Affinage

RFX2

DNA-binding protein RFX2 · UniProt P48378

Length
723 aa
Mass
80.0 kDa
Annotated
2026-06-10
23 papers in source corpus 17 papers cited in narrative 16 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

RFX2 is a winged-helix transcription factor that binds X-box DNA elements to direct the gene expression programs underlying ciliogenesis and spermiogenesis across vertebrates (PMID:14743396, PMID:22227339, PMID:26162102). It was first purified from testis nuclear extracts as an X-box-binding protein that activates the H1t histone promoter, occupying both TE1 and TE2 X-box subelements for maximal activation (PMID:14743396, PMID:15526285); the testis-specific X-box complex contains RFX2 (probably as a homodimer) whereas somatic complexes are dominated by RFX1 (PMID:15229132). At target promoters RFX2 occupies the X-box in vivo and functions combinatorially with adjacent factors such as the CCAAT-binding NF-Y (PMID:18247329). In the spermatocyte transcriptional hierarchy RFX2 acts downstream of A-MYB, which binds the Rfx2 promoter, and RFX2 in turn directly activates targets including the TFIIA variant Alf (PMID:20003220). Genetic loss of Rfx2 causes male sterility through arrest of spermatid development, with disrupted Golgi-derived acrosome formation and complete failure of flagellar axoneme assembly, and RNA-seq/ChIP-seq define >100 directly bound spermiogenic and cilium-function genes (PMID:26162102, PMID:26853561, PMID:26248850). In multiciliated and other ciliated tissues RFX2 is required for cilia formation and elongation, controls left-right asymmetry via ciliated organizer structures, coordinates ciliogenic gene programs, and cell-autonomously drives apical surface expansion in nascent multiciliated cells (PMID:22227339, PMID:22233545, PMID:24424412, PMID:25419512). In cancer contexts RFX2 directly activates RASSF1 to sustain Hippo/YAP signaling and PAF1 to promote tumor stemness, and acts as a transcriptional suppressor of BNIP3; its protein level is set by competition between ACK1 and the E3 ligase MIB1 over RFX2 ubiquitination, linking RFX2 stability to BNIP3 de-repression and mitophagy (PMID:38057505, PMID:40715489, PMID:40069841).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 2004 High

    Established the biochemical identity of the testis X-box-binding activity and showed RFX2 is a functional transcriptional activator, answering what protein reads the X-box element in germ cells.

    Evidence Affinity purification on the H1t TE1 X-box, EMSA supershift, and co-transfection reporter assays with promoter mutagenesis in germinal cells

    PMID:14743396 PMID:15229132

    Open questions at the time
    • Dimerization state inferred rather than structurally resolved
    • Did not define the full target gene repertoire
  2. 2005 Medium

    Defined the cis-architecture of RFX2 action, showing it can bind either X-box independently but requires occupancy of both for maximal promoter activation.

    Evidence Single and double X-box mutagenesis with reporter assays in GC-2spd cells

    PMID:15526285

    Open questions at the time
    • Single lab, single promoter context
    • Cooperativity mechanism between elements not biochemically dissected
  3. 2008 High

    Demonstrated that RFX2 occupies its target X-box in vivo and acts combinatorially with the CCAAT-binding factor NF-Y, moving from in vitro binding to in vivo promoter occupancy.

    Evidence ChIP in pachytene spermatocytes, EMSA, and co-transfection reporter assays

    PMID:18247329

    Open questions at the time
    • Direct vs indirect RFX2-NF-Y interaction not resolved
    • Limited to the H1t promoter
  4. 2009 High

    Placed RFX2 within the spermatocyte transcriptional hierarchy by identifying A-MYB as its upstream activator and Alf as a downstream RFX2 target.

    Evidence EMSA, ChIP, reporter assays, and A-myb knockout mice with immunohistology

    PMID:20003220

    Open questions at the time
    • Other upstream regulators not surveyed
    • Full RFX2 target set not yet defined at this stage
  5. 2011 High

    Extended RFX2 function from germ cells to ciliogenesis, showing it is broadly required for cilia formation and for left-right patterning in vertebrate embryos.

