SPI1
SPI1, also known as PU.1, SPI-A, SFPI1 and SPI-1, is an ETS-domain pioneer transcription factor that controls haematopoietic cell fate. It binds the purine-rich PU-box and activates genes required for myeloid and B-lymphoid development. Browse Assay Genie's current range of SPI1 research reagents below, or read on for the biology behind the target.
SPI1 is a pioneer transcription factor that determines haematopoietic cell fate by decompacting stem cell heterochromatin, allowing other transcription factors to reach genomic sites that would otherwise be inaccessible. Once in open chromatin, the protein can directly control gene expression by binding regulatory elements. It can also influence transcription more broadly by recruiting other factors, such as interferon regulatory factors (IRFs), to previously inaccessible regions.
The SPI1 protein binds through its ETS domain to the purine-rich core sequence 5'-GAGGAA-3', known as the PU-box, found near the promoters of target genes. It activates genes important for myeloid and lymphoid lineages, such as CSF1R. At some promoters, possibly those with low-affinity binding sites, activation is cooperative with other transcription factors; FCER1A transactivation, for example, occurs together with GATA1. SPI1 may be particularly important for the pro- to pre-B cell transition. It can also regulate alternative splicing of target genes, and in vitro it can bind RNA and interfere with pre-mRNA splicing. Multiple transcript variants encoding different isoforms have been reported for the SPI1 gene.
SPI1 belongs to the ETS transcription factor family and is a nuclear protein. Its previous name, spleen focus forming virus (SFFV) proviral integration oncogene, reflects its original identification, and the protein is widely referred to as PU.1. Mouse and rat each have a Spi1 ortholog, which is useful for comparative studies of myeloid and B-lymphoid development.
SPI1 controls haematopoietic lineage choice by opening stem cell heterochromatin, making it a central subject in studies of how blood cell identity is established.
SPI1 activates gene expression during myeloid and B-lymphoid development and may be important for the pro- to pre-B cell transition.
As a pioneer factor, SPI1 allows other transcription factors, including IRFs, to access closed genomic regions, informing work on transcriptional cooperation.
SPI1 can regulate alternative splicing of target genes and binds RNA in vitro, pointing to roles beyond promoter-based transcriptional control.
SPI1 is a pioneer transcription factor that decompacts heterochromatin in haematopoietic stem cells, giving other transcription factors access to DNA. It binds the PU-box through its ETS domain and activates genes for myeloid and B-lymphoid development, such as CSF1R. It can also regulate alternative splicing.
SPI1 is commonly called PU.1, and also SPI-A, SFPI1, SPI-1 and OF. Its HGNC full name is Spi-1 proto-oncogene, and the earlier name was spleen focus forming virus (SFFV) proviral integration oncogene. Multiple transcript variants encoding different isoforms have been described.
Yes. Mouse and rat both have a Spi1 ortholog, so the gene can be studied in rodent models of haematopoietic development. SPI1 sits in the ETS transcription factor family. Check the datasheet of any product for its validated reactivity.
Other Spi-related genes and similarly named serine peptidase inhibitors with products at Assay Genie.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P17947; product specifications from Assay Genie datasheets.