YY1 Oligomerization Is Regulated by Its OPB Domain and Competes with Its Regulation of Oncoproteins.

Yin Yang 1 (YY1) plays an oncogenic role through regulating the expression of various cancer-related genes and activating key oncoproteins. Previous research reported that YY1 protein formed dimers or oligomers without definite biological implications. In this study, we first demonstrated the oncoprotein binding (OPB) and zinc finger (ZF) domains of YY1 as the regions involved in its intermolecular interactions. ZFs are well-known for protein dimerization, so we focused on the OPB domain. After mutating three hydrophobic residues in the OPB to alanines, we discovered that YY1(F219A) and YY1(3A), three residues simultaneously replaced by alanines, were defective of intermolecular interaction. Meanwhile, the OPB peptide could robustly facilitate YY1 protein oligomerization. When expressed in breast cancer cells with concurrent endogenous YY1 knockdown, YY1(F219A) and (3A) mutants showed better capacity than wt in promoting cell proliferation and migration, while their interactions with EZH2, AKT and MDM2 showed differential alterations, especially with improved EZH2 binding affinity. Our study revealed a crucial role of the OPB domain in facilitating YY1 oligomerization and suggested a mutually exclusive regulation between YY1-mediated enhancer formation and its activities in promoting oncoproteins.

A histidine cluster determines YY1-compartmentalized coactivators and chromatin elements in phase-separated enhancer clusters.

As an oncogenic transcription factor, Yin Yang 1 (YY1) regulates enhancer and promoter connection. However, gaps still exist in understanding how YY1 coordinates coactivators and chromatin enhancer elements to assemble enhancers and super-enhancers. Here, we demonstrate that a histidine cluster in YY1's transactivation domain is essential for its formation of phase separation condensates, which can be extended to additional proteins. The histidine cluster is also required for YY1-promoted cell proliferation, migration, clonogenicity and tumor growth. YY1-rich nuclear puncta contain coactivators EP300, BRD4, MED1 and active RNA polymerase II, and colocalize with histone markers of gene activation, but not that of repression. Furthermore, YY1 binds to the consensus motifs in the FOXM1 promoter to activate its expression. Wild-type YY1, but not its phase separation defective mutant, connects multiple enhancer elements and the FOXM1 promoter to form an enhancer cluster. Consistently, fluorescent in situ hybridization (FISH) assays reveal the colocalization of YY1 puncta with both the FOXM1 gene locus and its nascent RNA transcript. Overall, this study demonstrates that YY1 activates target gene expression through forming liquid-liquid phase separation condensates to compartmentalize both coactivators and enhancer elements, and the histidine cluster of YY1 plays a determinant role in this regulatory mechanism.

Comparative study of structural properties and biological activities of polysaccharides extracted from Chroogomphus rutilus by four different approaches.

Extraction processes significantly alter the structural and functional properties of polysaccharides. In this study, we extracted polysaccharides from Chroogomphis rutilus fruiting bodies (designated as CRP) using four methods, including hot water, ultrasound, microwave and sequential ultrasound-microwave, and designated these polysaccharides as CRP-H, CRP-M, CRP-U and CRP-UM, respectively. All CRPs were heteropolysaccharides with semblable monosaccharide types of glucose, mannose and galactose, mainly constituted of α-d-glucopyranosyl-(1 â†’ 4). The extraction processes significantly affected the molecular weights, monosaccharide proportions, glycosidic bond ratios, branching degrees, triple-helix conformation and surface morphology of the CRPs. Among them, CRP-UM showed the highest yield and most potent antioxidative capacity in vitro and in HL-7702 cells, but the weakest activation of immunostimulatory response in RAW264.7 cells. In contrast, CRP-H exhibited the lowest yield but strongest immunostimulatory activity. Overall, microwave extraction could be utilized as a general and practical CRP extraction approach, based on its relatively high yield and bioactivities.

Disruption of YY1-EZH2 Interaction Using Synthetic Peptides Inhibits Breast Cancer Development.

Enhancer of zeste homolog 2 (EZH2) is a methyltransferase to mediate lysine 27 trimethylation in histone H3 (i.e., H3K27me3) and repress gene expression. In solid tumors, EZH2 promotes oncogenesis and is considered a therapeutic target. As a transcription factor, Yin Yang 1 (YY1) recruits EZH2 through its oncoprotein binding (OPB) domain to establish gene repression. In this study, we mapped the YY1 protein binding (YPB) domain on EZH2 to a region of 27 amino acids. Both YPB and OPB domain synthetic peptides could disrupt YY1EZH2 interaction, markedly reduce breast cancer cell viability, and efficiently inhibit tumor growth in a xenograft mouse model. We analyzed MDA-MB-231 cells treated with YPB, OPB, and control peptides by chromatin immunoprecipitation DNA sequencing (ChIP-seq) using an antibody against H3K27me3. YPB and OPB treatments altered H3K27me3 on 465 and 1137 genes, respectively, compared to the control. Of these genes, 145 overlapped between the two peptides. Among them, PTENP1, the PTEN pseudogene, showed reduced H3K27me3 signal when treated by either YPB or OPB peptide. Consistently, the two peptides enhanced both PTENP1 and PTEN expression with concomitantly reduced AKT activation. Further studies validated PTENP1's contribution to the anticancer activity of YPB and OPB peptides.

