Histone Methyltransferase SUV39H2 Supports Nasopharyngeal Carcinoma Cell Metastasis by Regulation of SIRT1.

Nasopharyngeal carcinoma (NPC) is a malignant tumor with high metastatic features originating from the nasopharynx. However, the underlying mechanism of Suppressor of variegation 3-9 homolog 2 (SUV39H2) in NPC remains poorly understood. RT-qPCR was carried out to examine SUV39H2 and SIRT1 expression in NPC tissues and cells. Kaplan-Meier method was utilized to evaluate the association between SUV39H2 level and overall survival. The function of SUV39H2 and SIRT1 in NPC cell viability, metastasis, and apoptosis was tested through CCK-8, transwell, and flow cytometry experiments. Here, it was uncovered that SUV39H2 level was augmented in NPC tissues and cells. Moreover, SUV39H2 expedited NPC cell viability, metastasis, and inhibited apoptosis, while SIRT1 addition reversed these impacts. Besides, SUV39H2 induced H3K9me3 enhancement to repress SIRT1 transcription via binding to SIRT1 promoter. Collectively, our results demonstrated upregulated SUV39H2 aggravated NPC tumorigenesis through SIRT1, which may offer a potential therapeutic target for NPC.

The role of H3K9me3 in oral squamous cell carcinoma.

Carcinogenesis is often associated with alteration of epigenetic marks, including histone modifications. The global level and local distribution of specific histone modifications have been revealed to be prognostic factors in many cancers. However, the functional roles of histone modifications in oral squamous cell carcinoma (OSCC) remain unclear. This study investigates the levels of various histone modifications in 6 types of OSCC cell lines. We found that the level of H3K9me3 was significantly high in metastatic cell lines. In addition, the loss of H3K9me3 by SUV39H1 and SUV39H2 knockdown suppressed cell proliferation and cell migration. Our results indicate that a high level of H3K9me3 could be a marker of metastasis and possibly a therapeutic target for OSCC treatment.

Histone Methyltransferases as a New Target for Epigenetic Action of Vorinostat.

Epigenetic genome regulation during malignant cell transformation is characterized by the aberrant methylation and acetylation of histones. Vorinostat (SAHA) is an epigenetic modulator actively used in clinical oncology. The antitumor activity of vorinostat is commonly believed to be associated with the inhibition of histone deacetylases, while the impact of this drug on histone methylation has been poorly studied. Using HeLa TI cells as a test system allowing evaluation of the effect of epigenetically active compounds from the expression of the GFP reporter gene and gene knockdown by small interfering RNAs, we showed that vorinostat not only suppressed HDAC1, but also reduced the activity of EZH2, SUV39H1, SUV39H2, and SUV420H1. The ability of vorinostat to suppress expression of EZH2, SUV39H1/2, SUV420H1 was confirmed by Western blotting. Vorinostat also downregulated expression of SUV420H2 and DOT1L enzymes. The data obtained expand our understanding of the epigenetic effects of vorinostat and demonstrate the need for a large-scale analysis of its activity toward other enzymes involved in the epigenetic genome regulation. Elucidation of the mechanism underlying the epigenetic action of vorinostat will contribute to its more proper use in the treatment of tumors with an aberrant epigenetic profile.

Elevated SUV39H2 attributes to the progression of nasopharyngeal carcinoma via regulation of NRIP1.

Nasopharyngeal carcinoma (NPC) is a prevalent tumor in southern China and southeast Asia. Recent studies have demonstrated that viral infection, somatic genetic changes, and epigenetic changes synergistically contribute to NPC pathogenesis. Genome-wide studies show that epigenetic aberrations likely drive nasopharyngeal carcinoma development and progression. This work is aimed at investigating the effect of histone methyltransferase SUV39H2 in NPC. The elevated expression of SUV39H2 in NPC is observed by analyzing GSE53819 and GSE12452 downloaded from the Gene Expression Omnibus (GEO) database. SUV39H2 knockdown inhibits NPC proliferation and induces the apoptosis of cancer cells. At last, RNaseq analysis identifies a variety of SUV39H2 downstream genes related with cancer, in which, NRIP1 is identified as a critical downstream target of SUV39H2 in NPC. Taken together, these findings provide a theoretical basis for understating the biological roles of SUV39H2 in NPC.

