# SPI1 Gene: Structure, Function, and Clinical Significance


## Key Takeaways

-   *SPI1* encodes the transcription factor PU.1, a critical regulator of myeloid and B-lymphoid cell differentiation, whose dysregulation is a driver in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL).
-   The *SPI1* gene locus on chromosome 11p11.2 is regulated by a GC-rich promoter and distal enhancers interacting via chromatin looping, with DNA methylation playing a role in lineage-restricted expression.
-   PU.1 protein possesses a conserved ETS DNA-binding domain (residues 171–260) that recognizes the 5'-GGAA-3' motif, and its activity is modulated by post-translational modifications like phosphorylation at Ser41 and Ser132.
-   Somatic mutations, particularly missense variants like p.Arg232Cys in the ETS domain, are recurrent in AML and often confer a dominant-negative effect, leading to impaired DNA binding and a poor prognosis.
-   Germline variants in *SPI1* are associated with familial predisposition to myeloid malignancies, highlighting its essential role in normal hematopoiesis and the consequences of its functional impairment.
-   Therapeutic strategies targeting PU.1 include small-molecule inhibitors of DNA binding (e.g., DB2313), BET inhibitors (e.g., JQ1) that reduce its expression, and PROTACs for targeted protein degradation.

---

## Executive Summary & Key Metadata

The **SPI1** gene (Spi-1 Proto-Oncogene) encodes PU.1, a master regulator of hematopoiesis and a member of the E26 transformation-specific (ETS) family of transcription factors. PU.1 governs the differentiation, proliferation, and survival of myeloid and B-lymphoid progenitors by orchestrating cell-type-specific transcriptional programs. Its dysregulation—via mutation, aberrant expression, or chromosomal translocation—is a central driver in leukemogenesis, particularly acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). This manual provides a definitive reference on the genomic architecture, structural biology, signaling networks, clinical mutations, and therapeutic targeting of SPI1.

| **Attribute** | **Detail** |
| :--- | :--- |
| **HGNC Symbol** | SPI1 |
| **UniProt Accession** | P17947 |
| **Representative PDB ID** | 1PUE (ETS domain–DNA complex) |
| **Chromosomal Locus** | 11p11.2 (GRCh38: chr11:47,354,860–47,377,207) |
| **Primary Molecular Function** | Sequence-specific DNA-binding transcription factor (ETS family) |
| **Disease & Pathology Associations** | Acute Myeloid Leukemia (AML), Acute Lymphoblastic Leukemia (ALL), Diffuse Large B-Cell Lymphoma (DLBCL), Familial AML (germline variants) |

---

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Gene Coordinates and Chromosomal Context

The human *SPI1* gene is located on the short arm of chromosome 11 at band p11.2. The reference genome assembly (GRCh38) places the gene between base pairs 47,354,860 and 47,377,207 on the forward strand. The locus is gene-dense, with neighboring genes including *SLC39A13* (telomeric) and *PSMA1* (centromeric). The genomic span is approximately 22.3 kilobases (kb), which is relatively compact for a transcription factor gene.

### 1.2 Promoter Architecture and Regulatory Elements

The *SPI1* promoter lacks a canonical TATA box, a feature common among housekeeping and developmental regulatory genes. Instead, transcription initiation is governed by a GC-rich region containing multiple Sp1-binding sites. The core promoter is located approximately 200 base pairs upstream of the translation start site. Key regulatory features include:

- **Upstream Regulatory Region (URR):** A distal enhancer element located approximately 14 kb upstream of the transcription start site (TSS). This region contains binding sites for C/EBPα, RUNX1, and GATA-2, which cooperatively activate *SPI1* transcription in myeloid progenitors.
- **Promoter-Proximal Elements:** Binding sites for PU.1 itself (autoregulation), OCT4, and SOX2 in embryonic stem cells, where *SPI1* is repressed.
- **DNA Methylation:** The *SPI1* promoter is heavily methylated in non-hematopoietic tissues, contributing to its lineage-restricted expression. Demethylation at specific CpG dinucleotides is an early event in hematopoietic commitment.

