Functional genomic analysis of human mitochondrial RNA processing.

Area of Science:

• Mitochondrial biology
• Molecular genetics
• RNA processing

Background:

• Human mitochondrial DNA (mtDNA) is transcribed into large precursor RNAs that require precise processing into functional molecules.
• Nuclear-encoded proteins play critical roles in processing these mitochondrial RNAs (mtRNAs) for essential cellular functions like respiratory chain biogenesis.
• Dysfunctional mt-RNA processing is implicated in various mitochondrial diseases.

Purpose of the Study:

• To systematically identify nuclear-encoded proteins involved in mt-RNA processing within mitochondria.
• To develop and validate a high-throughput method for quantifying mtDNA transcripts.
• To investigate the roles of mitochondrial RNA-binding proteins in mt-RNA processing.

Main Methods:

• Development and validation of a multiplex MitoString assay to quantify 27 mature and precursor mtDNA transcripts.
• Application of MitoString profiling to assess the impact of silencing 107 predicted mitochondrial RNA-binding proteins.
• In vivo association studies to confirm the interaction of identified factors with mtRNAs.

Main Results:

• The MitoString assay effectively quantifies mtDNA transcripts.
• Silencing experiments identified known and novel nuclear-encoded proteins involved in mt-RNA processing.
• Unanticipated roles for known disease genes in mt-RNA processing were uncovered.
• FASTKD4 was identified as a factor that modulates mt-mRNA half-lives and associates with mtRNAs in vivo.

Conclusions:

• MitoString profiling is a powerful tool for dissecting mt-RNA processing pathways.
• New regulatory factors for mt-RNA processing were discovered, including FASTKD4.
• This research provides insights into the pathogenesis of mitochondrial DNA disorders and suggests potential diagnostic applications.