Histone methyltransferase SUV39H2 regulates cell growth and chemosensitivity in glioma via regulation of hedgehog signaling.

BACKGROUND: Malignant glioma is one of the essentially incurable tumors with chemoresistance and tumor recurrence. As a histone methyltransferase, SUV39H2 can trimethylate H3K9. SUV39H2 is highly expressed in many types of human tumors, while the function of SUV39H2 in the development and progression of glioma has never been elucidated. METHODS: RT-qPCR and IHC were used to test SUV39H2 levels in glioma tissues and paired normal tissues. The clinical relevance of SUV39H2 in glioma was analyzed in a public database. Colony formation assays, CCK-8 assays, and flow cytometry were conducted to explore the role of SUV39H2 in the growth of glioma cells in vitro. A cell line-derived xenograft model was applied to explore SUV39H2's role in U251 cell proliferation in vivo. Sphere formation assays, RT-qPCR, flow cytometry, and IF were conducted to illustrate the role of SUV39H2 in the stemness and chemosensitivity of glioma. Luciferase reporter assays and WB were applied to determine the function of SUV39H2 in Hh signaling. RESULTS: SUV39H2 was highly expressed in glioma tissues relative to normal tissues. SUV39H2 knockdown inhibited cell proliferation and stemness and promoted the chemosensitivity of glioma cells in vitro. In addition, SUV39H2 knockdown also significantly inhibited glioma cell growth in vivo. Moreover, we further uncovered that SUV39H2 regulated hedgehog signaling by repressing HHIP expression. CONCLUSIONS: Our findings delineate the role of SUV39H2 in glioma cell growth and chemosensitivity as a pivotal regulator of the hedgehog signaling pathway and may support SUV39H2 as a potential target for diagnosis and therapy in glioma management.

Suv39h2 deficiency ameliorates diet-induced steatosis in mice.

Steatosis is a prototypical metabolic disorder characterized by accumulation of lipid droplets in the liver, extensive hepatic inflammation, and, in advanced stages, accelerated liver fibrogenesis. The molecular mechanism underlying steatosis is not completely understood. In the present study we investigated the involvement of the histone methyltransferase Suv39h2 in the pathogenesis of steatosis. Expression of Suv39h2 was up-regulated in the liver in two different mouse models of steatosis. Suv39h2 knockout (KO) mice developed a less severe form of steatosis fed on a methione-and-choline deficient (MCD) diet, compared to wild type (WT) littermates, as evidenced by reduced levels of plasma ALT, down-regulated expression of pro-inflammatory mediators, and decreased infiltration of macrophages. In addition, Masson's trichrome staining as well as qPCR measurements of fibrogenic genes suggested that liver fibrosis was attenuated in MCD diet-fed KO mice compared to WT mice. Further analysis found that Suv39h2 repressed SIRT1 expression in the liver by stimulating histone H3K9 trimethylation surrounding the SIRT1 promoter and that Suv39h2 deficiency alleviated SIRT1 expression in MCD diet-fed mice. Therefore, our data support a role of Suv39h2 in promoting steatosis in mice likely through contributing to SIRT1 trans-reperssion.

Dynamic changes of histone H3 lysine 9 following trimethylation in bovine oocytes and pre-implantation embryos.

