect of pharmacologic in vitro treatments with lipopolysaccharide (LPS), growth hormone, ghrelin, and dexamethasone on GOAT messenger RNA (mRNA) expression, and to study the GOAT mRNA profile during chondrocyte differentiation. Methods Murine and human GOAT and ghrelin mRNA levels were determined by the SYBR Green,based quantitative real-time polymerase chain reaction method. Results GOAT mRNA was expressed in murine cartilage explants as well as in the cultured murine chondrogenic ATDC-5 cell line. GOAT was also expressed in human immortalized chondrocyte cell lines and in human cultured primary chondrocytes. In addition, GOAT mRNA expression in differentiating ATDC-5 cells was lower at the early stage of differentiation (days 3,7), whereas GOAT mRNA levels increased progressively at the late stages. Finally, among the drugs and hormones tested, only LPS was able to strongly decrease GOAT mRNA expression. Conclusion These data indicate that chondrocytes are equipped with biochemical machinery for the synthesis of acylated ghrelin and suggest a novel role of the ghrelin axis in prehypertrophic and hypertrophic chondrocyte differentiation during endochondral ossification. [source] Production, purification, crystallization and preliminary X-ray diffraction studies of the nucleoside diphosphate kinase b from Leishmania majorACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 11 2009Celisa Caldana Costa Tonoli Nucleoside diphosphate kinases (NDKs; EC 2.7.4.6) play an essential role in the synthesis of nucleotides from intermediates in the salvage pathway in all parasitic trypanosomatids and their structural studies will be instrumental in shedding light on the biochemical machinery involved in the parasite life cycle and host,parasite interactions. In this work, NDKb from Leishmania major was overexpressed in Escherichia coli, purified to homogeneity and crystallized using the sitting-drop vapour-diffusion method. The NDK crystal diffracted to 2.2,Å resolution and belonged to the trigonal crystal system, with unit-cell parameters a = 114.2, c = 93.9,Å. Translation-function calculations yielded an unambiguous solution in the enantiomorphic space group P3221. [source] Live cell fluorescence microscopy to study microbial pathogenesisCELLULAR MICROBIOLOGY, Issue 4 2009Adam D. Hoppe Summary Advances in microscopy and fluorescent probes provide new insight into the nanometer-scale biochemistry governing the interactions between eukaryotic cells and pathogens. When combined with mathematical modelling, these new technologies hold the promise of qualitative, quantitative and predictive descriptions of these pathways. Using the light microscope to study the spatial and temporal relationships between pathogens, host cells and their respective biochemical machinery requires an appreciation for how fluorescent probes and imaging devices function. This review summarizes how live cell fluorescence microscopy with common instruments can provide quantitative insight into the cellular and molecular functions of hosts and pathogens. 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