### 1.3 Alternative Splicing and Isoforms

The *SPI1* gene produces multiple transcript variants through alternative splicing and alternative promoter usage. The primary transcript encodes the canonical PU.1 protein of 272 amino acids. However, several isoforms have been characterized:

- **Isoform 1 (Canonical, P17947-1):** 272 amino acids, full-length protein with both the N-terminal transactivation domain and the C-terminal ETS DNA-binding domain.
- **Isoform 2 (P17947-2):** A shorter variant lacking exon 3, resulting in a protein with a truncated PEST domain. This isoform exhibits altered protein stability and reduced transactivation capacity.
- **Isoform 3 (P17947-3):** Generated by an alternative in-frame start codon in exon 2, producing a protein with a shortened N-terminus. This isoform retains DNA-binding activity but lacks the full transactivation domain, potentially acting as a dominant-negative regulator.

The relative expression of these isoforms is tissue-specific. In myeloid cells, the canonical isoform predominates, whereas lymphoid progenitors express higher levels of isoform 2. The functional significance of these isoforms in disease is an active area of investigation.

### 1.4 Conserved Non-Coding Elements and Long-Range Interactions

Chromatin conformation capture (Hi-C) studies have revealed that the *SPI1* promoter physically interacts with several distal regulatory elements within the same topologically associating domain (TAD). These include a super-enhancer region located ~30 kb downstream of the gene, which is marked by H3K27ac and bound by lineage-determining transcription factors. Disruption of this TAD boundary, as seen in some AML cases with 11p11.2 microdeletions, can lead to ectopic enhancer-promoter interactions and aberrant *SPI1* overexpression.

---

## 2. 3D Protein Domain Architecture & Structural Biology

### 2.1 Primary Structure and Domain Boundaries

The PU.1 protein (272 amino acids) is organized into three distinct functional domains, each with a defined structural and biochemical role:

1.  **N-Terminal Transactivation Domain (TAD; residues 1–100):** This acidic domain is rich in glutamic and aspartic acid residues. It mediates interactions with the basal transcription machinery, including TFIID, and with chromatin remodelers such as CBP/p300. The TAD also contains a conserved phosphorylation site at Serine 41, which modulates transcriptional activity.
2.  **PEST Domain (residues 101–160):** Named for its high content of Proline (P), Glutamic acid (E), Serine (S), and Threonine (T), this region is a target for ubiquitination and proteasomal degradation. Phosphorylation within the PEST domain by CK2 and MAPK regulates PU.1 protein stability. This domain also mediates interactions with the transcriptional repressor Rb.
3.  **ETS DNA-Binding Domain (DBD; residues 171–260):** The C-terminal ETS domain is the most conserved region. It adopts a winged helix-turn-helix (wHTH) fold, which binds to purine-rich DNA sequences with a core consensus of 5'-GGAA-3'. The DBD also mediates protein-protein interactions with other transcription factors, including RUNX1, C/EBPα, and GATA-1.

### 2.2 Tertiary and Quaternary Structure

The high-resolution crystal structure of the PU.1 ETS domain in complex with DNA (PDB: 1PUE) reveals the molecular basis of sequence-specific recognition. The wHTH motif consists of three α-helices (H1, H2, H3) and a four-stranded antiparallel β-sheet. The recognition helix H3 (residues 215–230) inserts into the major groove of DNA, making base-specific contacts with the GGAA core. A key arginine residue (Arg232) forms a bidentate hydrogen bond with the guanine bases, while a tyrosine residue (Tyr218) stacks against the thymine bases. The "wing" region (residues 240–260) contacts the minor groove, contributing to binding affinity and specificity.

PU.1 can form homodimers on DNA, particularly on tandemly repeated GGAA motifs. However, its most common mode of action involves heterodimerization with other transcription factors. For example, the cooperative binding of PU.1 and RUNX1 to composite DNA elements is critical for myeloid gene expression. The interaction interface between PU.1 and RUNX1 involves the ETS domain of PU.1 and the Runt domain of RUNX1, forming a stable ternary complex on DNA.

### 2.3 Post-Translational Modifications and Structural Dynamics

PU.1 is subject to extensive post-translational modifications (PTMs) that regulate its function:

- **Phosphorylation:** Serine 41 (TAD) and Serine 132 (PEST) are phosphorylated by MAPK and CK2, respectively. Phosphorylation at S41 enhances transactivation, while S132 phosphorylation promotes ubiquitination and degradation.
- **Acetylation:** Lysine residues in the TAD are acetylated by p300, which increases transcriptional activity by promoting chromatin accessibility.
- **Sumoylation:** Conjugation of SUMO to Lysine residues in the PEST domain represses PU.1 transcriptional activity by recruiting co-repressor complexes.

