SpiB, also known as Spi-B transcription factor, is a member of the E-twenty-six (ETS) transcription factor family. It is essential for the survival of mature B cells and participates in regulating various biological processes. SpiB is involved in multiple signaling pathways such as JAK1/STAT6, NF-κB, and JNK, and plays a significant role in B-cell-related functions, tumor development, and immune responses [1,3,4]. Mouse models, including gene knockout (KO) and conditional knockout (CKO) models, are valuable for studying its functions in vivo.

In IgG1+ cell-specific SpiB conditional knockout (cKO) mice, SpiB was found to be critical for the generation of late memory B cells but not early memory B cells or GC B cells. It suppresses plasma cell differentiation by regulating the expression of Blimp1 and Bach2, and upregulates anti-apoptosis and autophagy genes to control the survival of memory B cells [1]. In lung cancer cells, knockdown of SpiB by short hairpin RNA abrogated SNAP47 transcriptional activation upon matrix deprivation, indicating its role in autophagy-mediated anoikis resistance [2]. In ovarian cancer cells, SpiB knockdown inhibited cell proliferation, migration, and invasion, and boosted apoptosis by downregulating PD-L1 and inactivating the JAK/STAT pathway [3]. In colorectal cancer cells, overexpression of SpiB inhibited cell proliferation, migration, invasion, and angiogenesis, and induced cell cycle arrest and apoptosis. It also sensitized cells to oxaliplatin and 5-FU by activating the NF-κB and JNK signaling pathways through MAP4K1 [4]. In the placenta, down-regulated Prdx2 in recurrent miscarriage suppresses the SPIB-HDAC2 pathway, restraining trophoblast proliferation and migration [5]. In thymic microfold TECs, SpiB is required for their development and is essential for the generation of thymic IgA+ plasma cells [6].

In conclusion, SpiB has diverse functions in B-cell development, memory B-cell maintenance, and tumor-related processes. Mouse KO/CKO models have revealed its significance in these areas, contributing to a better understanding of the underlying mechanisms in diseases such as cancer, immune-related disorders, and pregnancy-associated pathologies.