Mir125b-2 is a microRNA with significant functional implications. MicroRNAs are known to play crucial roles in post-transcriptional regulation of gene expression, and Mir125b-2 is no exception, being involved in processes related to neural function and potentially cancer-related pathways [1,2].

In the study of Mir125b-2, gene knockout (KO) mouse models have provided key insights. In Mir125b-2m-/p-mice (where both maternal and paternal copies are absent), there were impairments in learning, memory, and increased anxiety, which were hippocampus-dependent. Hippocampal granule cells from these KO mice showed increased neuronal excitability, altered synaptic transmission (increased excitatory and decreased inhibitory), and up-regulation of Grin2a, a key synaptic plasticity regulator. This indicates that Mir125b-2 plays a role in regulating hippocampal function and circuit in mice, despite it being imprinted in human but not mouse brain [1].

In breast cancer research, aminoflavone was found to upregulate the tumor-suppressor miR125b-2-3p (a product of Mir125b-2), which inhibited luminal A breast cancer stem cell-like properties. The miR125b-2-3p mimic decreased the expression of stemness genes and reduced proliferation, migration, and mammosphere formation in breast cancer cells [2].

In conclusion, Mir125b-2 has essential functions in neural processes, as demonstrated by KO mouse models in relation to hippocampal-dependent learning, memory, and anxiety. It also shows potential as a tumor suppressor in breast cancer. The study of Mir125b-2 through these in vivo models provides valuable insights into its role in normal biological functions and disease conditions, contributing to a better understanding of related biological processes and potential therapeutic targets.