    Evidence Morpholino knockdown in Xenopus and zebrafish with cilia immunofluorescence and asymmetry-marker in situ hybridization

    PMID:22227339 PMID:22233545

    Open questions at the time
    • Morpholino knockdown not complemented by stable genetic null in these studies
    • Direct vs indirect regulation of ciliogenic targets not yet mapped genome-wide
  6. 2014 High

    Provided genome-wide direct targets in multiciliated cells and revealed an unexpected role in apical surface expansion and cell movement beyond classical ciliary gene control.

    Evidence ChIP-seq and RNA-seq in Xenopus MCCs with morpholino knockdown and in vivo imaging

    PMID:24424412 PMID:25419512

    Open questions at the time
    • Mechanism linking RFX2 targets to apical surface expansion not fully defined
    • Cofactor requirements at MCC targets not mapped
  7. 2015 High

    Genetic knockout in mice established RFX2 as essential for spermiogenesis, defining its requirement for acrosome biogenesis and flagellar axoneme assembly and identifying its direct spermiogenic target set.

    Evidence Conditional and gene-trap knockout mice with RNA-seq, ChIP-seq, and electron/fluorescence microscopy

    PMID:26162102 PMID:26248850

    Open questions at the time
    • Why neural tube and situs are spared in mouse nulls (unlike Xenopus/zebrafish knockdowns) unresolved
    • Cell-type-specific cofactors not identified
  8. 2016 High

    Independently confirmed the spermatid-arrest phenotype and direct cilia/testis target regulation, reinforcing RFX2 as the master spermiogenic ciliogenic regulator.

    Evidence Knockout mouse with RNA-seq, ChIP-PCR, histology, and immunofluorescence

    PMID:26853561

    Open questions at the time
    • Pathway from RFX2 loss to multinucleated giant cell apoptosis not mechanistically traced
  9. 2023 Medium

    Identified a cancer role, with RFX2 directly activating PAF1 to promote tumor stemness in spinal ependymoma.

    Evidence ChIP-qPCR, dual-luciferase reporter, siRNA knockdown with rescue, and xenografts

    PMID:38057505

    Open questions at the time
    • Single tumor type and single lab
    • Whether RFX2 acts as oncogene broadly across cancers not addressed
  10. 2025 Medium

    Expanded the cancer-context regulatory logic, showing RFX2 activates RASSF1/Hippo and suppresses BNIP3, and that its abundance is set by ACK1-MIB1 competition over ubiquitination.

    Evidence ChIP, dual-luciferase, Co-IP/mass spectrometry, ubiquitination assays, T-cell co-culture, and in vivo tumor models

    PMID:40069841 PMID:40715489

    Open questions at the time
    • Activator vs suppressor switch determinants not defined
    • Single study per target; integration with germ-cell/ciliary functions unclear
  11. 2025 Medium

    Positioned rfx2 transcription itself downstream of SWI/SNF chromatin remodeling in cilia gene regulation.

    Evidence ATAC-seq, RNA-seq, CUT&RUN/ChIP, and mRNA rescue in zebrafish actl6a mutants (preprint)

    PMID:bio_10.1101_2025.06.10.658863

    Open questions at the time
    • Preprint, not yet peer reviewed
    • Whether SWI/SNF directly binds the rfx2 locus in mammals untested

Open questions

Synthesis pass · forward-looking unresolved questions
  • How RFX2 selects between activator and repressor modes, and what cofactor/dimer-partner combinations distinguish its germ-cell, multiciliated-cell, and cancer programs, remain unresolved.
  • No structural model of RFX2 on X-box DNA in the corpus
  • Determinants of activation vs repression unknown
  • Tissue-specific dimerization partners largely uncharacterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 6 GO:0003677 DNA binding 4
Localization
GO:0005634 nucleus 3
Pathway
R-HSA-74160 Gene expression (Transcription) 4 R-HSA-1266738 Developmental Biology 3 R-HSA-1474165 Reproduction 3 R-HSA-1852241 Organelle biogenesis and maintenance 3
Partners
ACK1AMYBMIB1NFYA

