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Early Protein (early + protein)
Selected AbstractsCharacterization of HCF-1, a determinant of Autographa californica multiple nucleopolyhedrovirus host specificityINSECT MOLECULAR BIOLOGY, Issue 6 2003K. L. Hefferon Abstract Autographa californica multiple nucleopolyhedrovirus (AcMNPV) infects a wide variety of insect species. A number of AcMNPV late expression factors that are involved in replication have been identified as playing a role in determining host specificity. Host cell factor-1, or HCF-1, was previously demonstrated to be essential for viral replication in Tn -368 cells. Here we demonstrate that HCF-1 is an early protein and localizes to the cell nucleus. Coprecipitation experiments revealed that HCF-1 interacts with itself but none of the other late expression factors required for replication in Tn -368 cells. HCF-1 mutants were constructed and utilized to search for the domains involved in HCF-1 biological function and oligomerization. Possible roles of HCF-1 in determining host specificity are discussed. [source] IL-1,, an immediate early protein secreted by activated microglia, induces iNOS/NO in C6 astrocytoma cells through p38 MAPK and NF-,B pathwaysJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2006Yun-Jung Kim Abstract In the present study we sought to examine cell,cell interactions by investigating the effects of factors released by stimulated microglia on inducible nitric oxide (NO) synthase (iNOS) induction in astrocytoma cells. After examining the temporal profiles of proinflammatory molecules induced by lipopolysaccharide (LPS) stimulation in BV2 microglial cells, iNOS and IL-1, were observed to be the first immediate-response molecules. Removal of LPS after 3 hr stimulation abrogated NO release, whereas a full induction of IL-1, was retained in BV2 cells. We observed consistently that conditioned medium (CM) from activated microglia resulted in the induction of iNOS in C6 cells, and IL-1, was shown to be a key regulator of iNOS induction. An IL-1,-neutralizing antibody diminished NO induction. Incubation with recombinant IL-1, stimulated NO release to a lesser extent compared to microglial CM; co-treatment of LPS and IL-1, had a potent, synergistic effect on NO release from C6 cells. Transient transfection with MEK kinase 1 (MEKK1) or nuclear factor-kappa B (NF-,B) expression plasmids induced iNOS, and IL-1, further enhanced the MEKK1 response. Furthermore, IL-1,-mediated NO release from C6 cells was significantly suppressed by inhibition of p38 mitogen activated protein kinase (MAPK) or NF-,B by specific chemical inhibitors. Both IL-1, and MEKK1 stimulated p38 and JNK MAPKs, as well as the NF-,B pathway, to induce iNOS in C6 cells. Microglia may represent an anti-tumor response in the central nervous system, which is potentiated by the local secretion of immunomodulatory factors that in turn affects astrocytoma (glioma) cells. A better understanding of microglia,glioma or microglia,astrocyte interactions will help in the design of novel immune-based therapies for brain tumors or neuronal diseases. © 2006 Wiley-Liss, Inc. [source] High frequency of gastroduodenal cytomegalovirus infection in liver transplant patients,APMIS, Issue 2 2008LEENA HALME The prevalence and significance of cytomegalovirus (CMV) detected in biopsy specimens from the gastroduodenal mucosa of liver transplant patients, patients with chronic or acute liver failure and immunocompetent patients with dyspeptic symptoms were evaluated. 80 liver transplant patients with upper gastrointestinal symptoms, 132 patients with chronic and 25 with acute liver failure, and 33 immunocompetent, dyspeptic patients underwent oesophagogastroduodenoscopies, with biopsies from the duodenum and stomach. CMV was demonstrated by immunohistochemistry in frozen sections, using a monoclonal antibody against CMV-specific antigens (pp65 matrix protein), and in paraffin sections by a monoclonal antibody against delayed early protein (p52). 71% of the liver transplant patients, 45% of the patients with chronic liver disease, 20% with acute liver failure, and 45% of the immunocompetent, dyspeptic patients had CMV-positive findings in the gastroduodenal mucosa (liver transplant patients vs other groups, p<0.01). Histopathological findings in CMV-positive samples were focal inflammation, including increased inflammation of the lamina propria, infiltrating leukocytes intra-epithelially, regenerative changes in the epithelial cells and inclusion bodies. In conclusion, CMV-positive cells and inclusions are often found in the gastroduodenal mucosa of liver transplant patients, as well as in patients suffering from chronic liver disease or even in otherwise healthy patients with dyspeptic symptoms. [source] Development of tRNA synthetases and connection to genetic code and diseasePROTEIN SCIENCE, Issue 10 2008Paul Schimmel Abstract The genetic code is established by the aminoacylation reactions of aminoacyl tRNA synthetases, where amino acids are matched with triplet anticodons imbedded in the cognate tRNAs. The code established in this way is so robust that it gave birth to the entire tree of life. The tRNA synthetases are organized into two classes, based on their active site architectures. The details of this organization, and other considerations, suggest how the synthetases evolved by gene duplications, and how early proteins may have been statistical in nature, that is, products of a primitive code where one of several similar amino acids was used at a specific position in a polypeptide. The emergence of polypeptides with unique, defined sequences,true chemical entities,required extraordinary specificity of the aminoacylation reaction. This high specificity was achieved by editing activities that clear errors of aminoacylation and thereby prevent mistranslation. Defects in editing activities can be lethal and lead to pathologies in mammalian cells in culture. Even a mild defect in editing is casually associated with neurological disease in the mouse. Defects in editing are also mutagenic in an aging organism and suggest how mistranslation can lead to mutations that are fixed in the genome. Thus, clearance of mischarged tRNAs by the editing activities of tRNA synthetases was essential for development of the tree of life and has a role in the etiology of diseases that is just now being understood. [source] The immediate-early oncoproteins Fra-1, c-Fos, and c-Jun have distinguishable surface behavior and interactions with phospholipidsBIOPOLYMERS, Issue 9 2009Marķa Cecilia Gaggiotti Abstract This work explores the surface properties of the transcription factor Fra-1 and compares them with those of two other immediate early proteins, c-Fos and c-Jun, to establish generalities and differences in the surface behavior and interaction with phospholipids of this type of proteins. We present several experimental clues of the flexible nature of Fra-1, c-Fos, and c-Jun that support sequence-based predictions of their intrinsical disorder. The values of surface parameters for Fra-1 are similar in general to those of c-Fos and c-Jun. However, we find differences in the interactions of the three proteins with phospholipids. The closely related Fra-1 and c-Fos share affinity for anionic lipids but the former has more affinity for a condensed phase and senses a change in DPPC phase, while the latter has more affinity for an expanded phase. These features are in contrast with our previous finding that c-Jun is not selective for phospholipid polar head group or charge. We show here that at least some immediate early transcription factors can interact with membrane phospholipids in a distinguishable manner, and this shall provide a basis for their potential capacity to regulate membrane-mediated cellular processes. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 710,718, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] |