# Roles of Nebulin in Structure and Function of Striated Muscle

> **NIH NIH R01** · UNIVERSITY OF ARIZONA · 2022 · $499,735

## Abstract

Summary
This proposal focuses on the structure and function of nebulin, an unusually large sarcomeric protein that is
expressed in skeletal muscle. The giant size of nebulin has made it challenging to elucidate its functions but its
importance is supported by the many nebulin mutations that cause nemaline myopathy (NEM2), the most
common non-dystrophic congenital myopathy. The protein structure of nebulin consists of a large number of
simple repeats that are actin-binding, most of which are organized into super-repeats (SRs). Approaches to
treat NEM2 are sorely lacking and gaining an in-depth understanding of the many roles of nebulin in muscle
structure and function is essential. We will comprehensively study nebulin, building on major advances that we
and others have made in recent years. To help achieve our goals we utilize mouse models, some of which
mimic severe and others milder NEM2, as powerful tools for our basic science and translational studies. We
will investigate nebulin's functions from the single-molecule to the intact muscle levels, using multidisciplinary
approaches that involve transcriptomics, proteomics, super-resolution imaging, low-angle X-ray diffraction, and
biomechanics. Aim 1 focuses on thin filament length regulation. Our recent work supports that in slow muscle,
nebulin collaborates with leiomodin-2 (Lmod2), with nebulin regulating the length of a proximal thin filament
segment and Lmod2 regulating the length of a distal segment that is nebulin-free. Here we will critically test
this dual length regulation model and study whether it has translational potential, by determining whether
upregulating Lmod2 is an effective treatment for severe nebulin-based nemaline myopathy. Aim 2 studies the
functional significance of weak actin-binding of centrally-located nebulin SRs that bind actin more weakly than
those near the ends of the molecule. This is likely functionally important, considering that a mutation that
increases the binding affinity of a central SR causes a skeletal muscle myopathy in patients world-wide. We
will study mouse models in which centrally located weak-binding SRs have been converted into strong-binding
SRs using mechanical assays and X-ray diffraction on intact muscle. Aim 3 studies the C-terminus of nebulin,
its layout in the Z-disk, and the functions of nebulin's differentially expressed Z-repeats. Many NEM2 patients
have truncating mutations that result in the loss of most of the C-terminus (located within the Z disk), yet few
studies have investigated this region of the molecule. Nebulin's C-terminus contains Z-disk repeats that are
alternatively spliced (expressed at high levels in muscles with wide Z-disks). We will establish the layout of
nebulin in the Z-disk, the location of the Z-repeats, identify protein binding partners, and study the effects of
deleting differentially expressed nebulin Z-repeats on the Z-disk structure and function. Capitalizing on our
>15-year track record of innovative neb...

## Key facts

- **NIH application ID:** 10362940
- **Project number:** 2R01AR053897-16
- **Recipient organization:** UNIVERSITY OF ARIZONA
- **Principal Investigator:** Henk L. GRANZIER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $499,735
- **Award type:** 2
- **Project period:** 2022-08-01 → 2027-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10362940

## Citation

> US National Institutes of Health, RePORTER application 10362940, Roles of Nebulin in Structure and Function of Striated Muscle (2R01AR053897-16). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10362940. Licensed CC0.

---

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