Evidence

Reading pass · 16 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2004 RFX2 was purified from rat testis nuclear extracts using the H1t TE1 promoter element (an X-box consensus sequence) as an affinity chromatography probe, identifying it as an 85 kDa protein that binds specifically to the TE1 element; polyclonal antibodies against RFX2 supershifted the low-mobility testis nuclear protein complex in EMSA. Co-expression of RFX2 with an H1t promoter/reporter vector activated the H1t promoter in GC-2spd germinal cells, and mutation of either TE1 or TE2 subelements repressed this activity. Affinity chromatography purification, EMSA with supershift, co-transfection reporter assay, site-directed mutagenesis of promoter elements Journal of cellular biochemistry High 14743396
2004 Competitive band-shift assays and specific antisera showed that the H1t-60 CCTAGG palindrome (X-box) motif binds RFX family members; the testis-specific binding complex contains RFX2, probably as a homodimer, while somatic complexes contain RFX1 primarily as a heterodimer. Western blots confirmed RFX2 expression is greatly enhanced in adult testis and equally prominent in late pachytene spermatocytes and round spermatids. Competitive EMSA, antibody supershift, Western blot, immunohistochemistry Biology of reproduction High 15229132
2005 RFX2 can bind independently to either the TE1 or TE2 X-box element of the H1t promoter to partially activate transcription; simultaneous mutation of both X-box elements is required to totally abolish RFX2-mediated reactivation, indicating that maximal promoter activation requires simultaneous occupancy of both elements. Transient co-transfection reporter assays with individual and double X-box mutations in GC-2spd cells Journal of cellular biochemistry Medium 15526285
2006 RFX2 is most abundant in rat testis among tissues examined, is enriched in primary spermatocyte nuclei where H1t transcription is upregulated, and decreases in early spermatids where RFX1 levels increase and H1t transcription is downregulated; antibodies against RFX2 generate a shifted band in EMSA with H1t and testisin X-box probes using spermatocyte nuclear proteins. Western blot across tissues, EMSA with antibody supershift on spermatocyte nuclear extracts, subcellular fractionation Journal of cellular biochemistry Medium 16676351
2008 RFX2 occupies the H1t X-box in vivo in pachytene spermatocytes as shown by ChIP; transcription factor NF-Y binds the adjacent CCAAT-box and interacts directly or indirectly with RFX2; both the X-box and CCAAT-box are required for promoter activity; co-expression of RFX2 greatly enhances H1t promoter activity in GC-1spg cells. ChIP analysis, EMSA, Western blot, co-transfection reporter assay Journal of cellular biochemistry High 18247329
2009 The Rfx2 promoter contains a cluster of three MYB binding sites (MBS); A-MYB binds these sites as shown by electrophoretic gel-shift, ChIP, and co-transfection assays; Rfx2 expression is virtually eliminated in A-myb knockout testes, placing Rfx2 downstream of A-MYB in the spermatocyte transcriptional network. RFX2 also directly occupies and activates the Alf (TFIIA variant) promoter in vivo. EMSA, ChIP, co-transfection reporter assay, A-myb knockout mouse, immunohistology BMC developmental biology High 20003220
2011 Morpholino knockdown of Rfx2 in Xenopus results in fewer or truncated cilia in ciliated tissues (neural tube, gastrocoel roof plate, epidermal MCCs, otic vesicles, kidneys) and causes cilia-defective embryonic phenotypes. Rfx2 is required for expression of several ciliogenic genes including TTC25, which is itself required for ciliogenesis, Hedgehog signaling, and left-right patterning. Morpholino knockdown in Xenopus, in situ hybridization, immunofluorescence for cilia markers Developmental biology High 22227339
