CIN85 is required for Cbl-mediated regulation of antigen receptor signaling in human B cells

Hiroaki Niiro; Siamak Jabbarzadeh-Tabrizi; Yoshikane Kikushige; Takahiro Shima; Kumiko Noda; Shun-Ichiro Ota; Hirofumi Tsuzuki; Yasushi Inoue; Yojiro Arinobu; Hiromi Iwasaki; Shinji Shimoda; Eishi Baba; Hiroshi Tsukamoto; Takahiko Horiuchi; Tadayoshi Taniyama; Koichi Akashi

doi:10.1182/blood-2011-04-351965

CIN85 is required for Cbl-mediated regulation of antigen receptor signaling in human B cells

Blood. 2012 Mar 8;119(10):2263-73. doi: 10.1182/blood-2011-04-351965. Epub 2012 Jan 18.

Authors

Hiroaki Niiro¹, Siamak Jabbarzadeh-Tabrizi, Yoshikane Kikushige, Takahiro Shima, Kumiko Noda, Shun-Ichiro Ota, Hirofumi Tsuzuki, Yasushi Inoue, Yojiro Arinobu, Hiromi Iwasaki, Shinji Shimoda, Eishi Baba, Hiroshi Tsukamoto, Takahiko Horiuchi, Tadayoshi Taniyama, Koichi Akashi

Affiliation

¹ Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. hniiro@med.kyushu-u.ac.jp

PMID: 22262777
DOI: 10.1182/blood-2011-04-351965

Abstract

The aberrant regulation of B-cell receptor (BCR) signaling allows unwanted B cells to persist, thereby potentially leading to autoimmunity and B-cell malignancies. Casitas B-lineage lymphoma (Cbl) proteins suppress BCR signaling; however, the molecular mechanisms that control Cbl function in human B cells remain unclear. Here, we demonstrate that CIN85 (c-Cbl interacting protein of 85 kDa) is constitutively associated with c-Cbl, Cbl-b, and B-cell linker in B cells. Experiments using CIN85-overexpressing and CIN85-knockdown B-cell lines revealed that CIN85 increased c-Cbl phosphorylation and inhibited BCR-induced calcium flux and phosphorylation of Syk and PLCγ2, whereas it did not affect BCR internalization. The Syk phosphorylation in CIN85-overexpressing and CIN85-knockdown cells was inversely correlated with the ubiquitination and degradation of Syk. Moreover, CIN85 knockdown in primary B cells enhanced BCR-induced survival and growth, and increased the expression of BcLxL, A1, cyclin D2, and myc. Following the stimulation of BCR and Toll-like receptor 9, B-cell differentiation- associated molecules were up-regulated in CIN85-knockdown cells. Together, these results suggest that CIN85 is required for Cbl-mediated regulation of BCR signaling and for downstream events such as survival, growth, and differentiation of human B cells.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adaptor Proteins, Signal Transducing / genetics
Adaptor Proteins, Signal Transducing / metabolism*
Antigens, CD / metabolism
Antigens, Differentiation, T-Lymphocyte / metabolism
B-Lymphocytes / cytology
B-Lymphocytes / metabolism*
Blotting, Western
Calcium / metabolism
Cell Line, Tumor
Cell Proliferation
Cell Survival
Cells, Cultured
Cyclin D2 / metabolism
Humans
Intracellular Signaling Peptides and Proteins / metabolism
Lectins, C-Type / metabolism
Microscopy, Fluorescence
NFATC Transcription Factors / metabolism
Phospholipase C gamma / metabolism
Phosphorylation
Protein Binding
Protein-Tyrosine Kinases / metabolism
Proto-Oncogene Proteins c-cbl / metabolism*
Proto-Oncogene Proteins c-vav / metabolism
RNA Interference
Receptors, Antigen, B-Cell / metabolism*
Signal Transduction
Syk Kinase
Ubiquitination
bcl-X Protein / metabolism

Substances

Adaptor Proteins, Signal Transducing
Antigens, CD
Antigens, Differentiation, T-Lymphocyte
B cell linker protein
BCL2L1 protein, human
CD69 antigen
Cyclin D2
Intracellular Signaling Peptides and Proteins
Lectins, C-Type
NFATC Transcription Factors
Proto-Oncogene Proteins c-vav
Receptors, Antigen, B-Cell
SH3KBP1 protein, human
VAV2 protein, human
bcl-X Protein
Proto-Oncogene Proteins c-cbl
Protein-Tyrosine Kinases
SYK protein, human
Syk Kinase
Phospholipase C gamma
CBL protein, human
Calcium