Northern blot and real time RT-PCR analysis revealed that treatment with 20 muM iron led to ∼3-fold increase in elastin mRNA levels, while treatment with 200 muM iron decreased elastin message stability and subsequent mRNA levels.It has been implicated that iron imbalance is responsible for the elastic fiber defects in hereditary hemolytic disorders, and since the expression of several ECM is iron dependent, we speculated that iron might also modulate elastin gene expression.We conclude that a balance between these two iron-dependent mechanisms may constitute a novel factor regulating normal elastogenesis and that disturbance of this balance results in impaired elastic fiber production.The results of our immunocytochemical and metabolic studies assessing deposition of insoluble elastin, showed that treatment of cultured fibroblasts with 2--20 muM of iron (supplied as ferric ammonium citrate) induced an increase in elastin production, while treatment with 100--200-muM iron lead to intracellular reactive oxygen species generation, and a decrease in elastin production.