Regulation of asymmetric cell division and polarity by Scribble is not required for humoral immunity

Abstract

The production of protective antibody requires effective signalling of naive B cells following encounter with antigen, and the divergence of responding B lymphocytes into distinct lineages. Polarity proteins have recently been proposed as important mediators of both the initial B cell response, and potentially of asymmetric cell division. Here we show that, although polarity proteins of the Scribble complex, Scribble, Dlg1 and Lgl1, are expressed and polarized during early B cell activation, their deficiency has no effect on the in vivo outcome of immunization or challenge with influenza infection. Furthermore, we find a striking correlation in the differentiation outcome of daughters of single founder B cells in vitro. Taken together, our results indicate that B cell differentiation does not require polarity proteins of the Scribble complex, and the findings do not support a role for asymmetric cell division in B cell activation and differentiation.

The Scribble–Dlg–Lgl Module in Cell Polarity Regulation

“…Many studies have shown, using knockdown approaches, that Scribble and Dlg play key roles in the response of T and B cells to antigen presentation Round et al 2005Round et al , 2007Humphries et al 2012;Ludford-Menting et al 2005;Xavier et al 2004). However, gene knockout studies have shown minimal and/or transient effects of deletion of Scribble, Lgl1, and Dlg1 on hematopoiesis and immune cell function Hawkins et al 2013Hawkins et al , 2014Humphries et al 2012;Heidel et al 2013). The discrepancy between knockdown and knockout studies is thought to reflect compensatory mechanisms by which lymphocytes might adjust to deletion of the Scribble module genes over time (Humphries et al 2012;Pham et al 2014), and further studies are required to resolve this discrepancy.…”

Manipulation of B-cell responses with histone deacetylase inhibitors

“…All lymphocytes were isolated from 8-to 16-week-old C57BL/6 mice. B cells were prepared, CFSE labelled and cultured as described 30,60 . Cell numbers were determined by reference to FACS calibration beads as described 29,31 .…”

Why the immune system takes its chances with randomness

“…We and others find a great deal of cell fate heterogeneity under simple in vitro culture conditions [4][5][6]12,13 . Conversely, crucial molecular contributors to early developmental programmes, including asymmetric cell division, do not alter B cell or T cell responses in vivo 14 . Thus, although the 3D environment and asymmetric programming might have some role in modifying cell fate allocation, they are not the only sources of variation.…”