The three members of the protein kinase D (PKD) family, PKD1-3, have been identified as serine/threonine kinases with functions in fundamental cellular processes as diverse as adhe- sion and motility, proliferation and differentiation, membrane and protein trafficking, regula- tion of gene expression, apoptosis, and oxidative stress signaling. Numerous in vitro studies addressed cell context dependent activation and functional principles of the PKD isoforms. Thus, the molecular mechanisms of PKD regulation and functions are well understood today. However, research about the role of PKD family members in vivo is still in its infancy. Due to its structural characteristics PKD3 is supposed to play a unique role among the three isoforms. In this study, the expression pattern of PKD3 during mouse development was in- vestigated by immunohistochemistry. The expression is differentially regulated throughout early embryogenesis and organogenesis. Compared to other isoforms PKD3 is expressed more ubiquitously, implicating distinct and non-redundant functions within the PKD family. To further elucidate the potential role of PKD in vivo, transgenic mice overexpressing domi- nant-negative PKD mutants in an inducible and tissue specific manner were generated. Sev- eral transgenic lines for each of the three isoforms were established, genetically characterized and analyzed concerning transgene inducibility, expression level, biodistribution, and subcel- lular localization. For PKD1 and PKD2 transgenic lines were identified to facilitate a consider- able overexpression of dominant-negative PKD compared to endogenous PKD, which is re- quired to create a “functional knockout”. To identify potential phenotypes provoked by skeletal muscle-specific transgene expression the response of mice to voluntary wheel running was studied. The running performance of mice expressing dominant-negative PKD1 was significantly decreased compared to control mice. Analysis of skeletal muscle fiber type composition after voluntary wheel running re- vealed that exercise-induced muscle remodeling was blocked in animals with transgene ex-
د محمد محمود محمد عبد الفتاح | DR MOHAMMAD MAHMOUD MOHAMMAD ADEL FATAH | 9765