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1.  Role of Jhdm2a in regulating metabolic gene expression and obesity resistance 
Nature  2009;458(7239):757-761.
Recent studies indicate that the methylation state of histones can be dynamically regulated by histone methyltransferases and demethylases1,2. The H3K9-specific demethylase Jhdm2a (also known as Jmjd1a and Kdm3a) has an important role in nuclear hormone receptor-mediated gene activation and male germ cell development3,4. Through disruption of the Jhdm2a gene in mice, here we demonstrate that Jhdm2a is critically important in regulating the expression of metabolic genes. The loss of Jhdm2a function results in obesity and hyperlipidemia in mice. We provide evidence that the loss of Jhdm2a function disrupts β-adrenergic-stimulated glycerol release and oxygen consumption in brown fat, and decreases fat oxidation and glycerol release in skeletal muscles. We show that Jhdm2a expression is induced by β-adrenergic stimulation, and that Jhdm2a directly regulates peroxisome proliferator-activated receptor α (Ppara) and Ucp1 expression. Furthermore, we demonstrate that β-adrenergic activation-induced binding of Jhdm2a to the PPAR responsive element (PPRE) of the Ucp1 gene not only decreases levels of H3K9me2 (dimethylation of lysine 9 of histone H3) at the PPRE, but also facilitates the recruitment of Pparγ and Rxrα and their co-activators Pgc1aα(also known as Ppargc1a), CBP/ p300 (Crebbp) and Src1 (Ncoa1) to the PPRE. Our studies thus demonstrate an essential role for Jhdm2a in regulating metabolic gene expression and normal weight control in mice.
PMCID: PMC4085783  PMID: 19194461
2.  Inhibiting Cxcr2 disrupts tumor-stromal interactions and improves survival in a mouse model of pancreatic ductal adenocarcinoma 
The Journal of Clinical Investigation  2011;121(10):4106-4117.
Pancreatic ductal adenocarcinoma (PDAC), one of the most lethal neoplasms, is characterized by an expanded stroma with marked fibrosis (desmoplasia). We previously generated pancreas epithelium–specific TGF-β receptor type II (Tgfbr2) knockout mice in the context of Kras activation (mice referred to herein as Kras+Tgfbr2KO mice) and found that they developed aggressive PDAC that recapitulated the histological manifestations of the human disease. The mouse PDAC tissue showed strong expression of connective tissue growth factor (Ctgf), a profibrotic and tumor-promoting factor, especially in the tumor-stromal border area, suggesting an active tumor-stromal interaction. Here we show that the PDAC cells in Kras+Tgfbr2KO mice secreted much higher levels of several Cxc chemokines compared with mouse pancreatic intraepithelial neoplasia cells, which are preinvasive. The Cxc chemokines induced Ctgf expression in the pancreatic stromal fibroblasts, not in the PDAC cells themselves. Subcutaneous grafting studies revealed that the fibroblasts enhanced growth of PDAC cell allografts, which was attenuated by Cxcr2 inhibition. Moreover, treating the Kras+Tgfbr2KO mice with the CXCR2 inhibitor reduced tumor progression. The decreased tumor progression correlated with reduced Ctgf expression and angiogenesis and increased overall survival. Taken together, our data indicate that tumor-stromal interactions via a Cxcr2-dependent chemokine and Ctgf axis can regulate PDAC progression. Further, our results suggest that inhibiting tumor-stromal interactions might be a promising therapeutic strategy for PDAC.
PMCID: PMC3195452  PMID: 21926469
3.  Single small-interfering RNA expression vector for silencing multiple transforming growth factor-β pathway components 
Nucleic Acids Research  2005;33(15):e131.
Although RNA interference (RNAi) is a popular technique, no method for simultaneous silencing of multiple targets by small-hairpin RNA (shRNA)-expressing RNAi vectors has yet been established. Although gene silencing can be achieved by synthetic small-interfering RNA (siRNA) duplexes, the approach is transient and largely dependent on the transfection efficiency of the host cell. We offer a solution: a simple, restriction enzyme-generated stable RNAi technique that can efficiently silence multiple targets with a single RNAi vector and a single selection marker. In this study, we succeeded in simultaneous stable knockdown of transforming growth factor β (TGF-β) pathway-related Smads—Smad2, Smad3 and Smad4—at the cellular level. We observed distinct phenotypic changes in TGF-β-dependent cellular functions such as invasion, wound healing and apoptosis. This method is best suited for an analysis of complex signal transduction pathways in which silencing of a single gene cannot account for the whole process.
PMCID: PMC1188087  PMID: 16113239
4.  The NEDD8 system is essential for cell cycle progression and morphogenetic pathway in mice 
The Journal of Cell Biology  2001;155(4):571-580.
NEDD8/Rub1 is a ubiquitin (Ub)-like molecule that covalently ligates to target proteins through an enzymatic cascade analogous to ubiquitylation. This modifier is known to target all cullin (Cul) family proteins. The latter are essential components of Skp1/Cul-1/F-box protein (SCF)–like Ub ligase complexes, which play critical roles in Ub-mediated proteolysis. To determine the role of the NEDD8 system in mammals, we generated mice deficient in Uba3 gene that encodes a catalytic subunit of NEDD8-activating enzyme. Uba3−/− mice died in utero at the periimplantation stage. Mutant embryos showed selective apoptosis of the inner cell mass but not of trophoblastic cells. However, the mutant trophoblastic cells could not enter the S phase of the endoreduplication cycle. This cell cycle arrest was accompanied with aberrant expression of cyclin E and p57Kip2. These results suggested that the NEDD8 system is essential for both mitotic and the endoreduplicative cell cycle progression. β-Catenin, a mediator of the Wnt/wingless signaling pathway, which degrades continuously in the cytoplasm through SCF Ub ligase, was also accumulated in the Uba3−/− cytoplasm and nucleus. Thus, the NEDD8 system is essential for the regulation of protein degradation pathways involved in cell cycle progression and morphogenesis, possibly through the function of the Cul family proteins.
PMCID: PMC2198877  PMID: 11696557
NEDD8; ubiquitin; cullin; knock-out; cell cycle

Results 1-4 (4)