唾液酸酶(或神经氨酸酶)催化含唾液酸(Sia)分子的水解,主要是去除糖蛋白或糖脂的聚糖上的末端Sia(去唾液酸化)。因此,唾液酸酶可以调节靶糖蛋白或糖脂的功能,并且参与健康和疾病中的各种生物学途径。在哺乳动物细胞中,唾液酸酶有四种,根据它们的亚细胞位置和底物特异性,它们是Neu1、Neu2、Neu3和Neu4。Neu1是溶酶体唾液酸酶,Neu2是细胞溶质唾液酸酶,Neu3是质膜相关唾液酸酶,Neu4在溶酶体中发现,线粒体,和内质网。除了特定的亚细胞位置,唾液酸酶可以在特定的细胞条件和刺激下转移到不同的亚细胞定位,从而根据其基因座参与不同的细胞功能。溶酶体唾液酸酶Neu1可以在几种细胞类型的细胞激活后转移到细胞表面,包括免疫细胞,血小板,内皮细胞,和上皮细胞,它去唾液酸化受体,从而影响受体激活和信号传导。另一方面,细胞在激活时分泌唾液酸酶。分泌的唾液酸酶可以作为细胞外唾液酸酶,并导致细胞外糖蛋白或糖脂和细胞表面糖蛋白或糖脂在其自身和其他细胞上的去唾液酸化。从而在各种生物途径中发挥作用。这篇综述讨论了唾液酸酶在不同细胞中的易位和在不同条件下从不同细胞分泌以及它们参与生理和病理途径的最新进展和理解。
Sialidases (or neuraminidases) catalyze the hydrolysis of sialic acid (Sia)-containing molecules, mostly the removal of the terminal Sia on glycans (desialylation) of either glycoproteins or glycolipids. Therefore, sialidases can modulate the functionality of the target glycoprotein or glycolipid and are involved in various biological pathways in health and disease. In mammalian cells, there are four kinds of
sialidase, which are Neu1, Neu2, Neu3, and Neu4, based on their subcellular locations and substrate specificities. Neu1 is the lysosomal
sialidase, Neu2 is the cytosolic
sialidase, Neu3 is the plasma membrane-associated
sialidase, and Neu4 is found in the lysosome, mitochondria, and endoplasmic reticulum. In addition to specific subcellular locations, sialidases can translocate to different subcellular localizations within particular cell conditions and stimuli, thereby participating in different cellular functions depending on their loci. Lysosomal
sialidase Neu1 can translocate to the cell surface upon cell activation in several cell types, including immune cells, platelets, endothelial cells, and epithelial cells, where it desialylates receptors and thus impacts receptor activation and signaling. On the other hand, cells secrete sialidases upon activation. Secreted sialidases can serve as extracellular sialidases and cause the desialylation of both extracellular glycoproteins or glycolipids and cell surface glycoproteins or glycolipids on their own and other cells, thus playing roles in various biological pathways as well. This review discusses the recent advances and understanding of
sialidase translocation in different cells and secretion from different cells under different conditions and their involvement in physiological and pathological pathways.