OBJECTIVES: We have examined dynamic changes of histone H3 lysine 9 following trimethylation (H3K9me3), the mRNA expression levels of SUV39H1 and SUV39H2 in bovine oocytes and the role in the development of in vitro fertilization (IVF) pre-implantation embryos. RESULTS: There were strong H3K9me3 signals in germinal vesicle (GV) oocytes but no signals in MII oocytes. H3K9me3 signals were maintained during IVF pre-implantation embryo development. SUV39H1 and SUV39H2 showed significantly higher mRNA expression levels in GV oocytes than MII oocytes (P < 0.01). SUV39H1 showed high mRNA expression level in two-cell embryos, however, SUV39H2 showed high mRNA expression level in four-cell embryos. In other development stage, SUV39H1 and SUV39H2 showed low expression levels. CONCLUSION: Bovine IVF pre-implantation embryos maintain strong H3K9me3 signals and SUV39H1 and SUV39H2 are highly expressed at the early development stage of pre-implantation embryos.

Histone methyltransferase SUV39H2 regulates apoptosis and chemosensitivity in prostate cancer through AKT/FOXO signaling pathway.

Prostate cancer (PCa) is one of the most common malignant tumors that exhibit both chemoresistance and recurrence. SUV39H2 is highly expressed in many types of human tumors, but its role in the development and progression of PCa has never been clarified. The aim of this study is to elucidate the role of SUV39H2 in the development and progression of PCa, its association with the AKT/FOXO signaling pathway, and its potential implications for PCa diagnosis and treatment. SUV39H2 expression was analyzed in The Cancer Genome Atlas (TCGA) and genotype tissue expression pan-cancer data. The TCGA database was evaluated for SUV39H2 enrichment and its correlation to immune cell infiltration. SUV39H2 levels in PCa tissues and control tissues were determined in 30 patients using qPCR and IHC. Clinical relevance was assessed via The Cancer Genome Atlas (TCGA). In vitro assessments including colony formation assays, Western Blot analysis, CCK-8 assays, and flow cytometry were utilized to establish SUV39H2's contribution to PCa cell growth. The influence of SUV39H2 on PC3 and DU145 cell proliferation was assessed through a cell line-derived xenograft model. Sphere formation assays and qPCR were employed to delineate SUV39H2's role in PCa stemness and chemosensitivity. In vitro macrophage polarization assays provided insights into SUV39H2's association with M2 macrophages, while enrichment analysis shed light on its role in FOXO signaling. PCa tissues expressed higher levels of SUV39H2 than normal tissues. By knocking down SUV39H2, PCa cells were made more chemosensitive to docetaxel and cell proliferation and stemness were inhibited. Additionally, SUV39H2 knockdown significantly inhibited in vivo PCa cell growth and inhibited the polarization of macrophages. Furthermore, SUV39H2 was found to regulate AKT/FOXO signaling by increasing Akt and FOXO3a phosphorylation. Our findings highlight SUV39H2's role in PCa cell apoptosis and chemosensitivity mainly by regulating the AKT/FOXO signaling pathway and suggest that SUV39H2 could be a potential target for PCa diagnosis and treatment.

N6-methyadenosine modified SUV39H2 regulates homologous recombination through epigenetic repression of DUSP6 in gastric cancer.

Despite many advances in treatment over the past few years, the poor 5-year survival rate and high recurrence rate of gastric cancer (GC) remain unsatisfactory. As the most abundant epigenetic modification in the eukaryotic mRNA, N6-methyladenosine (m6A) methylation participates in tumor progression and tissue development. During tumor progression, DNA damage repair mechanisms can be reprogrammed to give new growth advantages on tumor clones whose genomic integrity is disturbed. Here we detected the elevated SUV39H2 expression in GC tissues and cell lines. Functionally, SUV39H2 promoted GC proliferation and inhibited apoptosis in vitro and in vivo. Mechanistically, METTL3-mediated m6A modification promotes mRNA stability of SUV39H2 in an IGF2BP2 dependent manner, resulting in upregulated mRNA expression of SUV39H2. As a histone methyltransferase, SUV39H2 was verified to increase the phosphorylation level of ATM through transcriptional repression of DUSP6, thereby promoting HRR and ultimately inhibiting GC chemosensitivity to cisplatin. Collectively, these results indicate the specific mechanism of m6A-modified SUV39H2 as a histone methyltransferase promoting HRR to inhibit the chemosensitivity of GC. SUV39H2 is expected to become a key target in the precision targeted therapy of GC.