Ellagic acid synergistically potentiates inhibitory activities of chemotherapeutic agents to human hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with poor prognosis. Various chemotherapeutics are used in treatment of HCC, but most of them have significant toxicity to patients. Thus, it is urgently needed to develop new therapeutic strategies to achieve high specificity and tolerable adverse effects. As a natural polyphenol, ellagic acid (EA) demonstrates inhibitory effects in cancers. PURPOSE: The goal of the present study to investigate the anticancer activity of EA with a focus on its stimulating effects on doxorubicin hydrochloride (DOX) and cisplatin (DDP) in HCC treatment. METHODS: HepG2, SMMC-7721 and HL-7702 cells were treated with EA, DOX, DDP or their combinations. Cell viability and apoptosis were examined to evaluate the cytotoxicity of these treatments. Western blot analysis and immunofluorescent assays were used to determine expression of genes related to the mitochondrial apoptosis pathway. To assess the anticancer activities and systemic toxicity of EA, DOX and EA+DOX treatments, a xenograft mouse model with inoculated HepG2 cells was employed, followed by immunohistochemical and histopathological evaluation. RESULTS: EA could both markedly potentiate anticancer activities of DOX and DDP to HCC HepG2 and SMMC-7721 cells, and reduce their cytotoxicity to normal liver HL-7702 cells. EA and its combination with DOX or DDP induced cell apoptosis through a pathway mediated by mitochondrial cytochrome c release. In nude mice, EA combination with a relatively low dosage of DOX effectively inhibited tumor growth without causing cardiotoxicity observed in mice treated by a high dosage of DOX. CONCLUSION: We discovered that EA synergistically potentiated DOX and DDP in suppressing HCC with significantly reduced side effects and this may represent a novel strategy in HCC therapies with both high anticancer efficiencies and low systemic toxicity in patients.

Re-thinking the evolution of microblade technology in East Asia: Techno-functional understanding of the lithic assemblage from Shizitan 29 (Shanxi, China).

The lithic assemblage from Shizitan 29, a late Upper Paleolithic open-air site in Shanxi, China, provides evidence for the earliest, well-dated microblade production in East Asia, ca. 26/24 Ka cal BP. To pursue a behavioral rather than traditional typological understanding of this key adaptive technology, we apply a techno-functional approach that enables us to reconstruct the entire operational sequence in behavioral terms through the derivation of technical objectives. This methodology can serve as a model to be applied to other assemblages for greater understanding of the origins and spread of the broadly distributed eastern Asian Late Pleistocene microblade industries. Within the eight cultural layers at Shizitan 29, microblade production abruptly appears at the top of Layer 7 following earlier core-and-flake production, supporting hypotheses of microblade technology arising within adaptive strategies to worsening Late Glacial Maximum environments. Significantly, reconstruction of the operational sequence supports microblade technology being introduced into the North China Loess Plateau from regions further north. It also allows us to re-think microblades' relationship in behavioral terms with earlier limited examples of East Asian blade production and the evolution and spread of microblade technology, providing new insights into the adaptive relationships between subsequent microblade productions.

Characterization of YY1 OPB Peptide for its Anticancer Activity.

BACKGROUND: The oncoprotein binding (OPB) domain of Yin Yang 1 (YY1) consists of 26 amino acids between G201 and S226, and is involved in YY1 interaction with multiple oncogene products, including MDM2, AKT, EZH2 and E1A. Through the OPB domain, YY1 promotes the oncogenic or proliferative regulation of these oncoproteins in cancer cells. We previously demonstrated that a peptide with the OPB sequence blocked YY1-AKT interaction and inhibited breast cancer cell proliferation. OBJECTIVE: In the current study, we characterized the OPB domain and determined a minimal region for peptide design to suppress cancer cells. METHODS: Using alanine-scan method, we identified that the amino acids at OPB C-terminal are essential to YY1 binding to AKT. Further studies suggested that serine and threonine residues, but not lysines, in OPB play a key role in YY1-AKT interaction. We generated GFP fusion expression vectors to express OPB peptides with serially deleted N-terminal and found that OPB1 (i.e. G201-S226) is cytoplasmic, but OPB2 (i.e. E206-S226), OPB3 (i.e. E206-S226) and control peptide were both nuclear and cytoplasmic. RESULTS: Both OPB1 and 2 inhibited breast cancer cell proliferation and migration, but OPB3 exhibited similar effects to control. OPB1 and 2 caused cell cycle arrest at G1 phase, increased p53 and p21 expression, and reduced AKT(S473) phosphorylation in MCF-7 cells, but not in MDA-MB-231 cells. CONCLUSION: Overall, the serines and threonines of OPB are essential to YY1 binding to oncoproteins, and OPB peptide can be minimized to E206-S226 that maintain inhibitory activity to YY1- promoted cell proliferation.

