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Title: PBC and MEIS class genes in the planarian Schmidtea mediterranea
Author: Felix, Daniel André
ISNI:       0000 0004 2743 4300
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2011
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Planarians have outstanding regenerative capabilities which depend on the presence of a pool of somatic stem cells. In addition planarians keep perfect proportion of the body while degrowing during starvation. While the establishment and maintenance of the anteroposterior (AlP) axis has been shown to depend on Wnt and Hedgehog signalling, not much is known about the subsequent patterning events. PBC and MEIS class genes are evolutionary conserved TALE homeobox genes with important functions in patteming and cell differentiation. They are well known co-factors of the Hox genes however they also have other Hox-independent functions. The aim of this study was to identify the planarian orthologs of the PBC and MEIS class genes and to examine their putative role in anteroposterior patteming. Here one PBC class gene, Smed-pbx, and the three MEIS class genes Smed-meis I , Smed-meis2 and Smed-prep were identified and orthology established through phylogenetic analyses. Smed-prep was found to define the cephalic area in which the anterior structures are formed, most prominently the brain. In anterior regenerating Smed-prep(RNAi) worms a reduction or even complete absence of the brain and anterior markers was observed. Importantly, the differentiation of stem cells into nerve cells was shown not to be dependent on Smed-prep. In step with its function the Smed-prep gene was found to have an anteroposterior bias in expression, being highly expressed in the head. While both Smed-meis genes were found to be important for regeneration and maintenance of the eyes and for the adaptation of the body to the new size of the animal after amputation, Smed-pbx was found to have pleiotropic functions, phenocopying aspects of all three MEIS class genes upon RNAi interference, and also producing additional phenotypes. This study has found that the four planarian orthologs of PBC and MEIS class genes are important players in regeneration. Two genes, Smed-pbx and especially Smed-prep, have been found to be necessary for anteroposterior patterning. This is the first time that a homeobox transcription factor has been directly implicated in anteroposterior patterning in planarians.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available