Expression of the human ferritin light chain in a frataxin mutant yeast affects ageing and cell death Liesbeth Desmyter a , Sylviane Dewaele a , Rieka Reekmans a , Thomas Nystrom b , Roland Contreras a, * , Cuiying Chen a a Fundamental and Applied Molecular Biology, Ghent University and Flanders Interuniversity Institute for Biotechnology, VIB Technologiepark 927 B-9052, Ghent Zwijnaarde, Belgium b Department of Cell and Molecular Biology—Microbiology, Goteborg University Medicinaregatan 9C, Goteborg, Sweden Received 2 July 2003; received in revised form 31 October 2003; accepted 22 January 2004 Abstract Ferritin is one of the major eukaryotic proteins involved in regulating iron metabolism and maintaining iron homeostasis. However, Saccaromyces cerevisiae is an exception, possessing no ferritin and using other means to store excess iron. The only potential iron storage protein identified in yeast so far is the homologue of human frataxin (YFH1p). In this study, we found that dysfunction of yeast frataxin shortens mean lifespan by 49% compared to the WT control. Interestingly, the human ferritin L gene can, at least partially, complement the function of yeast frataxin, extending lifespan and protecting cells from death induced by oxidative stress or excess iron. Our findings indicate that ferritin L can perform functions in yeast that are similar to its functions in mammals, and suggest that common mechanisms may exist for preventing iron and oxidative damage in single- and multi-cellular eukaryotic organisms. Clearly, elucidation of the function of human ferritin in yeast would help in gaining a better understanding the molecular basis of iron storage diseases. q 2004 Elsevier Inc. All rights reserved. Keywords: Ageing; Lifespan; Saccaromyces cerevisiae; Ferritin L; Frataxin; Oxidative stress; Iron stress 1. Introduction Iron is required for a variety of essential cellular functions, and is vital for proper growth and development. However, iron excess in the cytosol or in mitochondria leads to cell damage due to the ability of iron to generate free hydroxyl radicals via the Fenton reaction (Halliwell and Gutteridge, 1984; Kakhlon and Cabantchik, 2002). Thus, cellular free iron concentration must be tightly controlled, and organisms have developed mechanisms to improve solubility of iron and to control intracellular iron levels (Cabiscol et al., 2002; Sipos et al., 2002). An abnormality in a mechanism regulating iron metabolism and homeostasis may affect cell proliferation and survival. Ferritin is one of the major proteins involved in iron metabolism, and plays an important role in the control of the intracellular iron levels and maintenance of iron homeostasis (Kakhlon and Cabantchik, 2002; Picard et al., 1998). It is composed of heavy (FH; Mr 21,000) and light (FL; Mr 19,000) subunits which share extensive sequence homology, but are encoded by different genes (Harrison and Arosio, 1996). The FH and LH subunits assemble to form a shell of 24 subunits around an iron core. The composition of ferritin, however, varies in a consistent and tissue-specific manner. For example, the liver and spleen contain ferritin composed predominantly of FL subunits, whereas the heart and brain contain ferritin rich in the FH subunit (Theil, 1990). In general, L-rich ferritins have higher iron content than H-rich ferritins. The biodistribution of ferritins with different FH:FL contents supports the hypothesis that the two subunits may play different but complementary roles within the ferritin protein complexes (Harrison and Arosio, 1996). Furthermore, diverse experimental evidence supports the concept of distinct functions for the FH and FL subunits, revealing a prominent role for the FH subunit in rapid iron oxidation, and involvement of the FL subunit in stability of the ferritin protein complex (Levi et al., 1988; Santambrogio et al., 1992; Theil, 2003). 0531-5565/$ - see front matter q 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.exger.2004.01.008 Experimental Gerontology 39 (2004) 707–715 www.elsevier.com/locate/expgero * Corresponding author. Tel.: þ 32-93313631; fax: þ 32-93313502. E-mail address: roland.contreras@dmbr.ugent.be (R. Contreras).