Role of a novel zebrafish nup98 during embryonic development.
OBJECTIVE
The nucleoporin NUP98 is a component of the nuclear pore complex that regulates nucleocytoplasmic trafficking. It has been characterized in acute myeloid leukemia as a fusion partner during chromosomal translocation. In this study, we identified a zebrafish nup98 gene and examined its role in embryonic development.


METHODS
Two expressed sequence tags with translated sequences homologous to human NUP98 were identified. The gene was cloned by polymerase chain reaction from complementary DNA of zebrafish embryos. Cellular functions of zebrafish NUP98 were investigated in HeLa cells. nup98 expression and developmental functions in zebrafish embryos were investigated by whole-mount in situ hybridization and morpholino knockdown.


RESULTS
Protein sequence of zebrafish nup98 shared 65% identity with its human homolog. Ectopic expression of zebrafish nup98 rescued the defective messenger RNA export due to human NUP98 knockdown in HeLa cells. In zebrafish embryos, nup98 was expressed diffusely in eyes and the developing brain since 18 hours postfertilization. Knockdown of nup98 with morpholino upregulated pu.1 expression by 39% ± 15% (p = 0.0153) and scl expression by 36% ± 7.6% (p = 0.0017). Expression of genes associated with erythropoiesis was unchanged. The morphants also developed intracranial hemorrhage at 48 hours postfertilization due to defective blood vessel development.


CONCLUSIONS
A novel zebrafish nup98 was identified and it serves a role in nucleocytoplasmic trafficking similar to human NUP98. During development, it modulates hematopoietic stem cell and early myeloid development and maintains the integrity of cranial vasculature in the developing central nervous system.
Fung
Tsz-Kan
TK
Department of Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.
Chung
Martin I S
MI
Liang
Raymond
R
Leung
Anskar Y H
AY
D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005816:Genetic Complementation Test; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D017403:In Situ Hybridization; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D028861:Nuclear Pore Complex Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D034622:RNA Interference; D034443:RNA Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology
D028861:Nuclear Pore Complex Proteins; D012333:RNA, Messenger; D029961:Zebrafish Proteins; C093350:nuclear pore complex protein 98; D049452:Green Fluorescent Proteins