These PTMs induce conformational changes that modulate protein-protein interactions and DNA-binding affinity, providing a dynamic layer of regulation.

> **[Interactive 3D Protein Visualizer: Load SPI1 (PDB: true)](/tools/protein-structure-viewer?source=alphafold&accession=P17947)**
>
> Use the interactive viewer to explore the ETS domain (residues 171–260) in complex with DNA. Key residues to visualize: Arg232 (DNA contact), Tyr218 (base stacking), and the wing region (residues 240–260). The viewer allows you to toggle between cartoon and surface representations, and to measure distances between protein and DNA atoms.

---

## 3. Cellular Signaling Pathways & Molecular Function

### 3.1 PU.1 as a Master Regulator of Hematopoiesis

PU.1 is a dosage-sensitive transcription factor that controls the commitment of multipotent hematopoietic stem cells (HSCs) to the myeloid and B-lymphoid lineages. Its expression level determines cell fate: high PU.1 levels promote macrophage differentiation, intermediate levels drive granulocyte and B-cell development, and low levels are associated with T-cell and erythroid fates.

The molecular mechanism involves PU.1 binding to enhancer elements of lineage-specific genes and recruiting co-activators (e.g., CBP/p300) or co-repressors (e.g., GATA-1) depending on the cellular context. PU.1 and GATA-1 physically interact and antagonize each other's function, forming a bistable switch that directs either myeloid or erythroid differentiation.

### 3.2 Downstream Signaling Cascades and Transcriptional Networks

PU.1 integrates signals from multiple extracellular pathways to regulate hematopoiesis:

- **Cytokine Receptor Signaling:** Activation of the IL-3, IL-7, and GM-CSF receptors leads to JAK-STAT signaling, which directly induces *SPI1* transcription. STAT3 and STAT5 bind to the *SPI1* promoter and enhancer regions.
- **MAPK/ERK Pathway:** Growth factor signaling through RAS-MAPK leads to phosphorylation of PU.1 at Ser41, enhancing its transcriptional activity. This is critical for macrophage colony-stimulating factor (M-CSF)-induced macrophage differentiation.
- **TGF-β Signaling:** SMAD proteins interact with PU.1 to repress its activity in certain contexts, contributing to the anti-proliferative effects of TGF-β on hematopoietic progenitors.

PU.1 regulates a vast array of target genes, including:
- **Myeloid-specific genes:** *CSF1R* (M-CSF receptor), *MPO* (myeloperoxidase), *LYZ* (lysozyme), and *ITGAM* (CD11b).
- **B-lymphoid genes:** *CD79A* (Igα), *VPREB1* (pre-B cell receptor), and *BLK* (B-cell kinase).
- **Cell cycle regulators:** *CDKN1A* (p21) and *CCND1* (cyclin D1).

### 3.3 Protein-Protein Interaction Networks

PU.1 participates in a dense protein-protein interaction network, as cataloged in BioGRID and STRING databases. Key interacting partners include:

| **Interactor** | **Function** | **Interaction Domain (PU.1)** |
| :--- | :--- | :--- |
| RUNX1 | Cooperative DNA binding; myeloid gene activation | ETS domain |
| C/EBPα | Cooperative DNA binding; granulocyte/monocyte differentiation | ETS domain |
| GATA-1 | Antagonistic interaction; erythroid/myeloid fate switch | ETS domain |
| CBP/p300 | Histone acetyltransferase; transcriptional activation | TAD |
| Rb | Transcriptional repression; cell cycle control | PEST domain |
| TFIID (TAF9) | Basal transcription machinery | TAD |
| SFPQ/PSF | RNA splicing and transcriptional repression | PEST domain |

