Neuronal junctophilins recruit specific CaV and RyR isoforms to ER-PM junctions and functionally alter CaV2.1 and CaV2.2

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Abstract

Despite their recognized physiological importance, the molecular architecture of ER-PM junctions induced by neuronal junctophilins (JPH3 and JPH4) is still poorly understood and challenging to address in neurons. This is due to the small size of the junctions and to the multiple isoforms of candidate junctional proteins in different brain areas. Using colocalization of tagged proteins expressed in tsA201 cells, and electrophysiology, we compared the interactions of JPH3 and JPH4 with different calcium channels. We found that JPH3 and JPH4 caused junctional accumulation of all the tested high-voltage-activated Ca_V isoforms, but not a low-voltage-activated Ca_V. Also, JPH3 and JPH4 noticeably modify Ca_V2.1 and Ca_V2.2 inactivation rate. RyR3 moderately colocalized at junctions with JPH4, whereas RyR1 and RyR2 did not. By contrast, RyR1 and RyR3 strongly colocalized with JPH3, and RyR2 moderately. Likely contributing to this difference, JPH3 binds to cytoplasmic domain constructs of RyR1 and RyR3, but not of RyR2.

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Raw data for peak current vs voltage, inactivation vs voltage, and Pearson's coefficients have been provided with the uploaded manuscript files.

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Stefano Perni

Physiology & Biophysics, University of Colorado Anschutz Medical Campus, Aurora, United States

Competing interests
No competing interests declared.

"This ORCID iD identifies the author of this article:" 0000-0002-0591-4376
Kurt Beam

Physiology & Biophysics, University of Colorado Anschutz Medical Campus, Aurora, United States

For correspondence
kurt.beam@cuanschutz.edu

Competing interests
Kurt Beam, Reviewing editor, eLife.

"This ORCID iD identifies the author of this article:" 0000-0001-6902-085X

Funding

NIH Office of the Director (R01 AR070298)

Kurt Beam

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.