Biochemical and Biophysical Research Communications, Vol.417, No.1, 141-146, 2012
A checkpoint in B-Iymphopoiesis related to Notch resistance
While murine B- and T-Iymphopoiesis require overlapping molecules, they occur in separate organs: the bone marrow (BM) and the thymus, respectively. The BM microenvironment is incapable of supporting T-Iymphopoiesis because of insufficient interactions of Notch1 with delta-like ligand (DII). Notch1/DII interactions also play a role in the suppression of B-lymphopoiesis in the thymus. However, it is still unclear whether the Notch1/DII interaction alone explains why the thymus does not support B-lymphopoiesis. In this study, we compared the precursor population colonizing the thymus with that in the BM by culturing them on stromal cells expressing abundant DII1. We demonstrated that Flt3(+) I17r(+) B220(+) Cd19(+) BM cells gave rise to B cells under this condition. We defined them as resistant to DII1. In the thymus, DII1-resistant cells were undetectable. This suggested that the absence of DII1-resistant cells might explain the absence of B-lymphopoiesis in the thymus. (C) 2011 Elsevier Inc. All rights reserved.