# Molecular Insights into Outer Dynein Arm Defects in Primary Ciliary Dyskinesia: Involvement of ZMYND10 and GRP78

## TL;DR

This study explores how mutations in DNAH5 and ZMYND10, along with changes in GRP78, contribute to ciliary dysfunction in primary ciliary dyskinesia, linking it to cellular stress.

## Contribution

The study reveals a novel connection between outer dynein arm defects and cellular stress pathways in primary ciliary dyskinesia.

## Key findings

- CTCF levels of DNAH5, ZMYND10, and GRP78 were significantly different in PCD individuals compared to controls.
- Metabolomic analysis showed altered amino acid and lipid metabolism, indicating mitochondrial and ER stress in PCD.

## Abstract

Background: Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterized by recurrent sinopulmonary infections due to motile cilia defects. The disease is genetically heterogeneous, with abnormalities in structural ciliary proteins. Zinc finger MYND-type containing 10 (ZMYND10) is essential for the assembly of outer dynein arms (ODA), with chaperones like Glucose-regulated protein 78 (GRP78) facilitating protein folding. This study investigates ZMYND10 and Dynein axonemal heavy chain 5 (DNAH5) mutations in individuals with PCD. Methods: Eight individuals aged 14–22 with clinical PCD symptoms and confirmed DNAH5 mutations were included. We analyzed the correlation between DNAH5 abnormalities and preassembly/chaperone proteins using immunofluorescence labeling. Nasal swabs were double-labeled (DNAH5–β-tubulin, β-tubulin–ZMYND10, β-tubulin–GRP78) and examined via fluorescence microscopy. Serum metabolomics and proteomics were also assessed. Results: The corrected total cell fluorescence (CTCF) levels of DNAH5, ZMYND10, and GRP78 were significantly different between PCD individuals and controls. Metabolomic analysis showed reduced valine, leucine, and isoleucine biosynthesis, with increased malate and triacylglycerol biosynthesis, malate-aspartate and glycerol phosphate shuttles, and arginine/proline metabolism, suggesting mitochondrial and ER stress. Conclusions: The altered expression of DNAH5, ZMYND10, and GRP78, along with metabolic shifts, points to a complex link between ciliary dysfunction and cellular stress in PCD. Further studies are needed to clarify the underlying mechanisms.