BRD4770 inhibits vascular smooth muscle cell proliferation via SUV39H2, but not EHMT2 to protect against neointima formation.

The behavior of vascular smooth muscle cells (VSMCs) contributes to the formation of neointima. We previously found that EHMT2 suppressed autophagy activation in VSMCs. BRD4770, an inhibitor of EHMT2/G9a, plays a critical role in several kinds of cancers. However, whether and how BRD4770 regulates the behavior of VSMCs remain unknown. In this study, we evaluate the cellular effect of BRD4770 on VSMCs by series of experiments in vivo and ex vivo. We demonstrated that BRD4770 inhibited VSMCs' growth by blockage in G2/M phase in VSMCs. Moreover, our results demonstrated that the inhibition of proliferation was independent on autophagy or EHMT2 suppression which we previous reported. Mechanistically, BRD4770 exhibited an off-target effect from EHMT2 and our further study reveal that the proliferation inhibitory effect by BRD4770 was associated with suppressing on SUV39H2/KTM1B. In vivo, BRD4770 was also verified to rescue VIH. Thus, BRD4770 function as a crucial negative regulator of VSMC proliferation via SUV39H2 and G2/M cell cycle arrest and BRD4770 could be a molecule for the therapy of vascular restenosis.

SUV39H2/KMT1B Inhibits the cardiomyocyte senescence phenotype by down-regulating BTG2/PC3.

Suppressor of variegation 3-9 homolog 2 (SUV39H2/KMT1B), a member of the SUV39 subfamily of lysine methyltransferases (KMTs), functions as an oncogene in various types of cancers. Here, we demonstrate a novel function of SUV39H2 that drives the cardiomyocyte aging process through BTG2. In our study, cardiomyocyte aging was induced by H2O2 and aging cells exhibited increases in SUV39H2. Knockdown of SUV39H2 accelerated cardiomyocyte senescence, while overexpression of SUV39H2 inhibited the cardiomyocyte senescence phenotype. These effects of SUV39H2 on cardiomyocytes were independent of DNA damage and mitochondrial dysfunction. Interestingly, RNA sequencing and bioinformatics analyses identified a strong correlation between SUV39H2 and BTG2. In addition to this, BTG2 protein levels were significantly increased in SUV39H2-deficient cardiomyocytes, and BTG2 knockdown virtually rescued the cardiomyocyte senescence phenotype induced by SUV39H2 knockdown. Taken together, these results indicate that SUV39H2 protects cardiomyocytes from H2O2 exposure-induced oxidative stress, DNA damage, and mitochondrial dysfunction by regulating the p53-BTG2 pathway. Our findings provide evidence that the activation of SUV39H2 has therapeutic or preventive potential against cardiac aging.

H3K9 Methyltransferases Suv39h1 and Suv39h2 Control the Differentiation of Neural Progenitor Cells in the Adult Hippocampus.

