Loss of Sec-1 Family Domain-Containing 1 (scfd1) Causes Severe Cardiac Defects and Endoplasmic Reticulum Stress in Zebrafish

Inken G Huttner; Celine F Santiago; Arie Jacoby; Delfine Cheng; Gunjan Trivedi; Stephen Cull; Jasmina Cvetkovska; Renee Chand; Joachim Berger; Peter D Currie; Kelly A Smith; Diane Fatkin

doi:10.3390/jcdd10100408

Loss of Sec-1 Family Domain-Containing 1 (scfd1) Causes Severe Cardiac Defects and Endoplasmic Reticulum Stress in Zebrafish

J Cardiovasc Dev Dis. 2023 Sep 22;10(10):408. doi: 10.3390/jcdd10100408.

Authors

Inken G Huttner^{1

2}, Celine F Santiago^{1

2}, Arie Jacoby¹, Delfine Cheng^{1

2}, Gunjan Trivedi¹, Stephen Cull¹, Jasmina Cvetkovska¹, Renee Chand¹, Joachim Berger^{3

4}, Peter D Currie^{3

4}, Kelly A Smith⁵, Diane Fatkin^{1

2

6}

Affiliations

¹ Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia.
² School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Kensington, NSW 2052, Australia.
³ Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia.
⁴ European Molecular Biology Labs (EMBL) Australia, Victorian Node, Monash University, Clayton, VIC 3800, Australia.
⁵ Department of Anatomy & Physiology, The University of Melbourne, Parkville, VIC 3010, Australia.
⁶ Cardiology Department, St Vincent's Hospital, Darlinghurst, NSW 2010, Australia.

Abstract

Dilated cardiomyopathy (DCM) is a common heart muscle disorder that frequently leads to heart failure, arrhythmias, and death. While DCM is often heritable, disease-causing mutations are identified in only ~30% of cases. In a forward genetic mutagenesis screen, we identified a novel zebrafish mutant, heart and head (hah^vcc43), characterized by early-onset cardiomyopathy and craniofacial defects. Linkage analysis and next-generation sequencing identified a nonsense variant in the highly conserved scfd1 gene, also known as sly1, that encodes sec1 family domain-containing 1. Sec1/Munc18 proteins, such as Scfd1, are involved in membrane fusion regulating endoplasmic reticulum (ER)/Golgi transport. CRISPR/Cas9-engineered scfd1^vcc44 null mutants showed severe cardiac and craniofacial defects and embryonic lethality that recapitulated the phenotype of hah^vcc43 mutants. Electron micrographs of scfd1-depleted cardiomyocytes showed reduced myofibril width and sarcomere density, as well as reticular network disorganization and fragmentation of Golgi stacks. Furthermore, quantitative PCR analysis showed upregulation of ER stress response and apoptosis markers. Both heterozygous hah^vcc43 mutants and scfd1^vcc44 mutants survived to adulthood, showing chamber dilation and reduced ventricular contraction. Collectively, our data implicate scfd1 loss-of-function as the genetic defect at the hah^vcc43 locus and provide new insights into the role of scfd1 in cardiac development and function.

Keywords: ER stress; dilated cardiomyopathy; genetics; protein homeostasis; scfd1; zebrafish.

Grants and funding

This work was supported by the National Health and Medical Research Council of Australia (GNT1136567, GNT1144159, 1025008, 573732, GNT2016338), NSW Health Cardiovascular Research Capacity Program, Estate of the Late RT Hall and the St Vincent’s Clinic Foundation, Sydney, Australia.