Loss of Hfe leads to progression of tumor phenotype in primary retinal pigment epithelial cells

Jaya Pranava Gnana-Prakasam, Rajalakshmi Veeranan-Karmegam, Veena Coothankandaswamy, Sushma K. Reddy, Pamela Moore Martin, Muthusamy Thangaraju, Sylvia B Smith, Vadivel Ganapathy

Research output: Contribution to journalArticle

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Abstract

Purpose. Hemochromatosis is a disorder of iron overload arising mostly from mutations in HFE. HFE is expressed in retinal pigment epithelium (RPE), and Hfe-/- mice develop age-related iron accumulation and retinal degeneration associated with RPE hyperproliferation. Here, the mechanism underlying the hyperproliferative phenotype in RPE was inves tigated. Methods. Cellular senescence was monitored by β-galactosidase activity. Gene expression was monitored by real-time PCR. Survivin was analyzed by Western blot and immunofluorescence. Migration and invasion were monitored using appropriate kits. Glucose transporters (GLUTs) were monitored by 3-O-methyl-D-glucose uptake. Histone deacetylases (HDACs) were studied by monitoring catalytic activity and acetylation status of histones H3/H4. Results. Hfe-/- RPE cells exhibited slower senescence rate and higher survivin expression than wild type cells. Hfe-/- cells migrated faster and showed greater glucose uptake and increased expression of GLUTs. The expression of HDACs and DNA methyltransferase (DNMTs) also was increased. Similarly, RPE cells from hemojuvelin (Hjv)-knockout mice, another model of hemochromatosis, also had increased expression of GLUTs, HDACs, and DNMTs. The expression of Slc5a8 was decreased in Hfe-/- RPE cells, but treatment with a DNA methylation inhibitor restored the transporter expression, indicating involvement of DNA methylation in the silencing of Slc5a8 in Hfe-/- cells. Conclusions. RPE cells from iron-overloaded mice exhibit several features of tumor cells: decreased senescence, enhanced migration, increased glucose uptake, and elevated levels of HDACs and DNMTs. These features are seen in Hfe-/- RPE cells as well as in Hjv-/- RPE cells, providing a molecular basis for the hyperproliferative phenotype of Hfe-/- and Hjv-/- RPE cells.

Original languageEnglish (US)
Pages (from-to)63-71
Number of pages9
JournalInvestigative Ophthalmology and Visual Science
Volume54
Issue number1
DOIs
StatePublished - Jan 1 2013

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Retinal Pigments
Retinal Pigment Epithelium
Epithelial Cells
Phenotype
Histone Deacetylases
Neoplasms
Facilitative Glucose Transport Proteins
Methyltransferases
Hemochromatosis
Cell Aging
DNA Methylation
Histones
DNA
Iron
Galactosidases
3-O-Methylglucose
Glucose
Retinal Degeneration
Iron Overload
Acetylation

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this

Loss of Hfe leads to progression of tumor phenotype in primary retinal pigment epithelial cells. / Gnana-Prakasam, Jaya Pranava; Veeranan-Karmegam, Rajalakshmi; Coothankandaswamy, Veena; Reddy, Sushma K.; Martin, Pamela Moore; Thangaraju, Muthusamy; Smith, Sylvia B; Ganapathy, Vadivel.

In: Investigative Ophthalmology and Visual Science, Vol. 54, No. 1, 01.01.2013, p. 63-71.

Research output: Contribution to journalArticle

Gnana-Prakasam, Jaya Pranava ; Veeranan-Karmegam, Rajalakshmi ; Coothankandaswamy, Veena ; Reddy, Sushma K. ; Martin, Pamela Moore ; Thangaraju, Muthusamy ; Smith, Sylvia B ; Ganapathy, Vadivel. / Loss of Hfe leads to progression of tumor phenotype in primary retinal pigment epithelial cells. In: Investigative Ophthalmology and Visual Science. 2013 ; Vol. 54, No. 1. pp. 63-71.
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abstract = "Purpose. Hemochromatosis is a disorder of iron overload arising mostly from mutations in HFE. HFE is expressed in retinal pigment epithelium (RPE), and Hfe-/- mice develop age-related iron accumulation and retinal degeneration associated with RPE hyperproliferation. Here, the mechanism underlying the hyperproliferative phenotype in RPE was inves tigated. Methods. Cellular senescence was monitored by β-galactosidase activity. Gene expression was monitored by real-time PCR. Survivin was analyzed by Western blot and immunofluorescence. Migration and invasion were monitored using appropriate kits. Glucose transporters (GLUTs) were monitored by 3-O-methyl-D-glucose uptake. Histone deacetylases (HDACs) were studied by monitoring catalytic activity and acetylation status of histones H3/H4. Results. Hfe-/- RPE cells exhibited slower senescence rate and higher survivin expression than wild type cells. Hfe-/- cells migrated faster and showed greater glucose uptake and increased expression of GLUTs. The expression of HDACs and DNA methyltransferase (DNMTs) also was increased. Similarly, RPE cells from hemojuvelin (Hjv)-knockout mice, another model of hemochromatosis, also had increased expression of GLUTs, HDACs, and DNMTs. The expression of Slc5a8 was decreased in Hfe-/- RPE cells, but treatment with a DNA methylation inhibitor restored the transporter expression, indicating involvement of DNA methylation in the silencing of Slc5a8 in Hfe-/- cells. Conclusions. RPE cells from iron-overloaded mice exhibit several features of tumor cells: decreased senescence, enhanced migration, increased glucose uptake, and elevated levels of HDACs and DNMTs. These features are seen in Hfe-/- RPE cells as well as in Hjv-/- RPE cells, providing a molecular basis for the hyperproliferative phenotype of Hfe-/- and Hjv-/- RPE cells.",
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T1 - Loss of Hfe leads to progression of tumor phenotype in primary retinal pigment epithelial cells

