# Endothelial Cell Cycle Responses to Fluid Shear Stress

> **NIH NIH F31** · UNIV OF NORTH CAROLINA CHAPEL HILL · 2022 · $37,818

## Abstract

Project Summary/Abstract
 Proper blood vessel network formation and remodeling during development, disease, and wound healing
depend on heterogeneous responses of endothelial cells (EC) to incoming signals, including physiological blood
flow. Once mature, most of our vasculature is understood to be in G0, a quiescent and arrested cell cycle state.
However, how quiescence is achieved and potentially regulated by flow is not well defined. Our preliminary data
suggests that both p27 and DYRK1a, cell cycle inhibitor proteins, are required for the reduction in cell proliferation
under flow. Cells that are treated with p27 or DYRK1a knockdown do not experience a decline in cell proliferation
under flow, suggesting that these cells are not entering a quiescent state. Bulk RNA-seq data completed in the
lab on cells under static or flow conditions also show an upregulation of p27 under flow, highlighting its
importance. However, it is likely that other cell cycle inhibitor proteins play a critical role in response to fluid shear
stress and we still do not understand if this looks the same across all endothelial cells or if responses are largely
heterogeneous. These results have important implications for disease, specifically in regard to atherosclerosis
and wound healing. We hypothesize that laminar shear stress induces EC homeostasis via changes in cell cycle
inhibitor protein activity. First, we will determine endothelial cell cycle responses to laminar flow in vitro by
manipulating p27 and members of the quiescence DREAM complex pathway (aim 1). To test this, we will utilize
2D and 3D microfluidic units with endothelial cell cycle inhibitor knockdown. One challenge about utilizing cell
cycle tools, such as antibodies or flow cytometry, is that it only allows a fixed snapshot of cell cycle profile. Given
that we want to understand how cell cycle phase is changing overtime, we will utilize PIP-FUCCI, a fluorescent
cell cycle reporter, that will allow us to determine how cell cycle phases change under flow prior to quiescence.
Next, we will determine in vivo if cell cycle inhibitor proteins are required for quiescence response using CRISPR
knockout and manipulation of flow in PIP-FUCCI zebrafish models (aim 2). The ability to perform live imaging on
transparent fish as well as manipulate flow by chemical inhibition of heart contraction make zebrafish an optimal
model organism. Successful completion of these experiments will provide insight on how flow regulates vessel
quiescence during physiological angiogenesis and will serve as groundwork towards an improved understanding
of atherosclerosis and wound healing.

## Key facts

- **NIH application ID:** 10543036
- **Project number:** 5F31HL156527-02
- **Recipient organization:** UNIV OF NORTH CAROLINA CHAPEL HILL
- **Principal Investigator:** Natalie Theresa Tanke
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $37,818
- **Award type:** 5
- **Project period:** 2021-05-01 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10543036

## Citation

> US National Institutes of Health, RePORTER application 10543036, Endothelial Cell Cycle Responses to Fluid Shear Stress (5F31HL156527-02). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10543036. Licensed CC0.

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