三种内吞基序的不同亚群靶向介导透明质酸和肝素的HARE介导的内吞作用。
HARE-Mediated Endocytosis of Hyaluronan and Heparin Is Targeted by Different Subsets of Three Endocytic Motifs.
作者信息
Pandey Madhu S, Harris Edward N, Weigel Paul H
机构信息
Department of Biochemistry & Molecular Biology, Penn State Hershey College of Medicine, Hershey, PA 17033, USA.
Department of Biochemistry, University of Nebraska, Lincoln, NE 68588, USA.
出版信息
Int J Cell Biol. 2015;2015:524707. doi: 10.1155/2015/524707. Epub 2015 Mar 25.
The hyaluronan (HA) receptor for endocytosis (HARE) is a multifunctional recycling clearance receptor for 14 different ligands, including HA and heparin (Hep), which bind to discrete nonoverlapping sites. Four different functional endocytic motifs (M) in the cytoplasmic domain (CD) target coated pit mediated uptake: (YSYFRI(2485) (M1), FQHF(2495) (M2), NPLY(2519) (M3), and DPF(2534) (M4)). We previously found (Pandey et al. J. Biol. Chem. 283, 21453, 2008) that M1, M2, and M3 mediate endocytosis of HA. Here we assessed the ability of HARE variants with a single-motif deletion or containing only a single motif to endocytose HA or Hep. Single-motif deletion variants lacking M1, M3, or M4 (a different subset than involved in HA uptake) showed decreased Hep endocytosis, although M3 was the most active; the remaining redundant motifs did not compensate for loss of other motifs. Surprisingly, a HARE CD variant with only M3 internalized both HA and Hep, whereas variants with either M2 or M4 alone did not endocytose either ligand. Internalization of HA and Hep by HARE CD mutants was dynamin-dependent and was inhibited by hyperosmolarity, confirming clathrin-mediated endocytosis. The results indicate a complicated relationship among multiple CD motifs that target coated pit uptake and a more fundamental role for motif M3.
用于内吞作用的透明质酸(HA)受体(HARE)是一种多功能循环清除受体,可识别14种不同的配体,包括HA和肝素(Hep),它们与不同的非重叠位点结合。细胞质结构域(CD)中的四种不同功能的内吞基序(M)靶向有被小窝介导的摄取:(YSYFRI(2485) (M1)、FQHF(2495) (M2)、NPLY(2519) (M3)和DPF(2534) (M4))。我们之前发现(Pandey等人,《生物化学杂志》283, 21453, 2008)M1、M2和M3介导HA的内吞作用。在此,我们评估了单基序缺失或仅包含单个基序的HARE变体对内吞HA或Hep的能力。缺乏M1、M3或M4(与参与HA摄取的基序不同的子集)的单基序缺失变体显示Hep内吞作用降低,尽管M3最活跃;其余的冗余基序无法补偿其他基序的缺失。令人惊讶的是,仅具有M3的HARE CD变体可内化HA和Hep,而仅具有M2或M4的变体则不能内吞任何一种配体。HARE CD突变体对HA和Hep的内化作用依赖于发动蛋白,并且受到高渗的抑制,证实了网格蛋白介导的内吞作用。结果表明,靶向有被小窝摄取的多个CD基序之间存在复杂的关系,并且基序M3具有更重要的作用。