Generation and Initial Characterization of a c-KIT Cre-ERT2 Mouse Model
F Nagl, G Schneider, B Seidler, RM Schmid, D Saur. University of Tuebingen, Tuebingen, Germany; Technical University Munich, Munich, Germany
Background: The receptor tyrosine kinase c-KIT is physiologically expressed in embryonic and haematopoetic stem cells, eosinophilic granulocytes, melanocytes and interstitial cells of Cajal (ICCs). c-KIT is essential in hematopoiesis and germ cell evolution. In the GI tract, only mast cells and ICCs express the c-KIT receptor. The ICCs are responsible for generating slow wave motility. They are in close vicinity to the smooth muscle cells of the lamina muscularis propria and to the inhibitory and excitatory neurons. Mice with a diminished number of ICCs show a reduced NO dependent neurotransmission. This observation and their close vicinity to the enteric neurons and smooth muscle cells indicate that the ICCs are important for signal transduction in the GI tract.
Design: To obtain more information about the role and function of the ICCs, we generated a mouse model that expresses a tamoxifen activated cre-recombinase under the control of the c-KIT promoter (c-KIT Cre-ERT2). Thus a tissue and cell specific deletion of relevant genes (e.g. cGMP-dependent protein kinase type I (cGKI) known as downstream target of the NO signalling pathway) in c-KIT positive cells can be achieved. Because conventional c-KIT knock out mice (c-KIT W/W) die within the first days after birth, they are off limited usefulness for the investigation of ICCs. In our model specific genes can be influenced in a time and tissue specific manner to get more information about the role of ICCs in vivo.
Results: Here we show the successful tissue specific expression of the tamoxifen activating Cre-recombinase under the control of the c-KIT promoter using the pCAGGS-Promoter- lox-Lac-Z 3xpA-lox EGFP (Z/EG) reporter gene mouse model and the Rosa26+/LacZ reporter gene mouse model.
Conclusions: To prove that a cell specific cre-recombinase expression in the nucleus of c-KIT positive cells is present c-Kit Cre-ERT2 mice were crossbred with Z/EG reporter gene mice and the Rosa26+/LacZ reporter gene mice. After tamoxifen induced activation of the cre-recombinase a cell specific reporter-gene expression could be detected by confocal laser microscopy, confocal endo-microscopy and conventional light microscopy. Thus, this animal model established at the Department of Internal Medicine II of the Technical University of Munich is suitable for further studies of the role of ICCs in GI-motility and development of GISTs. To our knowledge this is the first mouse model expressing a tamoxifen activating cre-recombinase in ICCs.
Wednesday, March 11, 2009 9:30 AM
Poster Session V # 91, Wednesday Morning