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Jiang, Xiaofeng

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Jiang

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Xiaofeng

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Jiang, Xiaofeng
Author's Publications: search.filters.isAuthorOfPublication.8137d42b-46aa-4367-b5a3-a337d773184a

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    Genome-Wide Association Analysis in Asthma Subjects Identifies SPATS2L as a Novel Bronchodilator Response Gene
    (Public Library of Science, 2012) Himes, Blanca; Jiang, Xiaofeng; Hu, Ruoxi; Wu, Ann; Lasky-Su, Jessica; Klanderman, Barbara J.; Ziniti, John; Senter-Sylvia, Jody; Lima, John J.; Irvin, Charles G.; Peters, Stephen P.; Meyers, Deborah A.; Bleecker, Eugene R.; Kubo, Michiaki; Tamari, Mayumi; Nakamura, Yusuke; Szefler, Stanley J.; Lemanske, Robert F.; Zeiger, Robert S.; Strunk, Robert C.; Martinez, Fernando D.; Hanrahan, John P.; Koppelman, Gerard H.; Postma, Dirkje S.; Nieuwenhuis, Maartje A. E.; Vonk, Judith M.; Panettieri, Reynold A.; Markezich, Amy; Israel, Elliot; Carey, Vincent; Tantisira, Kelan; Litonjua, Augusto A.; Lu, Quan; Weiss, Scott
    Bronchodilator response (BDR) is an important asthma phenotype that measures reversibility of airway obstruction by comparing lung function (i.e. FEV1) before and after the administration of a short-acting β2-agonist, the most common rescue medications used for the treatment of asthma. BDR also serves as a test of β2-agonist efficacy. BDR is a complex trait that is partly under genetic control. A genome-wide association study (GWAS) of BDR, quantified as percent change in baseline FEV1 after administration of a β2-agonist, was performed with 1,644 non-Hispanic white asthmatic subjects from six drug clinical trials: CAMP, LOCCS, LODO, a medication trial conducted by Sepracor, CARE, and ACRN. Data for 469,884 single-nucleotide polymorphisms (SNPs) were used to measure the association of SNPs with BDR using a linear regression model, while adjusting for age, sex, and height. Replication of primary P-values was attempted in 501 white subjects from SARP and 550 white subjects from DAG. Experimental evidence supporting the top gene was obtained via siRNA knockdown and Western blotting analyses. The lowest overall combined P-value was 9.7E-07 for SNP rs295137, near the SPATS2L gene. Among subjects in the primary analysis, those with rs295137 TT genotype had a median BDR of 16.0 (IQR = [6.2, 32.4]), while those with CC or TC genotypes had a median BDR of 10.9 (IQR = [5.0, 22.2]). SPATS2L mRNA knockdown resulted in increased β2-adrenergic receptor levels. Our results suggest that SPATS2L may be an important regulator of β2-adrenergic receptor down-regulation and that there is promise in gaining a better understanding of the biological mechanisms of differential response to β2-agonists through GWAS.
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    The p400 ATPase Regulates Nucleosome Stability and Chromatin Ubiquitination During DNA Repair
    (The Rockefeller University Press, 2010) Xu, Ye; Sun, Yingli; Jiang, Xiaofeng; Ayrapetov, Marina; Moskwa, Patryk Pawel; Yang, Shenghong; Weinstock, David; Price, Brendan
    The complexity of chromatin architecture presents a significant barrier to the ability of the DNA repair machinery to access and repair DNA double-strand breaks (DSBs). Consequently, remodeling of the chromatin landscape adjacent to DSBs is vital for efficient DNA repair. Here, we demonstrate that DNA damage destabilizes nucleosomes within chromatin regions that correspond to the \(\gamma\)-H2AX domains surrounding DSBs. This nucleosome destabilization is an active process requiring the ATPase activity of the p400 SWI/SNF ATPase and histone acetylation by the Tip60 acetyltransferase. p400 is recruited to DSBs by a mechanism that is independent of ATM but requires mdc1. Further, the destabilization of nucleosomes by p400 is required for the RNF8-dependent ubiquitination of chromatin, and for the subsequent recruitment of brca1 and 53BP1 to DSBs. These results identify p400 as a novel DNA damage response protein and demonstrate that p400-mediated alterations in nucleosome and chromatin structure promote both chromatin ubiquitination and the accumulation of brca1 and 53BP1 at sites of DNA damage.