| Summary: | 碩士 === 國立臺灣大學 === 分子與細胞生物學研究所 === 96 === Processing bodies (P-bodies) are specific cytoplasmic foci containing proteins involved in the 5’ to 3’ mRNA decay pathway. Some proteins involved in translational repression, mRNA quality control pathway and RNA-mediated gene silencing together with their mRNA targets are also localized to P-bodies. The components of P-bodies are highly conserved among yeast, human and Drosophila. In human cells, Hedls (Human enhancer of decapping large subunit) is a scaffold protein which interacts with human decapping protein 1 (hDcp1a) and human decapping protein 2 (hDcp2). Hedls promotes dDcp1a to enhance hDcp2 decapping activity.
The aim of this thesis is to analyze the developmental function of Drosophila Hedls, dHedls, in oogenesis.
A dHedls strong mutant allele, dHedlsH159, was recovered from P-element excision screen. dHedlsH159 is a homozygous lethal line. 12% of dHedlsH159 GLC embryos displayed mild posterior group embryonic defects. Osk protein was mislocalized in a scattered manner at the posterior of 15% dHedlsH159 GLC oocytes.
In S2 cells, dHedls was colocalized with P-bodies markers such as dDcp1 and dDcp2. During oogenesis, dHedls was colocalized with dDcp1 and dDcp2 in nurse cells and follicle cells. The above experiments indicated that dHedls is a component of Drosophila P-bodies. Morever, the numbers of dDcp1 and dDcp2-staining bodies were decreased in dHedls mutant background. Overexpression of dHedls increased the numbers of dDcp1 and dDcp2-staining bodies in nurse cell. Therefore, dHedls plays an important role in targeting dDcp1 and dDcp2 to cytoplasmic P-bodies of nurse cells during oogenesis.
Egg chambers of dHedlsH159 GLC (germline clone) displayed pleiotropic phenotypes. First, abnormal ovary morphology was visible. Second, the entire of nurse cell nuclei protruded into oocyte. Third, the multinucleated nurse cells were observed.
Cortical actin cytoarchitecture of oocyte was disrupted in follicle cells of dHedlsH159 mutant clones. Some mutant follicle cells proliferated abnormally. We proposed that dHedls maintains actin cytoskeleton and is required for normal cell cytokinesis.
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