Zebrafish prox1b mutants develop a lymphatic vasculature, and prox1b does not specifically mark lymphatic endothelial cells.
BACKGROUND
The expression of the Prospero homeodomain transcription factor (Prox1) in a subset of cardinal venous cells specifies the lymphatic lineage in mice. Prox1 is also indispensible for the maintenance of lymphatic cell fate, and is therefore considered a master control gene for lymphangiogenesis in mammals. In zebrafish, there are two prox1 paralogues, the previously described prox1 (also known as prox1a) and the newly identified prox1b.


RESULTS
To investigate the role of the prox1b gene in zebrafish lymphangiogenesis, we knocked-down prox1b and found that depletion of prox1b mRNA did not cause lymphatic defects. We also generated two different prox1b mutant alleles, and maternal-zygotic homozygous mutant embryos were viable and did not show any lymphatic defects. Furthermore, the expression of prox1b was not restricted to lymphatic vessels during zebrafish development.


CONCLUSIONS
We conclude that Prox1b activity is not essential for embryonic lymphatic development in zebrafish.
Hubrecht Institute-Royal Netherlands Academy of Arts and Sciences and University Medical Centre, Utrecht, The Netherlands.
Shijie
S
Tao
Merlijn
M
Witte
Robert J
RJ
Bryson-Richardson
Peter D
PD
Currie
Benjamin M
BM
Hogan
Stefan
S
Schulte-Merker
D000818:Animals; D018398:Homeodomain Proteins / Q000235:genetics*; D042583:Lymphangiogenesis; D042601:Lymphatic Vessels / Q000166:cytology*; D009154:Mutation; D025521:Tumor Suppressor Proteins / Q000235:genetics*; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*; D000098551:Prospero-Related Homeobox 1 Protein
D018398:Homeodomain Proteins; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein