Apoptotic cells are rapidly engulfed and degraded by phagocytes through efferocytosis. Efferocytosis is a highly regulated process. It is triggered upon the activation of caspase-dependent apoptosis, which in turn promotes the expression of “eat me” signals on the surface of dying cells and the release of soluble “find me” signals for the recruitment of phagocytes. To date, many “eat me” signals have been recognized, including phosphatidylserine (PS), intercellular adhesion molecule-3, carbohydrates (e.g., amino sugars, mannose) and calreticulin. Among them, PS is the most studied one. PS recognition receptors are different functionally active receptors expressed by phagocytes. Various PS recognition receptors with different structure, cell type expression, and ability to bind to PS have been recognized. Although PS recognition receptors do not fall into a single classification or family of proteins due to their structural differences, they all share the common ability to activate downstream signaling pathways leading to the production of anti-inflammatory mediators. In this review, available evidence regarding molecular mechanisms underlying PS recognition receptor-regulated clearance of apoptotic cells is discussed. In addition, some efferocytosis-independent biological functions of PS recognition receptors are reviewed.

中文翻译：

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磷脂酰丝氨酸识别受体在多种生物学功能中的作用

凋亡细胞通过胞吞作用被吞噬细胞迅速吞噬和降解。胞吞作用是一个高度调控的过程。它是在半胱天冬酶依赖性细胞凋亡激活时触发的，进而促进垂死细胞表面“吃我”信号的表达，并释放可溶性“找到我”信号以招募吞噬细胞。迄今为止，许多“吃我”信号已被识别，包括磷脂酰丝氨酸（PS）、细胞间粘附分子3、碳水化合物（例如氨基糖、甘露糖）和钙网蛋白。其中，PS是研究最多的一种。PS识别受体是吞噬细胞表达的不同功能活性受体。具有不同结构、细胞类型表达和与PS结合的能力的各种PS识别受体已被识别。尽管 PS 识别受体由于其结构差异而不属于单一类别或蛋白质家族，但它们都具有激活下游信号传导途径从而产生抗炎介质的共同能力。在这篇综述中，讨论了有关 PS 识别受体调节的凋亡细胞清除的分子机制的现有证据。此外，还回顾了 PS 识别受体的一些与胞吞作用无关的生物学功能。