Mammalian mtDNA gene expression: Concepts learned from in vivo models

Area of Science:

• Cellular Biology
• Genetics
• Biochemistry

Background:

• Mitochondrial DNA (mtDNA) expression is vital for cellular energy production through oxidative phosphorylation (OXPHOPS).
• In vivo regulation of mtDNA expression is complex and not fully understood, despite in vitro characterization of the machinery.
• Understanding these regulatory mechanisms is critical for addressing mitochondrial disorders.

Purpose of the Study:

• To review insights from mouse models on the regulation of mammalian mitochondrial DNA expression.
• To identify key regulatory control points in vivo for mtDNA expression and OXPHOS biogenesis.
• To highlight the potential for developing targeted therapies for mitochondrial diseases based on in vivo findings.

Main Methods:

• Review of studies utilizing mouse models with genetic modifications to the mtDNA expression machinery.
• Analysis of data comparing in vitro findings with in vivo observations in mammalian systems.
• Integration of current and emerging genetic tools to decipher regulatory coordination.

Main Results:

• Mitochondrial transcription in vivo often exceeds immediate needs, suggesting it's not the primary rate-limiting step for OXPHOS.
• Mitochondria generate a transcript surplus regulated by nucleoid compaction and post-transcriptional stabilization.
• This surplus capacity, uncoupled from protein output basally, is critical during physiological stress or pathology.

Conclusions:

• In vivo studies using mouse models are essential for uncovering the true regulatory control points of mtDNA expression.
• Regulation of mtDNA expression involves transcript surplus management, nucleoid structure, and post-transcriptional processes.
• These findings pave the way for novel therapeutic strategies targeting mitochondrial disorders by addressing in vivo regulatory mechanisms.