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Jian Ouyang

Bio: Jian Ouyang is an academic researcher from Harvard University. The author has contributed to research in topics: Medicine & DNA damage. The author has an hindex of 15, co-authored 21 publications receiving 1746 citations. Previous affiliations of Jian Ouyang include Tufts University & Rockefeller University.

Papers
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Journal ArticleDOI
15 Mar 2017-Nature
TL;DR: It is reported that methylation at the 6 position of adenosine (m6A) in RNA is rapidly and transiently induced at DNA damage sites in response to ultraviolet irradiation, uncovering a novel function for RNA m6A modification in the ultraviolet-induced DNA damage response.
Abstract: Cell proliferation and survival require the faithful maintenance and propagation of genetic information, which are threatened by the ubiquitous sources of DNA damage present intracellularly and in the external environment. A system of DNA repair, called the DNA damage response, detects and repairs damaged DNA and prevents cell division until the repair is complete. Here we report that methylation at the 6 position of adenosine (m6A) in RNA is rapidly (within 2 min) and transiently induced at DNA damage sites in response to ultraviolet irradiation. This modification occurs on numerous poly(A)+ transcripts and is regulated by the methyltransferase METTL3 (methyltransferase-like 3) and the demethylase FTO (fat mass and obesity-associated protein). In the absence of METTL3 catalytic activity, cells showed delayed repair of ultraviolet-induced cyclobutane pyrimidine adducts and elevated sensitivity to ultraviolet, demonstrating the importance of m6A in the ultraviolet-responsive DNA damage response. Multiple DNA polymerases are involved in the ultraviolet response, some of which resynthesize DNA after the lesion has been excised by the nucleotide excision repair pathway, while others participate in trans-lesion synthesis to allow replication past damaged lesions in S phase. DNA polymerase κ (Pol κ), which has been implicated in both nucleotide excision repair and trans-lesion synthesis, required the catalytic activity of METTL3 for immediate localization to ultraviolet-induced DNA damage sites. Importantly, Pol κ overexpression qualitatively suppressed the cyclobutane pyrimidine removal defect associated with METTL3 loss. Thus, we have uncovered a novel function for RNA m6A modification in the ultraviolet-induced DNA damage response, and our findings collectively support a model in which m6A RNA serves as a beacon for the selective, rapid recruitment of Pol κ to damage sites to facilitate repair and cell survival.

592 citations

Journal ArticleDOI
TL;DR: It is concluded that SIZ1 regulates Arabidopsis growth and that this SUMO E3 ligase plays a role in drought stress response likely through the regulation of gene expression.
Abstract: Posttranslational modifications of proteins by small ubiquitin-like modifiers (SUMOs) regulate protein degradation and localization, protein–protein interaction, and transcriptional activity. SUMO E3 ligase functions are executed by SIZ1/SIZ2 and Mms21 in yeast, the PIAS family members RanBP2, and Pc2 in human. The Arabidopsis thaliana genome contains only one gene, SIZ1, that is orthologous to the yeast SIZ1/SIZ2. Here, we show that Arabidopsis SIZ1 is expressed in all plant tissues. Compared with the wild type, the null mutant siz1-3 is smaller in stature because of reduced expression of genes involved in brassinosteroid biosynthesis and signaling. Drought stress induces the accumulation of SUMO-protein conjugates, which is in part dependent on SIZ1 but not on abscisic acid (ABA). Mutant plants of siz1-3 have significantly lower tolerance to drought stress. A genome-wide expression analysis identified ∼1700 Arabidopsis genes that are induced by drought, with SIZ1 mediating the expression of 300 of them by a pathway independent of DREB2A and ABA. SIZ1-dependent, drought-responsive genes include those encoding enzymes of the anthocyanin synthesis pathway and jasmonate response. From these results, we conclude that SIZ1 regulates Arabidopsis growth and that this SUMO E3 ligase plays a role in drought stress response likely through the regulation of gene expression.

341 citations

Journal ArticleDOI
TL;DR: A SIRT1 corepressor complex containing the histone H3K4 demethylase LSD1/KDM1A and several other LSD1-associated proteins is described, offering new insights into conserved mechanisms of epigenetic gene repression and regulation of development by Sirt1 in metazoans.

