The influence of hydrostatic pressure on the distribution of histone mRNA in HeLa cells

Abstract

Hydrostatic pressure and HeLa S3 cells were used (as a model system) to investigate the relationship of the cytoskeleton and histone gene expression. Exposure of HeLa S3 cells to hydrostatic pressure of 1000 – 10 000 psi (6.89 × 103 – 6.89 × 104 kPa) disrupts the cytoskeleton and reduces H1 and core histone mRNA and actin mRNA levels as determined by hybridization to specific DNA probes. Soluble and insoluble cell fractions were isolated from HeLa cells after lysis in Triton X-100 buffered with PIPES and being subjected to low-speed centrifugation. The insoluble fraction was designated the cytoskeletal fraction. At atmospheric pressure, 76% of H4 histone mRNA is associated with the cytoskeletal fraction and 24% of the H4 histone mRNA is in the soluble fraction. At 6000 and 10 000 psi for a duration of 10 min, H4 mRNA levels in the cytoskeletal fraction were reduced to 52 and 41%, respectively. The reduction of mRNA in the cytoskeletal fraction is accompanied by a corresponding increase of mRNA in the soluble cell fraction. The other core (H2A, H2B, and H3) and H1 histone mRNA transcripts exhibited similar sensitivity to pressure treatment. The effects of pressure on histone gene regulation may be mediated through alteration of mRNA–cytoskeleton association.Key words: cytoskeleton, HeLa cells, histone mRNA, hydrostatic pressure.