In the dentate gyrus of the adult hippocampus new neurons are generated from neural precursor cells through different stages including proliferation and differentiation of neural progenitor cells and maturation of newborn neurons. These stages are controlled by the expression of specific transcription factors and epigenetic mechanisms, which together orchestrate the progression of the neurogenic process. However, little is known about the involvement of histone posttranslational modifications, a crucial epigenetic mechanism in embryonic neurogenesis that regulates fate commitment and neuronal differentiation. During embryonic development, the repressive modification trimethylation of histone H3 on lysine 9 (H3K9me3) contributes to the cellular identity of different cell-types. However, the role of this modification and its H3K9 methyltransferases has not been elucidated in adult hippocampal neurogenesis. We determined that during the stages of neurogenesis in the adult mouse dentate gyrus and in cultured adult hippocampal progenitors (AHPs), there was a dynamic change in the expression and distribution of H3K9me3, being enriched at early stages of the neurogenic process. A similar pattern was observed in the hippocampus for the dimethylation of histone H3 on lysine 9 (H3K9me2), another repressive modification. Among H3K9 methyltransferases, the enzymes Suv39h1 and Suv39h2 exhibited high levels of expression at early stages of neurogenesis and their expression decreased upon differentiation. Pharmacological inhibition of these enzymes by chaetocin in AHPs reduced H3K9me3 and concomitantly decreased neuronal differentiation while increasing proliferation. Moreover, Suv39h1 and Suv39h2 knockdown in newborn cells of the adult mouse dentate gyrus by retrovirus-mediated RNA interference impaired neuronal differentiation of progenitor cells. Our results indicate that H3K9me3 and H3K9 methyltransferases Suv39h1 and Suv39h2 are critically involved in the regulation of adult hippocampal neurogenesis by controlling the differentiation of neural progenitor cells.

SUV39H2 controls trophoblast stem cell fate.

BACKGROUND: The placenta is formed by the coordinated expansion and differentiation of trophoblast stem (TS) cells along a multi-lineage pathway. Dynamic regulation of histone 3 lysine 9 (H3K9) methylation is pivotal to cell differentiation for many cell lineages, but little is known about its involvement in trophoblast cell development. METHODS: Expression of H3K9 methyltransferases was surveyed in rat TS cells maintained in the stem state and following differentiation. The role of suppressor of variegation 3-9 homolog 2 (SUV39H2) in the regulation of trophoblast cell lineage development was investigated using a loss-of-function approach in rat TS cells and ex vivo cultured rat blastocysts. RESULTS: Among the twelve-known H3K9 methyltransferases, only SUV39H2 exhibited robust differential expression in stem versus differentiated TS cells. SUV39H2 transcript and protein expression were high in the stem state and declined as TS cells differentiated. Disruption of SUV39H2 expression in TS cells led to an arrest in TS cell proliferation and activation of trophoblast cell differentiation. SUV39H2 regulated H3K9 methylation status at loci exhibiting differentiation-dependent gene expression. Analyses of SUV39H2 on ex vivo rat blastocyst development supported its role in regulating TS cell expansion and differentiation. We further identified SUV39H2 as a downstream target of caudal type homeobox 2, a master regulator of trophoblast lineage development. CONCLUSIONS: Our findings indicate that SUV39H2 contributes to the maintenance of TS cells and restrains trophoblast cell differentiation. GENERAL SIGNIFICANCE: SUV39H2 serves as a contributor to the epigenetic regulation of hemochorial placental development.

Sequencing two Tyr::CreERT2 transgenic mouse lines.

The Cre/loxP system is a powerful tool that has allowed the study of the effects of specific genes of interest in various biological settings. The Tyr::CreERT2 system allows for the targeted expression and activity of the Cre enzyme in the melanocyte lineage following treatment with tamoxifen, thus providing spatial and temporal control of the expression of specific target genes. Two independent transgenic mouse models, each containing a Tyr::CreERT2 transgene, have been generated and are widely used to study melanocyte transformation. In this study, we performed whole genome sequencing (WGS) on genomic DNA from the two Tyr::CreERT2 mouse models and identified their sites of integration in the C57BL/6 genome. Based on these results, we designed PCR primers to accurately, and efficiently, genotype transgenic mice. Finally, we discussed some of the advantages of each transgenic mouse model.

The Oncogenic Potential of SUV39H2: A Comprehensive and Perspective View.