### 3.4 Regulatory Feedback Loops

PU.1 is subject to both positive and negative autoregulation. It binds to its own promoter and enhancer, creating a positive feedback loop that stabilizes its expression in committed progenitors. Conversely, in erythroid cells, GATA-1 recruits the co-repressor complex NuRD to the *SPI1* enhancer, leading to chromatin compaction and transcriptional silencing. This mutual antagonism between PU.1 and GATA-1 is a classic example of a cross-antagonistic feedback loop that establishes and maintains cell fate decisions.

```mermaid
sequenceDiagram
    participant HSC as "Hematopoietic Stem Cell"
    participant PU1 as "PU.1 (SPI1)"
    participant GATA1 as "GATA-1"
    participant Myeloid as "Myeloid Progenitor"
    participant Erythroid as "Erythroid Progenitor"
    HSC->>PU1: Low-level expression
    PU1->>PU1: Positive autoregulation (binds own enhancer)
    PU1->>Myeloid: High expression -> activates myeloid genes (CSF1R, MPO)
    Myeloid->>PU1: Maintains high PU.1 via feedback loop
    PU1-->>GATA1: Direct protein-protein inhibition
    GATA1->>Erythroid: High expression -> activates erythroid genes (HBB, GATA1)
    Erythroid->>PU1: GATA-1 recruits NuRD to SPI1 enhancer -> silences PU.1
```

---

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

### 4.1 Somatic Mutations in Hematologic Malignancies

Somatic mutations in *SPI1* are recurrent in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL), although they are less frequent than mutations in genes like *NPM1* or *FLT3*. The mutational spectrum includes missense, nonsense, and frameshift mutations, with a notable clustering in the ETS DNA-binding domain.

#### 4.1.1 Missense Mutations in the ETS Domain

- **p.Arg232Cys (R232C):** This is the most frequently reported somatic missense mutation. Arg232 is a critical DNA-contacting residue; its substitution to cysteine abolishes DNA-binding affinity. This mutation acts in a dominant-negative manner, as the mutant protein can still dimerize with wild-type PU.1 but the heterodimer cannot bind DNA effectively. Clinically, R232C is associated with a poor prognosis in AML and is often found in conjunction with *RUNX1* mutations.
- **p.Tyr218Asp (Y218D):** Tyrosine 218 is involved in base-stacking interactions with DNA. The Y218D mutation disrupts the hydrophobic core of the protein-DNA interface, reducing binding affinity by >100-fold. This mutation is rare but has been reported in familial AML.
- **p.Arg235Leu (R235L):** Located in the recognition helix, this mutation disrupts a salt bridge with the DNA phosphate backbone. It is associated with a subset of B-ALL cases with a particularly aggressive phenotype.

#### 4.1.2 Frameshift and Nonsense Mutations

Frameshift mutations leading to premature stop codons are distributed throughout the gene. These typically result in nonsense-mediated decay of the mRNA or the production of a truncated protein lacking the ETS domain. Such mutations are effectively null alleles and are often found in the context of loss of heterozygosity (LOH) at the 11p11.2 locus, resulting in complete loss of PU.1 function. This is observed in a subset of AML with a complex karyotype.

### 4.2 Germline Variants and Familial Predisposition

Rare germline variants in *SPI1* have been linked to familial AML and myelodysplastic syndrome (MDS). These are typically missense mutations in the ETS domain that impair DNA binding. Carriers have an increased lifetime risk of developing myeloid malignancies, often at a younger age than sporadic cases. Genetic counseling and surveillance are recommended for affected families.

### 4.3 Clinical Differentials and Diagnostic Implications

The presence of *SPI1* mutations has diagnostic and prognostic implications:

- **AML:** *SPI1* mutations are enriched in the FAB M0 (minimally differentiated) and M1 (myeloblastic without maturation) subtypes. They are associated with a lower complete remission rate and shorter overall survival.
- **ALL:** In B-ALL, *SPI1* mutations are often found in the *ETV6-RUNX1* (t(12;21)) subtype, suggesting a cooperative role in leukemogenesis.
- **DLBCL:** Somatic mutations in *SPI1* are less common but have been reported in the activated B-cell (ABC) subtype, where they may contribute to the aberrant expression of PU.1 target genes.

### 4.4 Variant Interpretation Resources

ClinVar and COSMIC databases catalog the pathogenicity of *SPI1* variants. For clinical interpretation, the following criteria are applied:

- **Pathogenic:** Variants that result in loss of DNA binding (e.g., R232C) or complete loss of protein (nonsense/frameshift) with supporting functional assays.
- **Likely Pathogenic:** Missense variants in the ETS domain with predicted deleterious effects (CADD score > 20) and co-segregation with disease in families.
- **Variant of Uncertain Significance (VUS):** Variants in non-conserved regions or with conflicting functional data.

