Analysis of the biologic functions of H- and L-ferritins in HeLa cells by transfection with siRNAs and cDNAs: evidence for a proliferative role of L-ferritin.
We describe the use of small interfering RNAs (siRNAs) to down-regulate H- and L-ferritin levels in HeLa cells. siRNAs repressed H- and L-ferritin expression to about 20% to 25% of the background level in both stable and transient transfections. HeLa cells transfected with H- and L-ferritin cDNAs were analyzed in parallel to compare the effects of ferritin up- and down-regulation. We found that large modifications of L-ferritin levels did not affect iron availability in HeLa cells but positively affected cell proliferation rate in an iron-independent manner. The transient down-regulation of H-ferritin modified cellular iron availability and resistance to oxidative damage, as expected. In contrast, the stable suppression of H-ferritin in HeLa cell clones transfected with siRNAs did not increase cellular iron availability but made cells less resistant to iron supplementation and chelation. The results indicate that L-ferritin has no direct effects on cellular iron homeostasis in HeLa cells, while it has new, iron-unrelated functions. In addition, they suggest that H-ferritin function is to act as an iron buffer.
Cozzi
Anna
A
Department Biological and Technological Research, Instituto de Ricovero e Cure a Carattere Scientifico, San Rafaelle, Milan, Italy.
Corsi
Barbara
B
Levi
Sonia
S
Santambrogio
Paolo
P
Biasiotto
Giorgio
G
Arosio
Paolo
P
D002021:Buffers; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D018076:DNA, Complementary; D015536:Down-Regulation; D005290:Ferric Compounds / Q000633:toxicity*; D005293:Ferritins / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D007501:Iron / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology; D000644:Quaternary Ammonium Compounds / Q000633:toxicity*; D034741:RNA, Small Interfering; D014162:Transfection; D015854:Up-Regulation
D002021:Buffers; D018076:DNA, Complementary; D005290:Ferric Compounds; D000644:Quaternary Ammonium Compounds; D034741:RNA, Small Interfering; D005293:Ferritins; D007501:Iron; C013531:ferric ammonium citrate