MicroRNA expression in the livers of inbred mice

MicroRNAs are short, non-coding RNA sequences that regulate genes at the post-transcriptional level and have been shown to be important in development, tissue differentiation, and disease. Limited attention has been given to the natural variation in miRNA expression across genetically diverse populations even though it is well established that genetic polymorphisms can have a profound effect on mRNA levels. Expression level of 577 miRNAs in the livers of 70 strains of inbred mice was assessed, and we found that miRNA expression is highly stable across different strains. Globally, the expression of miRNA target transcripts does not correlate with miRNA expression, primarily due to the low variance of miRNA but high variance of mRNA expression across strains. Our results show that there is little genetic effect on the baseline miRNA levels in murine liver. The stability of mouse liver miRNA expression in a genetically diverse population suggests that treatment-induced disruptions in liver miRNA expression, a phenomenon established for a large number of toxicants, may indicate an important mechanism for the disturbance of normal liver function, and may prove to be a useful genetic background-independent biomarker of toxicant effect.

► Basal expression of many mammalian genes is tightly regulated by genetic polymorphisms.
► Few investigators have studied the effect of genetic variation among individuals on miRNA expression.
► In the present study, we profiled the expression of 577 miRNAs using microarrays in a BXD recombinant inbred cross and a panel of commonly used laboratory inbred mice.
► In contrast to studies in multiple cancer tissues, liver miRNA expression is highly conserved across genotype.
► Our findings, suggests that disruption in liver miRNAs expression may be a useful marker of liver injury, independent of genotype.