# Mechanical and Transcriptional Roles for Primary Cilia during Heart Development

> **NIH NIH F31** · YALE UNIVERSITY · 2023 · $24,901

## Abstract

Abstract: Congenital heart defects (CHD) are the most common birth defects, affecting 1% of all live births. Of
the known genetic contributors to CHD, the pathogenic mechanism is undetermined for most. Our lab has
identified de novo mutations in kruppel-like factors 2 and 4 (KLF2, 4) in CHD patients presenting with
hypoplastic left heart syndrome (HLHS). Klf2 and 4 are mechanosensitive transcription factors that regulate
endothelial to mesenchymal transition (EndoMT), a process necessary for cushion (heart valve progenitor)
development. Understanding how EndoMT is spatially and temporally controlled by mechanical modulation of
Klf2/4 will provide insights into the heart valve defects present in HLHS patients. Our lab has implicated
primary cilia (non-motile, rod-like mechanosensors) on the endocardium (EC) in cardiogenesis beyond their
known role in left-right asymmetry. However, whether EC primary cilia transduce mechanical signals into
regulation of Klf2/4 during cushion development has yet to be shown. The goal of this proposal is to discover
the relationship between mechanical forces, EC primary cilia and Klf2/4 during heart cushion formation in vivo.
Based on my preliminary results, the overall hypothesis of this proposal is that EC primary cilia link
mechanical forces and Klf2/4 transcription in a Ca2+ and cytoskeletal-dependent manner during
endocardial cushion formation in vivo. To address this hypothesis, we will utilize both mouse and zebrafish
models. Mouse hearts are more comparable to humans (zebrafish have two chambers), but the genetic
programs governing cardiogenesis are conserved. Events that may be lost in static mouse samples can
instead be observed using live zebrafish in time-lapse microscopy due to their optical clarity and external
development. Aim 1 will investigate how EC primary cilia and Klf2/4 expression change spatially over heart
cushion development, utilizing in situ hybridization and immunofluorescence in mice, and various transgenic
lines marking endocardium, cilia, and the promoter regions of Klf2/4 in live zebrafish. Aim 2 will test whether
Klf2/4 depend on cilia, ciliary Ca2+ and/or mechanical forces through use of various mutant backgrounds, such
as Ift20 and Kif3a (cilia KOs), Ncx/silent heart morpholino (heartbeat KO, mouse and zebrafish, respectively),
and Pkd2 (ciliary Ca2+ KO). Our data provides insight into the mechanism controlling Klf2/4 mechanosensitivity
during heart cushion formation, and highlight a ciliary role as mechanosensors during cardiogenesis. This
proposal addresses the NIH-NHLBI's objectives 1 and 2 in regards to investigating the genetic and mechanical
mechanism behind the valve defects present in many CHD patients. Our findings could also lead to treatments
to ameliorate the progressive valve dysfunction experienced by many CHD patients. My use of live, whole-
mount imaging will extend beyond the observations possible in static, fixed embryos and bring a rare
perspective of ciliary-depe...

## Key facts

- **NIH application ID:** 10677718
- **Project number:** 5F31HL158091-03
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** Kathryn Berg
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $24,901
- **Award type:** 5
- **Project period:** 2021-09-01 → 2024-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10677718

## Citation

> US National Institutes of Health, RePORTER application 10677718, Mechanical and Transcriptional Roles for Primary Cilia during Heart Development (5F31HL158091-03). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10677718. Licensed CC0.

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