An Essential Role for COPI in mRNA Localization to Mitochondria and Mitochondrial Function

Area of Science:

• Cell Biology
• Molecular Biology
• Mitochondrial Biology

Background:

• Nuclear-encoded mRNAs encoding mitochondrial proteins (mMPs) can localize to the mitochondrial surface.
• The mechanisms of mMP targeting to mitochondria and the role of RNA targeting in mitochondrial protein import and cellular metabolism remain unclear.

Purpose of the Study:

• To investigate the role of the COPI vesicle coat complex in mMP targeting to mitochondria.
• To determine if RNA targeting contributes to mitochondrial protein import and cellular metabolism.

Main Methods:

• Investigated the effect of COPI inactivation on mMP localization, mitochondrial membrane potential, protein import (in vivo and in vitro), and mitochondrial respiration.
• Utilized a model mMP (OXA1) to study the impact of COPI inactivation or mutation on mRNA localization and cellular respiration.

Main Results:

• COPI inactivation led to reduced mMP binding to COPI, dissociation of mMPs from mitochondria, decreased mitochondrial membrane potential, and impaired protein import.
• COPI inactivation resulted in severe deficiencies in mitochondrial respiration and altered mRNA localization for the OXA1 protein.
• COPI-mediated targeting is critical for mitochondrial protein import and function.

Conclusions:

• The COPI vesicle coat complex is necessary for mMP localization to mitochondria and essential for mitochondrial function.
• COPI-mediated mMP targeting is critical for mitochondrial protein import and cellular metabolism.
• Transcript delivery to mitochondria or the endoplasmic reticulum is regulated by cis-acting RNA sequences and trans-acting proteins.