Subject(s)
Clinical Clerkship/methods , Curriculum , General Surgery/education , Internet , CaliforniaABSTRACT
A complementary DNA encoding a member of the leucine-zipper class of proteins (human X-box-binding protein, hXBP-1) that binds to the 3' end of the conserved X box (X2) of the HLA-DRA major histocompatibility complex gene was recently described. Further gel-retardation analysis has demonstrated that hXBP-1 also binds to HLA-DPB X2 but not to other X2 sequences. Transient transfection of a mammalian expression vector with the hXBP-1 cDNA inserted in the antisense orientation represses the surface expression of HLA-DR and HLA-DP in Raji cells. Cotransfection of the antisense hXBP-1 vector with a HLA-DRA/chloramphenicol acetyltransferase (but not a HLA-DQB/chloramphenicol acetyltransferase) reporter plasmid decreases chloramphenicol acetyltransferase activity in Raji cells and in gamma-interferon-treated HeLa cells relative to cells cotransfected with a control antisense vector. Moreover, hXBP-1 is shown to form a stable heterodimer with the product of the c-fos protooncogene. These data suggest that the hXBP-1 c-fos heterodimer is critical for the transcription of a subset of the human class II major histocompatibility complex genes and that the regulatory mechanisms for the different class II genes are distinct.
Subject(s)
DNA-Binding Proteins/physiology , Genes, MHC Class II , Proto-Oncogene Proteins/metabolism , Transcription Factors/physiology , Transcription, Genetic , Antisense Elements (Genetics) , Base Sequence , DNA/genetics , DNA-Binding Proteins/genetics , Gene Expression Regulation , HLA-DP Antigens/genetics , HLA-DR Antigens/genetics , Humans , Immunosorbent Techniques , Macromolecular Substances , Molecular Sequence Data , Proto-Oncogene Proteins c-fos , Recombinant Fusion Proteins/metabolism , Regulatory Factor X Transcription Factors , Transcription Factors/genetics , TransfectionABSTRACT
Several mutants derived from transformed human B cell lines are defective in expressing major histocompatibility complex (MHC) class II genes. The failure to express a class II gene in at least one such mutant line has been mapped to the MHC class II X box, a conserved transcriptional element in the promoter region. A complementary DNA encoding a DNA-binding protein (human X box binding protein, hXBP-1) whose target is the human DR alpha X box and the 3' flanking region has now been cloned. This complementary DNA encoded a protein with structural similarities to the c-jun proto-oncogene product, and its target sequence was closely related to the palindromic target sequence of c-jun. Mutation of the hXBP-1 DNA target sequence decreased DR alpha promoter activity in vivo. These studies suggest that the hXBP-1 protein acts as a transcription factor in B cells.
Subject(s)
DNA-Binding Proteins/genetics , DNA/genetics , HLA-DR Antigens/genetics , Promoter Regions, Genetic , Transcription Factors/genetics , Amino Acid Sequence , B-Lymphocytes , Base Sequence , Binding Sites , Cell Line, Transformed , DNA-Binding Proteins/metabolism , HLA-DR Antigens/metabolism , Humans , Leucine , Molecular Sequence Data , Mutation , Proto-Oncogene Mas , Regulatory Factor X Transcription Factors , Transcription Factors/metabolism , TransfectionABSTRACT
90 subjects (45 boys and 45 girls) from Grades 3, 4, 5 were screened for eidetic imagery. Using Haber's criteria, 12 subjects were identified as having eidetic imagery. These subjects were randomly divided into two groups of six each with one group designated the experimental group and the other, the control group. Eidetic imagery was evoked in all subjects to the same stimuli. Members of the experimental group were tested for accuracy of recall while maintaining the images and those of the control group were tested for accuracy of recall after blinking their eyes and turning their heads to erase the images. Significantly more correct responses were given by the experimental than by the control group. Also, eidetic images were not always erased by blinking the eyes and turning the head, and eidetic images did not necessarily last longer than afterimages, as Haber has reported.