Epigenetic modifications at the histone level have attracted significant attention because of their roles in tumorigenesis. Suppressor of variegation 3-9 homolog 2 (SUV39H2, also known as KMT1B) is a member of the SUV39 subfamily of lysine methyltransferases (KMTs) that plays a significant role in histone H3-K9 di-/tri-methylation, transcriptional regulation and cell cycle. Overexpressions of SUV39H2 at gene, mRNA and protein levels are known to be associated with a range of cancers: leukemia, lymphomas, lung cancer, breast cancer, colorectal cancer, gastric cancer, hepatocellular cancer and so on. Accumulating evidence indicates that SUV39H2 acts as an oncogene and contributes to the initiation and progression of cancers. It could, therefore, be a promising target for anti-cancer treatment. In this review, we focus on the dysregulation of SUV39H2 in cancers, including its clinical prognostic predictor role, molecular mechanism involved in cancer occurrence and development, relevant inhibitors against cancer, and its epigenetic modification interaction with immunotherapy. A better understanding of the SUV39H2 will be beneficial to the development of molecular-targeted therapies in cancer.

Suppressor of Variegation 3-9 Homolog 2, a Novel Binding Protein of Translationally Controlled Tumor Protein, Regulates Cancer Cell Proliferation.

Suppressor of Variegation 3-9 Homolog 2 (SUV39H2) methylates the lysine 9 residue of histone H3 and induces heterochromatin formation, resulting in transcriptional repression or silencing of target genes. SUV39H1 and SUV39H2 have a role in embryonic development, and SUV39H1 was shown to suppress cell cycle progression associated with Rb. However, the function of human SUV39H2 has not been extensively studied. We observed that forced expression of SUV39H2 decreased cell proliferation by inducing G1 cell cycle arrest. In addition, SUV39H2 was degraded through the ubiquitin-proteasomal pathway. Using yeast two-hybrid screening to address the degradation mechanism and function of SUV39H2, we identified translationally controlled tumor protein (TCTP) as an SUV39H2-interacting molecule. Mapping of the interacting regions indicated that the N-terminal 60 amino acids (aa) of full-length SUV39H2 and the C-terminus of TCTP (120-172 aa) were critical for binding. The interaction of SUV39H2 and TCTP was further confirmed by co-immunoprecipitation and immunofluorescence staining for colocalization. Moreover, depletion of TCTP by RNAi led to up-regulation of SUV39H2 protein, while TCTP overexpression reduced SUV39H2 protein level. The half-life of SUV39H2 protein was significantly extended upon TCTP depletion. These results clearly indicate that TCTP negatively regulates the expression of SUV39H2 post-translationally. Furthermore, SUV39H2 induced apoptotic cell death in TCTP-knockdown cells. Taken together, we identified SUV39H2, as a novel target protein of TCTP and demonstrated that SUV39H2 regulates cell proliferation of lung cancer cells.

Development of novel SUV39H2 inhibitors that exhibit growth suppressive effects in mouse xenograft models and regulate the phosphorylation of H2AX.

Protein methyltransferase SUV39H2 was reported to methylate histone H2AX at lysine 134 and enhance the formation of phosphorylated H2AX (γ-H2AX), which causes chemoresistance of cancer cells. We found that a series of imidazo[1,2-a]pyridine compounds that we synthesized could inhibit SUV39H2 methyltransferase activity. One of the potent compounds, OTS193320, was further analyzed in in vitro studies. The compound decreased global histone H3 lysine 9 tri-methylation levels in breast cancer cells and triggered apoptotic cell death. Combination of OTS193320 with doxorubicin (DOX) resulted in reduction of γ-H2AX levels as well as cancer cell viability compared to a single agent OTS193320 or DOX. Further optimization of inhibitors and their in vivo analysis identified a compound, OTS186935, which revealed significant inhibition of tumor growth in mouse xenograft models using MDA-MB-231 breast cancer cells and A549 lung cancer cells without any detectable toxicity. Our results suggest that the SUV39H2 inhibitors sensitize cancer cells to DOX by reduction of γ-H2AX levels in cancer cells, and collectively demonstrate that SUV39H2 inhibition warrants further investigation as a novel anti-cancer therapy.

SUV39H2 promotes colorectal cancer proliferation and metastasis via tri-methylation of the SLIT1 promoter.

