Identification of Yin Yang 1-interacting partners at −1026C/A in the human iNOS promoter

Background/Aims: An increase in intracellular lipid droplet formation and hepatic triglyceride (TG) content usually results in nonalcoholic fatty liver disease. However, the mechanisms underlying the regulation of hepatic TG homeostasis remain unclear. Methods: Oil red O staining and TG measurement were performed to determine the lipid content. miRNA expression was evaluated by quantitative PCR. A luciferase assay was performed to validate the regulation of Yin Yang 1 (YY1) by microRNA (miR)-122. The effects of miR-122 expression on YY1 and its mechanisms involving the farnesoid X receptor and small heterodimer partner (FXR-SHP) pathway were evaluated by quantitative PCR and Western blot analyses. Results: miR-122 was downregulated in free fatty acid (FFA)-induced steatotic hepatocytes, and streptozotocin and high-fat diet (STZ-HFD) induced nonalcoholic steatohepatitis (NASH) in mice. Transfection of hepatocytes with miR-122 mimics before FFA induction inhibited lipid droplet formation and TG accumulation in vitro. These results were verified by overexpressing miR-122 in the livers of STZ-HFD-induced NASH mice. The 3’-untranslated region (3’UTR) of YY1 mRNA is predicted to contain an evolutionarily conserved miR-122 binding site. In silico searches, a luciferase reporter assay and quantitative PCR analysis confirmed that miR-122 directly bound to the YY1 3’UTR to negatively regulate YY1 mRNA in HepG2 and Huh7 cells. The (FXR-SHP) signaling axis, which is downstream of YY1, may play a key role in the mechanism of miR-122-regulated lipid homeostasis. YY1-FXR-SHP signaling, which is negatively regulated by FFA, was enhanced by miR-122 overexpression. This finding was also confirmed by overexpression of miR-122 in the livers of NASH mice. Conclusions: The present results indicate that miR-122 plays an important role in lipid (particularly TG) accumulation in the liver by reducing YY1 mRNA stability to upregulate FXR-SHP signaling.

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The transcriptional regulator Yin Yang 1 activates the myelin PLP gene

Journal of Neurochemistry ◽

10.1046/j.1471-4159.2001.00307.x ◽

2001 ◽

Vol 77 (3) ◽

pp. 935-942 ◽

Cited By ~ 29

Author(s):

Jo Ann Berndt ◽

Jin G. Kim ◽

Mirjana Tosic ◽

Christopher Kim ◽

Lynn D. Hudson

Keyword(s):

Transcriptional Regulator ◽

Yin Yang 1 ◽

Yin Yang

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Yin Yang 1

Zinc Finger Proteins - Molecular Biology Intelligence Unit ◽

10.1007/0-387-27421-9_25 ◽

2007 ◽

pp. 182-194 ◽

Cited By ~ 5

Author(s):

Huifei Liu ◽

Yang Shi

Keyword(s):

Yin Yang 1 ◽

Yin Yang

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Biochemical characterization of Yin Yang 1 – RNA complexes

Biochemistry and Cell Biology ◽

10.1139/o07-155 ◽

2008 ◽

Vol 86 (1) ◽

pp. 31-36 ◽

Cited By ~ 12

Author(s):

Zachery R. Belak ◽

Andrew Ficzycz ◽

Nick Ovsenek

Keyword(s):

Rna Binding ◽

Biochemical Characterization ◽

Ribonucleoprotein Complexes ◽

Yin Yang 1 ◽

Significant Difference ◽

Yin Yang ◽

Rna Interaction ◽

Rna Complexes

YY1 (Yin Yang 1) is present in the Xenopus oocyte cytoplasm as a constituent of messenger ribonucleoprotein complexes (mRNPs). Association of YY1 with mRNPs requires direct RNA-binding activity. Previously, we have shown YY1 has a high affinity for U-rich RNA; however, potential interactions with plausible in vivo targets have not been investigated. Here we report a biochemical characterization of the YY1–RNA interaction including an investigation of the stability, potential 5′-methylguanosine affinity, and specificity for target RNAs. The formation of YY1–RNA complexes in vitro was highly resistant to thermal, ionic, and detergent disruption. The endogenous oocyte YY1–mRNA interactions were also found to be highly stable. Specific YY1–RNA interactions were observed with selected mRNA and 5S RNA probes. The affinity of YY1 for these substrates was within an order of magnitude of that for its cognate DNA element. Experiments aimed at determining the potential role of the 7-methylguanosine cap on RNA-binding reveal no significant difference in the affinity of YY1 for capped or uncapped mRNA. Taken together, the results show that the YY1–RNA interaction is highly stable, and that YY1 possesses the ability to interact with structurally divergent RNA substrates. These data are the first to specifically document the interaction between YY1 and potential in vivo targets.

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