Regulation of multiple functions of SHPS-1, a transmembrane glycoprotein, by its cytoplasmic region.
SHPS-1 is a receptor-type transmembrane glycoprotein, which contains four tyrosine residues in its cytoplasmic region, and the phosphorylation of these tyrosine residues serves the binding sites for SHP-2 protein-tyrosine phosphatase. Its extracellular region interacts with another membrane protein, CD47, thereby constituting a cell-cell communication system. We analyzed this ligand-receptor interaction using Chinese hamster ovary (CHO) cells expressing wild-type (WT) or mutant SHPS-1. The binding affinity of an SHPS-1 mutant such as deltaCyto, that lacked most of cytoplasmic region, or 4F, in which all four tyrosine residues in cytoplasmic region were substituted with phenylalanine, for a recombinant CD47-Fc was greater than that of WT. In addition, oligomerization of deltaCyto or 4F mutant by binding of CD47-Fc was greater than WT. Chemical cross-linking of SHPS-1 indicated that SHPS-1 formed a cis-dimer. Furthermore, WT cells exhibited a less polarized cell shape with decreased formation of actin stress fibers, compared with parental CHO cells and mutant SHPS-1 expressing cells. Prominent lamellipodium formation and membrane ruffling were also observed at leading edges of migrating WT cells but not at those of other mutant SHPS-1 expressing cells. These results suggest that the binding affinity of SHPS-1 to CD47, clustering ability of SHPS-1, and cytoskeletal reorganization are regulated by the cytoplasmic region of SHPS-1.
Sato
Ryuji
R
Biosignal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-Machi, Maebashi, Gunma 371-8512, Japan.
Ohnishi
Hiroshi
H
Kobayashi
Hisae
H
Kiuchi
Daisuke
D
Hayashi
Akiko
A
Kaneko
Yuka
Y
Honma
Nakayuki
N
Okazawa
Hideki
H
Hirata
Yukio
Y
Matozaki
Takashi
T
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D000943:Antigens, Differentiation; D051928:CD47 Antigen; D016466:CHO Cells; D002352:Carrier Proteins / Q000378:metabolism; D048429:Cell Size; D006224:Cricetinae; D003599:Cytoskeleton / Q000648:ultrastructure; D011905:Genes, ras; D008024:Ligands; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D039842:Neural Cell Adhesion Molecule L1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011971:Receptors, Immunologic
D015703:Antigens, CD; D000943:Antigens, Differentiation; D051928:CD47 Antigen; D002352:Carrier Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D039842:Neural Cell Adhesion Molecule L1; D011971:Receptors, Immunologic