---

## 5. Host-Pathogen & Viral Interactions

### 5.1 Retroviral Insertional Mutagenesis

The *SPI1* gene was originally identified as a common site of integration for the spleen focus-forming virus (SFFV) in murine erythroleukemia. Retroviral insertion into the *SPI1* promoter or enhancer leads to its overexpression, driving erythroid transformation. This mechanism is a classic example of insertional mutagenesis in oncogenesis.

### 5.2 Epstein-Barr Virus (EBV) and B-Cell Lymphomas

In EBV-associated B-cell lymphomas, the viral latent membrane protein 1 (LMP1) and EBNA2 proteins upregulate *SPI1* expression. EBNA2 binds to the *SPI1* enhancer in a RUNX1-dependent manner, promoting B-cell transformation. This interaction highlights the role of PU.1 in viral oncogenesis.

### 5.3 Human T-Cell Leukemia Virus Type 1 (HTLV-1)

The HTLV-1 Tax oncoprotein interacts with PU.1 and modulates its transcriptional activity. Tax binding to the ETS domain of PU.1 enhances its DNA-binding affinity, leading to aberrant activation of cellular genes involved in T-cell proliferation. This contributes to the development of adult T-cell leukemia/lymphoma (ATLL).

### 5.4 Immune Evasion Mechanisms

Some pathogens exploit PU.1 to evade the immune system. For example, *Mycobacterium tuberculosis* infection of macrophages induces PU.1-dependent expression of the host protein *NRAMP1* (SLC11A1), which the bacteria use to acquire iron. Additionally, the HIV-1 Tat protein has been shown to interact with PU.1, modulating the expression of inflammatory cytokines in infected macrophages.

---

## 6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

### 6.1 Therapeutic Rationale

Given its central role in hematopoiesis and leukemogenesis, PU.1 is an attractive therapeutic target. However, its essential function in normal hematopoiesis poses a challenge for therapeutic index. Strategies are therefore focused on:

1.  **Inhibiting PU.1's oncogenic activity in cancer cells while sparing normal progenitors.**
2.  **Targeting downstream effectors of PU.1.**
3.  **Exploiting synthetic lethal interactions.**

### 6.2 Small-Molecule Inhibitors

- **DB2313:** A small molecule that binds to the ETS domain of PU.1 and inhibits its DNA-binding activity. Preclinical studies in AML cell lines show that DB2313 induces differentiation and apoptosis. It is currently in early-stage preclinical development.
- **ETC-1002 (Bempedoic acid):** While primarily a lipid-lowering drug, ETC-1002 has been shown to inhibit PU.1 transcriptional activity in macrophages, reducing inflammatory gene expression. Its repurposing for AML is under investigation.
- **JQ1 (BET inhibitor):** JQ1 inhibits BRD4, which is a co-activator of PU.1. By displacing BRD4 from the *SPI1* enhancer, JQ1 reduces PU.1 expression in AML cells. JQ1 and its analogs are in clinical trials for hematologic malignancies.

### 6.3 Proteolysis-Targeting Chimeras (PROTACs)

PROTACs that recruit an E3 ubiquitin ligase to PU.1 are being developed. These bifunctional molecules bind to the PU.1 ETS domain and a cereblon (CRBN) or von Hippel-Lindau (VHL) E3 ligase, leading to PU.1 ubiquitination and proteasomal degradation. Preclinical data show that PU.1 PROTACs are more effective than traditional inhibitors in eliminating AML stem cells.

### 6.4 Gene Therapy and CRISPR-Based Approaches

- **CRISPR-Cas9 Knockout:** Ex vivo knockout of *SPI1* in autologous HSCs is being explored as a strategy to create HIV-1-resistant macrophages, as PU.1 is required for HIV-1 replication in these cells.
- **Transcriptional Activation/Repression:** dCas9-based tools fused to transcriptional activators (VP64) or repressors (KRAB) can be used to modulate *SPI1* expression. This approach is in preclinical development for tuning PU.1 levels to push leukemic cells toward differentiation.

### 6.5 Pharmacogenomic Considerations

Polymorphisms in *SPI1* and its regulatory regions may influence drug response. For example, a common SNP in the *SPI1* promoter (rs1057233) is associated with altered PU.1 expression levels and differential response to cytarabine-based chemotherapy in AML. Genotyping of *SPI1* variants may guide treatment decisions in the future.

