Clinicopathological images. Gastric polyps.
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Biomedical subjects
Publications and source records attributed to N Paslidis.
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The binding of nuclear proteins of hematopoietic cells to transcriptional enhancers of interferon-inducible genes has been studied before and after exposure to alpha-interferon. Mobility shift assays show that a complex formed with interferon-inducible transcriptional enhancers before interferon induction contains a 73- and 84-kDa protein. Amino acid sequencing of the oligoaffinity column purified 73- and 84-kDa proteins showed that they belonged to a family of DNA-binding proteins which have been previously identified to exhibit binding in a sequence nonspecific manner to the ends of fragmented DNA or the origin of replication of adenovirus Type 2 DNA and sequence-specific binding to the distal regions of the U1 small nuclear RNA promoter, the promoter of the transferrin receptor gene, and the transcriptional regulatory regions of HLA genes. Following exposure to alpha-interferon, more slowly migrating complexes appeared which contained a 48-kDa protein, a 95-kDa protein, and a 105-kDa protein which bound to the 9-27 transcriptional enhancer in a sequence-specific manner.
Nuclear proteins isolated from untreated lymphoid cells formed complexes with the interferon-inducible transcriptional enhancer (IITE) containing a 73- and an 84-kDa protein, whereas the nuclear proteins of untreated myeloid cells formed complexes with the IITE which contained 50-, 65-, and 73-, but not 84-kDa nuclear proteins. The difference in the molecular masses of the nuclear proteins binding to the IITE in lymphoid and myeloid cells was due to a phosphatase present in the cytoplasm of the myeloid cells. Induction of transcriptional activation by interferon was accompanied by the binding of a 95-kDa nuclear protein to the IITE 1-4 h after the start of exposure to interferon. Cycloheximide did not inhibit the binding of the 95-kDa nuclear protein or the transcriptional activation of alpha-interferon-inducible genes. These data suggest that the induction of gene transcription by alpha-interferon in hematopoietic cells may be associated with post-translational changes in a 95-kDa nuclear protein that binds to IITE, thereby leading to transcriptional activation.
Cytoplasmic protein extracts from chronic myelogenous leukemia (CML) cells contained an activity that altered the electrophoretic mobility of complexes formed between nuclear proteins and the transcriptional enhancers of interferon (IFN)-inducible genes. Exposure of CML cells to IFN-alpha diminished the effect of the CML cytoplasmic proteins on these nuclear protein-DNA complexes. The presence of clinical responsiveness to IFN-alpha correlated with the sensitivity to the IFN-induced change in the electrophoretic mobility of nuclear protein-DNA complexes. These data suggest that the action of IFN-alpha in CML may be linked to a pathway that can result in posttranslational modification of nuclear proteins.