Tetraspanin CD9 modulates ADAM17-mediated shedding of LR11 in leukocytes.
LR11, also known as SorLA or SORL1, is a type-I membrane protein from which a large extracellular part, soluble LR11 (sLR11), is released by proteolytic shedding on cleavage with a disintegrin and metalloproteinase 17 (ADAM17). A shedding mechanism is presumed to have a key role in the functions of LR11, but the evidence for this has not yet been demonstrated. Tetraspanin CD9 has been recently shown to regulate the ADAM17-mediated shedding of tumor necrosis factor-α and intercellular adhesion molecule-1 on the cell surface. Here, we investigated the role of CD9 on the shedding of LR11 in leukocytes. LR11 was not expressed in THP-1 monocytes, but it was expressed and released in phorbol 12-myristate 13-acetate (PMA)-induced THP-1 macrophages (PMA/THP-1). Confocal microscopy showed colocalization of LR11 and CD9 proteins on the cell surface of PMA/THP-1. Ectopic neo-expression of CD9 in CCRF-SB cells, which are LR11-positive and CD9-negative, reduced the amount of sLR11 released from the cells. In contrast, incubation of LR11-transfected THP-1 cells with neutralizing anti-CD9 monoclonal antibodies increased the amount of sLR11 released from the cells. Likewise, the PMA-stimulated release of sLR11 increased in THP-1 cells transfected with CD9-targeted shRNAs, which was negated by treatment with the metalloproteinase inhibitor GM6001. These results suggest that the tetraspanin CD9 modulates the ADAM17-mediated shedding of LR11 in various leukemia cell lines and that the association between LR11 and CD9 on the cell surface has an important role in the ADAM17-mediated shedding mechanism.
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Shokichi
S
Tsukamoto
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Masahiro
M
Takeuchi
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Takeharu
T
Kawaguchi
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Emi
E
Togasaki
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Atsuko
A
Yamazaki
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Yasumasa
Y
Sugita
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Tomoya
T
Muto
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan [3] Division of Transfusion Medicine and Cell Therapy, Chiba University Hospital, Chiba, Japan.
Shio
S
Sakai
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Yusuke
Y
Takeda
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Chikako
C
Ohwada
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Emiko
E
Sakaida
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan [3] Division of Transfusion Medicine and Cell Therapy, Chiba University Hospital, Chiba, Japan.
Naomi
N
Shimizu
Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Keigo
K
Nishii
Department of Clinical-Laboratory and Experimental-Research Medicine, Toho University Medical Center Sakura Hospital, Sakura, Japan.
Meizi
M
Jiang
Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Koutaro
K
Yokote
Department of Clinical-Laboratory and Experimental-Research Medicine, Toho University Medical Center Sakura Hospital, Sakura, Japan.
Hideaki
H
Bujo
1] Department of Hematology, Chiba University Hospital, Chiba, Japan [2] Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
Chiaki
C
Nakaseko
D051722:ADAM Proteins / Q000378:metabolism*; D000072198:ADAM17 Protein; D045744:Cell Line, Tumor; D006801:Humans; D026502:LDL-Receptor Related Proteins / Q000235:genetics / Q000378:metabolism*; D007962:Leukocytes / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis; D060245:Tetraspanin 29 / Q000235:genetics / Q000378:metabolism*
D026502:LDL-Receptor Related Proteins; D026901:Membrane Transport Proteins; C102582:SORL1 protein, human; D060245:Tetraspanin 29; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human