Oct4 is an embryonic stem cell specific transcription factor. ESCs grown in petri dishes are fed media that contain basic fibroblast growth factor (bFGF) which keeps the ESCs undifferentiated. They examine Oct4 mRNA levels in human ESCs (hESCs), hESCs with exogenous miR-223 (micro RNA 223), hESCs with exogenous miR-223 that do not have bFGF in the media, and hESCs without bFGF but with miR-223 inhibitor. Based on this data, what is the relationship between miR-223 and ESC differentiation?

miR-223 inhibits the expression of the fibroblast growth factor (bFGF) gene, and thereby ESCs cells maintain their undifferentiated state .

Explanation:

Non-coding RNA (ncRNAs) are molecules that regulate gene expression, thereby playing important biological functions in cell differentiation, cell cycle, apoptosis, etc. MicroRNAs (miRNAs) are a type of ncRNAs capable of controlling gene expression patterns by regulating mRNA stability and by suppressing their translation into proteins. It has been shown that miRNAs function by imperfectly base-pairing with the 3′ UTR of target mRNAs (Pillai et al. 2005).

Citation:

R. S. Pillai, S. N. Bhattacharyya, C. G. Artus,   T.  Zoller, et al. (2005). Inhibition of translational initiation by Let-7 MicroRNA in human cells. Science, 309(5740), 1573-1576.

the answer would be   10%