SPIC (Spi-C) is an ETS-family transcription factor of the SPI subgroup, related to PU.1 (SPI1) and SPI-B, that binds purine-rich PU-box/Ets elements as a monomer through its C-terminal ETS domain and activates transcription through an N-terminal acidic transactivation domain. It is expressed mainly in spleen, lymph node, bone marrow and fetal liver. In mouse, Spi-C is the lineage-determining factor for iron-recycling macrophages: it is required cell-autonomously for development of splenic red pulp macrophages and VCAM1-high bone marrow macrophages, which phagocytose senescent erythrocytes, and Spic-deficient mice accumulate iron in the splenic red pulp. Spic is induced in monocytes by heme released from engulfed erythrocytes, which inactivates the repressor BACH1; it is also induced by TLR/NF-kB signalling in activated macrophages, where it dampens pro-inflammatory cytokine expression and promotes ferroportin expression. VCAM1 is a known direct target. In B cells, Spi-C antagonizes PU.1 and SPI-B at shared sites, repressing targets such as Nfkb1, Rag1 and Igkappa and modulating pre-B and mature B cell differentiation.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000785 chromatin | ISA GO_REF:0000113 | ACCEPT | Summary: Chromatin location inferred from TFClass membership of SPIC in the ETS/SPI subfamily (3.5.2). Mouse Spi-C is recruited to gene-regulatory elements genome-wide in pre-B cells and occupies the Rag1 promoter by ChIP. Reason: A sequence-specific DNA-binding transcription factor acts on chromatin-embedded cis-regulatory elements. Chromatin occupancy of the ortholog is shown by ChIP (SPIC/BCLAF1 at B cell regulatory elements; Rag1 promoter), so the TFClass-based inference holds for the human protein. Supporting Evidence: PMID:31644907 SPIC recruits BCLAF1 to gene-regulatory elements that control expression of key B cell developmental genes PMID:37195219 Using chromatin immunoprecipitation analysis, we identified an interaction site for PU.1 and Spi-C located in the Rag1 promoter region file:human/SPIC/SPIC-uniprot.txt Transcription factor that binds to the PU-box, a purine-rich DNA sequence (5'-GAGGA[AT]-3') that can act as a lymphoid-specific enhancer |
| GO:0000978 RNA polymerase II cis-regulatory region sequence-specific DNA binding | IEA GO_REF:0000107 | ACCEPT | Summary: RNA polymerase II cis-regulatory region sequence-specific DNA binding, transferred by Ensembl Compara from mouse Spic (IMP, PMID:12749910). Spi-C binds PU-box/Ets elements in the kappaY element and the VCAM-1 promoter. Reason: Directly supported for the mouse ortholog by band-shift, methylation interference and site selection on the kappaY element, and by EMSA on the VCAM-1 proximal promoter Ets element, whose deletion abolishes Spi-C-driven reporter activity. The ETS domain is conserved in human SPIC (residues 111-194). Core molecular activity. Supporting Evidence: PMID:10187812 Spi-C interacted with DNA similarly to PU.1 as judged by methylation interference, band-shift and site selection analysis, and activated transcription of a kappaY element reporter gene upon co-transfection of HeLa cells PMID:19037245 An Ets consensus element within the proximal VCAM-1 promoter forms complexes with PU.1 and Spi-C in EMSA PMID:19037245 Deletion of the Ets element within the VCAM-1 promoter eliminated reporter augmentation by both PU.1 and Spi-C file:human/SPIC/SPIC-uniprot.txt Transcription factor that binds to the PU-box, a purine-rich DNA sequence (5'-GAGGA[AT]-3') that can act as a lymphoid-specific enhancer |