2011 Morpholino knockdown of Rfx2 in zebrafish Kupffer's Vesicle (ciliated organ of asymmetry) reduces KV cilia length and randomizes left-right asymmetry, including Nodal signaling gene expression (southpaw, lefty1, lefty2) and organ situs. Rfx2 is also required for ciliogenesis in zebrafish pronephric duct. Morpholino knockdown in zebrafish, immunofluorescence, in situ hybridization for asymmetry markers Developmental biology High 22233545
2014 ChIP-seq and RNA-seq in Xenopus MCCs identified direct genomic targets of Rfx2, showing it coordinates gene expression programs for ciliogenesis, cilia function, and cell movement. Rfx2 cell-autonomously controls apical surface expansion in nascent MCCs, a previously unrecognized role for an RFX factor in cell movement. ChIP-seq, RNA-seq, morpholino knockdown with in vivo imaging, bioinformatics eLife High 24424412 25419512
2015 Targeted knockout of Rfx2 in mice causes complete male sterility due to arrest of spermatid development just prior to elongation, with altered Golgi organization leading to failure of acrosomal cap formation from proacrosomal vesicles, and complete failure to form flagellar axoneme. RNA-seq and ChIP-seq identified 139 genes directly controlled by RFX2 during spermiogenesis, enriched for cilium function genes. Conditional knockout mouse, RNA-seq, ChIP-seq, electron and fluorescence microscopy PLoS genetics High 26162102
2016 Rfx2 knockout mice exhibit male sterility due to arrest of spermatogenesis at the early round spermatid step; Rfx2-null spermatids detach from seminiferous tubules forming multinucleated giant cells that undergo apoptosis, and flagellum formation is inhibited at its earliest stage. RNA-seq and ChIP-PCR identified numerous cilia-related and testis-specific genes directly regulated by RFX2. Knockout mouse, RNA-seq, ChIP-PCR, histology, immunofluorescence Scientific reports High 26853561
2015 A lacZ gene trap insertion into the first intron of Rfx2 creates a null allele (no Rfx2 mRNA detected); Rfx2gt/gt mice develop normally without neural tube or situs defects, but males are infertile due to a defect in spermatid maturation at or before the round/elongating spermatid stage. Gene trap null allele in mouse, RT-PCR, histology, beta-galactosidase reporter Genesis High 26248850
2023 RFX2 binds to the PAF1 promoter (by ChIP-qPCR) and activates PAF1 transcription (by dual-luciferase assay) in spinal ependymoma cells. RFX2 knockdown reduces tumor stemness markers and sphere formation; PAF1 overexpression rescues these effects, placing RFX2 upstream of PAF1 in a stem cell-promoting axis. ChIP-qPCR, dual-luciferase reporter assay, siRNA knockdown, in vivo xenograft Journal of neuro-oncology Medium 38057505
2025 ACK1 interacts with RFX2 through its MHR domain (by co-immunoprecipitation and mass spectrometry) and competitively inhibits RFX2 ubiquitination by E3 ubiquitin ligase MIB1; ACK1 inhibition facilitates MIB1-mediated RFX2 ubiquitination and proteasomal degradation. RFX2 is a transcriptional suppressor of BNIP3 (by luciferase reporter and ChIP), so RFX2 degradation de-represses BNIP3 and activates PINK1/PARKIN-mediated mitophagy. Co-immunoprecipitation, mass spectrometry, ChIP, luciferase reporter assay, ubiquitination assay, in vitro and in vivo cell models Oncogene Medium 40715489
2025 RFX2 binds the RASSF1 promoter and activates RASSF1 transcription (by dual-luciferase assay and ChIP) in lung adenocarcinoma cells; loss of RFX2 reduces RASSF1 expression, decreases YAP phosphorylation, and impairs Hippo pathway signaling, thereby promoting immune escape. ChIP, dual-luciferase reporter assay, RFX2 overexpression and siRNA knockdown, co-culture with CD8+ T cells, in vivo tumor model Cell division Medium 40069841
2025 Depletion of Actl6a (SWI/SNF complex component) in zebrafish downregulates rfx2 at the transcriptional, chromatin accessibility, and SWI/SNF binding levels; overexpression of rfx2 mRNA partially rescues cilia disassembly and cystic kidney in actl6a mutants, placing rfx2 downstream of SWI/SNF complexes in cilia gene regulation. ATAC-seq, RNA-seq, CUT&RUN/ChIP, morpholino/CRISPR knockdown in zebrafish, mRNA rescue experiment bioRxivpreprint Medium bio_10.1101_2025.06.10.658863

