Affinage

SP5

Transcription factor Sp5 · UniProt Q6BEB4

Length
398 aa
Mass
42.0 kDa
Annotated
2026-06-10
44 papers in source corpus 17 papers cited in narrative 17 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

SP5 is a GC-box-binding C2H2 zinc-finger transcription factor that operates as a direct, conserved downstream target of Wnt/β-catenin signaling and feeds back to shape Wnt transcriptional output across development from cnidarians to mammals (PMID:16273202, PMID:26969725, PMID:30659200, PMID:31626630). Its proximal promoter carries TCF/LEF and TCF4-binding elements that mediate transactivation by β-catenin/Tcf complexes (PMID:16273202, PMID:17090534), and SP5 binds the GC box through its C-terminal zinc fingers (PMID:11071760). SP5 functions dually: it acts as a transcriptional repressor through three independent repressor domains, with the R1 domain recruiting the corepressor mSin3a, and it can repress Sp1 target genes and the Wnt3 promoter to enforce a negative-feedback loop that terminates WNT-induced transcriptional programs and restricts organizer activity (PMID:17090534, PMID:29044119, PMID:30659200); conversely, together with Sp8 it acts as a coactivator, binding GC boxes in Wnt target enhancers and interacting with chromatin-bound Tcf1/Lef1 to facilitate β-catenin recruitment, such that combined Sp5/Sp8 loss phenocopies loss of core Wnt pathway components (PMID:26969725). Through these activities SP5 patterns mesoderm and neuroectoderm downstream of Wnt8 (PMID:15797017), acts upstream of the neural-plate-border specifiers Msx1 and Pax3 in neural crest induction (PMID:24038420), and supports embryonic stem cell self-renewal and naive pluripotency by directly activating Nanog via its zinc fingers (PMID:26598557, PMID:28961274). The Sp5/Sp8 module is additionally required for primary and motile ciliogenesis, with combined loss producing situs inversus and hydrocephalus (PMID:40875857). In cancer contexts SP5 binding to promoters is modulated by CPT1A-mediated succinylation, which strengthens its occupancy of the PDPK1 promoter to activate AKT/mTOR signaling (PMID:38494680).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2000 Medium

    Establishing that Sp5 is a sequence-specific DNA-binding factor defined its molecular identity and linked it to developmental gene control.

    Evidence In vitro DNA binding to the GC box plus genetic epistasis with Brachyury in compound mutant mice

    PMID:11071760

    Open questions at the time
    • Does not establish whether Sp5 activates or represses its targets
    • No direct in vivo target gene confirmed
  2. 2005 High

    Identifying SP5 as a direct Wnt/β-catenin target placed it within a defined signaling cascade rather than as an isolated transcription factor.

    Evidence Zebrafish microarray, morpholino knockdown and rescue downstream of wnt8; human reporter assays and EMSA mapping a TCF4 element in the SP5 promoter

    PMID:15797017 PMID:16273202

    Open questions at the time
    • Whether SP5 output is activating or repressive on Wnt targets not resolved
    • Direct SP5 target genes not identified at this stage
  3. 2006 High

    Defining repressor domains and the mSin3a interaction explained how SP5 silences transcription while remaining a Wnt-induced gene.

    Evidence Gal4-fusion domain mapping, co-IP of mSin3a, and TCF/LEF site mutagenesis in mouse telencephalon

    PMID:17090534

    Open questions at the time
    • Genome-wide repressed targets not defined
    • Did not reconcile repressor function with later coactivator role
  4. 2016 High

    Demonstrating that Sp5/Sp8 recruit β-catenin to enhancers revealed an activating mode that complements its repressive activity.

    Evidence Conditional double-knockout mouse genetics, ChIP and co-IP showing GC-box binding and Tcf1/Lef1 interaction

    PMID:26969725

    Open questions at the time
    • How the activator/repressor switch is selected at individual enhancers unknown
    • Structural basis of β-catenin recruitment not defined
  5. 2017 High

    Genome-wide binding and pluripotency studies showed SP5 both terminates Wnt programs and directly sustains stem cell self-renewal.

    Evidence ChIP-seq plus mutant RNA-seq in hPSCs; ChIP and knockdown showing direct Nanog promoter activation in mESCs

    PMID:28961274 PMID:29044119

    Open questions at the time
    • Determinants of which Wnt targets are repressed vs activated unresolved
    • Cofactors directing Nanog activation not identified
  6. 2019 High

    Cross-species feedback studies established SP5 as a conserved repressor of Wnt ligand genes that restricts organizer/axial patterning.

