Dishevelled: In Vivo Roles of a Multifunctional Gene Family During Development - Current Topics in Developmental Biology - page 226

Dvl1 - ECFP and Dvl3 - EYFP ( Etheridge et al., 2008 ), are also expressed at
levels comparable to endogenous alleles and completely rescue single- and
double-mutant phenotypes. Dvl1 - ECFP and Dvl3 - EYFP ,

like the

Dvl2 - EGFP allele, are also conditional alleles in vivo .

15. DVL TRANSGENES DEMONSTRATE FUNCTIONAL
REDUNDANCY
The generation of fully functional Dvl transgenes allowed us to use a
genetic approach to further determine redundancy of function between the
Dvl proteins during development ( Etheridge et al., 2008 ). We determined
whether an extra copy of either Dvl1 or Dvl2 , in the form of Dvl1 - ECFP
and Dvl2 - EGFP BAC transgenes (which we will refer to here as Dvl1TG
and Dvl2TG , respectively), was able to rescue lethal Dvl3 / phenotype.
As noted above, Dvl3 / mutants (which still have two copies of the
Dvl1 allele and two copies of the Dvl2 allele) cannot survive. Surprisingly,
addition of the Dvl1TG rescued the Dvl3 / phenotype such that Dvl3 / ;
Dvl1TG mutants (now Dvl3 / with three copies of Dvl1 and two copies
of Dvl2 ) survived in expected numbers. In a similar cross using the Dvl2TG ,
we found that an extra copy of the Dvl2 , as the Dvl2TG , also rescued the
Dvl3 / lethal phenotype to at least 90% efficiency. As 50% of Dvl2 /
mutants die perinatally, we used a similar strategy to determine whether
additional copies of Dvl1 or Dvl3 could rescue Dvl2 / lethality. There
was an approximately 96% rescue of the Dvl2 / phenotype with an extra
copy of Dvl3 . However, the Dvl1TG was not able to rescue Dvl2 / mutant
phenotype, in contrast to the rescue of the Dvl2 / phenotype by the
Dvl3TG and the Dvl3 / phenotype by the Dvl2TG or Dvl1TG . These
results, along with the double-mutant phenotypes, strongly support the no-
tion that the three Dvl genes have redundant functions during development.

16. DVL2 ALLELIC SERIES TO DISTINGUISH WNT
AND PCP PATHWAY PHENOTYPES IN VIVO
We wanted tools that would allow us to determine whether any of the
Dvl phenotypes we observed were due to defects in Wnt and/or PCP path-
way signaling. We took advantage of the studies in Xenopus and Drosophila
(described above) that defined protein domains in Dvls required for canon-
ical Wnt and PCP signaling. Therefore, we made a Dvl2 allelic series ( D DIX ,

D DEP , and a dsh1 point mutant) to determine whether the canonical Wnt or