Project description:Yin Yang 1 (YY1) is a critical transcription factor controlling cell proliferation, development and DNA damage responses. Although two homologous Drosophila YY family members (pleiohomeotic (pho)) and pleiohomeotic-like (phol)) are redundant, the functional significance of a recently described mammalian YY1-like gene (YY2) is unknown. Using microarray and gene set enrichment analysis (GSEA), we found that lentiviral constructs containing short hairpin loop YY1- and YY2-specific inhibitory RNAs (shYY1 and shYY2) caused significant changes in both redundant and distinguishable expression patterns. Ribosomal protein genes were the most significant gene set up-regulated by both shYY1 and shYY2, although combined shYY1/shYY2 knockdowns were not additive. In contrast, shYY2 reversed anti-proliferative effects of shYY1 on E2F target genes, and shYY2 particularly altered UV damage response, platelet-specific genes and mitochondrial function genes. The most YY2-specific gene was the platelet glycoprotein CD36 whose ligand is thrombospondin - a key UV response gene. We found that decreases in YY1 or YY2 caused inverse changes in UV sensitivity, and that their combined loss reversed their respective individual effects. Taken together, our studies show that YY2 is not redundant to YY1, and YY2 is a significant regulator of genes previously thought to uniquely respond to YY1. Functions of thrombospondin and CD36 in inflammation, atherogenesis, innate immunity and malaria pathogenesis reveal new potential regulatory roles for YY1 and YY2. Four treatment groups were used that included control vector (pLKO) virus, shYY1, shYY2 and shYY1 combined with shYY2. Three replicas were performed for all except shYY2, where we performed four replicas. Target gene comparison of YY1 And YY2 homologous genes.
Project description:Yin Yang 1 (YY1) is a critical transcription factor controlling cell proliferation, development and DNA damage responses. Although two homologous Drosophila YY family members (pleiohomeotic (pho)) and pleiohomeotic-like (phol)) are redundant, the functional significance of a recently described mammalian YY1-like gene (YY2) is unknown. Using microarray and gene set enrichment analysis (GSEA), we found that lentiviral constructs containing short hairpin loop YY1- and YY2-specific inhibitory RNAs (shYY1 and shYY2) caused significant changes in both redundant and distinguishable expression patterns. Ribosomal protein genes were the most significant gene set up-regulated by both shYY1 and shYY2, although combined shYY1/shYY2 knockdowns were not additive. In contrast, shYY2 reversed anti-proliferative effects of shYY1 on E2F target genes, and shYY2 particularly altered UV damage response, platelet-specific genes and mitochondrial function genes. The most YY2-specific gene was the platelet glycoprotein CD36 whose ligand is thrombospondin - a key UV response gene. We found that decreases in YY1 or YY2 caused inverse changes in UV sensitivity, and that their combined loss reversed their respective individual effects. Taken together, our studies show that YY2 is not redundant to YY1, and YY2 is a significant regulator of genes previously thought to uniquely respond to YY1. Functions of thrombospondin and CD36 in inflammation, atherogenesis, innate immunity and malaria pathogenesis reveal new potential regulatory roles for YY1 and YY2.
Project description:Ferroptosis is a type of programmed cell death caused by disruption of redox homeostasis, and is closely linked to amino acid metabolism. Yin Yang 2 (YY2) and its homolog Yin Yang 1 (YY1) are members of the YY family with high homology, especially in their zinc-finger domains. Furthermore, they share consensus DNA binding motif. In contrast with the oncogenic YY1, increasing evidences have demonstrated the tumor suppressive effect of YY2; however, at present, little is known about its biological and pathological functions. Here we found that YY2 induces tumor cells ferroptosis and subsequently, suppresses tumorigenesis, by inhibiting SLC7A11 transcription, leading to the decreased glutathione biosynthesis. Furthermore, we reveal that YY2 and YY1 bind competitively to SLC7A11 promoter and antagonistically regulate tumor cells ferroptosis, thus suggesting the molecular mechanism underlying their opposite regulation on tumorigenesis. Moreover, we showed that mutations of YY2 zinc-finger domains in clinical cancer patients abrogated YY2/SLC7A11 axis and tumor cells ferroptosis. Together, these results provide a new insight regarding the regulatory mechanism of ferroptosis, and a mechanistic explanation regarding the tumor suppressive effect of YY2. Furthermore, our findings demonstrate that homeostasis between YY1 and YY2 is crucial for maintaining redox homeostasis in tumor cells.