    Evidence Hydra RNAi multi-headed phenotype with Wnt3 promoter reporters; β-catenin RNAi epistasis in planarians and acoels

    PMID:30659200 PMID:31626630

    Open questions at the time
    • Mechanism of Wnt3 promoter repression in vertebrates not fully mapped
    • Conservation of mSin3a recruitment across species untested
  7. 2024 Medium

    Discovery of CPT1A-mediated succinylation introduced a post-translational mechanism modulating SP5 promoter occupancy in cancer.

    Evidence Co-IP, ChIP, reporter and metabolic assays linking SP5 succinylation to PDPK1/AKT/mTOR activation in prostate cancer cells

    PMID:38494680

    Open questions at the time
    • Succinylation sites and stoichiometry not defined
    • Whether this modification operates in normal development unknown
  8. 2025 High

    Identifying a ciliogenesis requirement extended the Sp5/Sp8 module beyond direct Wnt transcriptional feedback to organelle biogenesis.

    Evidence Conditional double-knockout mouse genetics with ciliopathy readouts and stem cell gain-of-function sufficiency for SP8

    PMID:40875857

    Open questions at the time
    • Direct cilia gene targets of SP5/8 not enumerated
    • Whether ciliogenesis role is Wnt-dependent unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • How SP5 selects between its repressor and coactivator modes at individual enhancers, and how post-translational modifications integrate with this switch, remains unresolved.
  • No structural model of SP5 in activator vs repressor complexes
  • Rules governing context-specific cofactor choice unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 5 GO:0003677 DNA binding 4
Localization
GO:0005634 nucleus 3
Pathway
R-HSA-162582 Signal Transduction 5 R-HSA-1266738 Developmental Biology 3 R-HSA-74160 Gene expression (Transcription) 3
Partners
CPT1ACTNNB1LEF1SIN3ASP8TCF7TCF7L2

