A human 3' miR-499 mutation alters cardiac mRNA targeting and function

Area of Science:

• Cardiovascular Biology
• Molecular Genetics
• RNA Biology

Background:

• MyomiRs, including miR-499, regulate cardiac myosin gene expression.
• MicroRNA (miR) function is determined by sequence complementarity with mRNA targets.
• The impact of human myomiR sequence variants on function remains largely unknown.

Purpose of the Study:

• To identify and characterize mutations in human myomiRs.
• To investigate how natural sequence variations affect miR-mRNA targeting.
• To understand the consequences of these variations on end-organ function.

Main Methods:

• Screening of approximately 2,600 individuals for myomiR sequence variants.
• In vitro luciferase reporter assays to assess miR-mRNA interactions.
• Cardiac-specific transgenic mouse models to evaluate in vivo effects of miR-499 variants.

Main Results:

• A rare mutation (c17) in miR-499 was identified in the 3' end, outside the seed region.
• The miR-499 c17 mutation altered the suppression of specific mRNA targets in vitro.
• Transgenic expression revealed that both wild-type and mutant miR-499 induced heart failure, but the mutant favorably impacted cardiac function by altering target mRNA recruitment.

Conclusions:

• A naturally occurring miR-499 mutation outside the seed sequence can modify mRNA targeting and end-organ function.
• This study provides the first in vivo evidence of functional consequences from a natural human miR mutation outside the seed sequence.
• Findings support further investigation into the role of miR mutations in individual phenotypes and disease modification.