Further characterization of Hungarian acatalasemia by Hinf1 polymorphism of catalase gene.

An Hinf1 associated restriction length polymorphism pattern is reported for the catalase gene of Hungarian normocatalasemic individuals and acatalasemic patients. The 2.4-kb pCAT 10 probe revealed 9 bands (2.1, 1.5, 1.2, 1.1, 0.9, 0.8, 0.6, 0.5 and 0.4 kb) with 9 distinct patterns for the controls. The same patterns were detected for the Hungarian acatalasemic patients. The examination of the A to T mutation of the Hungarian acatalasemic patients and their relatives at position -21 in the flanking region with Hinf1 polymorphism could not reveal any difference between the acatalasemic and the normocatalasemic catalase gene.

Transcriptional regulation of the c-myc protooncogene by 1,25-dihydroxyvitamin D3 in HL-60 promyelocytic leukemia cells.

Exposure of HL-60 promyelocytic leukemia cells to calcitriol results in a decrease in steady-state levels of c-myc mRNA and induces cellular differentiation. We have asked whether calcitriol has a direct effect on the transcription of the c-myc gene. 1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) decreased RNA elongation in a nuclear run-off transcription assay by 4 h after treatment. In the continuous presence of 1,25-(OH)2D3, HL-60 cell transcription of c-myc was decreased by 38% at 4 h and was abolished by 48 h. In contrast, the transcription of beta-actin was not affected by 1,25-(OH)2D3 treatment. The rate of transcription of c-myc and beta-actin was proportional to the number of nuclei and to time. Furthermore, specific hybridization of c-myc and beta-actin RNA was a linear function of RNA input. After a 48-h treatment, the c-myc/beta-actin ratio was decreased by 80-100% at [32P]RNA inputs ranging from 2 to 20 X 10(6) cpm/ml. These data temporally correlate inhibition of c-myc transcription with decreases in the steady-state levels of c-myc mRNA as assessed by Northern blot analysis. We conclude that the effect of 1,25-(OH)2D3 on c-myc expression occurs at the transcriptional level.