TY - JOUR
T1 - B cell endosomal RAB7 promotes TRAF6 K63 polyubiquitination and NF-κB activation for antibody class-switching
AU - Yan, Hui
AU - Fernandez, Maria
AU - Wang, Jingwei
AU - Wu, Shuai
AU - Wang, Rui
AU - Lou, Zheng
AU - Moroney, Justin B.
AU - Rivera, Carlos E.
AU - Taylor, Julia R.
AU - Gan, Huoqun
AU - Zan, Hong
AU - Kolvaskyy, Dmytro
AU - Liu, Dongfang
AU - Casali, Paolo
AU - Xu, Zhenming
N1 - Publisher Copyright:
© 2020 by The American Association of Immunologists, Inc.
PY - 2020/3/1
Y1 - 2020/3/1
N2 - Upon activation by CD40 or TLR signaling, B lymphocytes activate NF-κB to induce activation-induced cytidine deaminase and, therefore, Ig class switch DNA recombination, as central to the maturation of the Ab and autoantibody responses. In this study, we show that NF-κB activation is boosted by colocalization of engaged immune receptors, such as CD40, with RAB7 small GTPase on mature endosomes, in addition to signals emanating from the receptors localized on the plasma membrane, in mouse B cells. In mature endosomes, RAB7 directly interacts with TRAF6 E3 ubiquitin ligase, which catalyzes K63 polyubiquitination for NF-κB activation. RAB7 overexpression in Cd19+/creRosa26fl-STOP-fl-Rab7 mouse B cells upregulates K63 polyubiquitination activity of TRAF6, enhances NF-κB activation and activation-induced cytidine deaminase induction, and boosts IgG Ab and autoantibody levels. This, together with the extensive intracellular localization of CD40 and the strong correlation of RAB7 expression with NF-κB activation in mouse lupus B cells, shows that RAB7 is an integral component of the B cell NF-κB activation machinery, likely through interaction with TRAF6 for the assembly of "intracellular membrane signalosomes".
AB - Upon activation by CD40 or TLR signaling, B lymphocytes activate NF-κB to induce activation-induced cytidine deaminase and, therefore, Ig class switch DNA recombination, as central to the maturation of the Ab and autoantibody responses. In this study, we show that NF-κB activation is boosted by colocalization of engaged immune receptors, such as CD40, with RAB7 small GTPase on mature endosomes, in addition to signals emanating from the receptors localized on the plasma membrane, in mouse B cells. In mature endosomes, RAB7 directly interacts with TRAF6 E3 ubiquitin ligase, which catalyzes K63 polyubiquitination for NF-κB activation. RAB7 overexpression in Cd19+/creRosa26fl-STOP-fl-Rab7 mouse B cells upregulates K63 polyubiquitination activity of TRAF6, enhances NF-κB activation and activation-induced cytidine deaminase induction, and boosts IgG Ab and autoantibody levels. This, together with the extensive intracellular localization of CD40 and the strong correlation of RAB7 expression with NF-κB activation in mouse lupus B cells, shows that RAB7 is an integral component of the B cell NF-κB activation machinery, likely through interaction with TRAF6 for the assembly of "intracellular membrane signalosomes".
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U2 - 10.4049/jimmunol.1901170
DO - 10.4049/jimmunol.1901170
M3 - Article
C2 - 31932498
AN - SCOPUS:85079842279
SN - 0022-1767
VL - 204
SP - 1146
EP - 1157
JO - Journal of Immunology
JF - Journal of Immunology
IS - 5
ER -