PgmNr W4164: FAX-1 and UNC-42 transcription factors regulate developmental arrest in C. elegans.

Authors:
Bruce Wightman 1 ; Emily Bayer 1,2 ; Sheila Clever 1


Institutes
1) Muhlenberg College, Allentown, PA; 2) Columbia University, New York, NY.


Keyword: Timing of developmental events, and circadian rhythms

Abstract:

The fax-1 nuclear hormone receptor and unc-42 homeobox gene control interneuron identities in C. elegans. fax-1 is the ortholog of unfulfilled in Drosophila and PNR/NR3E3 in vertebrates, where it functions in the development and function of mushroom bodies and photoreceptors, respectively. The fax-1 and unc-42 transcription factors function in specifying the identities of an overlapping subset of nematode interneurons, including the command interneurons AVA and AVE, which function in coordinated movements. Both genes are required for the expression of neuron-specific genes, including glutamate receptors subunits, and axon pathfinding.

Mutations in both fax-1 and unc-42 cause an incompletely-penetrant slow-growth phenotype that arises from temporary arrest after hatching at the L1 stage. L1 arrest has been shown to be controlled by the insulin-like signaling pathway that also controls dauer formation and longevity. The daf-2 insulin receptor is a primary mediator of insulin signaling in C. elegans. Strong daf-2 mutations cause L1 arrest, while weak daf-2 mutations cause dauer-arrest. Both fax-1 and unc-42 mutations cause a fully-penetrant L1 arrest in combination with a weak daf-2 mutation. The L1 arrest can be reversed by a mutation in the daf-16 forkhead transcription factor, which functions downstream of daf-2. These observations indicate that the fax-1 and unc-42 transcription factors may function in insulin-signaling or another pathway that controls developmental progression. Given that both genes are required for the development of a limited set of interneurons, these experiments suggest a previously unappreciated role for interneuron function in regulating developmental temporal progression and arrest. Supported by NIGMS..



Wormbase Genetic Index
1. fax-1
2. unc-42
3. daf-2
4. daf-16