Alternative titles; symbols
HGNC Approved Gene Symbol: POU2F3
Cytogenetic location: 11q23.3 Genomic coordinates (GRCh38): 11:120,236,638-120,319,945 (from NCBI)
Tuft cells are chemosensory cells that coordinate immune and neural functions within mucosal epithelial tissues. POU2F3 is a class II POU domain transcription factor required for tuft cell development (summary by Wu et al., 2022).
Goldsborough et al. (1993) cloned mouse Oct11 from a thymus cDNA library. PCR analysis revealed Oct11 expression only in testis, thymus, and 14.5 days postcoitum embryos. PCR and Northern blot analysis also revealed expression in some myeloma cell lines.
Using mouse Skn1a as probe, followed by 3-prime RACE, Hildesheim et al. (1999) cloned full-length POU2F3, which they called SKN1A, from a primary keratinocyte cDNA library. The deduced 436-amino acid protein contains an N-terminal POU-specific domain, a hypervariable linker region, and a C-terminal POU homeodomain. The human and rat proteins share approximately 90% sequence identity, and sequences within the POU domain only diverge within the hypervariable linker region. Northern blot analysis revealed that human foreskin keratinocytes express 2.4- and 3.5-kb POU2F3 transcripts.
Using the POU domains of OCT1 (POU2F1; 164175) and OCT2 (POU2F2; 164176) to screen a human keratinocyte cDNA library, followed by 5-prime RACE, Cabral et al. (2003) cloned SKN1A and 2 novel splice variants, SKN1D1 and SKN1D2. SKN1D1 and SKN1D2 differ from the full-length SKN1A transcript at their 5-prime ends, with SKN1D1 and SKN1D2 initiating in introns 5 and 7, respectively. The SKN1D1 protein lacks 121 N-terminal amino acids compared with SKN1A, but it contains both POU domains. SKN1D2 has 2 potential start codons that result in proteins lacking 215 or 241 N-terminal amino acids compared with SKN1A, and both SKN1D2 isoforms lack part of the first POU domain. In vitro translation of SKN1D1 resulted in a major 35-kD protein, and in vitro translation of SKN1D2 resulted in 21.5- and 25-kD proteins. Northern blot analysis of 50 tissues using a probe common to all SKN1 variants revealed expression only in stratified squamous epithelia, including epidermis, cervix, and foreskin. Semiquantitative RT-PCR with isotype-specific primers showed variable expression of each variant in most squamous epithelia and cultured keratinocytes examined.
Using deletion analysis of SKN1A with target promoters, Hildesheim et al. (1999) determined that SKN1A contains 2 functional domains: a C-terminal transactivation domain and a combined N-terminal inhibitory domain and transactivation domain.
Using organotypic raft cultures of both primary and immortalized human keratinocytes, Hildesheim et al. (2001) found that SKN1A expression was associated with increased keratinocyte proliferation and reepithelialization of the dermal substrates, resulting in increased numbers of keratinocytes available for differentiation. In these same raft cultures, SKN1A expression enhanced differentiation as well as expression of keratinocyte differentiation genes. Conversely, expression of the dominant-negative SKN1A lacking the C-terminal transactivation domain blocked keratinocyte proliferation and stratification. Hildesheim et al. (2001) concluded that SKN1A contributes to epidermal stratification and homeostasis primarily by promoting keratinocyte proliferation and secondarily by enhancing keratinocyte differentiation.
Using electrophoretic mobility shift assays, Cabral et al. (2003) showed that SKN1A and SKN1D1, but not SKN1D2, bound SPRR2A (182267), a marker of keratinocyte terminal differentiation. Both SKN1A and SKN1D1 upregulated SPRR2A promoter activity following transfection in a human keratinocyte cell line. SKN1A functionally cooperated with ESE1 (ELF3; 602191) to enhance SPRR2A transactivation, whereas neither SKN1D1 nor SKN1D2 cooperated with ESE1 in SPRR2A transactivation. In contrast, SKN1D1 competed with SKN1A, resulting in complete abrogation of the synergistic effect.
Bishop and Guarente (2007) showed that increased longevity of diet-restricted C. elegans requires the transcription factor gene skn1, a homolog of human SKN1A, acting in the ASIs, a pair of neurons in the head. Dietary restriction activates skn1 in these 2 neurons, which signals peripheral tissues to increase metabolic activity. These findings demonstrated that increased life span in a diet-restricted metazoan depends on cell nonautonomous signaling from central neuronal cells to nonneuronal body tissues, and suggested that the ASI neurons mediate diet restriction-induced longevity by an endocrine mechanism.
