Sequence and expression analysis of Nhlh1: A basic helix-loop-helix gene implicated in neurogenesis

Nhlh1 is a basic helix-loop-helix (bHLH) gene thai has been implicated in m ouse neurogenesis. Previous studies have shown it to be expressed in region s in which there are differentiating neurons during late embryonic and feta l development, but detailed studies of the role of Nhlh 1 earlier in embryo nic development have not been performed, in this paper, we examine the expr ession of Nhlh I transcripts ai early embryonic stages (E8.5-E10.5), at the onset of neurogenesis, and compare the pattern of expression with that of Islet-1, a marker of postmitotic neurons. We show that Nhlh I is expressed in early postmitotic neurons but is down-regulated as these cells migrate f rom the ventricular zone. We have also determined the genomic structure of mouse Nhlh I and have characterised the promoter sequence, as a first step towards identifying factors that may control Nhlh 1 expression. Nhlh I has been implicated previously as a candidate for the neural tube defect mutant loop-tail (Lp); here, we present sequence and expression data indicating t hat Nhlh I is unlikely to be responsible for the ip mutation. (C) 1999 Wile y-Liss, Inc.