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Using siRNA to define functional interactions between melanopsin and multiple G Protein partners
Steven Hughes1, Aarti Jagannath, Doron Hickey
1Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, OX3 9DU, UK.
Cellular and Molecular Life Sciences : CMLS
|June 25, 2014
Summary
Melanopsin phototransduction involves multiple G protein subunits, including Gnaq, Gna11, and Gna14, in mouse retinal ganglion cells (pRGCs). This diversity contributes to pupillary light responses.
Area of Science:
- Ophthalmology
- Neuroscience
- Molecular Biology
Background:
- Photosensitive retinal ganglion cells (pRGCs) express melanopsin, a G protein-coupled receptor (GPCR) mediating non-image forming light responses.
- Melanopsin signaling is thought to involve Gnaq/11 type G proteins, but the specific Gα subunits are not fully identified.
Purpose of the Study:
- To identify the specific Gα subunits involved in melanopsin phototransduction in mouse pRGCs.
- To investigate the role of these G proteins in mediating pupillary light responses.
Main Methods:
- Quantitative co-expression analysis of Gnaq, Gna11, and Gna14 in mouse pRGCs.
- In vitro signaling assays using RNAi-mediated gene silencing to assess melanopsin activation.
- In vivo studies of pupillary light responses in genetically modified mice lacking rod and cone photoreceptors.
Main Results:
- Gnaq, Gna11, and Gna14 are highly co-expressed in mouse pRGCs.
- Melanopsin can signal through Gnaq, Gna11, or Gna14 in vitro.
- Multiple Gnaq/11 subfamily members, including Gna14 and Gnaq or Gna11, participate in in vivo melanopsin phototransduction and pupillary light responses in mice lacking other photoreceptors.
Conclusions:
- Melanopsin phototransduction utilizes a diverse set of Gα subunits from the Gnaq/11 subfamily.
- This G protein diversity contributes to the complexity of melanopsin signaling and light responses mediated by pRGCs.
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