Transient chloramphenicol acetyltransferase expression of the G gamma globin gene 5'-flanking regions containing substitutions of C----T at position -158, G----A at position -161, and T----A at position -175 in K562 cells

The expression of G gamma is affected by mutations that occur in promoter sequences located in the 5'-flanking region of the gene. We have assayed the promoter activity of G gamma genes that have mutations of C----T at position -158 or G----A at position -161. In addition, we determined the activity of a promoter fragment containing T----A at position -175 (in the octamer motif) in combination with a -158 C----T which was produced during the polymerase chain reaction amplification procedure. Constructs containing these fragments were transfected by electroporation into K562 cells and the promoter activity was measured as chloramphenicol acetyltransferase activity. The data show a 4-5-fold enhancement of activity for the -158 C----T and the -161 G----A promoters over the 'normal' G gamma promoter and an 8-fold increase in the activity of the promoter with the double mutation (-158 C----T and -175 T----A). These results are consistent with data involving the increase in G gamma production in patients heterozygous for these mutations.

Role of mevalonic acid in the regulation of natural killer cell cytotoxicity

Considerable evidence has accumulated for a role of a nonsteroidal mevalonate product in the regulation of DNA replication and cell division. We report here a similar requirement for mevalonate in a nonreplicative function, that of natural killer (NK) cell cytotoxicity. Treatment of NK cells with 10 microM compactin for 48 hr results in a significant inhibition of cytotoxicity which can be completely reversed by treatment with 1 mM mevalonate, but not cholesterol, dolichol, or isopentenyl adenine. Protein and RNA synthesis appear to be involved in this reversal. Treatment with compactin and reversal with mevalonate do not affect the phenotypic distribution of the effector cell population, and the cell type involved in the inhibition and reversal of cytotoxicity is a CD16 (Leu 11)-, Leu 19-positive, large granular lymphocyte. The conjugation of the target and effector cell early in the lytic pathway is inhibited by compactin treatment of the effector cell population, and this inhibition is reversed by mevalonate.