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 rol e in differentiation of several cell types including neurons. We isola ted chick bHLH transcription factor E12 cDNA and demonstrated its expr ession in developing neural tube interneurons. To examine the function of class A bHLH transcription factors we blocked their expression usi ng antisense oligonucleotides. Simultaneous blocking of class A bHLH t ranscription factors in cultured neural tube cells results in the redu ction of differentiating neurons. Blocking the expression of individua l class A bHLH transcription factors has no detectable effect. These r esults demonstrate that class A bHLH transcription factors have a func tional redundancy during neuronal development.