Loss of nono impairs cardiac morphogenesis and excitation–contraction coupling via the PI3K/Akt pathway in zebrafish

Q: What are the key findings of this study?

Loss of the nono gene in zebrafish models severely impaired cardiac structural integrity and excitation-contraction coupling, which was mitigated by exogenous nono mRNA delivery.

Q: What is the clinical evidence from this study?

Population: NONO-associated congenital heart disease. Intervention: nono gene knockout and knockdown vs. Wild-type (WT) and control morpholino. Primary outcome: Cardiac structural integrity and electrophysiological homeostasis.

Q: What does this research mean for the field?

Loss of nono impairs cardiac morphogenesis, sarcomere integrity, and excitation–contraction coupling via suppression of the PI3K/Akt pathway in zebrafish, defects which can be mitigated by nono mRNA restoration. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

Qiuping Zhang; Chongyang Yan; 刘瀚旻; Haiyang Zhao; Kaipeng Sun; Xiaoyan Peng; Yuan Lin; Xinrui Wang; Yuqing Lei; Hua Cao

doi:10.1038/s41598-026-74730-x

October 12, 2026Scientific ReportsOpen Access

Loss of nono impairs cardiac morphogenesis and excitation–contraction coupling via the PI3K/Akt pathway in zebrafish

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Key result

nono loss impairs cardiac structure and excitation-contraction coupling in zebrafish, rescued by mRNA delivery.

Why the study?

Pathogenic variants in NONO are linked to congenital heart disease, but in vivo mechanisms and gene-targeted interventions remain poorly explored.

Key Points

To elucidate the in vivo functional requirement of nono in cardiac morphogenesis and electrophysiological homeostasis, and to evaluate gene-based rescue strategies.
Generated stable nono knockout zebrafish with a 4-bp deletion in exon 2 via CRISPR/Cas9 and transient knockdown models using morpholino silencing.
Evaluated myocardial morphology, sarcomere ultrastructure, and apoptosis in adult hearts at 12 weeks post-fertilization (n=3–15 per group) using histology, electron microscopy, and TUNEL assays.
Assessed electrophysiological conduction velocity, repolarization heterogeneity, and calcium transients using high-speed optical mapping, alongside larval rescue via nono mRNA injection.
Adult knockout hearts showed significant ventricular distortion, increased normalized vertical depth (VD/BL) and length (VL/BL) ratios (P<0.05 or P<0.01), extensive fibrosis, and elevated apoptotic nuclei (P<0.01).
Ultrastructural analysis revealed disorganized myofibrils, increased sarcomere length, reduced sarcomere alignment density, and increased cardiomyocyte area, width, and length (P<0.01).
Knockout larvae exhibited downregulated nkx2.5 and gata4 expression, suppressed PI3K/Akt signaling, and conduction failure, all of which were restored by exogenous nono mRNA delivery.

Structured PICO

P

Population

Zebrafish dual-model system (knockout and knockdown) evaluating the role of nono in cardiac morphogenesis and excitation-contraction coupling.

I

Intervention

nono gene knockout via CRISPR/Cas9, nono gene knockdown via splice-blocking morpholino oligonucleotide (0.8 ng/embryo), and exogenous nono mRNA delivery (rescue).

C

Comparator

Wild-type (WT) zebrafish (for knockout model) and standard control morpholino (for knockdown model).

O

Outcome

Cardiac structural integrity (ventricular dimensions, myocardial fibrosis, sarcomere organization) and electrophysiological homeostasis (conduction velocity, conduction dispersion, action potential and Ca2+ transient kinetics).surrogate

The nono gene is essential for cardiac structural integrity and electrophysiological homeostasis in vivo, offering a proof-of-concept for its role in NONO-associated congenital heart disease.

Implication

Nono loss impairs zebrafish cardiac integrity with mRNA rescue; extends genetic associations to functional mechanism but leaves open human translation.

Abstract

Pathogenic variants in NONO are clinically linked to congenital heart disease (CHD), but in vivo mechanisms and gene-targeted interventions remain poorly explored. Using CRISPR/Cas9 gene editing and morpholino silencing, we established knockout (KO) and knockdown (KD) zebrafish models to study nono in cardiogenesis. Adult KO hearts displayed severe structural remodeling, characterized by ventricular distortion, disorganized sarcomeres, and myocardial fibrosis. High-speed optical mapping and calcium imaging revealed reduced conduction velocity, increased dispersion, and spatial heterogeneity in action potential and Ca 2+ transients, disrupting excitation–contraction coupling. In larvae, nono deficiency downregulated core transcription factors ( nkx2.5, gata4 ), suppressed the PI3K/Akt pathway, and triggered myocardial apoptosis. Exogenous delivery of nono mRNA (Rescue) restored PI3K/Akt signaling, mitigating embryonic cardiovascular defects and functional failure. Collectively, our dual-model system demonstrates that NONO is required for structural integrity and electrophysiological homeostasis. This study provides vital in vivo functional validation of nono as a molecular target for myocardial dysfunction, offering a proof-of-concept for gene-based therapeutic restoration in NONO -associated CHD.

Discussion

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Cite This Study

Zhang et al. (2026) studied NONO-associated congenital heart disease. nono gene knockout and knockdown vs. Wild-type (WT) and control morpholino was evaluated on Cardiac structural integrity and electrophysiological homeostasis. Loss of the nono gene in zebrafish models severely impaired cardiac structural integrity and excitation-contraction coupling, which was mitigated by exogenous nono mRNA delivery.

synapsesocial.com/papers/6acfc9cda2edbaa26e9eee18 https://doi.org/10.1038/s41598-026-74730-x

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Loss of nono impairs cardiac morphogenesis and excitation–contraction coupling via the PI3K/Akt pathway in zebrafish

Key Points

Structured PICO

Implication

Abstract

Discussion

Cite This Study

Loss of nono impairs cardiac morphogenesis and excitation–contraction coupling via the PI3K/Akt pathway in zebrafish

Key Points

Structured PICO

Implication

Abstract

Discussion

Cite This Study

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