PUBLICATION

Sex Reversal in Zebrafish fancl Mutants Is Caused by Tp53-Mediated Germ Cell Apoptosis

Authors

Rodriguez-Mari, A., Cañestro, C., Bremiller, R.A., Nguyen-Johnson, A., Asakawa, K., Kawakami, K., and Postlethwait, J.H.

ID

ZDB-PUB-100730-14

Date

2010

Source

PLoS Genetics 6(7): e1001034 (Journal)

Registered Authors

Cañestro-García, Cristian, Kawakami, Koichi, Postlethwait, John H., Rodriguez-Mari, Adriana

Keywords

Oocytes, Gonads, Germ cells, Apoptosis, Zebrafish, Sex determination, Meiosis, Ovaries

MeSH Terms

Sex Differentiation*
Cell Survival
Germ Cells/pathology*
Mutation*
Fanconi Anemia Complementation Group L Protein/genetics*
Fanconi Anemia Complementation Group L Protein/physiology
Zebrafish
Tumor Suppressor Protein p53/physiology*
Oocytes
Apoptosis*
Female
Male
Animals

(all 13)

PubMed

20661450 Full text @ PLoS Genet.

Abstract

The molecular genetic mechanisms of sex determination are not known for most vertebrates, including zebrafish. We identified a mutation in the zebrafish fancl gene that causes homozygous mutants to develop as fertile males due to female-to-male sex reversal. Fancl is a member of the Fanconi Anemia/BRCA DNA repair pathway. Experiments showed that zebrafish fancl was expressed in developing germ cells in bipotential gonads at the critical time of sexual fate determination. Caspase-3 immunoassays revealed increased germ cell apoptosis in fancl mutants that compromised oocyte survival. In the absence of oocytes surviving through meiosis, somatic cells of mutant gonads did not maintain expression of the ovary gene cyp19a1a and did not down-regulate expression of the early testis gene amh; consequently, gonads masculinized and became testes. Remarkably, results showed that the introduction of a tp53 (p53) mutation into fancl mutants rescued the sex-reversal phenotype by reducing germ cell apoptosis and, thus, allowed fancl mutants to become fertile females. Our results show that Fancl function is not essential for spermatogonia and oogonia to become sperm or mature oocytes, but instead suggest that Fancl function is involved in the survival of developing oocytes through meiosis. This work reveals that Tp53-mediated germ cell apoptosis induces sex reversal after the mutation of a DNA-repair pathway gene by compromising the survival of oocytes and suggests the existence of an oocyte-derived signal that biases gonad fate towards the female developmental pathway and thereby controls zebrafish sex determination.

Genes / Markers

Figures

Show all Figures

Expression

Gene	Fish	Conditions	Stage	Qualifier	Anatomy	Assay	Figure
amh	fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 21-29		gonad	ISH	Fig. 4
amh	fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 30-44		gonad	ISH	Fig. 4
amh	fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 14-20		immature gonad	ISH	Fig. 4
amh	WT	control	Days 21-29		gonad	ISH	Fig. 4
amh	WT	control	Days 30-44		gonad	ISH	Fig. 4
amh	WT	control	Days 14-20		immature gonad	ISH	Fig. 4
amh	WT + MO1-dnd1	standard conditions	Days 21-29		gonad	ISH	Fig. 4
amh	WT + MO1-dnd1	standard conditions	Days 30-44		gonad	ISH	Fig. 4
amh	WT + MO1-dnd1	standard conditions	Days 14-20		immature gonad	ISH	Fig. 4
cyp19a1a	fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 21-29	Not Detected	gonad	ISH	Fig. 4

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Phenotype

Fish	Conditions	Stage	Phenotype	Figure
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 14-20 to Days 21-29	immature gonad morphology, normal	Fig. 5
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 14-20 to Days 21-29	oocyte stage I normal amount, normal	Fig. 5
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 21-29	oocyte stage I absent, abnormal	Fig. 5
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 21-29	primordial germ cell apoptotic, abnormal	Fig. 7
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 21-29	primordial germ cell apoptotic, abnormal	Fig. 6
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 21-29	spermatogonium normal amount, normal	Fig. 5
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 30-44	oocyte absent, abnormal	Fig. 5
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 30-44	spermatocyte normal amount, normal	Fig. 5
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Days 30-44	spermatogonium normal amount, normal	Fig. 5
fancl^{nkhg10aEt/nkhg10aEt}	standard conditions	Adult	female organism absent, abnormal	Fig. 2

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Mutations / Transgenics

Allele	Construct	Type	Affected Genomic Region
nkhg10aEt	Et(T2KHG)	Transgenic Insertion	fancl
zdf1		Point Mutation	tp53

Human Disease / Model

Sequence Targeting Reagents

Target	Reagent	Reagent Type
dnd1	MO1-dnd1	MRPHLNO

Fish

Fish
fancl^{nkhg10aEt/nkhg10aEt}
tp53^zdf1/+; fancl^{nkhg10aEt/nkhg10aEt}
tp53^zdf1/zdf1
tp53^zdf1/zdf1; fancl^{nkhg10aEt/nkhg10aEt}
WT
WT + MO1-dnd1

Antibodies

Orthology

Engineered Foreign Genes

Marker	Marker Type	Name
EGFP	EFG	EGFP

Mapping

Rodriguez-Mari et al., 2010 ZDB-PUB-100730-14 PMID:20661450

Sex Reversal in Zebrafish fancl Mutants Is Caused by Tp53-Mediated Germ Cell Apoptosis

Rodriguez-Mari et al., 2010

ZDB-PUB-100730-14
PMID:20661450