Using phylogenetic and mutational analyses, Lehrbach et al. (2019) identified 4 conserved N-glycosylation sites on C. elegans Skn1a. Following release of N-glycosylated Skn1a from the endoplasmic reticulum (ER), C. elegans Skn1a was deglycosylated by Png1 (610661) to convert asparagine residues to aspartate residues. Subsequently, the deglycosylated Skn1a underwent proteolytic cleavage by the Ddi1 aspartic protease to generate a truncated and activated form of Skn1a. Ddi1-dependent protease cleavage removed the N-terminal ER-targeting domain of Skn1a, which allowed the protein to escape from proteasomal degradation. Lehrbach et al. (2019) suggested that conversion of 4 asparagine residues to aspartate residues likely introduced a new function to this domain, e.g., a binding site for cofactors that are critical for transcriptional regulation of proteasome subunit genes. The contribution of each of the 4 residues was not equivalent, and editing at N338 appeared to play the most important role. In line with these results, truncated and deglycosylated Skn1a constitutively increased proteasome levels and enhanced proteostasis in C. elegans, and protected them against protein aggregation. Lehrbach et al. (2019) also found that Skn1a and the shorter, non-ER-associated isoform Skn1c are distinct transcriptional regulators that respond to different stimuli and regulate distinct but overlapping sets of target genes.
Wu et al. (2022) demonstrated that POU2AF2 (620671) and POU2AF3 (615694) formed a complex with POU2F3 in a DNA-dependent manner, with all 3 proteins occupying the same chromatin fragments in the genome. Transcriptomic analysis suggested that POU2AF2 and POU2AF3 cooperated with POU2F3 to activate transcription of tuft cell-specific genes.
The small cell lung cancer (SCLC; see 182280)-P subtype is defined by expression of POU2F3 and lacks neuroendocrine markers. By analyzing the landscape of SCLC subtype-specific dependency, Szczepanski et al. (2022) identified POU2AF2 as a marker for SCLC-P. POU2AF2 was expressed at high levels in all 4 SCLC-P cell lines examined, and POU2AF2 expression correlated positively with the expression levels of POU2F3 in SCLC patient samples. Genetic depletion of POU2AF2 markedly reduced viability of cultured SCLC cells in vitro and significantly repressed tumor growth and delayed further progression of disease in a xenograft mouse model in vivo. POU2AF2 regulated lineage-specific gene expression at super enhancers and was involved in chromatin accessibility and maintenance of enhancer-driven transcriptional program in SCLC-P subtype cells. Mass spectrometry analysis revealed that POU2AF2 interacted with POU2F3, and the POU domain of POU2F3 was critical for the interaction. Further analysis suggested that POU2AF2 functions as a coactivator of POU2F3 that maintains chromatin accessibility at POU2F3-targeted genes in SCLC cells.
Cabral et al. (2003) determined that the POU2F3 gene contains 13 exons and spans 70 kb.
By FISH, Hildesheim et al. (1999) mapped the POU2F3 gene to chromosome 11q23.3.
By Southern blot and interspecific backcross analyses, Goldsborough et al. (1993) identified 2 genes corresponding to mouse Oct11. One gene, which they called Oct11a, maps to a proximal region of chromosome 9 that shows homology of synteny to human chromosome 11q23. The other gene, which they called Oct11b, maps to the middle of chromosome 1 and may be a pseudogene.
