Muscle stem cells in the zebrafish

We are interested in the role of satellite cells, the stem cells of muscle, during development and regeneration using zebrafish as a model system. In vertebrates, satellite cells are a source for muscle during development as well as regeneration. We find the transcription factors Pax7, known to mark satellite cells in other vertebrate models, expressed in cells located at the myotome borders in developing zebrafish larvae.

muscle fibres

Preliminary results show that these cells do contribute to muscle during regeneration. Our current research comprises several approaches:

By the incorporation of BrdU in combination with mitotic markers we will analyse the stem cell character of the identified cell type under developmental versus regenerative conditions.

The generation of transgenic fish expressing fluorescent proteins under the control of pax7 promoters (in progress) will open the opportunity to follow these cells in living animals under normal and regenerative conditions. Additionally, it will allow the profiling of gene expression of sorted fluorescent stem cells under various conditions.

As zebrafish mutants are not available, we applied the reverse genetic approach TILLING and identified a frameshift mutation in the pax7 gene. We will analyse the mutant phenotypes under developmental and regenerative conditions. Additionally, we are establishing biochemical experiments to identify Pax7-target genes and interactors.

We participated in the large-scale genetic screen 2005-2006 with the aim to isolate mutants showing changes in Pax7 antibody staining and/or patterning of satellite cells. Although we could not find mutants where Pax7 positive cells at the myotome borders are absent, several mutants do show aberrant satellite cell morphology. Currently, we are in the process of evaluating these mutants.

• Dr. Jana Krauß                                                Postdoc (01/04 - )

• Soeren Alsheimer                                           PhD student (07/06 - )
• Andrey Fadeev                                                 PhD student (01/10 - )
• Pantelis Astrinidis                                           Diploma student (12/09 - )
  

• Christian Weiler                                               Technician