Oct1 Is a Switchable, Bipotential Stabilizer of Repressed and Inducible Transcriptional States

Abstract

Little is known regarding how the Oct1 transcription factor regulates target gene expression. Using murine fibroblasts and two target genes, Polr2a and Ahcy, we show that Oct1 recruits the Jmjd1a/KDM3A lysine demethylase to catalyze the removal of the inhibitory histone H3K9 dimethyl mark and block repression. Using purified murine T cells and the Il2 target locus, and a colon cancer cell line and the Cdx2 target locus, we show that Oct1 recruits the NuRD chromatin-remodeling complex to promote a repressed state, but in a regulated manner can switch to a different capacity and mediate Jmjd1a recruitment to block repression. These findings indicate that Oct1 maintains repression through a mechanism involving NuRD and maintains poised gene expression states through an antirepression mechanism involving Jmjd1a. We propose that, rather than acting as a primary trigger of gene activation or repression, Oct1 is a switchable stabilizer of repressed and inducible states.The POU 2 (Pit-1, Oct1/2, Unc-86) transcription factor family includes ϳ13 mammalian paralogs as well as representatives from other metazoans (1). The best known example, Oct4/POU5F1, regulates embryonic stem (ES) cell identity and is a key factor used to generate induced pluripotent stem cells from somatic cells (2-5). Oct1/POU2F1 is related to Oct4 and possesses similar in vitro DNA binding specificity (for reviewed, see Ref. 6). As with many transcription factors, these proteins are known to regulate gene expression both positively and negatively (e.g. 7, 8); however, their activity has been thought to be determined by gene context and not subject to regulation.Loss of Oct1 inhibits oncogenic transformation in mouse embryonic fibroblasts (MEFs) and tumorigenicity in p53-deficient mice and xenograft assays, while having little effect on cell growth in culture or transformation by serial passage (9). One study indicates that Oct1 levels are increased in some human gastric cancers (10). In contrast, multiple studies have identified coordinate up-regulation of Oct1 target genes in lung and breast adenocarcinomas, leukemias, and myeloid leukemia stem cells, without concurrent up-regulation of Oct1 itself (11)(12)(13)(14), suggesting that Oct1 activity may be deregulated in malignancy. Recent findings showing post-translational regulation of Oct1 support this possibility (15). Although Oct1 has been studied intensively, our current understanding of how it regulates gene transcription is surprisingly limited (see for example, Ref. 16).Here, we show using three different systems (fibroblasts, primary T cells, and a colon cancer cell line) that Oct1 is a bipotential and switchable transcriptional regulator. In fibroblasts, Oct1 mediates recruitment of the Jmjd1a histone demethylase to target genes (Polr2a and Ahcy) following oxidative stress exposure. In the absence of Oct1, Jmjd1a fails to be recruited, H3K9me2 levels are elevated, and inappropriate repression is observed. In contrast, Oct1 recruits the nucleosome remodeling and histone deacetylation (NuRD/Mi...

HIF-KDM3A-MMP12 regulatory circuit ensures trophoblast plasticity and placental adaptations to hypoxia

“…This conclusion is based on the observed differential outcomes of loss-of-function and gain-of-function KDM3A manipulations in TS cells and the absence of conserved HIF binding motifs in regulatory regions binding KDM3A. In addition to HIF, there is evidence for other types of transcription factors (e.g., nuclear receptors and OCT1) guiding KDM3A to its genomic targets in various nontrophoblast cells (51)(52)(53). Mechanisms controlling KDM3A arrival at its target loci within the TS cell genome are yet to be elucidated.…”

Oct1 and OCA-B are selectively required for CD4 memory T cell function

“…Switching requires the MEK-ERK arm of the MAPK signaling pathway (Shakya et al, 2011). After removal of the stimulus, Jmjd1a is retained even in the absence of MAPK signals.…”

“…Mouse Il2 mRNA levels were measured as described previously (Shakya et al, 2011). Primer pairs for mouse Ifng and Zbtb32 were taken from Huffaker et al (2012) and Yoon et al (2012), respectively.…”

Vitamin C Promotes Maturation of T-Cells

“…Lymphoid cells isolated from OP9-DL1 cultures were fixed, sheared, and reacted with antibodies specific for histone proteins H3, H3K9me3, and H3K9me2 as previously described (29). Immunoprecipitates were collected using protein G-conjugated magnetic beads (Active Motif ).…”

“…DNA purified from immunoprecipitates was amplified using primers specific for the promoter region of Cd8a (forward, 5¢-AAT TCC TCCCAC TTG CTC TGC-3¢; reverse, 5¢-CTA GCT TGA CCTAAG CTG CTTG-3¢) and for b-actin as a normalization control. Data were processed as previously described (29) and are represented as fold enrichment of Cd8a relative to b-actin.…”