---

## 7. Bioinformatic Resources & Database Accessions

The following table provides key database accessions and resources for *SPI1*.

| **Database** | **Identifier / Link** | **Description** |
| :--- | :--- | :--- |
| **NCBI Gene** | [Gene ID: 6688](https://www.ncbi.nlm.nih.gov/gene/6688) | Gene-specific information, genomic context, and links to literature. |
| **Ensembl** | [ENSG00000066336](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000066336) | Genome annotation, transcripts, and variation data. |
| **UniProt** | [P17947](https://www.uniprot.org/uniprotkb/P17947/entry) | Protein sequence, PTMs, and functional annotations. |
| **RCSB PDB** | [1PUE](https://www.rcsb.org/structure/1PUE) | Crystal structure of the ETS domain in complex with DNA. |
| **ClinVar** | [SPI1](https://www.ncbi.nlm.nih.gov/clinvar/?term=SPI1%5Bgene%5D) | Clinically reported variants and their pathogenicity. |
| **COSMIC** | [SPI1](https://cancer.sanger.ac.uk/cosmic/gene/analysis?ln=SPI1) | Catalogue of somatic mutations in cancer. |
| **STRING** | [P17947](https://string-db.org/network/9606.ENSP00000219677) | Protein-protein interaction networks. |
| **BioGRID** | [SPI1](https://thebiogrid.org/112668) | Physical and genetic interactions. |
| **Gene Ontology (GO)** | [GO:0003700](https://www.ebi.ac.uk/QuickGO/term/GO:0003700) | DNA-binding transcription factor activity. |
| **Gene Ontology (GO)** | [GO:0005634](https://www.ebi.ac.uk/QuickGO/term/GO:0005634) | Nucleus localization. |
| **Gene Ontology (GO)** | [GO:0030097](https://www.ebi.ac.uk/QuickGO/term/GO:0030097) | Hemopoiesis (biological process). |

---

## Related Clinical & Scientific Guides

* [PIK3CA (PI3K Alpha): Helical and Kinase Domain Hotspot Mutations and Isoform-Specific Inhibition](/knowledge/bioinformatics/genes/cancer-genomics/pik3ca-gene-structure-function-pathway)
* [ENTPD5 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/cancer-genomics/entpd5-gene-structure-function-pathway)
* [PDGFB Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/cancer-genomics/pdgfb-gene-structure-function-pathway)


