Oxidative Modification of miR-184 Enables It to Target Bcl-xL and Bcl-w

Area of Science:

• Molecular Biology
• Cellular Biology
• Biochemistry

Background:

• MicroRNAs (miRNAs) are small non-coding RNAs regulating gene expression by targeting messenger RNAs (mRNAs).
• Reactive oxygen species (ROS) cause cellular damage through oxidative modification of macromolecules, linked to diseases like cancer and aging.
• The direct impact of ROS on miRNA function and targeting remains largely unexplored.

Purpose of the Study:

• To investigate whether microRNAs (miRNAs) can be oxidatively modified by reactive oxygen species (ROS).
• To identify specific miRNAs and their targets affected by oxidative modification.
• To elucidate the functional consequences of ROS-induced miRNA modification in cellular processes like apoptosis.

Main Methods:

• Utilized cell culture (rat heart cell line H9c2) and mouse models to study miRNA-ROS interactions.
• Employed molecular biology techniques to identify miRNA-mRNA interactions and assess oxidative modifications.
• Analyzed the role of modified miRNAs in regulating target gene expression and inducing apoptosis.

Main Results:

• Demonstrated that microRNAs (miRNAs) are susceptible to oxidative modification by reactive oxygen species (ROS).
• Identified oxidized miR-184 binding to the 3' untranslated regions (3' UTRs) of Bcl-xL and Bcl-w, which are not its native targets.
• Showed that this aberrant binding of oxidized miR-184 initiates apoptosis in H9c2 cells and in vivo mouse models.

Conclusions:

• Reactive oxygen species (ROS) can directly oxidatively modify microRNAs (miRNAs), altering their targeting specificity.
• Oxidized miR-184 aberrantly targets Bcl-xL and Bcl-w, leading to apoptosis initiation.
• This study reveals a novel regulatory pathway where ROS modulates cellular events through the oxidative modification of miRNAs.