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- Lerner, M, et al.
(författare)
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The RBCC gene RFP2 (Leu5) encodes a novel transmembrane E3 ubiquitin ligase involved in ERAD
- 2007
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Ingår i: Molecular biology of the cell. - : American Society for Cell Biology (ASCB). - 1059-1524 .- 1939-4586. ; 18:5, s. 1670-1682
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Tidskriftsartikel (refereegranskat)abstract
- RFP2, a gene frequently lost in various malignancies, encodes a protein with RING finger, B-box, and coiled-coil domains that belongs to the RBCC/TRIM family of proteins. Here we demonstrate that Rfp2 is an unstable protein with auto-polyubiquitination activity in vivo and in vitro, implying that Rfp2 acts as a RING E3 ubiquitin ligase. Consequently, Rfp2 ubiquitin ligase activity is dependent on an intact RING domain, as RING deficient mutants fail to drive polyubiquitination in vitro and are stabilized in vivo. Immunopurification and tandem mass spectrometry enabled the identification of several putative Rfp2 interacting proteins localized to the endoplasmic reticulum (ER), including valosin-containing protein (VCP), a protein indispensable for ER-associated degradation (ERAD). Importantly, we also show that Rfp2 regulates the degradation of the known ER proteolytic substrate CD3-δ, but not the N-end rule substrate Ub-R-YFP (yellow fluorescent protein), establishing Rfp2 as a novel E3 ligase involved in ERAD. Finally, we show that Rfp2 contains a C-terminal transmembrane domain indispensable for its localization to the ER and that Rfp2 colocalizes with several ER-resident proteins as analyzed by high-resolution immunostaining. In summary, these data are all consistent with a function for Rfp2 as an ERAD E3 ubiquitin ligase.
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- Kuchinskaya, E, et al.
(författare)
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Children and adults with acute lymphoblastic leukaemia have similar gene expression profiles
- 2005
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Ingår i: European Journal of Haematology. - Oxford : Blackwell Publishing. - 0902-4441 .- 1600-0609. ; 74:6, s. 466-480
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To compare the gene expression pattern in children and adults with acute lymphoblastic leukaemia (ALL) in order to improve our understanding of the difference in disease biology and prognosis.METHODS: The gene expression profiles in diagnostic samples from 29 children and 15 adults with ALL were analysed using the oligonucleotide chip Hu95ver2a, produced by Affymetrix.RESULTS: Unsupervised hierarchical cluster analysis revealed that, in spite of differences in outcome, patients clustered irrespective of age, first by T-cell or B-precursor immunophenotype, and second by cytogenetic changes within the B-precursor group. The expression pattern analysis allowed the reclassification of some samples into the proper cytogenetic group. We also showed that separate clustering of samples with the BCR/ABL translocation could be explained by different breakpoint regions in the BCR. No significant difference in gene expression was observed between samples with and without CDKN2A deletion within the B-precursor group. Analysis of different age groups revealed a similarity in expression profiles when infants with the MLL translocation and adults over 40 yr of age were compared irrespective of karyotype.CONCLUSIONS: In spite of the difference in clinical outcome, the gene expression pattern in children and adults with ALL is very similar and is primarily dependent on immunophenotype and cytogenetic aberrations. However, when age groups are compared, the expression patterns of infants and adults over 40 show a remarkable similarity.
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- Panaretakis, T, et al.
(författare)
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Doxorubicin requires the sequential activation of caspase-2, protein kinase Cdelta, and c-Jun NH2-terminal kinase to induce apoptosis
- 2005
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Ingår i: Molecular biology of the cell. - : American Society for Cell Biology (ASCB). - 1059-1524 .- 1939-4586. ; 16:8, s. 3821-3831
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Tidskriftsartikel (refereegranskat)abstract
- Here, we identified caspase-2, protein kinase C (PKC)δ, and c-Jun NH2-terminal kinase (JNK) as key components of the doxorubicin-induced apoptotic cascade. Using cells stably transfected with an antisense construct for caspase-2 (AS2) as well as a chemical caspase-2 inhibitor, we demonstrate that caspase-2 is required in doxorubicin-induced apoptosis. We also identified PKCδ as a novel caspase-2 substrate. PKCδ was cleaved/activated in a caspase-2–dependent manner after doxorubicin treatment both in cells and in vitro. PKCδ is furthermore required for efficient doxorubicin-induced apoptosis because its chemical inhibition as well as adenoviral expression of a kinase dead (KD) mutant of PKCδ severely attenuated doxorubicin-induced apoptosis. Furthermore, PKCδ and JNK inhibition show that PKCδ lies upstream of JNK in doxorubicin-induced death. Jnk-deficient mouse embryo fibroblasts (MEFs) were highly resistant to doxorubicin compared with wild type (WT), as were WT Jurkat cells treated with SP600125, further supporting the importance of JNK in doxorubicin-induced apoptosis. Chemical inhibitors for PKCδ and JNK do not synergize and do not function in doxorubicin-treated AS2 cells. Caspase-2, PKCδ, and JNK were furthermore implicated in doxorubicin-induced apoptosis of primary acute lymphoblastic leukemia blasts. The data thus support a sequential model involving caspase-2, PKCδ, and JNK signaling in response to doxorubicin, leading to the activation of Bak and execution of apoptosis.
