Class A basic helix-loop-helix transcription factors in early stages of chick neural tube development: evidence for functional redundancy.

Basic Helix-Loop-Helix (bHLH) transcription factors play essential role in differentiation of several cell types including neurons. We isolated chick bHLH transcription factor E12 cDNA and demonstrated its expression in developing neural tube interneurons. To examine the function of class A bHLH transcription factors we blocked their expression using antisense oligonucleotides. Simultaneous blocking of class A bHLH transcription factors in cultured neural tube cells results in the reduction of differentiating neurons. Blocking the expression of individual class A bHLH transcription factors has no detectable effect. These results demonstrate that class A bHLH transcription factors have a functional redundancy during neuronal development.