Twinkle helicase is essential for mtDNA maintenance and regulates mtDNA copy number

Area of Science:

• Mitochondrial biology
• Molecular genetics
• Genetics of aging and disease

Background:

• Mitochondrial DNA (mtDNA) maintenance is vital for preventing inherited diseases and aging.
• Twinkle, a mitochondrial DNA helicase, has been linked to progressive external ophthalmoplegia with multiple mtDNA deletions.
• Mouse Twinkle shares high similarity with its human counterpart, suggesting conserved functions.

Purpose of the Study:

• To characterize the mouse Twinkle gene and its expression profile.
• To elucidate the in vivo role of Twinkle in maintaining mitochondrial DNA copy number.
• To investigate Twinkle's regulatory role in mtDNA maintenance.

Main Methods:

• Generated transgenic mouse lines overexpressing wild-type Twinkle.
• Analyzed Twinkle gene and expression patterns in mice.
• Utilized RNA interference in cultured human cells to reduce Twinkle expression.

Main Results:

• Mouse Twinkle expression patterns are not conserved with humans but synchronized with the adjacent MrpL43 gene.
• Overexpression of Twinkle in mouse muscle and heart increased mtDNA copy number up to threefold.
• Reduced Twinkle expression in human cells led to a rapid decrease in mtDNA copy number.

Conclusions:

• Twinkle helicase is essential for mammalian mtDNA maintenance.
• Twinkle plays a key regulatory role in controlling mtDNA copy number.
• Understanding Twinkle's function offers insights into mtDNA-related diseases and aging.