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BioMed Research International
Volume 2013 (2013), Article ID 807240, 9 pages
http://dx.doi.org/10.1155/2013/807240
Research Article

Internalization of B Cell Receptors in Human EU12 μHC+ Immature B Cells Specifically Alters Downstream Signaling Events

1Department of Pathology and Microbiology, University of Nebraska Medical Center, LTC 11706A, Omaha, NE 68198-7660, USA
2Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
3Department of Internal Medicine, University of Nebraska Medical Center, LTC 11706A, Omaha, NE 68198-7660, USA
4Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, LTC 11706A, Omaha, NE 68198-7660, USA

Received 29 April 2013; Accepted 26 August 2013

Academic Editor: Hirokazu Murakami

Copyright © 2013 Jing Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

It has been recognized for a long time that engagement of B cell antigen receptors (BCRs) on immature B cells or mature B cells leads to completely opposite cell fate decisions. The underlying mechanism remains unclear. Here, we show that crosslinking of BCRs on human EU12 μHC+ immature B cells resulted in complete internalization of cell surface BCRs. After loss of cell surface BCRs, restimulation of EU12 μHC+ cells showed impaired Ca2+ flux, delayed SYK phosphorylation, and decreased CD19 and FOXO1 phosphorylation, which differ from those in mature Daudi or Ramos B cells with partial internalization of BCRs. In contrast, sustained phosphorylation and reactivation of ERK upon restimulation were observed in the EU12 μHC+ cells after BCR internalization. Taken together, these results show that complete internalization of cell surface BCRs in EU12 μHC+ cells specifically alters the downstream signaling events, which may favor receptor editing versus cell activation.