Evidence

Reading pass · 17 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 Mouse Sp5 protein binds to the GC box DNA motif (present in the Brachyury promoter and many other gene promoters) via its C-terminal C2H2 zinc finger domain, as shown by in vitro DNA binding studies. Sp5 genetically interacts with Brachyury, as compound mutant mice (Sp5lacZ/Sp5lacZ, T/+) show enhancement of the T/+ phenotype. In vitro DNA binding assay; genetic epistasis (compound mutant mice) Developmental biology Medium 11071760
2005 Zebrafish sp5-like (and its paralog sp5) are direct transcriptional targets of Wnt/β-catenin signaling and act downstream of wnt8 to pattern mesoderm and neuroectoderm; sp5-like overexpression posteriorizes the neuroectoderm and can partially rescue hindbrain patterning in wnt8 morphants, placing sp5 downstream of Wnt8 in a required mediator role. Zebrafish DNA microarray identification; morpholino knockdown; overexpression epistasis; genetic rescue experiments Current biology : CB High 15797017
2005 Human SP5 is identified as a direct downstream target of the β-catenin/TCF4 complex: reporter assays and EMSA mapped a TCF4-binding element between −285 and −279 in the SP5 5′ flanking region that mediates transcriptional activation by β-catenin/Tcf4. Luciferase reporter assay; electrophoretic mobility shift assay (EMSA); cDNA microarray after APC transduction into SW480 cells International journal of oncology Medium 16273202
2006 Sp5 functions as a transcriptional repressor with three independent repressor domains (R1, R2, R3). The R1 domain represses transcription via direct protein–protein interaction with the corepressor mSin3a. Sp5 has the same DNA binding specificity as Sp1 and represses Sp1 target genes such as p21. The Sp5 proximal promoter contains five TCF/LEF binding sites that mediate direct regulation by canonical Wnt/β-catenin signaling in the mouse embryonic telencephalon. Conditional Cre/loxP β-catenin activation in mouse; Gal4 fusion reporter assays defining repressor domains; co-immunoprecipitation of mSin3a; promoter reporter assays with TCF/LEF site mutations The Journal of biological chemistry High 17090534
2013 Xenopus Sp5 functions as a critical early regulator of neural crest specification downstream of Wnt/β-catenin and FGF signaling. Sp5 regulates neural plate border specifiers Msx1 and Pax3; overexpression of Msx1/Pax3 rescues neural crest marker expression in Sp5-depleted embryos, placing Sp5 upstream of these specifiers in the neural crest induction cascade. Morpholino knockdown; mRNA overexpression; epistasis rescue experiments; in situ hybridization of neural crest markers Developmental dynamics : an official publication of the American Association of Anatomists Medium 24038420
2015 Sp5 expression is activated by both LIF-Stat3 and Wnt/β-catenin signaling pathways in mouse ESCs, and forced Sp5 expression maintains mESC self-renewal and can convert epiblast stem cells to naïve pluripotency, functioning downstream of both pathways. Forced expression; signal inhibition; ESC self-renewal and conversion assays Journal of cell science Medium 26598557
2016 Sp5 and Sp8 are transcriptional coactivators in the Wnt/β-catenin pathway; they bind directly to GC boxes in Wnt target gene enhancers and interact with chromatin-bound Tcf1/Lef1 to facilitate recruitment of β-catenin to target gene enhancers. Combined null mutation of Sp5 and Sp8 phenocopies loss of core Wnt/β-catenin pathway components. Conditional double knockout mouse genetics; ChIP; co-immunoprecipitation; differentiating embryonic stem cells; chromatin accessibility assays Proceedings of the National Academy of Sciences of the United States of America High 26969725
2017 Sp5 induces expression of Nanog by directly binding the Nanog promoter (shown by ChIP), thereby mediating the self-renewal-promoting effect of Sp5 in mouse ESCs. The zinc finger domains of Sp5 are required for this function, and Nanog knockdown eliminates the self-renewal-promoting ability of Sp5. Chromatin immunoprecipitation (ChIP); overexpression; knockdown; knockout; mESC self-renewal assays PloS one Medium 28961274