Project description:Yin Yang 1 (YY1) is a multifunctional DNA-binding transcription factor shown to be critical in a variety of biological processes, and its activity and function have been shown to be regulated by multitude of mechanisms, which include but are not limited to post-translational modifications (PTMs), its associated proteins and cellular localization. YY2, the paralog of YY1 in mouse and human, has been proposed to function redundantly or oppositely in a context specific manner compared to YY1. Despite its functional importance, how YY2’s DNA binding activity and function is regulated, particularly by PTMs, remains completely unknown. Here we report the first PTM with functional characterization on YY2, namely lysine 247 mono-methylation (K247me1), which was found to be dynamically regulated by SET7/9 and LSD1 both in vitro and in cultured cells. Functional study revealed that SET7/9-mediated YY2 methylation regulated its DNA-binding activity in vitro and association with chromatin examined by ChIP-seq (chromatin immunoprecipitation coupled with sequencing) in cultured cells. Knockout of YY2, SET7/9 or LSD1 by CRISPR (clustered, regularly interspaced, short palindromic repeats) /Cas9-mediated gene editing followed by RNA-seq revealed that a subset of genes was positively-regulated by YY2 and SET7/9, but negatively-regulated by LSD1, which were enriched with genes involved in cell proliferation regulation. Importantly, YY2-regulated gene transcription, cell proliferation and tumor growth were dependent, at least partially, on YY2 K247 methylation. Finally, somatic mutations on YY2 found in cancer, which are in close proximity to K247, altered its methylation, DNA binding activity and gene transcription it controls. Our findings revealed the first PTM with functional implications imposed on YY2 protein, and linked YY2 methylation with its biological functions.
Project description:Yin Yang 1 (YY1) is a multifunctional DNA-binding transcription factor shown to be critical in a variety of biological processes, and its activity and function have been shown to be regulated by multitude of mechanisms, which include but are not limited to post-translational modifications (PTMs), its associated proteins and cellular localization. YY2, the paralog of YY1 in mouse and human, has been proposed to function redundantly or oppositely in a context specific manner compared to YY1. Despite its functional importance, how YY2’s DNA binding activity and function is regulated, particularly by PTMs, remains completely unknown. Here we report the first PTM with functional characterization on YY2, namely lysine 247 mono-methylation (K247me1), which was found to be dynamically regulated by SET7/9 and LSD1 both in vitro and in cultured cells. Functional study revealed that SET7/9-mediated YY2 methylation regulated its DNA-binding activity in vitro and association with chromatin examined by ChIP-seq (chromatin immunoprecipitation coupled with sequencing) in cultured cells. Knockout of YY2, SET7/9 or LSD1 by CRISPR (clustered, regularly interspaced, short palindromic repeats) /Cas9-mediated gene editing followed by RNA-seq revealed that a subset of genes was positively-regulated by YY2 and SET7/9, but negatively-regulated by LSD1, which were enriched with genes involved in cell proliferation regulation. Importantly, YY2-regulated gene transcription, cell proliferation and tumor growth were dependent, at least partially, on YY2 K247 methylation. Finally, somatic mutations on YY2 found in cancer, which are in close proximity to K247, altered its methylation, DNA binding activity and gene transcription it controls. Our findings revealed the first PTM with functional implications imposed on YY2 protein, and linked YY2 methylation with its biological functions.
Project description:By applying ChIP-seq, we generated genome-wide maps of YY1 in skeletal myoblasts and myotubes. We found that YY1 binds to 1820 confident target with a large portion residing in the intergenic regions. In addition, YY1 was found to activate many loci, and there is no significant overlap between YY1 and Ezh2 targets, suggensting a Ezh2-independent manner. Further detailed study revealed that YY1 can regulate some lincRNAs which are fucntional in skeletal myogenesis. In this study, we identified a YY1-Yam-1-miR-715 (TF-lincRNA-miRNA) regulatory curcuit in myogensis. Examination of YY1 targets in myoblast versus myotubes
Project description:The Yin Yang 2 (YY2) gene encodes a zinc finger transcription factor that is not well characterized, yet. By using chromatin immunoprecipitations combined with whole-genome human promoter microarray (ChIP-chip) in HEK293 cells, we identified a multiplicity of YY2-bound annotated promoters as well as additional chromosomal regions. Interestingly, gene ontology analyses linked YY2 to fundamental biological pathways associated to cancer and developmental processes. Identification of YY2 target genes in HEK293 cells in vivo
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.