( Iezzi M Kouri G Fukuda M ...)Your Data: Use of pSilencer 1.0-U6 siRNA Expression Vector in the Analysis of Synaptotagmin Location and Function

In a recently published paper in the Journal of Cell Science, Iezzi and colleagues used Ambions siRNA target finder and the pSilencer 1.0-U6 vector in an extensive study to investigate synaptotagmin location and function in rat pancreatic islets and in the clonal β cell line INS-1E. Synaptotagmins (Syts) are a family of proteins involved in Ca²⁺-triggered exocytosis (Chapman, 2002; Sdhof, 2002) of which vertebrates express at least 15 isoforms (Sdhof & Rizo, 1996; Rickman et al., 2004). Insulin exocytosis from pancreatic β cells is a Ca²⁺-dependent secretory process. However, previous studies have shown conflicting results as to which Syt isoform is present on the secretory granules in the native β cell. Iezzi and colleagues investigated Syt V and Syt IX as Syt V has been suggested to be one of the Ca²⁺ sensors for insulin exocytosis in the β cell (Gut et al., 2001). The involvement of Syt IX in insulin secretion was unclear at the time.

Western blotting and RT-PCR analysis revealed the presence of both Syt V and Syt IX in rat pancreatic islets and in INS-1E cells. The expression of Syt V was similar in the islets and in the cell lines, while Syt IX was expressed less in the rat pa
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