a transgenic mouse line expressing cre recombinase in undifferentiated postmitotic mouse retinal bipolar cell precursors转基因小鼠行表达cre重组酶在未分化postmitotic老鼠视网膜双极细胞前体.pdfVIP

A Transgenic Mouse Line Expressing Cre Recombinase in Undifferentiated Postmitotic Mouse Retinal Bipolar Cell Precursors 1 1 1 2 3 Philip E. B. Nickerson , Kara Ronellenfitch , Jason McEwan , Howard Kim , Roderick R. McInnes , Robert L. Chow1* 1 Department of Biology, University of Victoria, Victoria, British Columbia, Canada, 2 Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada, 3 Lady Davis Research Institute, Department of Biochemistry, McGill University, Montreal, Quebec, Canada Abstract Approaches for manipulating cell type-specific gene expression during development depend on the identification of novel genetic tools. Here, we report the generation of a transgenic mouse line that utilizes Vsx2 upstream sequences to direct Cre recombinase to developing retinal bipolar cells. In contrast to the endogenous Vsx2 expression pattern, transgene expression was not detected in proliferating retinal progenitor cells and was restricted to post-mitotic bipolar cells. Cre immunolabeling was detected in rod bipolar cells and a subset of ON and OFF cone bipolar cells. Expression was first observed at postnatal day 3 and was detectable between 24 hours and 36 hours after the last S-phase of the cell cycle. The appearance of Cre-immunolabeled cells preceded the expression of bipolar cell type-specific markers such as PKCa and Cabp5 suggesting that transgene expression is initiated prior to terminal differentiation. In the presence of a constitutive conditional reporter transgene, reporter fluorescence was detected in Cre-expressing bipolar cells in the mature retina as expected, but was also observed in Cre-negative Type 2 bipolar cells and occasiona