# Elucidating the Mechanisms Behind Basement Membrane Stretching

> **NIH NIH F31** · DUKE UNIVERSITY · 2022 · $11,590

## Abstract

Abstract
Basement membranes (BMs) are dense extracellular matrices that surround and structurally support tissues. A
primary component of BMs is type IV collagen, which forms a cross-linked network that protects BMs and tissues
from mechanical stress. Although the key role of type IV collagen in structural support is established, how this
network accommodates BM stretching in mechanically active tissues is unknown. BM stretching is critically
important in the cardiovascular system, where vessels must expand and contract to accommodate pulsatile
forces from the blood. Consistent with this important role, disruptions in the type IV collagen network can lead to
vascular diseases such as vascular thickening in diabetes, cerebral microbleeds, and hemorrhagic stroke.
Despite its significance, our understanding of BM stretching has been limited by a lack of in vivo models to study
how BMs dynamically expand. To fill this need, I have established the gonadal BM of the visually and genetically
tractable model organism C. elegans as a new in vivo model for BM stretching. I discovered that the region of
the gonadal BM specialized for fertilization/ovulation, the spermathecal BM, is stretched dramatically (~2-fold)
during ovulation. Using atomic force microscopy (AFM), I found that there is a stiffness gradient within the gonad
with the spermatheca being the least stiff. Furthermore, 20 BM components have been tagged with mNeonGreen
or mRuby using CRISPR/Cas-9, making C. elegans the only animal where all major BM components are
endogenously tagged. Using these strains, I found: (1) Increased levels of type IV collagen limit stretching during
ovulation; (2) there are high levels of peroxidasin-1, a protein that negatively regulates type IV collagen cross-
linking, in the spermathecal BM; and (3) fibulin, a BM protein thought to maintain type IV collagen, is enriched in
the spermatheca. My overall hypothesis is that levels and cross-linking of type IV collagen are precisely
regulated to allow the collagen network to maintain BM/tissue integrity while enabling BM/tissue
stretching. In Aim 1, I will use genetic analysis, conditional knockdown, live imaging, and AFM to test the
hypothesis that type IV collagen levels play a crucial role in BM stretching (low levels promote decreased
stiffness, increased stretching and eventual rupture; high levels increase stiffness and restrict stretching) and
determine whether the effects of type IV collagen α1 and α2 human disease mutations in C. elegans are due to
altered levels or location in unique domains associated with BM stretching. Aim 2 will test the hypothesis that
low type IV collagen cross-linking, mediated by peroxidasins, promotes BM stretching by reducing BM stiffness
and that fibulin maintains type IV collagen levels in this dynamic environment. In Aim 3, I will determine if
additional components regulate BM stretching by conducting a bioinformatics-driven RNAi screen to identify
vascular disease associated gen...

## Key facts

- **NIH application ID:** 10516008
- **Project number:** 5F31HL156438-02
- **Recipient organization:** DUKE UNIVERSITY
- **Principal Investigator:** Claire Gianakas
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $11,590
- **Award type:** 5
- **Project period:** 2021-07-01 → 2022-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10516008

## Citation

> US National Institutes of Health, RePORTER application 10516008, Elucidating the Mechanisms Behind Basement Membrane Stretching (5F31HL156438-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10516008. Licensed CC0.

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