| Summary: | 碩士 === 國立成功大學 === 生物化學研究所 === 99 === Pore-Forming toxins(PFTs) are bacterial toxins that form holes at the plasma membrane of cells and play important roles in the pathogenesis of many important human pathogens. Crystal(Cry) toxin is one type of the PFTs produced by Bacillus thuringiensis(Bt), and is also the most widely used natural insecticides in agriculture for many decades. It has been reported that C. elegans and other nematodes can be intoxicated and killed by the three-domain Bt Cry toxins, including Cry5B in this study.
Characterizations of the mode of action of Cry5B in C. elegans may pave the way for understanding the PFT-host interactions in vivo.
From our previous microarray data, we found significant transcriptional upregulation of the sir-2.3 gene after Cry5B treatment in
C. elegans. SIR-2.3 is a member of the SIR2 family proteins with a NAD-dependent histone deacetylase activity. We have demonstrated that DAF-2 insulin-like signaling pathway was important for the intrinsic
cellular defense against PFTs. Interestingly, it has been reported that the mammalian SIR-2.3 homolog, SIRT4, can also inhibit the insulin secretion in pancreatic ? cells. Our current data suggested that sir-2.3 and daf-2 all function in Cry5B intoxication, and we also analyzed the
interaction between these two genes.
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