| Description |
The vertebrate nervous system contains a diversity of neuronal and glial cell types, which are generated in the embryonic neural tube at appropriate times and locations. Proneural basic helix-loop-helix (bHLH) transcription factors are essential regulators in initiating neurogenesis and specifying different cell types, which are dependent upon inducing downstream target genes to regulate core neuronal differentiation program. Shared bHLH target gene 1 (SBT1) is a shared downstream target of multiple bHLH factors and plays critical roles in neurogenesis in the Xenopus open neural plate and retina. Mouse Sbt1 (Mus musculus RIKEN cDNA 3110035E14 gene, NCBI reference sequence: NM_178399.4) encodes a hypothetical protein LOC76982 (NP_848486), with uncharacterized expression and function. To determine whether Sbt1 is involved in mouse neurogenesis, I examined its temporal and spatial expression in the mouse nervous system. I found that Sbt1 is expressed in the developing cortex, brainstem, spinal cord and retina, and its expression in the spinal cord and cortex is maintained through adulthood. Moreover, its expression in the early embryonic brainstem and retina is regulated by Ngn2, suggesting that it acts as a downstream target of proneural bHLH factors in mammals. To further analyze Sbt1 function in nervous system development, I generated an Sbt1-eGFPCre knockin mouse. I followed GFP expression in the Sbt1-eGFPCre cortex, and found that it is mainly expressed in cortical neurons. I compared neuronal versus glial cell numbers in the Sbt1 mutant cortex and spinal cord with control. I also examined major cell types differentiation in the Sbt1 mutant retina. So far, no significant differences have been found. These results suggest that unlike its important function in Xenopus neurogenesis, Sbt1 function may be dispensable for mouse nervous system development. However, based on its dynamic expression in cortical neurons, it may be involved in neuronal maturation, which can be addressed in the future. Collectively, this work provides significant insight into our understanding of SBT1, a novel bHLH target, expression and function in the mouse nervous system. |