Infection of mice with the helminth N. brasiliensis (Nb) induces a type-2 immune response that leads to goblet cell hyperplasia as soon as 5 days after infection. Gerbe et al. (2016) found that Dclk1 (604742)-expressing tuft cells increased by 8.5-fold 5 days after Nb infection in intestinal crypts and 7 days after infection in villi. Mice lacking Pou2f3, which is also expressed by tuft cells, lacked tuft cells necessary for sensing sweet, umami, and bitter taste, Trpm5 (604600)-expressing chemosensory cells in nasal cavity, and Dclk1- and Sox9 (608160)-expressing cells in intestinal epithelium outside the crypt compartment. However, global immunity and intestinal epithelium formation were not affected in Pou2f3 -/- mice. Instead of clearing Nb after 2 weeks, Pou2f3 -/- mice were unable to expel Nb for at least 42 days. Seven days after Nb infection, Pou2f3 -/- mice did not display goblet cell hyperplasia, indicating a delayed type-2 response, and they also showed weak expression of the goblet cell-produced anti-helminthic molecule Retnlb (605645) and Il13 (147683). Mice lacking Pou2f3 had deficient Il25 (605658) production after Nb infection. Only tuft cells produced Il25 in wildtype mice, with a peak 9 days after Nb infection, at the time of worm expulsion and leading to group-2 innate lymphoid cell expansion. Gerbe et al. (2016) concluded that IL25 is a mechanistic link between tuft cells, promotion of type-2 responses, and worm expulsion, and that IL4 (147780)/IL13 drive tuft cell hyperplasia.
Bishop, N. A., Guarente, L. Two neurons mediate diet-restriction-induced longevity in C. elegans. Nature 447: 545-549, 2007. [PubMed: 17538612] [Full Text: https://doi.org/10.1038/nature05904]
Cabral, A., Fischer, D. F., Vermeij, W. P., Backendorf, C. Distinct functional interactions of human Skn-1 isoforms with Ese-1 during keratinocyte terminal differentiation. J. Biol. Chem. 278: 17792-17799, 2003. [PubMed: 12624109] [Full Text: https://doi.org/10.1074/jbc.M300508200]
Gerbe, F., Sidot, E., Smyth, D. J., Ohmoto, M., Matsumoto, I., Dardalhon, V., Cesses, P., Garnier, L., Pouzolles, M., Brulin, B., Bruschi, M., Harcus, Y., Zimmermann, V. S., Taylor, N., Maizels, R. M., Jay, P. Intestinal epithelial tuft cells initiate type 2 mucosal immunity to helminth parasites. Nature 529: 226-230, 2016. [PubMed: 26762460] [Full Text: https://doi.org/10.1038/nature16527]
Goldsborough, A. S., Healy, L. E., Copeland, N. G., Gilbert, D. J., Jenkins, N. A., Willison, K. R., Ashworth, A. Cloning, chromosomal localization and expression pattern of the POU domain gene Oct-11. Nucleic Acids Res. 21: 127-134, 1993. [PubMed: 8441607] [Full Text: https://doi.org/10.1093/nar/21.1.127]
Hildesheim, J., Foster, R. A., Chamberlin, M. E., Vogel, J. C. Characterization of the regulatory domains of the human Skn-1a/Epoc-1/Oct-11 POU transcription factor. J. Biol. Chem. 274: 26399-26406, 1999. [PubMed: 10473598] [Full Text: https://doi.org/10.1074/jbc.274.37.26399]
Hildesheim, J., Kuhn, U., Yee, C. L., Foster, R. A., Yancey, K. B., Vogel, J. C. The hSkn-1a POU transcription factor enhances epidermal stratification by promoting keratinocyte proliferation. J. Cell Sci. 114: 1913-1923, 2001. [PubMed: 11329378] [Full Text: https://doi.org/10.1242/jcs.114.10.1913]
Lehrbach, N. J., Breen, P. C., Ruvkun, G. Protein sequence editing of SKN-1A/Nrf1 by peptide:N-glycanase controls proteasome gene expression. Cell 177: 737-750, 2019. [PubMed: 31002798] [Full Text: https://doi.org/10.1016/j.cell.2019.03.035]
Szczepanski, A. P., Tsuboyama, N., Watanabe, J., Hashizume, R., Zhao, Z., Wang, L. POU2AF2/C11orf53 functions as a coactivator of POU2F3 by maintaining chromatin accessibility and enhancer activity. Sci. Adv. 8: eabq2403, 2022. [PubMed: 36197978] [Full Text: https://doi.org/10.1126/sciadv.abq2403]
Wu, X. S., He, X.-Y., Ipsaro, J. J., Huang, Y.-H., Preall, J. B., Ng, D., Shue, Y. T., Sage, J., Egeblad, M., Joshua-Tor, L., Vakoc, C. R. OCA-T1 and OCA-T2 are coactivators of POOU2F3 in the tuft cell lineage. Nature 607: 169-175, 2022. [PubMed: 35576971] [Full Text: https://doi.org/10.1038/s41586-022-04842-7]