Identification of PAX6 and NFAT4 as the transcriptional regulators of lncRNA Mrhl in neuronal progenitors

LncRNA Mrhl has been shown to be involved in regulating meiotic commitment of mouse spermatogonial progenitors and coordinating differentiation events in mouse embryonic stem cells. Here we have characterized the interplay of Mrhl with lineage-specific transcription factors during mouse neuronal lineage development. Our results demonstrate that Mrhl is predominantly expressed in the neuronal progenitor populations in mouse embryonic brains and in retinoic acid derived radial-glia like neuronal progenitor cells. Mrhl levels are significantly down regulated in postnatal brains and in maturing neurons. In neuronal progenitors, a master transcription factor, PAX6, acts to regulate the expression of Mrhl through direct physical binding at a major site in the distal promoter, located at 2.9kb usptream of the TSS of Mrhl. Furthermore, NFAT4 occupies the Mrhl proximal promoter at two sites, at 437bp and 143bp upstream of the TSS. ChIP studies reveal that PAX6 and NFAT4 interact with each other, suggesting co-regulation of lncRNA Mrhl expression in neuronal progenitors. Our studies herewith are crucial towards understanding how lncRNAs are regulated by major lineage-specific TFs towards defining specific development and differentiation events. Summary statement Transcriptional regulation of lncRNA Mrhl by multiple lineage-specific transcription factors in neuronal progenitors highlights context-dependent regulation important for lineage specification.