Effect of G protein-coupled receptor kinase 1 (Grk1) overexpression on rod photoreceptor cell viability

Tiffany Whitcomb, Keisuke Sakurai, Bruce M. Brown, Joyce E. Young, Lowell Sheflin, Cynthia Dlugos, Cheryl M. Craft, Vladimir J. Kefalov, Shahrokh C. Khani

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Purpose. Photoreceptor rhodopsin kinase (Rk, G protein-dependent receptor kinase 1 [Grk1]) phosphorylates light-activated opsins and channels them into an inactive complex with visual arrestins. Grk1 deficiency leads to human retinopathy and heightened susceptibility to light-induced photoreceptor cell death in the mouse. The goal of this study was to determine whether excess Grk1 activity is protective against photoreceptor cell death. Methods. Grk1-overexpressing transgenic mice (Grk1+) were generated by using a bacterial artificial chromosome (BAC) construct containing mouse Grk1, along with its flanking sequences. Quantitative reverse transcription-PCR, immunoblot analysis, immunostaining, and activity assays were combined with electrophysiology and morphometric analysis, to evaluate Grk1 overexpression and its effect on physiologic and morphologic retinal integrity. Morphometry and nucleosome release assays measured differences in resistance to photoreceptor cell loss between control and transgenic mice exposed to intense light. Results. Compared with control animals, the Grk1+ transgenic line had approximately a threefold increase in Grk1 transcript and immunoreactive protein. Phosphorylated opsin immunochemical staining and in vitro phosphorylation assays confirmed proportionately higher Grk1 enzyme activity. Grk1+ mice retained normal rod function, normal retinal appearance, and lacked evidence of spontaneous apoptosis when reared in cyclic light. In intense light, Grk1+ mice showed photoreceptor damage, and their susceptibility was more pronounced than that of control mice with prolonged exposure times. Conclusions. Enhancing visual pigment deactivation does not appear to protect against apoptosis; however, excess flow of opsin into the deactivation pathway may actually increase susceptibility to stress-induced cell death similar to some forms of retinal degeneration.

Original languageEnglish (US)
Pages (from-to)1728-1737
Number of pages10
JournalInvestigative Ophthalmology and Visual Science
Volume51
Issue number3
DOIs
StatePublished - Mar 1 2010

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G-Protein-Coupled Receptor Kinase 1
Retinal Rod Photoreceptor Cells
Cell Survival
Opsins
Photoreceptor Cells
Light
Cell Death
Transgenic Mice
Arrestins
Apoptosis
Bacterial Artificial Chromosomes
Retinal Degeneration
Retinal Pigments
Nucleosomes
Electrophysiology
GTP-Binding Proteins
Reverse Transcription
Phosphotransferases
Phosphorylation
Staining and Labeling

All Science Journal Classification (ASJC) codes

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this

Whitcomb, Tiffany ; Sakurai, Keisuke ; Brown, Bruce M. ; Young, Joyce E. ; Sheflin, Lowell ; Dlugos, Cynthia ; Craft, Cheryl M. ; Kefalov, Vladimir J. ; Khani, Shahrokh C. / Effect of G protein-coupled receptor kinase 1 (Grk1) overexpression on rod photoreceptor cell viability. In: Investigative Ophthalmology and Visual Science. 2010 ; Vol. 51, No. 3. pp. 1728-1737.
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abstract = "Purpose. Photoreceptor rhodopsin kinase (Rk, G protein-dependent receptor kinase 1 [Grk1]) phosphorylates light-activated opsins and channels them into an inactive complex with visual arrestins. Grk1 deficiency leads to human retinopathy and heightened susceptibility to light-induced photoreceptor cell death in the mouse. The goal of this study was to determine whether excess Grk1 activity is protective against photoreceptor cell death. Methods. Grk1-overexpressing transgenic mice (Grk1+) were generated by using a bacterial artificial chromosome (BAC) construct containing mouse Grk1, along with its flanking sequences. Quantitative reverse transcription-PCR, immunoblot analysis, immunostaining, and activity assays were combined with electrophysiology and morphometric analysis, to evaluate Grk1 overexpression and its effect on physiologic and morphologic retinal integrity. Morphometry and nucleosome release assays measured differences in resistance to photoreceptor cell loss between control and transgenic mice exposed to intense light. Results. Compared with control animals, the Grk1+ transgenic line had approximately a threefold increase in Grk1 transcript and immunoreactive protein. Phosphorylated opsin immunochemical staining and in vitro phosphorylation assays confirmed proportionately higher Grk1 enzyme activity. Grk1+ mice retained normal rod function, normal retinal appearance, and lacked evidence of spontaneous apoptosis when reared in cyclic light. In intense light, Grk1+ mice showed photoreceptor damage, and their susceptibility was more pronounced than that of control mice with prolonged exposure times. Conclusions. Enhancing visual pigment deactivation does not appear to protect against apoptosis; however, excess flow of opsin into the deactivation pathway may actually increase susceptibility to stress-induced cell death similar to some forms of retinal degeneration.",
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Whitcomb, T, Sakurai, K, Brown, BM, Young, JE, Sheflin, L, Dlugos, C, Craft, CM, Kefalov, VJ & Khani, SC 2010, 'Effect of G protein-coupled receptor kinase 1 (Grk1) overexpression on rod photoreceptor cell viability', Investigative Ophthalmology and Visual Science, vol. 51, no. 3, pp. 1728-1737. https://doi.org/10.1167/iovs.09-4499

