Extended Data Fig. 9: Regulation of BRISC–SHMT2 function in cells.

a, Schematic of pairwise comparison of Abraxas2^–/– MEFs treated with LPS and expressing the indicated forms of Abraxas 2 (top). Bar chart illustrates the IFN-type I-related genes that were increased by more than twofold in Abraxas 2 wild-type + LPS (black) and Abraxas 2(E144R) + LPS (blue), relative to Abraxas2^-/- + LPS. Data are presented as mean ± s.e.m. from three independent experiments (biological replicates). b, Native gel electrophoresis of whole MEF cell lysates cultured in B6-vitamer-free medium, with and without pyridoxal, and expressing the indicated forms of Flag–HA–SHMT2ΔN. c, d, Measurement of phosphorylated STAT1 levels (phosphorylated at Y701) in MEFs (c) or MEFs that stably express SHMT2 (d), cultured in B6-vitamer-free medium. Where indicated, cells were treated with 20 μM pyridoxal and/or 500 units per millilitre of IFNβ for 48 h. e, Immunoprecipitation performed using anti-Flag antibody in MEFs transiently transfected with Flag–HA epitope-tagged SHMT2 or mutants (cultured in DMEM). Immunoblot was performed for Abraxas 2 and SHMT2 as indicated. f, Phosphorylated STAT1 levels (phosphorylated at Y701) measured in MEFs cultured in DMEM containing vitamin B6 and the indicated forms of SHMT, after challenge with HSV. Data shown in b–f are representative of three independent experiments. For gel source data, see Supplementary Fig. 1.