| GO:0000981 DNA-binding transcription factor activity, RNA polymerase II-specific | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from the ETS family node PTN000218930: RNA polymerase II-specific DNA-binding transcription factor activity. Reason: SPIC sits inside the ETS clade with an intact ETS DNA-binding domain, and the mouse ortholog binds Ets/PU-box elements and regulates transcription of target genes (VCAM1, Fcer2a, Nfkb1, Rag1). The PAINT node placement is appropriate, and this is the right level of specificity for a factor that both activates and represses targets. Core function. Supporting Evidence: PMID:10187812 Spi-C interacted with DNA similarly to PU.1 as judged by methylation interference, band-shift and site selection analysis, and activated transcription of a kappaY element reporter gene upon co-transfection of HeLa cells PMID:19037245 Deletion of the Ets element within the VCAM-1 promoter eliminated reporter augmentation by both PU.1 and Spi-C file:human/SPIC/SPIC-uniprot.txt Belongs to the ETS family file:human/SPIC/SPIC-uniprot.txt Transcription factor that binds to the PU-box, a purine-rich DNA sequence (5'-GAGGA[AT]-3') that can act as a lymphoid-specific enhancer |
| GO:0000981 DNA-binding transcription factor activity, RNA polymerase II-specific | ISA GO_REF:0000113 | ACCEPT | Summary: TFClass-based inference of RNA polymerase II-specific DNA-binding transcription factor activity. Reason: Same claim as the IBA row; consistent with experimental data for mouse Spi-C (sequence-specific DNA binding plus transactivation through an N-terminal acidic domain). Core function. Supporting Evidence: PMID:10187812 Spi-C interacted with DNA similarly to PU.1 as judged by methylation interference, band-shift and site selection analysis, and activated transcription of a kappaY element reporter gene upon co-transfection of HeLa cells PMID:12749910 the transactivation activity is reduced to that of the DNA binding domain (DBD) alone when four aspartic acid residues are mutated to alanines file:human/SPIC/SPIC-uniprot.txt Transcription factor that binds to the PU-box, a purine-rich DNA sequence (5'-GAGGA[AT]-3') that can act as a lymphoid-specific enhancer |
| GO:0001228 DNA-binding transcription activator activity, RNA polymerase II-specific | IEA GO_REF:0000107 | ACCEPT | Summary: DNA-binding transcription activator activity (RNA polymerase II), transferred from the mouse Spic IMP (PMID:12749910, transactivation-domain mutagenesis). Reason: Mouse Spi-C has an N-terminal acidic transactivation domain and activates kappaY and VCAM-1 reporters and the Fcer2a gene. SPI-C also represses some PU.1 targets (e.g. Nfkb1), so activation is one context-dependent mode; GO:0000981 is the core term, but activator activity is directly evidenced and accepted. Supporting Evidence: PMID:12749910 the transactivation activity is reduced to that of the DNA binding domain (DBD) alone when four aspartic acid residues are mutated to alanines PMID:19037245 Deletion of the Ets element within the VCAM-1 promoter eliminated reporter augmentation by both PU.1 and Spi-C PMID:21057087 transcription of the Fcer2a gene encoding CD23 is activated by PU.1, Spi-B, and Spi-C |
| GO:0003700 DNA-binding transcription factor activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO (ETS domain) mapping to DNA-binding transcription factor activity. Reason: Correct but general. The gene already carries the more specific RNA polymerase II-specific child GO:0000981 (IBA, ISA), which the ortholog data support (Pol II promoter targets such as VCAM1). Proposed replacements: DNA-binding transcription factor activity, RNA polymerase II-specific Supporting Evidence: file:human/SPIC/SPIC-uniprot.txt Belongs to the ETS family PMID:19037245 Deletion of the Ets element within the VCAM-1 promoter eliminated reporter augmentation by both PU.1 and Spi-C |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | REMOVE | Summary: Generic protein binding from the HuRI binary yeast two-hybrid interactome map (partner MEOX1 or INTS11). Reason: Bare protein binding is uninformative under the project protein-binding policy. The high-throughput Y2H interaction does not indicate a specific molecular function, and no follow-up connects SPIC to MEOX1 or INTS11 biology. Removal does not assert that the interaction is false. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | REMOVE | Summary: Generic protein binding from the HuRI binary yeast two-hybrid interactome map (partner MEOX1 or INTS11). Reason: Bare protein binding is uninformative under the project protein-binding policy. The high-throughput Y2H interaction does not indicate a specific molecular function, and no follow-up connects SPIC to MEOX1 or INTS11 biology. Removal does not assert that the interaction is false. |
