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Identification and characterisation of three novel eyes absent genes in the cranial sensory placodes, the developing inner ear and lateral line in the zebrafish Danio rerio

Formella, Isabel :
Identification and characterisation of three novel eyes absent genes in the cranial sensory placodes, the developing inner ear and lateral line in the zebrafish Danio rerio.
TU Darmstadt
[Ph.D. Thesis], (2008)

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Item Type: Ph.D. Thesis
Title: Identification and characterisation of three novel eyes absent genes in the cranial sensory placodes, the developing inner ear and lateral line in the zebrafish Danio rerio
Language: English
Abstract:

Sequence analyses of the zebrafish eya2, eya3 and eya4 proteins have revealed two highly conserved domains; the eya homology region (eyaHR) and eya domain 2 (ED2). Moreover all three eya proteins contain sequence motifs equivalent to the family of phosphohydrolases, recently described for mouse Eya proteins by LI (2003) and RAYAPUREDDI (2003). Therefore zebrafish eya 2-4 proteins function as transcriptional co-factors which possess protein phosphatase activity. As a first step towards a functional analysis of the eya gene during sensory organ development, the expression patterns of the three zebrafish eya genes were analysed and compared. Expression pattern analysis was carried out by RNA in situ hybridisation. Both eya2 and eya4 are expressed in distinct patches within the cranial placodes and their derivates, otic vesicle, and in the neuromasts of the lateral line system. Eya2 expression is observed in the several cranial placodes and their cranial ganglia. Eya4 transcripts are found in some of the corresponding cranial ganglia and in developing somites. The significance and biological relevance of this observation is tested by overexpression experiments and the analysis of gene knock-down experiments by using in vitro synthesised eya1, eya2, and eya4 mRNA as well as antisense eya2 and eya4 Morpholino oligonucleotides respectively. Ectopically upregulated function of eya1, eya2 and eya4 revealed a reduced level of apoptosis-mediated cell death, while the loss-of-function of eya2 and eya4 triggers programmed cell death. These results maintain the idea of apoptosis affective activity, which was described for the loss-of-function for eyes absent in Drosophila, zebrafish (eya1/dor-eared) and mouse(Eya1-/-), as a general function of eya gene relatives.

Alternative Abstract:
Alternative AbstractLanguage
Sequenzanalysen der Zebrafisch Transkriptionsfaktoren eya2, eya3 und eya4 zeigten zwei hoch konservierte Funktionsdomänen, die eya Homologie Region (eyaHR) und die eya Domäne 2 (ED2). Zudem beinhalten alle der drei eya Gene einen weiteren konservierten Sequenzabschnitte, ein Äquivalent der Phosphohydrolase Familien. Damit wirken diese Proteine nicht nur als Transcriptionsaktivatoren sondern besitzen zusätzlich Phosphataseaktivität. Expressionsmusteranalysen der eya Proteine anhand von in situ Hybridisierungen zeigten distinkte Expression sowohl für eya 2 als auch für eya4 während der frühen embryonalen Entwicklung in den cranial sensorischen Plakoden sowie deren Derivate, dem otischen Vesikel und den Neuromasten des Seitenliniensystems. Eya2 Expression wurde beobachtet in verschiedenen cranialen Plakoden sowie Ganglien, während eya4, mit Ausnahme der otischen Plakode ausschließlich in differenzierten Ganglien und den Somiten transkribiert wird. Funktionale Analysen durch die Überexpression in vitro synthetisierter eya1, eya2 und eya4 mRNA sowie Morpholino knock-down Versuche zeigten, dass bei dem Verlust der Funktion von eya Genen die Apoptoseaktivität steigt, ektopische eya Expression reduziert die Anzahl toter Zellen durch programmierten Zelltod. Für Drosophila, Zebrafisch (eya1/dog-eared Mutante) und Mause (Eya1-/-) wurde gezeigt, dass der Verlust der Funktion von eya zu erhöhter Apoptose führt. Die hier gezeigten Daten unterstützen die Hypothese, dass eya Gene bei der Kontrolle der apoptotische Aktivität der Zelle eine wichtige Rolle spielen.German
Uncontrolled Keywords: apoptosis, ear, eya, lateral line, placodes, zebrafish
Alternative keywords:
Alternative keywordsLanguage
apoptosis, ear, eya, lateral line, placodes, zebrafishEnglish
Classification DDC: 500 Naturwissenschaften und Mathematik > 590 Tiere (Zoologie)
500 Naturwissenschaften und Mathematik > 570 Biowissenschaften, Biologie
Divisions: Biology
Date Deposited: 17 Oct 2008 09:22
Last Modified: 07 Dec 2012 11:53
URN: urn:nbn:de:tuda-tuprints-9861
License: Creative Commons: Attribution-Noncommercial-No Derivative Works 3.0
Referees: Layer, Prof. Dr. Paul G. and Thiel, Prof. Dr. Gerhard
Refereed: 23 May 2008
URI: http://tuprints.ulb.tu-darmstadt.de/id/eprint/986
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