Mir125b-1 is Not Imprinted in Human Brain and Shows Developmental Expression Changes in Mouse Brain.

Genomic imprinting is a predominantly brain and placenta-specific epigenetic process that contributes to parent-of-origin-specific gene expression. While microRNAs are highly expressed in the brain, their imprinting status in this tissue remains poorly studied. Previous research demonstrated that Mir125b-2 is imprinted in the human brain and regulates hippocampal circuits and functions in mice. However, the imprinting status of another isoform of miR125b, Mir125b-1, in the human brain, as well as its spatiotemporal expression patterns in mice, have not been elucidated. Here, we show MIR125B1 is not imprinted in the human brain. Moreover, miR-125b-1 was highly expressed in the brains of mice. Furthermore, miR-125b-1 was down-regulated during brain development in mice. Specifically, miR-125b-1 displayed preferential expression in the olfactory bulb, thalamus, and hypothalamus of the mouse brain. Notably, miR-125b-1 was enriched in GABAergic neurons, particularly somatostatin-expressing GABAergic neurons, compared with glutamatergic neurons. Taken together, our findings provide the imprinting status and comprehensive spatiotemporal expression profiling of Mir125b-1 in the brain.