| GO:0005634 nucleus | IBA GO_REF:0000033 | ACCEPT | Summary: IBA: nucleus, from the ETS family node. Reason: Nuclear localization is expected for an ETS transcription factor; the UniProt curated location is Nucleus, and in mouse osteoclast precursors RANKL drives nuclear translocation of Spi-C. Supporting Evidence: file:human/SPIC/SPIC-uniprot.txt SUBCELLULAR LOCATION: Nucleus PMID:32341419 RANKL stimulation induced the translocation of Spi-C from the cytoplasm into the nucleus during osteoclastogenesis |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: Nucleus from UniProt subcellular location mapping. Reason: Consistent with transcription factor function and with ortholog evidence of nuclear translocation. Supporting Evidence: file:human/SPIC/SPIC-uniprot.txt SUBCELLULAR LOCATION: Nucleus PMID:32341419 RANKL stimulation induced the translocation of Spi-C from the cytoplasm into the nucleus during osteoclastogenesis |
| GO:0006355 regulation of DNA-templated transcription | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO: regulation of DNA-templated transcription. Reason: Correct but general. SPIC targets are RNA polymerase II genes (VCAM1, Fcer2a, Nfkb1, Rag1), and the gene already carries GO:0006357 (IBA, IEA). Proposed replacements: regulation of transcription by RNA polymerase II Supporting Evidence: PMID:19037245 Deletion of the Ets element within the VCAM-1 promoter eliminated reporter augmentation by both PU.1 and Spi-C PMID:25769919 Spi-B was shown to directly activate the Nfkb1 gene, whereas Spi-C was shown to repress this gene |
| GO:0006357 regulation of transcription by RNA polymerase II | IBA GO_REF:0000033 | ACCEPT | Summary: IBA: regulation of transcription by RNA polymerase II. Reason: Mouse Spi-C both activates (VCAM1, Fcer2a) and represses (Nfkb1, Rag1, Igkappa) Pol II target genes, so the bidirectional regulation term is the appropriate summary process. Core. Supporting Evidence: PMID:19037245 Deletion of the Ets element within the VCAM-1 promoter eliminated reporter augmentation by both PU.1 and Spi-C PMID:21057087 transcription of the Fcer2a gene encoding CD23 is activated by PU.1, Spi-B, and Spi-C PMID:25769919 Spi-B was shown to directly activate the Nfkb1 gene, whereas Spi-C was shown to repress this gene |
| GO:0006357 regulation of transcription by RNA polymerase II | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO (ETS family) mapping to regulation of transcription by RNA polymerase II. Reason: Same claim as the IBA row, supported by ortholog target-gene studies. Supporting Evidence: PMID:21057087 transcription of the Fcer2a gene encoding CD23 is activated by PU.1, Spi-B, and Spi-C PMID:25769919 Spi-B was shown to directly activate the Nfkb1 gene, whereas Spi-C was shown to repress this gene |
| GO:0030154 cell differentiation | IBA GO_REF:0000033 | MODIFY | Summary: IBA: cell differentiation, from the ETS family node. Reason: True but general. The specific differentiation process SPI-C drives is known: Spic-/- mice have a cell-autonomous defect in red pulp macrophage development that retroviral Spi-C rescues, and also lack VCAM1-high bone marrow macrophages; heme-induced Spic drives monocytes to pre-RPM and RPM. As a transcription factor whose target program (e.g. VCAM1) defines the lineage, SPI-C does regulatory work in this differentiation rather than only being required for it. Comparator: mouse PU.1 (Sfpi1, P17433) carries GO:0030225. GO has no red-pulp-macrophage-specific child, so macrophage differentiation is the most specific available term. