Imbalanced mitochondrial function provokes heterotaxy via aberrant ciliogenesis.

Area of Science:

• Developmental Biology
• Genetics
• Cell Biology

Background:

• Congenital heart disease (CHD) affects ~1% of newborns.
• Aberrant cilia function is implicated in CHD and heterotaxy (visceral organ misplacement).
• Mitochondrial pathways, like mTOR, influence ciliogenesis and can cause heterotaxy-like phenotypes.

Purpose of the Study:

• To investigate the role of mitochondrial function in ciliogenesis and heterotaxy.
• To explore the link between mitochondrial dysfunction and heterotaxy-associated CHD.
• To identify genetic factors contributing to mitochondrial dysfunction and ciliopathies.

Main Methods:

• Analysis of mitochondrial DNA content in patient biopsies.
• Experimental manipulation of mitochondrial function in zebrafish, human fibroblasts, and Tetrahymena.
• Exome sequencing of heterotaxy patients and controls.
• Gene knockdown studies in zebrafish.

Main Results:

• Reduced mitochondrial DNA content observed in heterotaxy patient biopsies.
• Mitochondrial function directly influences ciliogenesis and cilia-dependent processes.
• Heterotaxy patients exhibit an increased burden of rare damaging variants in mitochondria-associated genes.
• Knockdown of candidate genes induced ciliopathy-like phenotypes in zebrafish.

Conclusions:

• Ciliogenesis is intrinsically coupled to mitochondrial abundance and function.
• Disturbed mitochondrial function is a causal factor in heterotaxy-linked CHD.
• This study provides a mechanistic link between mitochondrial disease phenotypes and ciliopathies.