19-P041 The role of IP3 signalling during embryonic wound healing in Xenopus

MECHANISMS OF DEVELOPMENT

1 2 6 ( 2 0 0 9 ) S 2 9 1 –S 3 0 4

S303

ing that neural progenitor cells reverse their fate. Finally, we found

growing evidence suggest that endothelial precursor cells (EPCs)

signaling molecules expressed in the 500 lm zone, which shows

present in the circulating blood express vascular markers such

complemented pattern from the down regulation of the neural pro-

Flk-1 and Tie2 and can lead to vasculogenesis in adults. In

genitor markers.

order to explore this possibility, we have begun to develop tools

doi:10.1016/j.mod.2009.06.828

tadpoles. We have several transgenic lines that label the vascu-

to analyze putative EPCs and vascular regeneration in Xenopus lature in living tadpoles (e.g., Tie2GFP and Flk1GFP lines). Interestingly we have found that both the Tie2GFP and the Flk1GFP 19-P041 The role of IP3 signalling during embryonic wound healing in Xenopus Ximena Soto, Enrique Amaya University of Manchester, Manchester, Lancashire, United Kingdom

transgenic lines contain a subset of GFP+ cells in the circulation. These labelled cells are also present within tissues and are highly migratory. By using FACS analysis we determinate that circulating Flk1 marked cells do not express lymphocytes markers such a CD8 and CD5. Real time PCR analysis of GFP+ sorted cells confirmed the expression of Flk-1 and shown expression of Tie2, Fli1 and CD45, suggesting an endothelial/

A major goal in regenerative medicine is to understand and

haematopoietic linage. We are now investigating whether these

ultimately facilitate our body’s ability to repair itself following

extra-vascular Flk1 and Tie2 positive cells may represent vascu-

injury. As a first step toward this goal, we have begun to investi-

lar progenitor cells and contribute to the regeneration of the

gate the molecular and cellular basis of embryonic wound heal-

vasculature in Xenopus tadpoles.

ing, given that embryos have the capacity to heal wounds quickly and completely. Tissue repair resembles embryo morpho-

doi:10.1016/j.mod.2009.06.830

genesis in several ways, including cell migration, proliferation and differentiation. In a screen for genes involved in morphogenesis in Xenopus, we identified an Ins(1,4,5)P3 phosphatase (IPP), which impairs embryonic wound healing, suggesting that IP3 signalling plays a role in this process. This finding has motivated us to investigate the role of IP3 signalling during embryonic wound healing, using Xenopus as a model system. Two sets of enzymes regulate this pathway, the IP3 kinases and IPPs. IPP, such as Ins(1,4,5)P3-5 phosphatase (IPP5), promote Ins(1,4)P2 generation,

19-P043 Investigations of muscle stem cells in the zebrafish Claudia Seger1, Phil W. Ingham2 1

Centre for Developmental and Biomedical Genetics, University of

Sheffield, Sheffield, United Kingdom 2

Institute of Molecular and Cell Biology, Singapore, Singapore

which is an inactive product, while IP3 kinases generate Ins(1,3,4,5)P4, which is involved in calcium release modulation.

Satellite cells contribute to the regeneration and growth of

We have cloned IP3 kinase-B and IPP5-A from Xenopus tropicalis

skeletal muscle upon injury and disease. Yet little is known the

and have begun to investigate theirs effects during embryonic

genetic programme controlling their formation, the maintenance

wound healing. By misexpressing IPP5-A we inhibited wound

of their quiescence, their activation, self-renewal and terminal

healing while IP3 kinase-B accelerated it during early develop-

differentiation. Identifying them and characterising their genetic

ment in embryonic wound healing assays. Opposite to this effect

profile in the zebrafish has many advantages due to the simple

knocking down IP3 kinase-B we inhibited wound healing. Finally,

embryology of this animal model and the ability to dissect com-

we are investigating the consequence of these manipulations on

plex molecular pathways. Further, the zebrafish’s optic clarity

the organization of the cytoskeleton such as analyzing microtu-

allows the use of cell labelling techniques to observe their

bules, tau2, or F-actin, moesin and phalloidin-rhodamine, and

movements.

investigating which pathways are modulated by IP3 signalling during wound healing.

The focus of this study is the identification of satellite cells in embryonic and adult zebrafish, based on morphological studies and on in situ hybridisation and antibody stainings of genes

doi:10.1016/j.mod.2009.06.829

shown to be expressed in satellite cells. Pax7 has been identified as a critical transcription factor for satellite cell biology as Pax-7 null mice lack satellite cells in all skeletal muscle groups exam-

19-P042 Isolation and characterization of putative endothelial progenitor cells in Xenopus Roberto Paredes, Nick Love, Enrique Amaya University of Manchester, Manchester, United Kingdom

ined [Seale et al., 2000]. We created Pax7:GFP and Pax3:GFP transgenic lines to follow satellite cells during development, injury and regeneration processes. Further we designed an injury model to confirm satellite cell identity by functional assessment. We monitored cell proliferation and the up-regulation of myogenic genes such as MyoD and Myf5 within candidate satellite cells after muscle injury by using proliferation markers and fluorescent protein

During tail regeneration in Xenopus, the major veins and arteries of the tadpole reform, a process more akin to vasculo-

lines. We have found that Pax7 is a potential marker of satellite cells and their progenitors.

genesis, which refers to the de novo formation of new blood vessels from angioblasts. Until recently, vasculogenesis was believed to be a process limited to embryogenesis. However,

doi:10.1016/j.mod.2009.06.831