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Activation Activity (activation + activity)
Selected AbstractsSimultaneous activation of JAK1 and JAK2 confers IL-3 independent growth on Ba/F3 pro-B cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2005Huei-Mei Huang Abstract JAK1 and JAK2 are tyrosine kinases involved in the regulation of cell proliferation, differentiation, and survival. These proteins may play a key role in mediating the effects of the cytokine IL-3 on hematopoietic cells. IL-3 induces tyrosine phosphorylation of both JAK1 and JAK2. However, it is not clear whether the activation of JAK1, JAK2, or both is sufficient to confer factor-independent growth in IL-3 dependent cells. To address this issue, fusion proteins CD16/CD7/JAK (CDJAK), comprised of a CD16 extracellular domain, a CD7 transmembrane domain, and a JAK cytoplasmic region (either a wild-type JAK or a dominant negative mutant of JAK) were constructed. We established several Ba/F3 derivatives that stably overexpress the conditionally active forms of either CDJAK1, CDJAK2, or both these fusion proteins. In this study, the autophosphorylation of CDJAK1 or CDJAK2 was induced by crosslinking with anti-CD16 antibody. We demonstrated that, like their wild-type counterparts, CDJAK1 and CDJAK2 were preassociated with the IL-3 receptor beta and alpha subunits, respectively. Furthermore, the simultaneous activation of both CDJAK1 and CDJAK2 fusion proteins, but not either one alone, led to the tyrosine phosphorylation of the IL-3 receptor beta subunit, the activation of downstream signaling molecules, including STAT5, Akt, and MAPK, and the conferring of factor-independent growth to IL-3-dependent Ba/F3 cells. Coexpression of dominant negative mutants CDJAK1KE or CDJAK2KE with wild type CDJAK2 or CDJAK1, respectively, inhibited these activation activities. These results suggest that JAK1 and JAK2 must work cooperatively and not independently and that their actions are dependent on having normal kinase activity to trigger downstream signals leading to IL-3 independent proliferation and survival of Ba/F3 cells. © 2005 Wiley-Liss, Inc. [source] Characterization of a Novel RING Finger Gene OsRFP1, which is Induced by Ethylene, Salicylic Acid and Blast Fungus Infection in RiceJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2008Shanyue Zhou Abstract OsRFP1, a C3H2C3 -type zinc finger gene, was isolated through screening a blast-induced rice cDNA library. The full-length cDNA of the OsRFP1 gene is 1393 bp with an open reading frame (ORF) encoding 302 amino acid residues. The deduced amino acid sequence of OsRFP1 contains an N-terminal Pfam:zf-CHY domain and a C-terminal C3H2C3 -type RING signature. OsRFP1 was found localizing in the nucleus based on the fluorescence emitted by OsRFP1-GFP fusion protein expressed in onion epidermal cells. GAL4 DNA-binding vector pBD-containing OsRFP1 could activate expression of the reporter genes of His/Ade/LacZ in yeast strain AH109 indicating that OsRFP1 has the transcriptional activation activity. RNA blot analysis showed that expression of the OsRFP1 gene was significantly induced by ethylene (ET), salicylic acid (SA) and blast fungus infection. Together, these results indicate that the OsRFP1 may function as a transcriptional regulator in ET-dependent signal pathway in plant defense. [source] AtNAC2, a transcription factor downstream of ethylene and auxin signaling pathways, is involved in salt stress response and lateral root developmentTHE PLANT JOURNAL, Issue 6 2005Xin-Jian He Summary An NAC-type transcription factor gene AtNAC2 was identified from Arabidopsis thaliana when expression patterns of the genes from a microarray analysis were examined. The AtNAC2 expression was induced by salt stress and this induction was reduced in magnitude in the transgenic Arabidopsis plants overexpressing tobacco ethylene receptor gene NTHK1. AtNAC2 is localized in the nucleus and has transcriptional activation activity. It can form a homodimer in yeast. AtNAC2 was highly expressed in roots and flowers, but less expressed in other organs examined. In addition to the salt induction, the AtNAC2 can also be induced by abscisic acid (ABA), ACC and NAA. The salt induction was enhanced in the ethylene overproducer mutant eto1-1, but suppressed in the ethylene-insensitive mutants etr1-1 and