Seoul National University's Narry Kim and her group have retracted their 2011 Molecular Cell paper on microRNA decay because they discovered that a reagent they used, TRIzol, affects GC-rich miRNAs or miRNAs with secondary structures differently, Retraction Watch reports. In the retraction notice, the researchers write that "based on our results, we proposed that some miRNAs are selectively destabilized depending on the adhesion status of the cells. However, in subsequent studies, we discovered that structured miRNAs with low GC content, such as miR-141, miR-29b, miR-21, miR-106b, miR-15a, and miR-34a, are selectively lost during sample preparation rather than degraded in the cell."
In a separate letter to the editor article, Kim and her colleagues present new data comparing the TRIzol RNA isolation method with the less-commonly used mirVana approach, which they applied to both high- and low-density cell samples. Using TRIzol, they found that miR-141 levels were lower in the low- density culture as compared to the dense culture. However with the mirVana approach, there was only a slight difference between the two cultures. "The inconsistency between data from two protocols raised a serious concern that certain miRNAs may be lost during RNA preparation depending on the protocol of choice," Kim et al. write.
"Scientists inevitably live with a number of assumptions that may turn out to be wrong later. We also have a number of technical limitations which are unrecognized at the time of the study. So, making a mistaken conclusion is sometimes unavoidable. What is important is to be honest and to correct the mistake as soon as we realize it," Kim tells Retraction Watch.