| Summary: | 碩士 === 國立臺灣大學 === 分子與細胞生物學研究所 === 94 === Recent studies in our lab have revealed the pro-apoptotic function of dapk-1 during programmed cell death. To understand how dapk-1 acts in programmed cell death, we performed structure-function analysis of dapk-1. Like its human homolog DAPk, DAPK-1 contains multiple domains including kinase domain, ankyrin repeats, and death domain. We found that kinase and death domains of DAPK-1 are required for its pro-apoptotic function. To our knowledge, this is the first evidence showing the involvement of death domain in C. elegans programmed cell death, implying the potential role of an extrinsic cell death pathway. Taking a candidate gene approach, we showed that the netrin receptor unc-5 might be the death receptor acting in the DAPK-1 mediated extrinsic cell death pathway. Other regions such as cytoskeleton binding region is dispensable and ankyrin repeats are not absolutely necessary for DAPK-1 pro-apoptotic function. This result is distinct from the previous finding that these regions are required for the apoptosis-promoting activity of human DAPk. More complicatedly, human DAPk is also known as a positive mediator of autophagy, implying the potential interplay of apoptotic and autophagic pathways. Therefore, we tried to include the autophagic genes in C. elegans programmed cell death. In this study we observed that autophagic genes such as bec-1 and unc-51 bring inhibitory effects to C. elegans programmed cell death and at least some bec-1 mediated cell deaths do not require egl-1. Moreover, from double-mutant analysis we found that in addition to developmentally regulated cell death, dapk-1 may also mediate autophagy-dependent cell death.
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