Transcription factor Oct1 protects against hematopoietic stress and promotes acute myeloid leukemia

Helicobacter pylori SlyD stabilizes TPT1 via hnRNPK and enhances OCT1-mediated CDX2 transcriptional activation to drive gastric intestinal metaplasia

BACKGROUND

Gastric intestinal metaplasia (GIM) represents an important precancerous lesion in intestinal-type gastric cancer, triggered by persistent Helicobacter pylori (H. pylori) infection. In a previous study, we unveiled SlyD as a novel virulence factor of H. pylori, establishing its role in GIM induction through TPT1. However, the underlying mechanism remains undetermined.

METHODS

Gastric epithelial cells were stimulated with H. pylori 26695, a SlyD inactivated mutant (ΔSlyD), and purified HpSlyD protein, respectively. Real-time qPCR and western blot were subsequently used to assess the expression levels of hnRNPK, TPT1, OCT1, and GIM markers. RNA sequencing was employed to identify differentially expressed genes associated with H. pylori SlyD infection. Protein stability was evaluated using cycloheximide. Molecular interactions were investigated through co-immunoprecipitation, chromatin immunoprecipitation, and dual-luciferase reporter assays. Additionally, molecular docking was utilized to predict TPT1 inhibitors. Immunohistochemistry staining was conducted to validate hnRNPK, TPT1, OCT1, and CDX2 expression in gastric tissue samples from both human and Mongolian gerbils.

RESULTS

H. pylori SlyD upregulates TPT1 and induces the expression of GIM markers through hnRNPK. The interaction between hnRNPK and TPT1 enhances TPT1 protein stability, with H. pylori SlyD intensifying this association. TPT1 promotes the expression of GIM markers mediated via OCT1, which binds to CDX2 promoter region, thereby modulating its transcriptional activity. Dihydroartemisinin has the potential to target TPT1, inhibiting the H. pylori SlyD-induced expression of GIM markers.

CONCLUSIONS

In vitro and in vivo experiments verified that H. pylori SlyD enhances TPT1 stability through hnRNPK, leading to OCT1-mediated transcriptional activation of CDX2 and the initiation of the GIM process. Our study offers novel perspectives on the pathogenesis of H. pylori-related gastric precancerous conditions.

Bovine Transcription Factor POU Class 2 Homeobox 1 (POU2F1/Oct1) Protein Promotes BoHV-1 Replication in MDBK Cells

Bovine herpesvirus type 1 (BoHV-1) causes severe diseases in bovine species and great economic burden to the cattle industry worldwide. Due to its complex life cycle, many host factors that affect BoHV-1 replication remain to be explored. To understand the possible roles that the Oct1 cellular protein could play in this process, we first created Oct1-deficient MDBK cells using CRISPR/Cas9-mediated genome editing. Upon infection, the absence of Oct1 in MDBK cells significantly impacted BoHV-1 replication, a phenotype rescued by over-expressing the wild-type Oct1 protein in the deficient cells. We further found that the expression of all three classes of temporal genes, including essential and non-essential viral genes, were significantly reduced in Oct1 knockout MDBK cells, following both high and low multiplicity of infection. In summary, our findings confirm that the bovine Oct1 protein acts as a pro-viral factor for BoHV-1 replication by promoting its viral gene transcription in MDBK cells.

A conserved nutrient responsive axis mediates autophagic degradation of miRNA-mRNA hybrids in blood cell progenitors

In animals, microRNAs are amongst the primary non-coding RNAs involved in regulating the gene expression of a cell. Most mRNAs in a cell are targeted by one or many miRNAs. Although several mechanisms can be attributed to the degradation of miRNA and mRNA within a cell, but the involvement of autophagy in the clearance of miRNA and its target mRNA is not known. We discover a leucine-responsive axis in blood cell progenitors that can mediate an autophagy-directed degradation of miRNA-bound mRNA in Drosophila melanogaster and Homo sapiens. This previously unknown miRNA clearance axis is activated upon amino acid deprivation that can traffic miRNA-mRNA-loaded Argonaute for autophagic degradation in a p62-dependent manner. Thus, our research not only reports a novel axis that can address the turnover of a catalytically active miRISC but also elucidates a slicer-independent mechanism through which autophagy can selectively initiate the clearance of target mRNA.

Temperature modulates the osmosensitivity of tilapia prolactin cells

In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different combinations of temperatures (20, 26 and 32 °C) and osmolalities (280, 330 and 420 mOsm/kg) for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188, but not Prl177, was suppressed at 20 °C. In SW fish, mRNA expression of prl188 increased with rising temperatures at lower osmolalities, while and prl177 decreased at 32 °C and higher osmolalities. In Prl cells of SW-acclimated tilapia incubated in hyperosmotic media, the expressions of Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4,decreased at 32 °C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32 °C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity.

Temperature modulates the osmosensitivity of tilapia prolactin cells

In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different temperature (20, 26 and 32°C) and osmolality (280, 330 and 420 mOsm/kg) combinations for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188 was inhibited at 20°C. In SW fish, mRNA expression of prl188 and prl177 showed direct and inverse relationships with temperature, respectively. In SW-acclimated tilapia Prl cells incubated in hyperosmotic media, Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4, were inhibited at 32°C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32°C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity.

