Expression and iron-dependent regulation of succinate receptor GPR91 in retinal pigment epithelium

Jaya Pranava Gnana-Prakasam, Sudha Ananth, Puttur D Prasad, Ming Zhang, Sally S. Atherton, Pamela Moore Martin, Sylvia B Smith, Vadivel Ganapathy

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Purpose. GPR91, a succinate receptor, is expressed in retinal ganglion cells and induces vascular endothelial growth factor (VEGF) expression. RPE also expresses VEGF, but whether this cell expresses GPR91 is not known. Excessive iron is also proangiogenic, and hemochromatosis is associated with iron overload. Therefore, we examined the expression and iron-dependent regulation of GPR91 in the RPE. Methods. GPR91 expression was examined by RT-PCR and immunohistochemistry. Hemochromatosis mice, cytomegalovirus (CMV) infection of retina, expression of CMV-US2 in RPE, and exposure of RPE to ferric ammonium citrate (FAC) were used to examine the iron-dependent regulation of GPR91 expression. VEGF expression was quantified by qPCR. Knockdown of GPR91 in ARPE-19 cells was achieved with shRNA. Results. GPR91 was expressed in RPE but only in the apical membrane. Retinal expression of GPR91 was higher in hemochromatosis (Hfe -/-) mice than in wild-type (WT) mice. Primary RPE cells from Hfe -/- mice had increased GPR91 expression compared with WT RPE cells. Iron accumulation in cells induced by CMV infection, expression of CMV-US2, or treatment with FAC increased GPR91 expression. VEGF expression in the Hfe -/- mouse retina was increased at ages younger than18 months, but the expression was downregulated at older ages. The involvement of GPR91 in succinate-induced expression of VEGF in RPE cells was confirmed with GPR91-specific shRNA. Conclusions. GPR91 is expressed in the RPE with specific localization to the apical membrane, indicating that succinate in the subretinal space serves as the GPR91 agonist. Excessive iron in the retina and RPE enhances GPR91 expression; however, VEGF expression does not always parallel GPR91 expression.

Original languageEnglish (US)
Pages (from-to)3751-3758
Number of pages8
JournalInvestigative Ophthalmology and Visual Science
Volume52
Issue number6
DOIs
StatePublished - May 1 2011

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Retinal Pigment Epithelium
Succinic Acid
Vascular Endothelial Growth Factor A
Iron
Hemochromatosis
Retina
Cytomegalovirus Infections
Cytomegalovirus
Small Interfering RNA
Muromegalovirus
Iron Overload
Membranes
Retinal Ganglion Cells
Down-Regulation
Immunohistochemistry
Polymerase Chain Reaction

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience
  • Medicine(all)

Cite this

Expression and iron-dependent regulation of succinate receptor GPR91 in retinal pigment epithelium. / Gnana-Prakasam, Jaya Pranava; Ananth, Sudha; Prasad, Puttur D; Zhang, Ming; Atherton, Sally S.; Martin, Pamela Moore; Smith, Sylvia B; Ganapathy, Vadivel.

In: Investigative Ophthalmology and Visual Science, Vol. 52, No. 6, 01.05.2011, p. 3751-3758.

Research output: Contribution to journalArticle

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abstract = "Purpose. GPR91, a succinate receptor, is expressed in retinal ganglion cells and induces vascular endothelial growth factor (VEGF) expression. RPE also expresses VEGF, but whether this cell expresses GPR91 is not known. Excessive iron is also proangiogenic, and hemochromatosis is associated with iron overload. Therefore, we examined the expression and iron-dependent regulation of GPR91 in the RPE. Methods. GPR91 expression was examined by RT-PCR and immunohistochemistry. Hemochromatosis mice, cytomegalovirus (CMV) infection of retina, expression of CMV-US2 in RPE, and exposure of RPE to ferric ammonium citrate (FAC) were used to examine the iron-dependent regulation of GPR91 expression. VEGF expression was quantified by qPCR. Knockdown of GPR91 in ARPE-19 cells was achieved with shRNA. Results. GPR91 was expressed in RPE but only in the apical membrane. Retinal expression of GPR91 was higher in hemochromatosis (Hfe -/-) mice than in wild-type (WT) mice. Primary RPE cells from Hfe -/- mice had increased GPR91 expression compared with WT RPE cells. Iron accumulation in cells induced by CMV infection, expression of CMV-US2, or treatment with FAC increased GPR91 expression. VEGF expression in the Hfe -/- mouse retina was increased at ages younger than18 months, but the expression was downregulated at older ages. The involvement of GPR91 in succinate-induced expression of VEGF in RPE cells was confirmed with GPR91-specific shRNA. Conclusions. GPR91 is expressed in the RPE with specific localization to the apical membrane, indicating that succinate in the subretinal space serves as the GPR91 agonist. Excessive iron in the retina and RPE enhances GPR91 expression; however, VEGF expression does not always parallel GPR91 expression.",
author = "Gnana-Prakasam, {Jaya Pranava} and Sudha Ananth and Prasad, {Puttur D} and Ming Zhang and Atherton, {Sally S.} and Martin, {Pamela Moore} and Smith, {Sylvia B} and Vadivel Ganapathy",
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T1 - Expression and iron-dependent regulation of succinate receptor GPR91 in retinal pigment epithelium