186 citations

Journal ArticleDOI
TL;DR: It is demonstrated here that SENP5, a previously uncharacterized Ulp1 homolog, has SUMO C-terminal hydrolase and SUMO isopeptidase activities and suggested that mechanisms involving both the catalytic and noncatalytic domains determine the distinct substrate specificities of the mammalian SUMO-specific proteases.
Abstract: Posttranslational modification of substrates by the small ubiquitin-like modifier, SUMO, regulates diverse biological processes, including transcription, DNA repair, nucleocytoplasmic trafficking, and chromosome segregation. SUMOylation is reversible, and several mammalian homologs of the yeast SUMO-specific protease Ulp1, termed SENPs, have been identified. We demonstrate here that SENP5, a previously uncharacterized Ulp1 homolog, has SUMO C-terminal hydrolase and SUMO isopeptidase activities. In contrast to other SENPs, the C-terminal catalytic domain of SENP5 preferentially processed SUMO-3 compared to SUMO-1 precursors and preferentially removed SUMO-2 and SUMO-3 from SUMO-modified RanGAP1 in vitro. In cotransfection assays, SENP5 preferentially reduced high-molecular-weight conjugates of SUMO-2 compared to SUMO-1 in vivo. Full-length SENP5 localized to the nucleolus. Deletion of the noncatalytic N-terminal domain led to loss of nucleolar localization and increased de-SUMOylation activity in vivo. Knockdown of SENP5 by RNA interference resulted in increased levels of SUMO-1 and SUMO-2/3 conjugates, inhibition of cell proliferation, defects in nuclear morphology, and appearance of binucleate cells, revealing an essential role for SENP5 in mitosis and/or cytokinesis. These findings establish SENP5 as a SUMO-specific protease required for cell division and suggest that mechanisms involving both the catalytic and noncatalytic domains determine the distinct substrate specificities of the mammalian SUMO-specific proteases.

178 citations

Journal ArticleDOI
Jia-Min Zhang1, Tribhuwan Yadav1, Jian Ouyang1, Li Lan1, Lee Zou1 
TL;DR: An assay is described to visualize ALT-mediated telomeric DNA synthesis in AlT-associated PML bodies (APBs) without DNA-damaging agents or replication inhibitors, suggesting that ALT occurs through a RAD52-dependent and a RAD 52-independent BIR pathway.

163 citations


Cited by
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Journal ArticleDOI
15 Jun 2017-Cell
TL;DR: Roles for mRNA modification in nearly every aspect of the mRNA life cycle, as well as in various cellular, developmental, and disease processes are revealed.

1,855 citations

Journal ArticleDOI
TL;DR: A decade has passed since SUMO was discovered to be a reversible post-translational protein modifier and many enzymes that participate in regulated SUMO-conjugation and -deconjugation pathways have been identified and characterized.
Abstract: A decade has passed since SUMO (small ubiquitin-related modifier) was discovered to be a reversible post-translational protein modifier. During this time many enzymes that participate in regulated SUMO-conjugation and -deconjugation pathways have been identified and characterized. In parallel, the search for SUMO substrates has produced a long list of targets, which appear to be involved in most cellular functions. Sumoylation is a highly dynamic process and its outcomes are extremely diverse, ranging from changes in localization to altered activity and, in some cases, stability of the modified protein. At first glance, these effects have nothing in common; however, it seems that they all result from changes in the molecular interactions of the sumoylated proteins.

1,663 citations

Journal ArticleDOI
TL;DR: The mammalian sirtuin protein family (comprising SIRT1–SIRT7) has received much attention for its regulatory role, mainly in metabolism and ageing, thereby acting as crucial regulators of the network that controls energy homeostasis and as such determines healthspan.
Abstract: Since the beginning of the century, the mammalian sirtuin protein family (comprising SIRT1-SIRT7) has received much attention for its regulatory role, mainly in metabolism and ageing. Sirtuins act in different cellular compartments: they deacetylate histones and several transcriptional regulators in the nucleus, but also specific proteins in other cellular compartments, such as in the cytoplasm and in mitochondria. As a consequence, sirtuins regulate fat and glucose metabolism in response to physiological changes in energy levels, thereby acting as crucial regulators of the network that controls energy homeostasis and as such determines healthspan.

1,604 citations

Journal ArticleDOI
TL;DR: Although the nucleolus is primarily associated with ribosome biogenesis, several lines of evidence now show that it has additional functions, such as regulation of mitosis, cell-cycle progression and proliferation, many forms of stress response and biogenesis of multiple ribonucleoprotein particles.
Abstract: The nucleolus is a distinct subnuclear compartment that was first observed more than 200 years ago. Nucleoli assemble around the tandemly repeated ribosomal DNA gene clusters and 28S, 18S and 5.8S ribosomal RNAs (rRNAs) are transcribed as a single precursor, which is processed and assembled with the 5S rRNA into ribosome subunits. Although the nucleolus is primarily associated with ribosome biogenesis, several lines of evidence now show that it has additional functions. Some of these functions, such as regulation of mitosis, cell-cycle progression and proliferation, many forms of stress response and biogenesis of multiple ribonucleoprotein particles, will be discussed, as will the relation of the nucleolus to human diseases.

1,353 citations

Journal ArticleDOI
TL;DR: Although removal of histone acetyl epigenetic modification by HDACs regulates chromatin structure and transcription, deacetylation of nonhistones controls diverse cellular processes.
Abstract: Histone deacetylases (HDACs) are enzymes that catalyze the removal of acetyl functional groups from the lysine residues of both histone and nonhistone proteins. In humans, there are 18 HDAC enzymes that use either zinc- or NAD(+)-dependent mechanisms to deacetylate acetyl lysine substrates. Although removal of histone acetyl epigenetic modification by HDACs regulates chromatin structure and transcription, deacetylation of nonhistones controls diverse cellular processes. HDAC inhibitors are already known potential anticancer agents and show promise for the treatment of many diseases.

1,226 citations