Source papers

Stage 0 corpus · 23 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2014 Coordinated genomic control of ciliogenesis and cell movement by RFX2. eLife 121 24424412
2011 RFX2 is broadly required for ciliogenesis during vertebrate development. Developmental biology 90 22227339
2015 RFX2 Is a Major Transcriptional Regulator of Spermiogenesis. PLoS genetics 55 26162102
2016 Transcription Factor RFX2 Is a Key Regulator of Mouse Spermiogenesis. Scientific reports 53 26853561
2011 RFX2 is essential in the ciliated organ of asymmetry and an RFX2 transgene identifies a population of ciliated cells sufficient for fluid flow. Developmental biology 46 22233545
2009 Candida albicans RFX2 encodes a DNA binding protein involved in DNA damage responses, morphogenesis, and virulence. Eukaryotic cell 42 19252121
2004 RFX2 is a potential transcriptional regulatory factor for histone H1t and other genes expressed during the meiotic phase of spermatogenesis. Biology of reproduction 40 15229132
2009 RFX2 is a candidate downstream amplifier of A-MYB regulation in mouse spermatogenesis. BMC developmental biology 29 20003220
2004 Regulatory factor X2 (RFX2) binds to the H1t/TE1 promoter element and activates transcription of the testis-specific histone H1t gene. Journal of cellular biochemistry 22 14743396
1996 Locations of human and mouse genes encoding the RFX1 and RFX2 transcription factor proteins. Genomics 17 8661125
1992 The genes for MHC class II regulatory factors RFX1 and RFX2 are located on the short arm of chromosome 19. Genomics 14 1505960
2006 Transcription factor RFX2 is abundant in rat testis and enriched in nuclei of primary spermatocytes where it appears to be required for transcription of the testis-specific histone H1t gene. Journal of cellular biochemistry 13 16676351
2015 Rfx2 is required for spermatogenesis in the mouse. Genesis (New York, N.Y. : 2000) 12 26248850
2008 Binding of RFX2 and NF-Y to the testis-specific histone H1t promoter may be required for transcriptional activation in primary spermatocytes. Journal of cellular biochemistry 12 18247329
2005 Transcriptional activation of the testis-specific histone H1t gene by RFX2 may require both proximal promoter X-box elements. Journal of cellular biochemistry 10 15526285
2014 Identifying direct targets of transcription factor Rfx2 that coordinate ciliogenesis and cell movement. Genomics data 9 25419512
2021 Novel variations in spermatogenic transcription regulators RFX2 and TAF7 increase risk of azoospermia. Journal of assisted reproduction and genetics 5 34762273
2017 Association of the common SNPs in RNF212, STAG3 and RFX2 gene with male infertility with azoospermia in Chinese population. European journal of obstetrics, gynecology, and reproductive biology 5 29277047
2023 RFX2 promotes tumor cell stemness through epigenetic regulation of PAF1 in spinal ependymoma. Journal of neuro-oncology 3 38057505
2025 RFX2 downregulates RASSF1 expression and YAP phosphorylation through Hippo signaling to promote immune escape in lung adenocarcinoma. Cell division 2 40069841
2023 Molecular characteristics and transcriptional regulatory of spermatogenesis-related gene RFX2 in adult Banna mini-pig inbred line (BMI). Animal reproduction 2 36922987
2025 RFX2-BNIP3 axis-driven adaptive mitophagy promotes resistance to ACK1-targeted therapy in non-small cell lung cancer. Oncogene 1 40715489
2022 The First Report of a Missense Variant in RFX2 Causing Non-Syndromic Tooth Agenesis in a Consanguineous Pakistani Family. Frontiers in genetics 1 35145545

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