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- Panaretakis, T, et al.
(författare)
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Interferon alpha induces nucleus-independent apoptosis by activating extracellular signal-regulated kinase 1/2 and c-Jun NH2-terminal kinase downstream of phosphatidylinositol 3-kinase and mammalian target of rapamycin
- 2008
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Ingår i: Molecular biology of the cell. - : American Society for Cell Biology (ASCB). - 1939-4586 .- 1059-1524. ; 19:1, s. 41-50
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Tidskriftsartikel (refereegranskat)abstract
- Interferon (IFN)α induces apoptosis via Bak and Bax and the mitochondrial pathway. Here, we investigated the role of known IFNα-induced signaling cascades upstream of Bak activation. By pharmacological and genetic inhibition of the kinases protein kinase C (PKC)δ, extracellular signal-regulated kinase (ERK), and c-Jun NH2-terminal kinase (JNK) in U266-1984 and RHEK-1 cells, we could demonstrate that all three enzymes are critical for the apoptosis-associated mitochondrial events and apoptotic cell death induced by IFNα, at a step downstream of phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin (mTOR). Furthermore, the activation of JNK was found to occur in a PKCδ/ERK-dependent manner. Inhibition of these kinases did not affect the canonical IFNα-stimulated Janus tyrosine kinase-signal transducer and activator of transcription signaling or expression of IFN-responsive genes. Therefore, enucleated cells (cytoplasts) were examined for IFNα-induced apoptosis, to test directly whether this process depends on gene transcription. Cytoplasts were found to undergo apoptosis after IFNα treatment, as analyzed by several apoptosis markers by using flow cytometry, live cell imaging, and biochemical analysis of flow-sorted cytoplasts. Furthermore, inhibition of mTOR, ERK, and JNK blocked IFNα-induced apoptosis in cytoplasts. In conclusion, IFNα-induced apoptosis requires activation of ERK1/2, PKCδ, and JNK downstream of PI3K and mTOR, and it can occur in a nucleus-independent manner, thus demonstrating for the first time that IFNα induces apoptosis in the absence of de novo transcription.
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- Szeps, M, et al.
(författare)
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Human papillomavirus, viral load and proliferation rate in recurrent respiratory papillomatosis in response to alpha interferon treatment
- 2005
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Ingår i: The Journal of general virology. - : Microbiology Society. - 0022-1317 .- 1465-2099. ; 86:Pt 6, s. 1695-1702
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to identify recurrent respiratory papillomatosis patients who may benefit from interferon (IFN)-α treatment and to determine the means of IFN-α action. The presence of human papillomavirus (HPV) and viral load and proliferation rate in pre-, ongoing and post-treatment respiratory papillomatosis biopsies were examined retrospectively in 25 patients, 18 of whom were IFN-α treated and seven of whom were IFN-α non-treated. Using PCR, HPV was found to be present in 20/25 respiratory papillomatosis patients and HPV type was determined for 18/25 patients (12 HPV6 and six HPV11). Eighteen of the patients were treated with IFN-α, 14 of whom were HPV positive (eight HPV6, five HPV11 and one undefined HPV). Response to IFN-α therapy was observed in 12 patients (7/8 HPV6, 3/5 HPV11, 1/1 undefined HPV and 1/4 HPV negative), while six patients (1/8 HPV6, 2/5 HPV11 and 3/4 HPV negative) did not respond to therapy. Viral load, determined by quantitative real-time PCR (between 0·03 and 533 HPV copies per cell), and proliferation rate, determined as the percentage of Ki-67-positive cells (between 8 and 54 %), were similar in IFN-α-treated and non-treated patients and were generally unaffected by IFN-α treatment. In summary, most (12/18) IFN-α-treated patients responded to therapy. Moreover, there was a tendency for patients with HPV6-positive (7/8) respiratory papillomatosis to respond more frequently to IFN-α therapy than patients with HPV11 (3/5) or HPV-negative (1/4) respiratory papillomatosis. Finally, the presence of HPV and viral load and proliferation in respiratory papillomatosis biopsies was similar in patients treated or not with IFN-α and were in general unaffected by IFN-α treatment.
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