Environmentally induced foregut remodeling by PHA-4/FoxA and

DaF-12/NHR1Wanyuan Ao, 1Jeb Gaudet, 2W. james Kent, 1Srikanth

Muttumu, 1Susan E. Mango1Huntsman cancer institute, University of Utah

2Genome bioinformatics Group, University of California

Pharyngeal devleopment depends on pha-4

Embryos that lack pha-4 fail to generate pharyngeal cells.

Many and possibly all genes expressed in the pharynx(at all stages) require pha-4 for activation

What causes variation in expression?

Combinatorial regulation

Multiple TF’s working towards common or different goals to attain the outcome necessary for tissue differentiation and activity.

1 The Aproach

Expression profiles for 339 pharyngeal genes Identified by microarray analysis

Five clusters of genes with shared expression profiles were determined for use with topographical expression maps

Ph-M (muscle) Ph-MC(marginal cells) Ph-MMC(combine above) Ph-G(glands) Epi (epithelial)

2

Algorithm created to Identify potential cis-regulatory elements

Uses set of 194 randomly selected genes not expressed in pharynx as a negative control

Seven candidate elements determined

Uncharacterized genes used to validate assignments

Five displayed enhancer activity

Proposed mechanism for expression

PHA-4 sites contribute to organ-wide activation throughout pharynx and additional elements impart positional (29-4) cell type (M-2,12-1,12-5) information

3 the M-2 motif

Highly selective for pharyngeal muscle.

Four genes selected which carried consensus in both C elegans and C briggsae and were expressed in pharyngeal muscle.

M-2 not effected byT-box binding proteins

Yeast one hybrid used to discover transcription factor which binds M-2

Daf-12 is determined a regulatory element in vivo

4

• Choice of Growth phase and Dauer development depends on insulin, TGF-B and heterotrimeric guanine nucleotide-binding protein coupled receptor signaling pathways.

• DAF-12 is affected, what effect does it have on these biological functions?

Down regulation observed in Dauer animals

Food restoration returned animals to growth phase

Daf12 effect repression or loss of activation

PHA-4 binding sites not required for repression