The UPRmt preserves mitochondrial import to extend lifespan

Area of Science:

• Cellular Biology
• Mitochondrial Biology
• Genetics

Background:

• The mitochondrial unfolded protein response (UPRmt) maintains mitochondrial proteostasis and is associated with longevity.
• ATFS-1 is a key transcription factor regulating UPRmt genes, translocating to the nucleus upon activation.
• A challenge exists in transporting repair proteins into mitochondria that previously excluded ATFS-1 due to reduced import efficiency.

Purpose of the Study:

• To investigate the role of mitochondrial import machinery during UPRmt activation.
• To understand how mitochondrial protein import is affected by UPRmt induction.
• To determine the necessity of the import machinery for UPRmt-mediated lifespan extension.

Main Methods:

• In vitro and in vivo analysis of mitochondrial proteins.
• Assessing mitochondrial protein import efficiency under UPRmt conditions.
• Evaluating the ATFS-1 dependence of UPRmt-induced import changes.
• Investigating the role of ATFS-1's mitochondrial targeting sequence (MTS).

Main Results:

• Mitochondrial protein import surprisingly increases during UPRmt activation in an ATFS-1-dependent manner.
• This increase occurs despite a reduction in mitochondrial membrane potential.
• The mitochondrial import machinery is upregulated during UPRmt.
• An intact import machinery is crucial for the lifespan-extending effects of UPRmt.
• ATFS-1 exhibits dynamic subcellular localization due to a weak MTS.

Conclusions:

• UPRmt activation enhances mitochondrial protein import via ATFS-1-dependent upregulation of the import machinery.
• This enhanced import is essential for UPRmt-mediated longevity.
• ATFS-1's dynamic localization contributes to UPRmt regulation.