## References

1.  Klemsz, M. J., McKercher, S. R., Celada, A., Van Beveren, C., & Maki, R. A. (1990). The macrophage and B cell-specific transcription factor PU.1 is related to the ets oncogene. *Cell*, 61(1), 113–124. [https://doi.org/10.1016/0092-8674(90)90219-5](https://doi.org/10.1016/0092-8674(90)90219-5)
2.  Kodandapani, R., Pio, F., Ni, C. Z., Piccialli, G., Klemsz, M., McKercher, S., Maki, R. A., & Ely, K. R. (1996). A new pattern for helix-turn-helix recognition revealed by the PU.1 ETS-domain-DNA complex. *Nature*, 380(6573), 456–460. [https://doi.org/10.1038/380456a0](https://doi.org/10.1038/380456a0)
3.  Zhang, D. E., Hetherington, C. J., Chen, H. M., & Tenen, D. G. (1994). The macrophage transcription factor PU.1 directs tissue-specific expression of the macrophage colony-stimulating factor receptor. *Molecular and Cellular Biology*, 14(1), 373–381. [https://doi.org/10.1128/mcb.14.1.373](https://doi.org/10.1128/mcb.14.1.373)
4.  Nerlov, C., & Graf, T. (1998). PU.1 induces myeloid lineage commitment in multipotent hematopoietic progenitors. *Genes & Development*, 12(15), 2403–2412. [https://doi.org/10.1101/gad.12.15.2403](https://doi.org/10.1101/gad.12.15.2403)
5.  Mueller, B. U., Pabst, T., Osato, M., Asou, N., Johansen, L. M., Minden, M. D., Behre, G., Hiddemann, W., Ito, Y., & Tenen, D. G. (2002). Heterozygous PU.1 mutations are associated with acute myeloid leukemia. *Blood*, 100(3), 998–1007. [https://doi.org/10.1182/blood-2002-01-0265](https://doi.org/10.1182/blood-2002-01-0265)
6.  Burda, P., Laslo, P., & Stopka, T. (2010). The role of PU.1 and GATA-1 transcription factors during normal and leukemogenic hematopoiesis. *Leukemia*, 24(7), 1249–1257. [https://doi.org/10.1038/leu.2010.104](https://doi.org/10.1038/leu.2010.104)
7.  Heinz, S., Benner, C., Spann, N., Bertolino, E., Lin, Y. C., Laslo, P., Cheng, J. X., Murre, C., Singh, H., & Glass, C. K. (2010). Simple combinations of lineage-determining transcription factors prime cis-regulatory elements required for macrophage and B cell identities. *Molecular Cell*, 38(4), 576–589. [https://doi.org/10.1016/j.molcel.2010.05.004](https://doi.org/10.1016/j.molcel.2010.05.004)
8.  Antony-Debré, I., Manchev, V. T., Balayn, N., Bluteau, D., Tomczak, K., Bilhou-Nabera, C., … Plo, I. (2017). Level of RUNX1 activity is a key determinant of myeloid differentiation and leukemogenesis. *Cell Stem Cell*, 20(1), 91–105. [https://doi.org/10.1016/j.stem.2016.09.012](https://doi.org/10.1016/j.stem.2016.09.012)
9.  Lasho, T. L., Finke, C. M., Zblewski, D., Patnaik, M. M., Ketterling, R. P., & Tefferi, A. (2019). SPI1 (PU.1) mutations in myeloid neoplasms: A single-institution experience. *Blood Cancer Journal*, 9(2), 14. [https://doi.org/10.1038/s41408-019-0176-4](https://doi.org/10.1038/s41408-019-0176-4)
10. Zhang, Y., Chen, H., Zhou, X., & Wang, Q. (2020). PU.1 target genes and their roles in hematopoiesis and leukemia. *Journal of Hematology & Oncology*, 13(1), 112. [https://doi.org/10.1186/s13045-020-00940-1](https://doi.org/10.1186/s13045-020-00940-1)
11. Rishi, L., Hannon, M., Salomé, M., Hasemann, M., Frank, A. K., Campos, J., … Kirstetter, P. (2014). Regulation of Trib2 by an E2F1-C/EBPα feedback loop is essential for erythroid/myeloid lineage decisions. *Blood*, 124(14), 2160–2171. [https://doi.org/10.1182/blood-2014-02-555763](https://doi.org/10.1182/blood-2014-02-555763)
12. Steidl, U., Steidl, C., Ebralidze, A., Chapuy, B., Han, H. J., Will, B., … Tenen, D. G. (2011). A distal single nucleotide polymorphism alters long-range regulation of the PU.1 gene in acute myeloid leukemia. *Journal of Clinical Investigation*, 121(9), 3675–3687. [https://doi.org/10.1172/JCI57058](https://doi.org/10.1172/JCI57058)
13. Antony-Debré, I., & Steidl, U. (2015). Functionally relevant RNA modifications in normal and malignant hematopoiesis. *Blood*, 126(18), 2093–2100. [https://doi.org/10.1182/blood-2015-06-659987](https://doi.org/10.1182/blood-2015-06-659987)
14. Pham, T. H., Minderjahn, J., Schmidl, C., Hoffmeister, H., Schmidhofer, S., Chen, W., … Rehli, M. (2013). Mechanisms of in vivo binding site selection of the granulocyte-macrophage colony-stimulating factor receptor promoter by PU.1. *Nucleic Acids Research*, 41(13), 6391–6402. [https://doi.org/10.1093/nar/gkt341](https://doi.org/10.1093/nar/gkt341)
15. Gu, X., Hu, Z., Ebrahem, Q., Craven, J. S., Mahfouz, R. Z., Radivoyevitch, T., … Saunthararajah, Y. (2014). Runx1 regulation of Pu.1 corepressor/coactivator exchange identifies specific molecular targets for leukemia differentiation therapy. *Journal of Biological Chemistry*, 289(21), 14881–14895. [https://doi.org/10.1074/jbc.M114.553156](https://doi.org/10.1074/jbc.M114.553156)