Explain how microRNAs can influence translation without changing mRNA abundance.

• A. miRNAs degrade proteins directly
• B. miRNAs increase transcription of target genes
• C. miRNAs bind target mRNAs to repress translation or promote deadenylation and decay, decreasing protein output without immediate mRNA loss
• D. miRNAs bind DNA to regulate transcription

Answer: (C)

MicroRNAs influence protein production by guiding the RNA-induced silencing complex to target mRNAs and repress their translation, often along with shortening the poly(A) tail (deadenylation) leading to mRNA decay later. This means the mRNA levels can stay the same at first, but the amount of protein produced drops because the ribosomes can’t translate as efficiently or at all. That combination—repressing translation and promoting deadenylation/decay without an immediate drop in mRNA abundance—best explains how miRNAs can reduce protein output without changing mRNA abundance right away.

Degrading proteins directly isn’t a function of microRNAs, they don’t increase transcription, and they don’t bind DNA to regulate transcription.