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SpKrl: a direct target of (beta)-catenin regulation required for endoderm differentiation in sea urchin embryos

Authors: 
Howard EW, Newman LA, Oleksyn DW, Angerer RC, Angerer LM
Citation: 
Development 2001 128(3):365-375
Abstract: 
Localization of nuclear beta-catenin initiates specification of vegetal fates in sea urchin embryos. We have identified SpKrl, a gene that is activated upon nuclear entry of beta-catenin. SpKrl is upregulated when nuclear beta-catenin activity is increased with LiCl and downregulated in embryos injected with molecules that inhibit beta-catenin nuclear function. LiCl-mediated SpKrl activation is independent of protein synthesis, indicating that SpKrl is a direct target of beat-catenin and TCF. Embryos in which SpKrl translation is inhibited with morpholino antisense oligonucleotides lack endoderm. Conversely, SpKrl mRNA injection rescues some vegetal structures in beta-catenin-deficient embryos. SpKrl negatively regulates expression of the animalizing transcription factor, SpSoxB1. We propose that SpKrl functions in patterning the vegetal domain by suppressing animal regulatory activities.
Organism or Cell Type: 
Sea urchins
Delivery Method: 
Microinjection