| Summary: | 碩士 === 國立陽明大學 === 微生物及免疫學研究所 === 105 === Apoptosis is a process of programmed cell death, which helps our body to execute dysfunctional cells in immunologically “silent” way. During positive and negative selection in the thymus, our body eliminates T cells that could attack our own tissues. Biochemical events lead to characteristic changes in cell morphology during apoptosis. Phosphatidylserine (PS) is an important phospholipid membrane component, which is exposed to the outer leaflet of the plasma membrane on the surface of apoptotic cells. In addition to serving as a marker for apoptosis, PS also acts as a signal for macrophages to engulf the cells (“eat-me” signal). The ‘eat-me’ signal PS is recognized by several different engulfment receptors on the phagocytes, which results in signaling events that facilitate uptake of the apoptotic cellular corpse. Most of the knowledge of apoptosis comes from in vitro studies, however, the progression of apoptosis especially in presence of phagocytes in vivo is still unclear. We developed a method for observation of apoptosis events in mouse model by using secreted Annexin V-mVenus fusion protein. In addition to reporting PS externalization – an early marker of apoptosis, this fluorescent protein also prevents its recognition by PS receptors. We found that PS blocking affects phagocytosis in thymus and spleen both in vitro and in vivo.
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