2017 SP5 acts as a negative feedback regulator of WNT transcriptional programs in human pluripotent stem cells: genome-wide SP5 binding (ChIP-seq) integrated with transcriptomics of wild-type and SP5 mutant cells shows SP5 binds and diminishes expression of genes previously activated by WNT signaling, thereby terminating WNT-induced transcriptional programs. Genome-wide ChIP-seq; RNA-seq of WT vs SP5 mutant hPSCs; WNT pathway activation assays Nature communications High 29044119
2018 Sp5 inhibits proliferation of HCT116 colorectal cancer cells by directly upregulating transcription of the cell cycle inhibitor p27. Overexpression; knockdown; cell proliferation assays; reporter/transcriptional assays Oncology letters Low 29456745
2019 Hydra Sp5 acts as a transcriptional repressor of Wnt3 and is positively regulated by Wnt/β-catenin signaling, creating a negative feedback loop that restricts head organizer activity. Sp5 represses Wnt3 promoter activity (shown in both Hydra and zebrafish), and Hydra Sp5 activates its own expression likely via β-catenin/TCF interaction. Knockdown of Sp5 in Hydra produces a robust multi-headed phenotype. RNAi knockdown in Hydra; Wnt3 promoter reporter assays; β-catenin silencing; comparative transcriptomics; luciferase reporter assays Nature communications High 30659200
2019 sp5 is rapidly downregulated after β-catenin RNAi in both planarians and acoels, confirming it as a conserved direct downstream target of Wnt/β-catenin signaling. In planarians, sp5 inhibits trunk gene expression in the tail, thereby promoting separate tail-trunk body domains. β-catenin RNAi followed by transcriptomic profiling; loss-of-function sp5 RNAi with gene expression readouts in two species PLoS genetics Medium 31626630
2024 CPT1A (a succinyltransferase) promotes succinylation of SP5, which strengthens SP5 binding to the PDPK1 gene promoter, thereby activating PDPK1 transcription. PDPK1 then activates the AKT/mTOR signaling pathway to promote viability and glycolysis of prostate cancer cells. Co-immunoprecipitation; ChIP; luciferase reporter assay; Seahorse metabolic assay; CCK-8 viability assay; siRNA silencing Cancer biology & therapy Medium 38494680
2025 SP5 and SP8 together regulate primary and motile cilia formation in mouse embryos; loss of both Sp5 and Sp8 results in shorter and fewer cilia across cell types, causing situs inversus and hydrocephalus. SP8 expression alone is sufficient to induce primary cilia in unciliated cells, demonstrating a direct role for this Sp5/8 module in ciliogenesis. Conditional double knockout mouse genetics; stem cell gain-of-function; multi-omics (transcriptomics of ciliated vs. unciliated cells); cilia length/number quantification Science (New York, N.Y.) High 40875857
2025 SP5 binds the SERPING1 gene promoter and activates SERPING1 transcription, suppressing lung adenocarcinoma progression via the TSC2/mTOR pathway. ChIP; luciferase reporter assay; in vitro and in vivo loss-of-function/gain-of-function Cell death & disease Low 39962118
2005 Human SP5 protein contains multiple transcriptional regulatory domains: an N-terminal activation domain, an intrinsic repressive element, and a C-terminal synergistic domain, as revealed by Gal4-Sp5 fusion protein reporter assays. Gal4-fusion reporter assays in human cancer cells; inducible overexpression with microarray Biochemical and biophysical research communications Low 16380080
2025 Sp5/8 regulate the dynamic exchange of activating and repressive Tcf complexes at Wnt-responsive enhancers in neuromesodermal progenitors (NMCs), and bind a novel enhancer essential for Wnt3a expression and feedback-loop integrity. Their expression is controlled by Wnt, Fgf and retinoic acid signaling, and they cooperate with Tbxt, Tcf7 and Cdx2 to sustain NMC maintenance. Conditional mouse genetics; ChIP; multi-omics (chromatin accessibility, transcriptomics); enhancer functional assays bioRxivpreprint Medium bio_10.1101_2025.06.03.657492

