Abnormal nuclear pore formation triggers apoptosis in the intestinal epithelium of elys-deficient zebrafish.
OBJECTIVE
Zebrafish mutants generated by ethylnitrosourea-mutagenesis provide a powerful tool for dissecting the genetic regulation of developmental processes, including organogenesis. One zebrafish mutant, "flotte lotte" (flo), displays striking defects in intestinal, liver, pancreas, and eye formation at 78 hours postfertilization (hpf). In this study, we sought to identify the underlying mutated gene in flo and link the genetic lesion to its phenotype.


METHODS
Positional cloning was employed to map the flo mutation. Subcellular characterization of flo embryos was achieved using histology, immunocytochemistry, bromodeoxyuridine incorporation analysis, and confocal and electron microscopy.


RESULTS
The molecular lesion in flo is a nonsense mutation in the elys (embryonic large molecule derived from yolk sac) gene, which encodes a severely truncated protein lacking the Elys C-terminal AT-hook DNA binding domain. Recently, the human ELYS protein has been shown to play a critical, and hitherto unsuspected, role in nuclear pore assembly. Although elys messenger RNA (mRNA) is expressed broadly during early zebrafish development, widespread early defects in flo are circumvented by the persistence of maternally expressed elys mRNA until 24 hpf. From 72 hpf, elys mRNA expression is restricted to proliferating tissues, including the intestinal epithelium, pancreas, liver, and eye. Cells in these tissues display disrupted nuclear pore formation; ultimately, intestinal epithelial cells undergo apoptosis.


CONCLUSIONS
Our results demonstrate that Elys regulates digestive organ formation.
de Jong-Curtain
Tanya A
TA
Ludwig Institute for Cancer Research, Royal Melbourne Hospital, Parkville, Victoria, Australia.
Parslow
Adam C
AC
Trotter
Andrew J
AJ
Hall
Nathan E
NE
Verkade
Heather
H
Tabone
Tania
T
Christie
Elizabeth L
EL
Crowhurst
Meredith O
MO
Layton
Judith E
JE
Shepherd
Iain T
IT
Nixon
Susan J
SJ
Parton
Robert G
RG
Zon
Leonard I
LI
Stainier
Didier Y R
DY
Lieschke
Graham J
GJ
Heath
Joan K
JK
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology; D019070:Cell Lineage / Q000502:physiology; D017615:Enteric Nervous System / Q000002:abnormalities / Q000473:pathology / Q000502:physiology; D005124:Eye Abnormalities / Q000473:pathology / Q000503:physiopathology; D018507:Gene Expression Regulation, Developmental; D007413:Intestinal Mucosa / Q000002:abnormalities* / Q000473:pathology / Q000502:physiology*; D007422:Intestines / Q000002:abnormalities / Q000473:pathology / Q000502:physiology; D008099:Liver / Q000002:abnormalities / Q000473:pathology / Q000502:physiology; D008854:Microscopy, Electron; D022022:Nuclear Pore / Q000473:pathology* / Q000502:physiology / Q000648:ultrastructure; D028861:Nuclear Pore Complex Proteins / Q000235:genetics* / Q000378:metabolism; D010179:Pancreas / Q000002:abnormalities / Q000473:pathology / Q000502:physiology; D010641:Phenotype; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
C533929:AHCTF1 protein, zebrafish; D028861:Nuclear Pore Complex Proteins; D029961:Zebrafish Proteins