Suppressor of variegation 3-9 homolog 2 (SUV39H2) is a member of the SUV39H subfamily of lysine methyltransferases. Its role in colorectal cancer (CRC) proliferation and metastasis has remained unexplored. Here, we determined that SUV39H2 was upregulated in CRC tissues compared with that in adjacent non-neoplastic tissues. Further statistical analysis revealed that high SUV39H2 expression was strongly associated with distant metastasis (P = 0.016) and TNM stage (P = 0.038) and predicted a shorter overall survival (OS; P = 0.018) and progression-free survival (PFS; P = 0.018) time for CRC patients. Both in vitro and in vivo assays demonstrated that ectopically expressed SUV39H2 enhanced CRC proliferation and metastasis, while SUV39H2 knockdown inhibited CRC proliferation and metastasis. A molecular screen of SUV39H2 targets found that SUV39H2 negatively regulated the expression of SLIT guidance ligand 1 (SLIT1). Moreover, rescue assays suggested that SLIT1 could antagonize the function of SUV39H2 in CRC. Mechanistic studies indicated that SUV39H2 can directly bind to the SLIT1 promoter, suppressing SLIT1 transcription by catalyzing histone H3 lysine 9 (H3K9) tri-methylation. In summary, we propose that SUV39H2 can predict CRC patient prognosis and stimulate CRC malignant phenotypes via SLIT1 promoter tri-methylation.

Androgen receptor regulation by histone methyltransferase Suppressor of variegation 3-9 homolog 2 and Melanoma antigen-A11.

Androgen receptor (AR) transcriptional activity depends on interactions between the AR NH2-terminal region and transcriptional coregulators. A yeast two-hybrid screen of a human testis library using predicted α-helical NH2-terminal fragment AR-(370-420) as bait identified suppressor of variegation 3-9 homolog 2 (SUV39H2) histone methyltransferase as an AR interacting protein. SUV39H2 interaction with AR and the AR coregulator, melanoma antigen-A11 (MAGE-A11), was verified in two-hybrid, in vitro glutathione S-transferase affinity matrix and coimmunoprecipitation assays. Fluorescent immunocytochemistry colocalized SUV39H2 and AR in the cytoplasm without androgen, in the nucleus with androgen, and with MAGE-A11 in the nucleus independent of androgen. Chromatin immunoprecipitation using antibodies raised against SUV39H2 demonstrated androgen-dependent recruitment of AR and SUV39H2 to the androgen-responsive upstream enhancer of the prostate-specific antigen gene. SUV39H2 functioned cooperatively with MAGE-A11 to increase androgen-dependent AR transcriptional activity. SUV39H2 histone methyltransferase is an AR coactivator that increases androgen-dependent transcriptional activity through interactions with AR and MAGE-A11.

Major satellite repeat RNA stabilize heterochromatin retention of Suv39h enzymes by RNA-nucleosome association and RNA:DNA hybrid formation.

The Suv39h1 and Suv39h2 histone lysine methyltransferases are hallmark enzymes at mammalian heterochromatin. We show here that the mouse Suv39h2 enzyme differs from Suv39h1 by containing an N-terminal basic domain that facilitates retention at mitotic chromatin and provides an additional affinity for major satellite repeat RNA. To analyze an RNA-dependent interaction with chromatin, we purified native nucleosomes from mouse ES cells and detect that Suv39h1 and Suv39h2 exclusively associate with poly-nucleosomes. This association was attenuated upon RNaseH incubation and entirely lost upon RNaseA digestion of native chromatin. Major satellite repeat transcripts remain chromatin-associated and have a secondary structure that favors RNA:DNA hybrid formation. Together, these data reveal an RNA-mediated mechanism for the stable chromatin interaction of the Suv39h KMT and suggest a function for major satellite non-coding RNA in the organization of an RNA-nucleosome scaffold as the underlying structure of mouse heterochromatin.