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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS, RESULTS. Meshes: ABO Blood-Group System, Base Sequence, Basic Helix-Loop-Helix Transcription Factors, Cell Line, Tumor, DNA-Binding Proteins, Gene Expression Regulation, Genes, Regulator, Humans, Molecular Sequence Data, Promoter Regions, Genetic, Transcription Factors, Transcription, Genetic.
user
Is transcriptional regulation of the human ABO histo-blood group genes dependent on the N box upstream of the proximal promoter? Context: Our previous studies of the transcriptional regulation of the human ABO gene indicated that negative regulatory elements are present in the sequence just upstream from the proximal promoter. The role of the -275 to -118 region in regulation of ABO gene transcription is further characterized. Transient transfection experiments into various cells were performed with luciferase reporter plasmids carrying ABO upstream sequences, and electrophoretic mobility shift assay was carried out with a nuclear extract prepared from the human gastric cancer KATOIII cells. It is shown that the -202 to -118 region is involved in the negative regulation of ABO gene transcription in all cell lines examined. Transient transfection experiments in KATOIII cells with a reporter plasmid carrying mutated N box at -196 to -191 demonstrate that the N box is a negative regulatory element in the -202 to -118 sequence. Electrophoretic mobility shift assays indicate that the N box binds with a nuclear factor from KATOIII cells.
assistant
These results indicate that repression of transcription from the ABO proximal promoter is partially dependent upon the N box. Therefore, reduced binding of the protein with the N box might play a direct role in ABO gene expression. Final Decision: yes