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

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. (C) 1999 Federation of European Biochemical Societies.