TY - JOUR
T1 - The iron carrier transferrin is upregulated in retinas from patients with age-related macular degeneration
AU - Chowers, Itay
AU - Wong, Robert
AU - Dentchev, Tzvete
AU - Farkas, Ronald H.
AU - Iacovelli, Jared
AU - Gunatilaka, Tushara L.
AU - Medeiros, Nancy E.
AU - Presley, J. Brett
AU - Campochiaro, Peter A.
AU - Curcio, Christine A.
AU - Dunaief, Joshua L.
AU - Zack, Donald J.
PY - 2006/5
Y1 - 2006/5
N2 - PURPOSE. Iron can cause oxidative stress, and elevated iron levels have been associated with several neurodegenerative diseases including age-related macular degeneration (AMD). Transferrin, an iron transport protein, is expressed at high levels in the retina. The purpose of this study was to assess transferrin involvement in AMD by determining the expression profile of transferrin in retinas with AMD compared with retinas without evidence of disease. METHODS. Postmortem retinas were obtained from AMD and non-AMD eyes. Expression of transferrin was assessed in a microarray dataset from 33 retinas of unaffected donors and 12 retinas of patients with AMD (six with neovascular AMD and six with non-neovascular AMD). Quantitative real-time RT-PCR (QPCR) was used to confirm the microarray results. Transferrin protein expression was assessed by semiquantitative Western blot analysis and immunohistochemistry. RESULTS. In comparison to unaffected retinas, mean transferrin mRNA levels, as measured by microarray analysis were elevated 3.5- and 2.1-fold in non-neovascular and neovascular AMD retinas, respectively. Semiquantitative Western blot analysis demonstrated a 2.1-fold increase in transferrin protein in AMD eyes. Immunohistochemistry showed more intense and widespread transferrin label in AMD maculas, particularly in large drusen, Müller cells, and photoreceptors. CONCLUSIONS. These data demonstrate that transferrin expression is increased in the retinas of patients with AMD relative to those of healthy control patients of comparable age. Along with previous studies that have demonstrated elevated iron levels in AMD retinas, early onset drusen formation in a patient with retinal iron overload resulting from aceruloplasminemia, and retinal degeneration with some features of macular degeneration in the iron-overloaded retinas of ceruloplasmin/hephestin knockout mice, the present study suggests that altered iron homeostasis is associated with AMD.
AB - PURPOSE. Iron can cause oxidative stress, and elevated iron levels have been associated with several neurodegenerative diseases including age-related macular degeneration (AMD). Transferrin, an iron transport protein, is expressed at high levels in the retina. The purpose of this study was to assess transferrin involvement in AMD by determining the expression profile of transferrin in retinas with AMD compared with retinas without evidence of disease. METHODS. Postmortem retinas were obtained from AMD and non-AMD eyes. Expression of transferrin was assessed in a microarray dataset from 33 retinas of unaffected donors and 12 retinas of patients with AMD (six with neovascular AMD and six with non-neovascular AMD). Quantitative real-time RT-PCR (QPCR) was used to confirm the microarray results. Transferrin protein expression was assessed by semiquantitative Western blot analysis and immunohistochemistry. RESULTS. In comparison to unaffected retinas, mean transferrin mRNA levels, as measured by microarray analysis were elevated 3.5- and 2.1-fold in non-neovascular and neovascular AMD retinas, respectively. Semiquantitative Western blot analysis demonstrated a 2.1-fold increase in transferrin protein in AMD eyes. Immunohistochemistry showed more intense and widespread transferrin label in AMD maculas, particularly in large drusen, Müller cells, and photoreceptors. CONCLUSIONS. These data demonstrate that transferrin expression is increased in the retinas of patients with AMD relative to those of healthy control patients of comparable age. Along with previous studies that have demonstrated elevated iron levels in AMD retinas, early onset drusen formation in a patient with retinal iron overload resulting from aceruloplasminemia, and retinal degeneration with some features of macular degeneration in the iron-overloaded retinas of ceruloplasmin/hephestin knockout mice, the present study suggests that altered iron homeostasis is associated with AMD.
UR - http://www.scopus.com/inward/record.url?scp=33744752089&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33744752089&partnerID=8YFLogxK
U2 - 10.1167/iovs.05-1135
DO - 10.1167/iovs.05-1135
M3 - Article
C2 - 16639025
AN - SCOPUS:33744752089
SN - 0146-0404
VL - 47
SP - 2135
EP - 2140
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 5
ER -