Increased numbers of B-1 cells and enhanced responses against TI-2 antigen in mice lacking APS, an adaptor molecule containing PH and SH2 domains.
APS (adaptor molecule containing PH and SH2 domains) is an intracellular adaptor protein that forms an adaptor family along with Lnk and SH2-B. While experiments using cultured cell lines have demonstrated that APS is phosphorylated in response to various stimuli, its in vivo functions remain unclear. We attempted to determine the physiological roles of APS by generating APS-deficient (APS(-/-)) mice. APS(-/-) mice were viable and fertile and showed no abnormalities or growth retardation. Immunologically, APS(-/-) mice showed normal development and distribution of lymphocytes and myeloid cells, except for increased numbers of B-1 cells in the peritoneal cavity. APS(-/-) mice exhibited an enhanced humoral immune response against trinitrophenol-Ficoll, a thymus-independent type 2 antigen, while APS(-/-) B-2 cells exhibited normal proliferative responses and tyrosine phosphorylation of intracellular proteins upon B-cell receptor (BCR) cross-linking. APS colocalized with filamentous actin (F-actin) accumulated during the capping of BCRs in APS-transgenic B cells. After BCR stimulation, F-actin contents were lower in APS(-/-) B-1 cells than in wild-type B-1 cells. Our results indicate that APS might have a novel regulatory role in actin reorganization and control of B-1 cell compartment size.
Iseki
Masanori
M
Division of Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan.
Kubo
Chiyomi
C
Kwon
Sang-Mo
SM
Yamaguchi
Akiko
A
Kataoka
Yuki
Y
Yoshida
Nobuaki
N
Takatsu
Kiyoshi
K
Takaki
Satoshi
S
D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000737:chemistry / Q000172:deficiency* / Q000235:genetics; D000818:Animals; D000955:Antigens, T-Independent; D016175:B-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation; D018655:Lymphocyte Count; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000378:metabolism; D015398:Signal Transduction; D018909:src Homology Domains
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000955:Antigens, T-Independent; D011947:Receptors, Antigen, B-Cell; D017978:Receptors, Growth Factor; C488161:Sh2b2 protein, mouse