PUBLICATION

Habenular Neurogenesis in Zebrafish Is Regulated by a Hedgehog, Pax6 Proneural Gene Cascade

Authors

Halluin, C., Madelaine, R., Naye, F., Peers, B., Roussigné, M., Blader, P.

ID

ZDB-PUB-160709-12

Date

2016

Source

PLoS One 11: e0158210 (Journal)

Registered Authors

Blader, Patrick, Halluin, Caroline, Madelaine, Romain, Peers, Bernard, Roussigné, Myriam

Keywords

Embryos, Hedgehog signaling, Neurogenesis, Neurons, Zebrafish, Diencephalon, Developmental signaling, In situ hybridization

MeSH Terms

Habenula/embryology*
Zebrafish Proteins/physiology*
Animals
Animals, Genetically Modified
Polymerase Chain Reaction
Heterozygote
Genotype
Transcription Factors/metabolism
Neurons/metabolism
Gene Expression Regulation, Developmental
Mutation
Hedgehog Proteins/physiology*
Signal Transduction*
Zebrafish/embryology*
Body Patterning
PAX6 Transcription Factor/physiology*
Nerve Tissue Proteins/physiology
Basic Helix-Loop-Helix Transcription Factors/physiology
Neurogenesis*

(all 19)

PubMed

27387288 Full text @ PLoS One

Abstract

The habenulae are highly conserved nuclei in the dorsal diencephalon that connect the forebrain to the midbrain and hindbrain. These nuclei have been implicated in a broad variety of behaviours in humans, primates, rodents and zebrafish. Despite this, the molecular mechanisms that control the genesis and differentiation of neural progenitors in the habenulae remain relatively unknown. We have previously shown that, in zebrafish, the timing of habenular neurogenesis is left-right asymmetric and that in the absence of Nodal signalling this asymmetry is lost. Here, we show that habenular neurogenesis requires the homeobox transcription factor Pax6a and the redundant action of two proneural bHLH factors, Neurog1 and Neurod4. We present evidence that Hedgehog signalling is required for the expression of pax6a, which is in turn necessary for the expression of neurog1 and neurod4. Finally, we demonstrate by pharmacological inhibition that Hedgehog signalling is required continuously during habenular neurogenesis and by cell transplantation experiments that pathway activation is required cell autonomously. Our data sheds light on the mechanism underlying habenular development that may provide insights into how Nodal signalling imposes asymmetry on the timing of habenular neurogenesis.

Genes / Markers

Figures

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Expression

Gene	Fish	Conditions	Stage	Qualifier	Anatomy	Assay	Figure
cxcr4b	neurog1^{hi1059Tg/hi1059Tg}	standard conditions	Prim-25		epithalamus	ISH	Fig. 1
cxcr4b	neurog1^{hi1059Tg/hi1059Tg} + MO1-neurod4	standard conditions	Prim-25		epithalamus	ISH	Fig. 1
cxcr4b	pax6b^sa86/sa86	standard conditions	Prim-25		epithalamus	ISH	Fig. 2
cxcr4b	pax6b^sa86/sa86 + MO5-pax6a	standard conditions	Prim-25	Not Detected	epithalamus	ISH	Fig. 2
cxcr4b	smo^{hi229Tg/hi229Tg}	standard conditions	Prim-25	Not Detected	epithalamus	ISH	Fig. 4
cxcr4b	smo^{hi229Tg/hi229Tg}	standard conditions	Prim-25		eye	ISH	Fig. 4
cxcr4b	WT	standard conditions	Prim-25		epithalamus	ISH	Fig. 4
cxcr4b	WT	standard conditions	Prim-25		epithalamus	ISH	Fig. 1
cxcr4b	WT	standard conditions	Prim-25		epithalamus	ISH	Fig. 2
cxcr4b	WT	control	14-19 somites		epithalamus	ISH	Fig. 5

1 - 10 of 60

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Phenotype

Fish	Conditions	Stage	Phenotype	Figure
WT	chemical treatment by environment: Cyclopamine	14-19 somites	epithalamus cxcr4b expression absent, abnormal	Fig. 5
WT	chemical treatment by environment: Cyclopamine	14-19 somites	epithalamus pou4f1 expression absent, abnormal	Fig. 5
WT	chemical treatment by environment: Cyclopamine	14-19 somites	habenula development delayed, abnormal	Fig. 5
WT	chemical treatment by environment: Cyclopamine	20-25 somites	epithalamus cxcr4b expression decreased amount, abnormal	Fig. 5
WT	chemical treatment by environment: Cyclopamine	20-25 somites	epithalamus pou4f1 expression decreased amount, abnormal	Fig. 5
WT	chemical treatment by environment: Cyclopamine	20-25 somites	habenula development delayed, abnormal	Fig. 5
WT	chemical treatment by environment: Cyclopamine	Prim-5	epithalamus cxcr4b expression decreased amount, abnormal	Fig. 5
WT	chemical treatment by environment: Cyclopamine	Prim-5	epithalamus pou4f1 expression decreased amount, abnormal	Fig. 5
WT	chemical treatment by environment: Cyclopamine	Prim-5	habenula development delayed, abnormal	Fig. 5
WT	chemical treatment by environment: Cyclopamine	Prim-25	habenula development disrupted, abnormal	Fig. 6

1 - 10 of 20

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Mutations / Transgenics

Allele	Construct	Type	Affected Genomic Region
b641		Point Mutation	smo
hi229Tg	Tg(F5)	Transgenic Insertion	smo
hi1059Tg	Tg(nLacz-GTvirus)	Transgenic Insertion	neurog1
knu3Tg	Tg(elavl3:EGFP)	Transgenic Insertion
sa86		Point Mutation	pax6b
sb1Tg	Tg(-8.4neurog1:GFP)	Transgenic Insertion
tbx392		Point Mutation	shha

1 - 7 of 7

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Human Disease / Model

Sequence Targeting Reagents

Target	Reagent	Reagent Type
neurod4	MO1-neurod4	MRPHLNO
neurod4	MO2-neurod4	MRPHLNO
pax6a	MO5-pax6a	MRPHLNO

Fish

Fish
knu3Tg
neurog1^{hi1059Tg/hi1059Tg}
neurog1^{hi1059Tg/hi1059Tg} + MO1-neurod4
pax6b^sa86/sa86
pax6b^sa86/sa86 + MO5-pax6a
sb1Tg
shha^{tbx392/tbx392}
smo^{hi229Tg/hi229Tg}
WT
WT + MO1-neurod4

Antibodies

Name	Type	Antigen Genes	Isotypes	Host Organism
Ab1-elavl	monoclonal	elavl3 elavl4	IgG2b	Mouse

Orthology

Engineered Foreign Genes

Marker	Marker Type	Name
EGFP	EFG	EGFP
GFP	EFG	GFP

Mapping

Halluin et al., 2016 ZDB-PUB-160709-12 PMID:27387288

Habenular Neurogenesis in Zebrafish Is Regulated by a Hedgehog, Pax6 Proneural Gene Cascade

Halluin et al., 2016

ZDB-PUB-160709-12
PMID:27387288