ein2-1, and in the auxin-insensitive mutant tir1-1when compared with that in wild-type plants. However, the salt induction of AtNAC2 was not significantly affected in the ABA-insensitive mutants abi2-1, abi3-1 and abi4-1. These results indicate that the salt response of AtNAC2 requires ethylene signaling and auxin signaling pathways but does not require ABI2, ABI3 and ABI4, intermediates of the ABA signaling pathway. Overexpression of AtNAC2 in transgenic Arabidopsis plants resulted in promotion of lateral root development. AtNAC2 also promoted or inhibited downstream gene expressions. These results indicate that AtNAC2 may be a transcription factor incorporating the environmental and endogenous stimuli into the process of plant lateral root development. [source] Identifying Putative Promoter Regions of Hermansky-Pudlak Syndrome Genes by Means of Phylogenetic FootprintingANNALS OF HUMAN GENETICS, Issue 4 2009Horia Stanescu Summary HPS is an autosomal recessive disorder characterized by oculocutaneous albinism and prolonged bleeding. Eight human genes are described resulting in the HPS subtypes 1,8. Certain HPS proteins combine to form Biogenesis of Lysosome-related Organelles Complexes (BLOCs), thought to function in the formation of intracellular vesicles such as melanosomes, platelet dense bodies, and lytic granules. Specifically, BLOC-2 contains the HPS3, HPS5 and HPS6 proteins. We used phylogenetic footprinting to identify conserved regions in the upstream sequences of HPS3, HPS5 and HPS6. These conserved regions were verified to have in vitro transcription activation activity using luciferase reporter assays. Transcription factor binding site analyses of the regions identified 52 putative sites shared by all three genes. When analysis was limited to the conserved footprints, seven binding sites were found shared among all three genes: Pax-5, AIRE, CACD, ZF5, Zic1, E2F and Churchill. The HPS3 conserved upstream region was sequenced in four patients with decreased fibroblast HPS3 RNA levels and only one HPS3 mutation in the coding exons and surrounding exon/intron boundaries; no mutation was found. These findings illustrate the power of phylogenetic footprinting for identifying potential regulatory regions in non-coding sequences and define the first putative promoter elements for any HPS genes. [source] Characterization of New PPAR, Agonists: Analysis of Telmisartan's Structural ComponentsCHEMMEDCHEM, Issue 3 2009Matthias Goebel Abstract Telmisartan was originally designed as an AT1 antagonist but was later also characterized as a selective PPAR, modulator. This study focused on the identification of the essential structural motifs of telmisartan for PPAR, activation activity, elucidating the individual SAR of each different component (shown). In addition to a proven efficacy in lowering blood pressure, the AT1 receptor blocker telmisartan has recently been shown to exert pleiotropic effects as a partial agonist of the nuclear peroxisome proliferator-activated receptor gamma (PPAR,). Based on these findings and an excellent side-effect profile, telmisartan may serve as a lead structure for the development of new PPAR, ligands. Therefore, we analyzed the structural components of telmisartan to identify those necessary for PPAR, activation. Synthesized compounds were tested in a differentiation assay using 3T3-L1 preadipocytes and a luciferase assay with COS-7 cells transiently transfected with pGal4-hPPAR,DEF, pGal5-TK-pGL3 and pRL-CMV. The data obtained in this structure,activity relationship (SAR) study provide the basis for the development of new PPAR, ligands, which could lead to active compounds with a distinct, beneficial pharmacological profile compared with the existing full agonists. The basic 1-(biphenyl-4-ylmethyl)-1H -benzimidazole scaffold of telmisartan was identified as an essential moiety with either a carboxylic acid or tetrazole group at the C-2 position of the biphenyl. For maximum potency and activity, the alkyl chain in position 2 requires a minimum length of at least two C atoms (ethyl group), while the methyl group at position 4 of the benzimidazole core seems to contribute to partial activity. An additional benzimidazole at position 6 appears to be a further determinant of potency. Similar conclusions can be drawn for the methyl group in position 1. [source] | ||||||||||