# Structural Basis of Peripheral Coupling Sites Regulating Arterial Smooth Muscle Contractility (A1)

> **NIH NIH R01** · UNIVERSITY OF NEVADA RENO · 2020 · $530,202

## Abstract

The contractility of vascular smooth muscle cells (SMC) encircling arteries and arterioles is critical for blood
flow regulation. Localized Ca2+ signaling modalities, typified by Ca2+ sparks generated by release of Ca2+ from
the sarcoplasmic reticulum (SR) that are functionally coupled with Ca2+-dependent ion channels on the plasma
membrane (PM) have significant influence on SMC contractility. Although these indispensable pathways are
reliant on tight spatial alignment of the SR with the PM, little is currently known about the structural
organization of these membranes in contractile SMC. Thus, the major objective of the research proposed here
is to elucidate the molecular architecture and functional significance of peripheral coupling sites maintaining
close (≤20 nm) interactions between the PM and SR in native SMCs from mouse and human resistance
arteries. We will test the original mechanistic hypothesis that junctophilin-2 (JPH2), a protein essential for dyad
formation and excitation-contraction coupling in cardiac muscle, and stromal interaction molecule 1 (STIM1),
traditionally viewed only as a sensor of Ca2+ store depletion, orchestrate the formation of these sites in native
SMCs. We further propose, supported by our unpublished preliminary data, that these structures are critically
important for defining the spatial and temporal properties of subcellular Ca2+ signals regulating ion channel
activity, membrane potential, and contractility of SMCs and intact arteries. The goal of Aim 1 is to elucidate the
molecular architecture of peripheral coupling sites in arterial myocytes. Proposed studies will use a
combination of GSDIM super-resolution and live-cell confocal microscopy to test the hypothesis that JPH2 and
STIM1 are critically important for SR-PM juxtaposition and the formation of Ca2+ signaling complexes in SMC.
The goal of Aim 2 is to elucidate the role of JPH2 and STIM1 in establishing Ca2+ signaling microdomains that
regulate Ca2+-activated ion channel activity in arterial myocytes. These studies will use next-generation SMC-
specific acta-2–GCaMP5-mCherry Ca2+ biosensor mice, high-speed confocal and TIRFM Ca2+ imaging, and
patch-clamp electrophysiology to determine the impact SR-PM interactions maintained by JPH2 and STIM1 on
localized Ca2+ signaling and ion channel activity in SMC. Aim 3 will determine the importance of JPH2 and
STIM1 in the regulation of arterial contractility. Proposed studies will examine the physiological significance of
peripheral coupling sites maintained by JPH2 and STIM1 in loss-of-function experiments investigating
fundamental vasomotor responses of intact resistance arteries from mice and human donors. Elucidation of
the structure/function relationships of SR-PM complexes in vascular SMC is likely to be highly significant, and
will undoubtly shed new insights into vascular function in health and disease, as has been done for cardiac and
skeletal muscle. Further, using selective genetic and pharmacologica...

## Key facts

- **NIH application ID:** 9855070
- **Project number:** 5R01HL137852-03
- **Recipient organization:** UNIVERSITY OF NEVADA RENO
- **Principal Investigator:** Scott Earley
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $530,202
- **Award type:** 5
- **Project period:** 2018-02-01 → 2021-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9855070

## Citation

> US National Institutes of Health, RePORTER application 9855070, Structural Basis of Peripheral Coupling Sites Regulating Arterial Smooth Muscle Contractility (A1) (5R01HL137852-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9855070. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*