miR-190 is a Key Regulator in Establishing Cell Polarity and Specification in the Drosophila Nervous System.

Asymmetric cell division generates cellular diversity in developing tissues, particularly in the CNS. In Drosophila neuroblasts, this process relies on polarity complexes and fate determinants, yet its molecular regulation remains unclear. Here, we identify miRNA-190 as a key regulator of neuroblast polarity and differentiation. Single-cell RNA sequencing and transcriptome analysis reveal that miR-190 deficiency disrupts CNS cell populations, reducing neurons while increasing neural progenitors and glia. Mechanistically, miR-190 is required for proper localization of the Par complex and basal determinants during mitosis. In miR-190 mutants, these factors mislocalize, leading to defective polarity and fate specification in embryonic neuroblast. qPCR analysis shows that miR-190 targets RhoGAP, which modulates Cdc42 activation and Par-6, crucial factors in neuroblast polarity. We propose a model in which miR-190 ensures proper Cdc42 activation and polarity establishment by targeting transcripts for degradation. miR-190 has been implicated in various cancers, and our findings provide a mechanistic framework for understanding miR-190's roles in tumorigenesis and its broader involvement in metabolic diseases.