The Stargazin-Related Protein {gamma}7 Interacts with the mRNA-Binding Protein Heterogeneous Nuclear Ribonucleoprotein A2 and Regulates the Stability of Specific mRNAs, Including CaV2.2
Abstract
The role(s) of the novel stargazin-like {gamma}-subunit proteins remain controversial. We have shown previously that the neuron-specific {gamma}7 suppresses the expression of certain calcium channels, particularly CaV2.2, and is therefore unlikely to operate as a calcium channel subunit. We now show that the effect of {gamma}7 on CaV2.2 expression is via an increase in the degradation rate of CaV2.2 mRNA and hence a reduction of CaV2.2 protein level. Furthermore, exogenous expression of {gamma}7 in PC12 cells also decreased the endogenous CaV2.2 mRNA level. Conversely, knockdown of endogenous {gamma}7 with short-hairpin RNAs produced a reciprocal enhancement of CaV2.2 mRNA stability and an increase in endogenous calcium currents in PC12 cells. Moreover, both endogenous and expressed {gamma}7 are present on intracellular membranes, rather than the plasma membrane. The cytoplasmic C terminus of {gamma}7 is essential for all its effects, and we show that {gamma}7 binds directly via its C terminus to a heterogeneous nuclear ribonucleoprotein (hnRNP A2), which also binds to a motif in CaV2.2 mRNA, and is associated with native CaV2.2 mRNA in PC12 cells. The expression of hnRNP A2 enhances CaV2.2 IBa, and this enhancement is prevented by a concentration of {gamma}7 that alone has no effect on IBa. The effect of {gamma}7 is selective for certain mRNAs because it had no effect on {alpha}2{delta}-2 mRNA stability, but it decreased the mRNA stability for the potassium-chloride cotransporter, KCC1, which contains a similar hnRNP A2 binding motif to that in CaV2.2 mRNA. Our results indicate that {gamma}7 plays a role in stabilizing CaV2.2 mRNA.
Additional Information
© 2008 Society for Neuroscience. This article is freely available online through the J Neurosci Open Choice option. Received June 13, 2008; revised Aug. 22, 2008; accepted Sept. 2, 2008. This work was supported by the Wellcome Trust, the Biotechnology and Biological Sciences Research Council (BBSRC), and the Medical Research Council for support. L.F. held a fellowship from Fondation pour la Recherche Medicale, and J.L. held a Wellcome Trust International fellowship. D.J.C. was supported by a BBSRC PhD studentship and D.W. by a British Heart Foundation PhD studentship. We are grateful to Dr. W. J. Frith for mathematical advice, Kanchan Chaggar for technical assistance, Dr. R. Nichols for the hnRNP A2 constructs, Dr. J. Caceres for hnRNPA1 cDNA, Dr. S. Alper for KCC1 cDNA, Dr. T. J. Shafer for PC12 cells, and Drs. A. Cahill and A. Fox for pG418–shRNA–Empty vector.Attached Files
Published - FERjns08.pdf
Supplemental Material - FERjns08fig1.pdf
Supplemental Material - FERjns08fig2.pdf
Supplemental Material - FERjns08fig3.pdf
Supplemental Material - FERjns08fig4.pdf
Supplemental Material - FERjns08fig5.pdf
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Additional details
- PMCID
- PMC2669593
- Eprint ID
- 12014
- Resolver ID
- CaltechAUTHORS:FERjns08
- Wellcome Trust
- Biotechnology and Biological Sciences Research Council (BBSRC)
- Medical Research Council (UK)
- Fondation pour la Recherche Médicale Française
- British Heart Foundation
- Created
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2008-10-20Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field