AU - Gnana-Prakasam, Jaya Pranava

AU - Ananth, Sudha

AU - Prasad, Puttur D

AU - Zhang, Ming

AU - Atherton, Sally S.

AU - Martin, Pamela Moore

AU - Smith, Sylvia B

AU - Ganapathy, Vadivel

PY - 2011/5/1

Y1 - 2011/5/1

N2 - Purpose. GPR91, a succinate receptor, is expressed in retinal ganglion cells and induces vascular endothelial growth factor (VEGF) expression. RPE also expresses VEGF, but whether this cell expresses GPR91 is not known. Excessive iron is also proangiogenic, and hemochromatosis is associated with iron overload. Therefore, we examined the expression and iron-dependent regulation of GPR91 in the RPE. Methods. GPR91 expression was examined by RT-PCR and immunohistochemistry. Hemochromatosis mice, cytomegalovirus (CMV) infection of retina, expression of CMV-US2 in RPE, and exposure of RPE to ferric ammonium citrate (FAC) were used to examine the iron-dependent regulation of GPR91 expression. VEGF expression was quantified by qPCR. Knockdown of GPR91 in ARPE-19 cells was achieved with shRNA. Results. GPR91 was expressed in RPE but only in the apical membrane. Retinal expression of GPR91 was higher in hemochromatosis (Hfe -/-) mice than in wild-type (WT) mice. Primary RPE cells from Hfe -/- mice had increased GPR91 expression compared with WT RPE cells. Iron accumulation in cells induced by CMV infection, expression of CMV-US2, or treatment with FAC increased GPR91 expression. VEGF expression in the Hfe -/- mouse retina was increased at ages younger than18 months, but the expression was downregulated at older ages. The involvement of GPR91 in succinate-induced expression of VEGF in RPE cells was confirmed with GPR91-specific shRNA. Conclusions. GPR91 is expressed in the RPE with specific localization to the apical membrane, indicating that succinate in the subretinal space serves as the GPR91 agonist. Excessive iron in the retina and RPE enhances GPR91 expression; however, VEGF expression does not always parallel GPR91 expression.

AB - Purpose. GPR91, a succinate receptor, is expressed in retinal ganglion cells and induces vascular endothelial growth factor (VEGF) expression. RPE also expresses VEGF, but whether this cell expresses GPR91 is not known. Excessive iron is also proangiogenic, and hemochromatosis is associated with iron overload. Therefore, we examined the expression and iron-dependent regulation of GPR91 in the RPE. Methods. GPR91 expression was examined by RT-PCR and immunohistochemistry. Hemochromatosis mice, cytomegalovirus (CMV) infection of retina, expression of CMV-US2 in RPE, and exposure of RPE to ferric ammonium citrate (FAC) were used to examine the iron-dependent regulation of GPR91 expression. VEGF expression was quantified by qPCR. Knockdown of GPR91 in ARPE-19 cells was achieved with shRNA. Results. GPR91 was expressed in RPE but only in the apical membrane. Retinal expression of GPR91 was higher in hemochromatosis (Hfe -/-) mice than in wild-type (WT) mice. Primary RPE cells from Hfe -/- mice had increased GPR91 expression compared with WT RPE cells. Iron accumulation in cells induced by CMV infection, expression of CMV-US2, or treatment with FAC increased GPR91 expression. VEGF expression in the Hfe -/- mouse retina was increased at ages younger than18 months, but the expression was downregulated at older ages. The involvement of GPR91 in succinate-induced expression of VEGF in RPE cells was confirmed with GPR91-specific shRNA. Conclusions. GPR91 is expressed in the RPE with specific localization to the apical membrane, indicating that succinate in the subretinal space serves as the GPR91 agonist. Excessive iron in the retina and RPE enhances GPR91 expression; however, VEGF expression does not always parallel GPR91 expression.

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