Clusterin (SGP-2) gene expression is cell cycle dependent in normal human dermal fibroblasts

Abstract

In confluent human dermal fibroblasts brought to quiescence (G 0) by serum starvation, the S phase peaked at 24 h after serum re-addiction and G 2/M phase peaked at 36 h. This was confirmed by titration of h-gas1 mRNA (a marker of G 0 phase) and histone H3 (a marker of S phase). Clusterin mRNA accumulation progressively increased in cells proceeding to confluence after seeding and to quiescence upon serum starvation, and peaked at around G 0, in parallel with h-gas1 mRNA. At 6 h (roughly G 1 phase) clusterin transcript formed a second peak, followed by a gradual decrease until 36 h. Correspondence of clusterin protein accumulation to its mRNA occurred solely with regard to the G 0 peak but not to the second one. The possible meaning of the cell cycle related clusterin gene expression is discussed.