Early UPR-affiliated gene expression occurs before Blimp1 upregulation and independent of canonical ER-stress activated Xbp1.  In linked companion studies we detailed how Xbp1-independent activation of early plasma cell specific UPR-affiliated gene expression occurs prior to Blimp1 upregulation.  Having observed that these genes overlapped with canonical mTORC1 signature genes and that PC-poised marginal zone B cells have higher base line mTORC1 signaling we designed this experiment to assess the dependence of early ER-remodeling on mTORC1 signaling in plasma cell differentiation.  To this end we mated mice harboring a floxed allele for the mTORC1 adapter Raptor (B6.Rptor-flox) to mice expressing a tamoxifen-inducible cre recombinase under the control of the human CD20 promoter (B6.hCD20-TamCre). These mice and their hCD20-TamCre-Rptor-wt litermates were fed oral tamoxifen in their diet for two weeks and follicular B cells were prepared for in-vitro plasma cell differentiation studies.  We report here that as early as 24 hours of stimulation in culture we see a marked defect in the ability of Rptor null B cells to upregulate UPR-affiliated genes associated with plasma cell differentiation. SOURCE: Brian,Thomas,GaudetteBrian Gaudette University of Pennsylvania

Pluto Bioinformatics

GSE141421: Transcriptomic analysis of in-vitro plasma cell generation from follicular B cells lacking Raptor [Raptor_PC_stim]