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: PANTHER:PTN000218930 · ETS family tree node SUPPORTS TRANSFER A family-wide node can only assert generic cell differentiation because ETS members specify different lineages; SPIC's own lineage (red pulp and bone marrow iron-recycling macrophages) is known from mouse knockout data, so the issue is granularity, not divergence. Proposed replacements: macrophage differentiation Supporting Evidence: PMID:19037245 Spic(-/-) mice have a cell-autonomous defect in the development of red pulp macrophages that is corrected by retroviral Spi-C expression in bone marrow cells, but have normal monocyte and other macrophage subsets PMID:24630724 Spic−/− mice were found to be deficient in F4/80hi VCAM1hi BMM in addition to the previously reported loss of RPM PMID:24630724 These results demonstrate the role of heme in generating pre-RPM and RPM from monocytes. |
| GO:0043565 sequence-specific DNA binding | IEA GO_REF:0000120 | MODIFY | Summary: Combined automated (ARBA + InterPro) sequence-specific DNA binding. Reason: Correct but general. The gene carries the more specific RNA polymerase II cis-regulatory region sequence-specific DNA binding (GO:0000978), supported by EMSA on Pol II promoter elements for the ortholog. Proposed replacements: RNA polymerase II cis-regulatory region sequence-specific DNA binding Supporting Evidence: PMID:19037245 An Ets consensus element within the proximal VCAM-1 promoter forms complexes with PU.1 and Spi-C in EMSA PMID:10187812 Spi-C interacted with DNA similarly to PU.1 as judged by methylation interference, band-shift and site selection analysis, and activated transcription of a kappaY element reporter gene upon co-transfection of HeLa cells |
| GO:0045944 positive regulation of transcription by RNA polymerase II | IEA GO_REF:0000107 | ACCEPT | Summary: Positive regulation of transcription by RNA polymerase II, transferred from the mouse Spic IMP (PMID:12749910). Reason: Mouse Spi-C activates VCAM-1 through a promoter Ets element, and Fcer2a; transactivation depends on its acidic N-terminal domain. Accepted; SPI-C also represses some targets, which GO:0006357 captures. Supporting Evidence: PMID:19037245 Deletion of the Ets element within the VCAM-1 promoter eliminated reporter augmentation by both PU.1 and Spi-C PMID:21057087 transcription of the Fcer2a gene encoding CD23 is activated by PU.1, Spi-B, and Spi-C PMID:12749910 the transactivation activity is reduced to that of the DNA binding domain (DBD) alone when four aspartic acid residues are mutated to alanines |
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Download this section (compressed HTML)Q: Is human SPIC required for red pulp / iron-recycling macrophage identity as mouse Spic is, and do human loss-of-function variants associate with splenic iron accumulation or altered erythrocyte clearance?
Q: Does BACH1 bind the SPIC locus directly, and is heme-BACH1 de-repression of SPIC conserved in human monocytes beyond the induction seen with heme-loaded red-cell vesicles?
Q: Is SPI-C repression of PU.1/SPI-B targets (Nfkb1, Rag1, Igkappa) intrinsic repressor activity, or competitive occupancy of PU-box sites without recruiting PU.1 partners such as IRF4/PIP?
Q: Beyond VCAM1, which genes of the red pulp macrophage program (CD163, SLC40A1, HMOX1) are direct SPI-C targets in vivo, given that SPI-C expression in RAW264.7 induced VCAM-1 but not CD163 or ferroportin?
Experiment: SPIC ChIP-seq or CUT&RUN combined with RNA-seq in Spic-deficient versus wild-type heme-treated monocyte-derived red pulp macrophage precursors to define the direct target set of the iron-recycling macrophage program.
Experiment: CRISPR knockout of SPIC in human monocyte-derived macrophages exposed to heme or senescent erythrocytes, measuring VCAM1, CD163 and ferroportin expression and erythrophagocytic capacity.
Experiment: Mutational analysis (acidic transactivation domain D-to-A mutants; ETS-domain DNA-binding mutants) at reporter and endogenous loci to test whether repression of PU.1 targets needs only DNA binding or also corepressor recruitment.
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