2026-11-092026-11-09https://scholars.csmu.edu.tw/handle/123456789/38038Multiple factors have been implicated in the pathogenesis of autoimmune diseases; however, the underlying mechanisms are still obscure. Failure in the clearance of apoptotic cells has been suggested to be involved in the development of autoimmune diseases, especially systemic lupus erythematosus (SLE). This hypothesis is supported by observations that apoptotic cells are accumulated in the germinal center of the lymph nodes in patients with SLE. Likewise, transgenic mice defective in the removal of apoptotic cells develops lupus-like symptoms. Elimination of apoptotic cells is obligatory for tissue homeostasis, and certainly important to avoid unwanted inflammatory responses. This safeguard function is accomplished by proper interactions between apoptotic cells and phagocytes. Apoptotic cells release “come-get-me” signals to attract phagocytes. When they come close, the “eat-me” signals displayed on the surface of dying cells are recognized by phagocytes, triggering the uptake of apoptotic cells. A specific set of receptors on phagocytes is responsible for interacting with apoptotic cells, and this interaction induces the subsequent immunosuppresion. Transglutaminases are a family of proteins that catalyze a Ca+2-dependent transamidating reaction, resulting in protein crosslinking or incorporation of polyamines into protein substrates. Transglutaminse 2 (TG2), also named as tissue transglutaminase (tTG), is distinct from other members of this family as it possesses GTPase and ATPase activity and functions as a signaling molecule (Ghα). In addition, TG2 can exert a variety of functions, including cell adhesion and spreading, angiogenesis, transmigration and apoptosis. A recent study revealed that TG2-/- mice developed autoantibodies and immune complex glomerulonephritis, and their macrophages are impaired to engulf apoptotic cells. These observations strongly suggest that deregulation of TG2 might play a role in the pathogenesis of SLE. Thus, we aim to study the role of TG2 in the clearance of apoptotic cells in this project. We will start with the examination of TG2 expression, activity and localization in cells derived from the lupus-prone MRLlpr/lpr and (NZB x NZW)F1 mice and their counterparts followed by assessment of the phagocytic ability of macrophages, in order to establish a correlation of TG2 expression with macrophage phagocytosis as well as disease progression. To further define the role of TG2, we will manipulate TG2 expression, activation and localization in apoptotic cells or phagocytes by transfection with various constructs, and examine their effects on the uptake of apoptotic cells. Lastly, we wish to identify more potential targets of TG2 since TG2-mediated protein modification might generate new antigens responsible for SLE. A proteomic approach will be used to identify these targets. Follow-up studies on the possibility that these modified proteins interact with autoantibodies will be conducted. Our studies will thus bring insight into the mechanisms for the pathogenesis of SLE. It also helps for designing strategies for treatment.自體免疫疾病是由多重因子所造成，然而其致病機轉仍不是很清楚。不良於清除凋亡細 胞被認為與自體免疫疾病的發生有關，尤其是紅斑性狼瘡。因為曾在此類病人淋巴結中發現 有死細胞的堆積。此外，清除功能有缺陷的基因轉殖鼠亦被證實產生類似紅斑性狼瘡的症狀。 移除凋亡細胞可以維持組織的恆定，並防止不必要的發炎反應。這個功能是藉由凋亡細 胞與吞噬細胞的交互作用而達成。死細胞釋放出“come-get-me”的訊號以吸引吞噬細胞的靠 近，並在其細胞表面呈現出“eat-me” 的訊號以便吞噬細胞的辨識，進而誘發其吞噬作用移除 死細胞。吞噬細胞亦具備特殊的受體接收這些訊號並將其傳入細胞內引起免疫抑制的反應。 轉麩胺脢族（Transglutaminases）催化轉胺反應，造成蛋白的聚合（crosslinking）或多胺 類的嵌入。第二型轉麩胺脢（Transglutaminases 2）又稱為組織型轉麩胺脢，它與其他型不同 之處在於它另含GTPase 的活性，因而參與訊息傳遞。除此之外，第二型轉麩胺脢還能促進 細胞的黏附及展開、移動、血管生成及細胞凋亡。最近的一篇文獻指出第二型轉麩胺脢基因 剔除小鼠會產生自體抗體並出現血管球性腎炎的症狀，且其巨噬細胞無法正常地清除凋亡細 胞。這些結果顯示第二型轉麩胺脢的調控失常應與紅斑性狼瘡的致病機理有關。因此，在本 計劃中我們將探討第二型轉麩胺脢在清除凋亡細胞時所扮演的角色。 首先我們將檢測第二型轉麩胺脢在兩株易患狼瘡的小鼠MRLlpr/lpr 和(NZB x NZW)F1細 胞中的表現、活性及位置。而細胞對凋亡的敏感性和巨噬細胞的吞噬能力也將一一被檢驗， 以期了解第二型轉麩胺脢與細胞的吞噬能力、疾病進程是否有一相關性。接著，利用轉染的 方法我們將分別改變第二型轉麩胺脢在凋亡細胞或巨噬細胞中的表現、活性及位置，並檢測 其對巨噬細胞吞噬凋亡細胞的影響。第二型轉麩胺脢的作用可對蛋白分子產生修飾，並可能 因此成為新的抗原。所以我們最後將以蛋白體分析的方法找尋第二型轉麩胺脢的受質，並檢 測其經第二型轉麩胺脢作用後與紅斑性狼瘡病人血清作用之情形。我們相信這個研究將有助 於對紅斑性狼瘡的了解，並提供未來治療此病的可能方向。Project