AU - Gnana-Prakasam, Jaya Pranava

AU - Veeranan-Karmegam, Rajalakshmi

AU - Coothankandaswamy, Veena

AU - Reddy, Sushma K.

AU - Martin, Pamela Moore

AU - Thangaraju, Muthusamy

AU - Smith, Sylvia B

AU - Ganapathy, Vadivel

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N2 - Purpose. Hemochromatosis is a disorder of iron overload arising mostly from mutations in HFE. HFE is expressed in retinal pigment epithelium (RPE), and Hfe-/- mice develop age-related iron accumulation and retinal degeneration associated with RPE hyperproliferation. Here, the mechanism underlying the hyperproliferative phenotype in RPE was inves tigated. Methods. Cellular senescence was monitored by β-galactosidase activity. Gene expression was monitored by real-time PCR. Survivin was analyzed by Western blot and immunofluorescence. Migration and invasion were monitored using appropriate kits. Glucose transporters (GLUTs) were monitored by 3-O-methyl-D-glucose uptake. Histone deacetylases (HDACs) were studied by monitoring catalytic activity and acetylation status of histones H3/H4. Results. Hfe-/- RPE cells exhibited slower senescence rate and higher survivin expression than wild type cells. Hfe-/- cells migrated faster and showed greater glucose uptake and increased expression of GLUTs. The expression of HDACs and DNA methyltransferase (DNMTs) also was increased. Similarly, RPE cells from hemojuvelin (Hjv)-knockout mice, another model of hemochromatosis, also had increased expression of GLUTs, HDACs, and DNMTs. The expression of Slc5a8 was decreased in Hfe-/- RPE cells, but treatment with a DNA methylation inhibitor restored the transporter expression, indicating involvement of DNA methylation in the silencing of Slc5a8 in Hfe-/- cells. Conclusions. RPE cells from iron-overloaded mice exhibit several features of tumor cells: decreased senescence, enhanced migration, increased glucose uptake, and elevated levels of HDACs and DNMTs. These features are seen in Hfe-/- RPE cells as well as in Hjv-/- RPE cells, providing a molecular basis for the hyperproliferative phenotype of Hfe-/- and Hjv-/- RPE cells.

AB - Purpose. Hemochromatosis is a disorder of iron overload arising mostly from mutations in HFE. HFE is expressed in retinal pigment epithelium (RPE), and Hfe-/- mice develop age-related iron accumulation and retinal degeneration associated with RPE hyperproliferation. Here, the mechanism underlying the hyperproliferative phenotype in RPE was inves tigated. Methods. Cellular senescence was monitored by β-galactosidase activity. Gene expression was monitored by real-time PCR. Survivin was analyzed by Western blot and immunofluorescence. Migration and invasion were monitored using appropriate kits. Glucose transporters (GLUTs) were monitored by 3-O-methyl-D-glucose uptake. Histone deacetylases (HDACs) were studied by monitoring catalytic activity and acetylation status of histones H3/H4. Results. Hfe-/- RPE cells exhibited slower senescence rate and higher survivin expression than wild type cells. Hfe-/- cells migrated faster and showed greater glucose uptake and increased expression of GLUTs. The expression of HDACs and DNA methyltransferase (DNMTs) also was increased. Similarly, RPE cells from hemojuvelin (Hjv)-knockout mice, another model of hemochromatosis, also had increased expression of GLUTs, HDACs, and DNMTs. The expression of Slc5a8 was decreased in Hfe-/- RPE cells, but treatment with a DNA methylation inhibitor restored the transporter expression, indicating involvement of DNA methylation in the silencing of Slc5a8 in Hfe-/- cells. Conclusions. RPE cells from iron-overloaded mice exhibit several features of tumor cells: decreased senescence, enhanced migration, increased glucose uptake, and elevated levels of HDACs and DNMTs. These features are seen in Hfe-/- RPE cells as well as in Hjv-/- RPE cells, providing a molecular basis for the hyperproliferative phenotype of Hfe-/- and Hjv-/- RPE cells.

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