Open AccessMultiple neural bHLHs ensure the precision of a neuronal specification event in Caenorhabditis elegans
Author(s) -
Konstantina Filippopoulou,
Carole Couillault,
Vincent Bertrand
Publication year - 2021
Publication title -
biology open
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.936
H-Index - 41
ISSN - 2046-6390
DOI - 10.1242/bio.058976
Subject(s) - caenorhabditis elegans , biology , transcription factor , gene , neuroscience , transcription (linguistics) , computational biology , microbiology and biotechnology , genetics , linguistics , philosophy
Neural bHLH transcription factors play a key role in the early steps of neuronal specification in many animals. We have previously observed that the Achaete-Scute HLH-3, the Olig HLH-16 and their binding partner the E-protein HLH-2 activate the terminal differentiation program of a specific class of cholinergic neurons, AIY, in Caenorhabditis elegans. Here we identify a role for a fourth bHLH, the Neurogenin NGN-1, in this process, raising the question of why so many neural bHLHs are required for a single neuronal specification event. Using quantitative imaging we show that the combined action of different bHLHs is needed to activate the correct level of expression of the terminal selector transcription factors TTX-3 and CEH-10 that subsequently initiate and maintain the expression of a large battery of terminal differentiation genes. Surprisingly, the different bHLHs have an antagonistic effect on another target, the proapoptotic BH3-only factor EGL-1, normally not expressed in AIY and otherwise detrimental for its specification. We propose that the use of multiple neural bHLHs allows robust neuronal specification while, at the same time, preventing spurious activation of deleterious genes.