Effect of G protein-coupled receptor kinase 1 (Grk1) overexpression on rod photoreceptor cell viability. / Whitcomb, Tiffany; Sakurai, Keisuke; Brown, Bruce M.; Young, Joyce E.; Sheflin, Lowell; Dlugos, Cynthia; Craft, Cheryl M.; Kefalov, Vladimir J.; Khani, Shahrokh C.

In: Investigative Ophthalmology and Visual Science, Vol. 51, No. 3, 01.03.2010, p. 1728-1737.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effect of G protein-coupled receptor kinase 1 (Grk1) overexpression on rod photoreceptor cell viability

AU - Whitcomb, Tiffany

AU - Sakurai, Keisuke

AU - Brown, Bruce M.

AU - Young, Joyce E.

AU - Sheflin, Lowell

AU - Dlugos, Cynthia

AU - Craft, Cheryl M.

AU - Kefalov, Vladimir J.

AU - Khani, Shahrokh C.

PY - 2010/3/1

Y1 - 2010/3/1

N2 - Purpose. Photoreceptor rhodopsin kinase (Rk, G protein-dependent receptor kinase 1 [Grk1]) phosphorylates light-activated opsins and channels them into an inactive complex with visual arrestins. Grk1 deficiency leads to human retinopathy and heightened susceptibility to light-induced photoreceptor cell death in the mouse. The goal of this study was to determine whether excess Grk1 activity is protective against photoreceptor cell death. Methods. Grk1-overexpressing transgenic mice (Grk1+) were generated by using a bacterial artificial chromosome (BAC) construct containing mouse Grk1, along with its flanking sequences. Quantitative reverse transcription-PCR, immunoblot analysis, immunostaining, and activity assays were combined with electrophysiology and morphometric analysis, to evaluate Grk1 overexpression and its effect on physiologic and morphologic retinal integrity. Morphometry and nucleosome release assays measured differences in resistance to photoreceptor cell loss between control and transgenic mice exposed to intense light. Results. Compared with control animals, the Grk1+ transgenic line had approximately a threefold increase in Grk1 transcript and immunoreactive protein. Phosphorylated opsin immunochemical staining and in vitro phosphorylation assays confirmed proportionately higher Grk1 enzyme activity. Grk1+ mice retained normal rod function, normal retinal appearance, and lacked evidence of spontaneous apoptosis when reared in cyclic light. In intense light, Grk1+ mice showed photoreceptor damage, and their susceptibility was more pronounced than that of control mice with prolonged exposure times. Conclusions. Enhancing visual pigment deactivation does not appear to protect against apoptosis; however, excess flow of opsin into the deactivation pathway may actually increase susceptibility to stress-induced cell death similar to some forms of retinal degeneration.

AB - Purpose. Photoreceptor rhodopsin kinase (Rk, G protein-dependent receptor kinase 1 [Grk1]) phosphorylates light-activated opsins and channels them into an inactive complex with visual arrestins. Grk1 deficiency leads to human retinopathy and heightened susceptibility to light-induced photoreceptor cell death in the mouse. The goal of this study was to determine whether excess Grk1 activity is protective against photoreceptor cell death. Methods. Grk1-overexpressing transgenic mice (Grk1+) were generated by using a bacterial artificial chromosome (BAC) construct containing mouse Grk1, along with its flanking sequences. Quantitative reverse transcription-PCR, immunoblot analysis, immunostaining, and activity assays were combined with electrophysiology and morphometric analysis, to evaluate Grk1 overexpression and its effect on physiologic and morphologic retinal integrity. Morphometry and nucleosome release assays measured differences in resistance to photoreceptor cell loss between control and transgenic mice exposed to intense light. Results. Compared with control animals, the Grk1+ transgenic line had approximately a threefold increase in Grk1 transcript and immunoreactive protein. Phosphorylated opsin immunochemical staining and in vitro phosphorylation assays confirmed proportionately higher Grk1 enzyme activity. Grk1+ mice retained normal rod function, normal retinal appearance, and lacked evidence of spontaneous apoptosis when reared in cyclic light. In intense light, Grk1+ mice showed photoreceptor damage, and their susceptibility was more pronounced than that of control mice with prolonged exposure times. Conclusions. Enhancing visual pigment deactivation does not appear to protect against apoptosis; however, excess flow of opsin into the deactivation pathway may actually increase susceptibility to stress-induced cell death similar to some forms of retinal degeneration.

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