Endoplasmic reticulum/plasma membrane (ER/PM) junctions are best understood in muscle and immune cells where they mediate contraction and lymphocyte activation. Despite the early electron microscopic detection of sub-surface cisterns in neurons the function and molecular interactions responsible for the maintenance of this membrane junction are poorly understood. Our preliminary data demonstrate that the Kv2.1 delayed rectifier K+ channel plays a central role in the formation of neuronal ER/PM junctions. This channel forms highly stable cell surface clusters on the neuronal soma that reside in close apposition the ER membrane. Most of these localized channels are non-conducting and play a direct structural role by enhancing the ER/PM junctions and dramatically increasing the junction surface area, likely by binding unknown ER membrane proteins. Our published data indicate that the Kv2.1 enhanced ER/PM junctions are trafficking hubs, providing platforms for delivery and retrieval for multiple types of membrane proteins. In addition, our preliminary data indicate that calcium signaling proteins localize to the neuronal Kv2.1/ER/PM junction. We propose the Kv2.1-stabilized ER/PM junctions represent a macromolecular plasma membrane complex that functions as a scaffolding site for both membrane trafficking and Ca2+ signaling. Given that this complex is regulated by stroke-related neuronal insults, an improved understanding of the components, function and dynamics within this cell surface microdomain is needed. This proposal assembles an interdisciplinary team from four institutions with combined expertise in intracellular Ca2+ dynamics, ion channel electrophysiology, molecular and cell biology, nanoSIMS cellular imaging technology, high-resolution real time imaging, optics, and quantitative analysis of single molecule diffusion.
Aim 1 seeks to identify the proteins and lipids involved in the Kv2.1/ER/PM complex, Aim 2 examines L-type calcium channel function at the Kv2.1/ER/PM junction and Aim 3 studies calcium channel/beta2 adrenergic receptor dynamics within this domain.

Public Health Relevance

The proposed research studies the structure and function of a newly discovered neuronal organelle that is damaged following ischemic stroke. Completion of the proposed research will lead to new strategies for the treatment of stroke. EDITOR'S COMMENTS

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
1R01GM109888-01
Application #
8668504
Study Section
Special Emphasis Panel (ZGM1)
Program Officer
Nie, Zhongzhen
Project Start
Project End
Budget Start
Budget End
Support Year
1
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Colorado State University-Fort Collins
Department
Veterinary Sciences
Type
Schools of Veterinary Medicine
DUNS #
City
Fort Collins
State
CO
Country
United States
Zip Code
80521