From General Aberrant Alternative Splicing in Cancers and Its Therapeutic Application to the Discovery of an Oncogenic DMTF1 Isoform.

Alternative pre-mRNA splicing is a crucial process that allows the generation of diversified RNA and protein products from a multi-exon gene. In tumor cells, this mechanism can facilitate cancer development and progression through both creating oncogenic isoforms and reducing the expression of normal or controllable protein species. We recently demonstrated that an alternative cyclin D-binding myb-like transcription factor 1 (DMTF1) pre-mRNA splicing isoform, DMTF1ß, is increasingly expressed in breast cancer and promotes mammary tumorigenesis in a transgenic mouse model. Aberrant pre-mRNA splicing is a typical event occurring for many cancer-related functional proteins. In this review, we introduce general aberrant pre-mRNA splicing in cancers and discuss its therapeutic application using our recent discovery of the oncogenic DMTF1 isoform as an example. We also summarize new insights in designing novel targeting strategies of cancer therapies based on the understanding of deregulated pre-mRNA splicing mechanisms.

Yin Yang 1 promotes mTORC2-mediated AKT phosphorylation.

Yin Yang 1 (YY1) regulates both gene expression and protein modifications, and has shown a proliferative role in cancers. In this study, we demonstrate that YY1 promotes AKT phosphorylation at S473, a marker of AKT activation. YY1 expression positively correlated with AKT(S473) phosphorylation in a tissue microarray and cultured cells of breast cancer, but negatively associated with the distant metastasis-free survival of 166 breast cancer patients. YY1 promotes AKT phosphorylation at S473 through direct interaction with AKT, and the AKT-binding site is mapped to the residues G201-S226 on YY1. These residues are also involved in YY1 interaction with Mdm2, Ezh2, and E1A, and thus are designated as the oncogene protein binding (OPB) domain. YY1-promoted AKT phosphorylation relies on the OPB domain but is independent of either transcriptional activity of YY1 or the activity of phosphoinositide-3-kinases. We also determine that YY1-promoted mTORC2 access to AKT leads to its phosphorylation at S473. Importantly, a peptide based on the OPB domain blocks YY1 interaction with AKT and reduces AKT phosphorylation and cell proliferation. Thus, we demonstrate for the first time that YY1 promotes mTORC2-mediated AKT activation and disrupting YY1-AKT interaction by OPB domain-based peptide may represent a potential strategy for cancer therapy.

The role of YY1 in oncogenesis and its potential as a drug target in cancer therapies.

Yin Yang 1 (YY1) is a multifunctional protein regulating both gene transcription and protein modifications. Recent studies reveal a proliferative role of YY1 in oncogenesis. Consistently, YY1 overexpression has been observed in various human malignancies and its levels correlate with poor prognoses of many types of cancers. In this review, we focus on the signaling pathways and regulatory proteins that YY1 modulates to promote tumor cell growth, proliferation, migration and metastasis. We also discuss the signals and molecules that regulate YY1 expression and function in cancer-related context. Based on the expression feature and regulatory activities in tumor cells, YY1 possesses a great potential as a biomarker for many cancers and can serve as a therapeutic target clinically to impede cancer development and progression or sensitize cancer cells to anticancer drugs.

Paleolithic human exploitation of plant foods during the last glacial maximum in North China.

Three grinding stones from Shizitan Locality 14 (ca. 23,000-19,500 calendar years before present) in the middle Yellow River region were subjected to usewear and residue analyses to investigate human adaptation during the last glacial maximum (LGM) period, when resources were generally scarce and plant foods may have become increasingly important in the human diet. The results show that these tools were used to process various plants, including Triticeae and Paniceae grasses, Vigna beans, Dioscorea opposita yam, and Trichosanthes kirilowii snakegourd roots. Tubers were important food resources for Paleolithic hunter-gatherers, and Paniceae grasses were exploited about 12,000 y before their domestication. The long tradition of intensive exploitation of certain types of flora helped Paleolithic people understand the properties of these plants, including their medicinal uses, and eventually led to the plants' domestication. This study sheds light on the deep history of the broad spectrum subsistence strategy characteristic of late Pleistocene north China before the origins of agriculture in this region.