Source papers

Stage 0 corpus · 44 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1987 Low molecular weight human pulmonary surfactant protein (SP5): isolation, characterization, and cDNA and amino acid sequences. Proceedings of the National Academy of Sciences of the United States of America 193 3479771
2005 The Sp1-related transcription factors sp5 and sp5-like act downstream of Wnt/beta-catenin signaling in mesoderm and neuroectoderm patterning. Current biology : CB 180 15797017
1991 Characterization of Sp-5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole- 3',5'-monophosphorothioate (Sp-5,6-DCl-cBiMPS) as a potent and specific activator of cyclic-AMP-dependent protein kinase in cell extracts and intact cells. The Biochemical journal 145 1659381
2000 Sp5, a new member of the Sp1 family, is dynamically expressed during development and genetically interacts with Brachyury. Developmental biology 109 11071760
2019 An evolutionarily-conserved Wnt3/β-catenin/Sp5 feedback loop restricts head organizer activity in Hydra. Nature communications 73 30659200
2006 Wnt-mediated down-regulation of Sp1 target genes by a transcriptional repressor Sp5. The Journal of biological chemistry 68 17090534
2017 The WNT target SP5 negatively regulates WNT transcriptional programs in human pluripotent stem cells. Nature communications 60 29044119
2008 SP5: improving protein fold recognition by using torsion angle profiles and profile-based gap penalty model. PloS one 58 18523556
2016 Sp5 and Sp8 recruit β-catenin and Tcf1-Lef1 to select enhancers to activate Wnt target gene transcription. Proceedings of the National Academy of Sciences of the United States of America 54 26969725
2015 Wnt/β-catenin and LIF-Stat3 signaling pathways converge on Sp5 to promote mouse embryonic stem cell self-renewal. Journal of cell science 53 26598557
2001 The novel transcription factor gene Sp5 exhibits a dynamic and highly restricted expression pattern during mouse embryogenesis. Mechanisms of development 47 11231070
2018 Genome Analysis of Fimbriiglobus ruber SP5T, a Planctomycete with Confirmed Chitinolytic Capability. Applied and environmental microbiology 46 29374042
2005 Identification of SP5 as a downstream gene of the beta-catenin/Tcf pathway and its enhanced expression in human colon cancer. International journal of oncology 39 16273202
2005 Elevated expression and potential roles of human Sp5, a member of Sp transcription factor family, in human cancers. Biochemical and biophysical research communications 39 16380080
2019 A small set of conserved genes, including sp5 and Hox, are activated by Wnt signaling in the posterior of planarians and acoels. PLoS genetics 34 31626630
1994 Studies on intrachromosomal recombination in SP5/V79 Chinese hamster cells upon exposure to different agents related to carcinogenesis. Carcinogenesis 34 7955071
2022 Genomic Insight Into Lacticaseibacillus paracasei SP5, Reveals Genes and Gene Clusters of Probiotic Interest and Biotechnological Potential. Frontiers in microbiology 28 35783439
2013 Role of Sp5 as an essential early regulator of neural crest specification in xenopus. Developmental dynamics : an official publication of the American Association of Anatomists 21 24038420
2024 CPT1A mediates the succinylation of SP5 which activates transcription of PDPK1 to promote the viability and glycolysis of prostate cancer cells. Cancer biology & therapy 20 38494680
2015 D-SP5 Peptide-Modified Highly Branched Polyethylenimine for Gene Therapy of Gastric Adenocarcinoma. Bioconjugate chemistry 20 26052814
2011 Analysis of the surface proteins of Acidithiobacillus ferrooxidans strain SP5/1 and the new, pyrite-oxidizing Acidithiobacillus isolate HV2/2, and their possible involvement in pyrite oxidation. Archives of microbiology 19 21698546
1992 Reversion of the hprt mutant clone SP5 by intrachromosomal recombination. Carcinogenesis 19 1576714
2022 Investigating the plant growth promoting and biocontrol potentiality of endophytic Streptomyces SP. SP5 against early blight in Solanum lycopersicum seedlings. BMC microbiology 18 36447141
2017 Sp5 induces the expression of Nanog to maintain mouse embryonic stem cell self-renewal. PloS one 11 28961274
1994 cDNA cloning and expression of Xenopus sperm-specific basic nuclear protein 5 (SP5) gene. Molecular reproduction and development 11 8011321
2017 Amphioxus Sp5 is a member of a conserved Specificity Protein complement and is modulated by Wnt/β-catenin signalling. The International journal of developmental biology 10 29319119
2018 Sp5 negatively regulates the proliferation of HCT116 cells by upregulating the transcription of p27. Oncology letters 8 29456745
2016 In vitro cytotoxicity and antimicrobial activity of Talaromyces flavus SP5 inhabited in the marine sediment of Southern Coast of India. Chinese journal of natural medicines 8 28262118
2021 The hokW-sokW Locus Encodes a Type I Toxin-Antitoxin System That Facilitates the Release of Lysogenic Sp5 Phage in Enterohemorrhagic Escherichia coli O157. Toxins 7 34822580
2023 Evolutionarily conserved Wnt/Sp5 signaling is critical for anterior-posterior axis patterning in sea urchin embryos. iScience 6 38179064
2015 A recombined fusion protein SP5.2/tTF induce thrombosis in tumor blood vessel. Neoplasma 6 25997964
1993 The effect of splenopentin (DA SP-5) on in vitro myelopoiesis and on AZT-induced bone marrow toxicity. International journal of immunopharmacology 6 8505137
2024 The Wnt/β-catenin/TCF/Sp5/Zic4 Gene Network That Regulates Head Organizer Activity in Hydra Is Differentially Regulated in Epidermis and Gastrodermis. Biomedicines 5 38927481
1997 Upregulation of HLA class-I gene transcription in K562 cells by analogs of splenopentin (SP-5). Biochemistry and molecular biology international 5 9090459
2025 Transcription factors SP5 and SP8 drive primary cilia formation in mammalian embryos. Science (New York, N.Y.) 4 40875857
2025 Organizer formation, organizer maintenance and epithelial cell plasticity in Hydra: Role of the Wnt3/β-catenin/TCF/Sp5/Zic4 gene network. Cells & development 3 39929422
2025 WNT inhibitor SP5-mediated SERPING1 suppresses lung adenocarcinoma progression via TSC2/mTOR pathway. Cell death & disease 3 39962118
2024 Divergent functions of the evolutionarily conserved, yet seemingly dispensable, Wnt target, sp5. Differentiation; research in biological diversity 3 39675112
2019 Xenopus laevis FGF16 activates the expression of genes coding for the transcription factors Sp5 and Sp5l. The International journal of developmental biology 3 32149373
2023 Circular RNA circSP5 promotes liver metastasis of colorectal cancer via SP5-mediated BAMBI transcription. Functional & integrative genomics 2 37596430
1989 Prevention of graft-vs-host reaction induced immunodeficiency by treatment with splenopentin (DAc-SP5). Allergie und Immunologie 1 2624251
2025 Transcription factors SP5 and SP8 drive primary cilia formation. bioRxiv : the preprint server for biology 0 40501818
2010 [Construction of eukaryotic vector of small hairpin interfering RNA against NYD-SP5]. Zhonghua nan ke xue = National journal of andrology 0 20684327
1996 Relative amounts of basic nuclear proteins SP4 and SP5 in Xenopus laevis sperm correlate with gene copy number. Development, growth & differentiation 0 37281109

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