EXPRESSION AND REGULATION OF SUPEROXIDE-DISMUTASE ACTIVITY IN HUMAN SKIN FIBROBLASTS FROM DONORS OF DIFFERENT AGES

We have determined the activities, protein, and mRNA abundances as wel l as the level of transcriptional activation of two intracellular form s of the free radical metabolizing enzyme superoxide dismutase in 29 h uman skin fibroblast lines established from donors of different ages. SOD-1 (a copper and zinc containing form of SOD) and SOD-2 (a manganes e containing form of the enzyme) activities were both observed to be s ignificantly lower in cell lines derived from fetal skin than in lines established from postnatal skin (ages 17-94 years). The percent of to tal activity contributed by SOD-1 decreased in an age-associated manne r from approximately 50% in the fetal lines to less than 20% in lines established from old tissue donors. All of the cell lines were screene d to exclude the possibility that they contained a polymorph ism known to influence SOD-2 activity. Northern blot analysis revealed three SO D-1 mRNA transcripts that were 0.5, 0.7, and 1.9 kb in length. Althoug h SOD-1 protein abundance was lower in fetal lines than in lines deriv ed from postnatal donors, SOD-1 mRNA abundance did not differ between fetal cells and cell lines derived from young donors. SOD-2 protein ab undance and mRNA abundance were both significantly lower in fetal line s than in postnatal lines. No postnatal age-dependent differences were observed in any of the SOD-2 parameters examined. Nuclear run-on anal ysis revealed that fetal cell lines exhibited a lower level of transcr iptional initiation far SOD-1 than postnatal lines. The transcription of SOD-2 was readily detected in postnatal lines, but undetectable in fetal lines. These results are consistent with multiple levels of cont rol for SOD-1 expression and with a strong transcriptional influence o n SOD-2 expression. (C) 1995 Wiley-Liss, Inc.