5-Azacytidine Suppresses the Expression of Tissue-Specific Oct-1 Isoform in Namalwa Burkitt's Lymphoma Cell Culture

Overexpression of the transcription factor POU2F1 (Oct-1) increases the malignant potential of the tumor and determines the unfavorable prognosis for both solid and hematological cases of the disease in human carcinogenesis. The Oct-1 level determines the rate of development of the disease in acute myelodysplastic leukemia (AML), and a decrease in its expression significantly delays the development of leukemia in mice; however, a complete knockout of Oct-1 leads to the death of the animals. POU2F1 (Oct-1) is expressed as several isoforms transcribed from alternative promoters. They include both ubiquitous and tissue-specific isoforms. It was shown that in Burkitt’s lymphoma Namalwa cells 5-azacytidine specifically suppresses the expression of the tissue-specific isoform Oct-1L mRNA (level of Oct-1L is abnormally increased in these cells), while not causing changes in the amount of the ubiquitous isoform Oct-1A mRNA. These results show that it is possible to selectively reduce the transcription level of the Oct-1L isoform aberrantly expressed in human tumor cells.

The Cross Marks the Spot: The Emerging Role of JmjC Domain-Containing Proteins in Myeloid Malignancies

Histone methylation tightly regulates chromatin accessibility, transcription, proliferation, and cell differentiation, and its perturbation contributes to oncogenic reprogramming of cells. In particular, many myeloid malignancies show evidence of epigenetic dysregulation. Jumonji C (JmjC) domain-containing proteins comprise a large and diverse group of histone demethylases (KDMs), which remove methyl groups from lysines in histone tails and other proteins. Cumulating evidence suggests an emerging role for these demethylases in myeloid malignancies, rendering them attractive targets for drug interventions. In this review, we summarize the known functions of Jumonji C (JmjC) domain-containing proteins in myeloid malignancies. We highlight challenges in understanding the context-dependent mechanisms of these proteins and explore potential future pharmacological targeting.

Pterostilbene leads to DNMT3B-mediated DNA methylation and silencing of OCT1-targeted oncogenes in breast cancer cells

Transcription factor (TF)-mediated regulation of genes is often disrupted during carcinogenesis. The DNA methylation state of TF-binding sites may dictate transcriptional activity of corresponding genes. Stilbenoid polyphenols, such as pterostilbene (PTS), have been shown to exert anticancer action by remodeling DNA methylation and gene expression. However, the mechanisms behind these effects still remain unclear. Here, the dynamics between oncogenic TF OCT1 binding and de novo DNA methyltransferase DNMT3B binding in PTS-treated MCF10CA1a invasive breast cancer cells has been explored. Using chromatin immunoprecipitation (ChIP) followed by next generation sequencing, we determined 47 gene regulatory regions with decreased OCT1 binding and enriched DNMT3B binding in response to PTS. Most of those genes were found to have oncogenic functions. We selected three candidates, PRKCA, TNNT2, and DANT2, for further mechanistic investigation taking into account PRKCA functional and regulatory connection with numerous cancer-driving processes and pathways, and some of the highest increase in DNMT3B occupancy within TNNT2 and DANT2 enhancers. PTS led to DNMT3B recruitment within PRKCA, TNNT2, and DANT2 at loci that also displayed reduced OCT1 binding. Substantial decrease in OCT1 with increased DNMT3B binding was accompanied by PRKCA promoter and TNNT2 and DANT2 enhancer hypermethylation, and gene silencing. Interestingly, DNA hypermethylation of the genes was not detected in response to PTS in DNMT3B-CRISPR knockout MCF10CA1a breast cancer cells. It indicates DNMT3B-dependent methylation of PRKCA, TNNT2, and DANT2 upon PTS. Our findings provide a better understanding of mechanistic players and their gene targets that possibly contribute to the anticancer action of stilbenoid polyphenols.

Regulation of stress-induced hematopoiesis

PURPOSE OF REVIEW

The hematopoietic compartment is tasked with the establishment and maintenance of the entire blood program in steady-state and in response to stress. Key to this process are hematopoietic stem cells (HSCs), which possess the unique ability to self-renew and differentiate to replenish blood cells throughout an organism's lifetime. Though tightly regulated, the hematopoietic system is vulnerable to both intrinsic and extrinsic factors that influence hematopoietic stem and progenitor cell (HSPC) fate. Here, we review recent advances in our understanding of hematopoietic regulation under stress conditions such as inflammation, aging, mitochondrial defects, and damage to DNA or endoplasmic reticulum.

RECENT FINDINGS

Recent studies have illustrated the vast mechanisms involved in regulating stress-induced hematopoiesis, including cytokine-mediated lineage bias, gene signature changes in aged HSCs associated with chronic inflammation, the impact of clonal hematopoiesis and stress tolerance, characterization of the HSPC response to endoplasmic reticulum stress and of several epigenetic regulators that influence HSPC response to cell cycle stress.

SUMMARY

Several key recent findings have deepened our understanding of stress hematopoiesis. These studies will advance our abilities to reduce the impact of stress in disease and aging through clinical interventions to treat stress-related outcomes.