A CRISPR/Cas9-mediated screen identifies regulators of early plasma cell differentiation

ABSTRACT: The differentiation of B cells into antibody-secreting cells depends on cell division-coupled, epigenetic and other cellular processes that are incompletely understood. We have developed a CRISPR/Cas9-based screen that models an early stage of T cell-dependent plasma cell differentiation and measures B cell survival or proliferation versus the formation of CD138+ plasmablasts. Here, we refined and extended this screen to more than 500 candidate genes that are highly expressed in plasma cells. Among known genes whose deletion preferentially affected plasmablast formation were the transcriptional regulators Prdm1, Irf4 and Pou2af1, and the Ern1 gene encoding the ER stress sensor IRE1a. Moreover, we newly identified several genes involved in NF-kB or p38 signaling (Pim2, Nfkbia, Mapk14), vesicle trafficking (Arf4, Preb) and epigenetic regulators that form part of the NuRD complexes (Hdac1, Mta2, Mbd2). Defective plasmablast formation caused by Ern1 deletion could not be rescued by spliced XBP1 (XBP1s), a transcription factor dependent on and downstream of IRE1a, suggesting that in early plasma cell differentiation IRE1a acts independently of XBP1s. The deletion of ARF4, a small GTPase required for ER-to-Golgi transport, impaired plasmablast formation by blocking antibody secretion. Plasmablast formation after Hdac1 deletion was consistently reduced by about 50%, while deletion of the closely related Hdac2 gene had no effect. Hdac1 knock-out led to strongly perturbed protein expression of antagonistic transcription factors that specify plasma cell versus B cell identity (by decreasing IRF4 and BLIMP1 and increasing BACH2 and PAX5). Taken together, our results highlight specific and non-redundant roles for Ern1, Arf4 and Hdac1 in the early steps of plasma cell differentiation.

INSTRUMENT(S): Q Exactive HF-X, Q Exactive Plus

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): B Cell, Blood Plasma

DISEASE(S): B-cell Lymphoma

SUBMITTER: Oliver Popp  

LAB HEAD: Van Trung Chu

PROVIDER: PXD038201 | Pride | 2022-12-22

REPOSITORIES: Pride