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Cheong J.,Pusan National University | Cheong J.,Mitochondria Hub Regulation Center | Kim H.Y.,Pusan National University | Cho H.K.,Pusan National University | Yoo S.K.,Korea Advanced Institute of Science and Technology
Experimental and Molecular Medicine

Six transmembrane protein of prostate 2 (STAMP2) plays a key role in linking inflammatory and diet-derived signals to systemic metabolism. STAMP2 is induced by nutrients/feeding as well as by cytokines such as TNFα, IL-1β, and IL-6. Here, we demonstrated that STAMP2 protein physically interacts with and decreases the stability of hepatitis B virus X protein (HBx), thereby counteracting HBx-induced hepatic lipid accumulation and insulin resistance. STAMP2 suppressed the HBx-mediated transcription of lipogenic and adipogenic genes. Furthermore, STAMP2 prevented HBx-induced degradation of IRS1 protein, which mediates hepatic insulin signaling, as well as restored insulin-mediated inhibition of gluconeogenic enzyme expression, which are gluconeogenic genes. We also demonstrated reciprocal expression of HBx and STAMP2 in HBx transgenic mice. These results suggest that hepatic STAMP2 antagonizes HBx-mediated hepatocyte dysfunction, thereby protecting hepatocytes from HBV gene expression. © 2012 by the Korean Society for Biochemistry and Molecular Biology. Source

Kim K.J.,Pusan National University | Kim H.Y.,Pusan National University | Cho H.K.,Pusan National University | Kim K.H.,Pusan National University | And 2 more authors.

Fatty acid synthase (FASN), a key enzyme that synthesizes longchain fatty acids, is involved in both normal lipid synthesis and cancer development. Overexpression and increased activity of FASN represents one of the most frequent phenotypic alterations in cancer cells. Multiple growth factors and growth factor receptors have emerged as major contributors to FASN overexpression. However, the ultimate mechanisms responsible for tumor-associated FASN overexpression are not completely understood. Here, we show that the stromal cell-derived factor-1 alpha (SDF-1α)/CXCR4 axis can induce the FASN expression via the nuclear translocation of sterol regulatory element-binding protein-1, α major modulator of FASN transcription. We also identified that recombinant SDF-1α-induced phosphatidylinositol-3′-kinase/protein kinase B (Akt) phosphorylation was involved in the expression or activities of FASN. Finally, we demonstrated that FASN inhibition significantly reduced the SDF-1α-mediated G1 cyclin expression and cell viability. Taken together, our findings manifest that the SDF-1α/CXCR4 axis is a novel upstream pathway of FASN expression and is associated with mediating its prosurvival effect. © The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org. Source

Lee S.G.,Dong - A University | Lee S.G.,Mitochondria Hub Regulation Center | Kim J.Y.,Dong - A University | Chung J.-Y.,Dong - A University | And 12 more authors.
Environmental Health Perspectives

Background: Bisphenol A (BPA) has been detected in human body fluids, such as serum and ovarian follicular fluids. Several reports indicated that BPA exposure is associated with the occurrence of several female reproductive diseases resulting from the disruption of steroid hormone biosynthesis in the adult ovary. Objective: We hypothesized that long-term exposure to low concentrations of BPA disrupts 17β estradiol (E2) production in granulosa cells via an alteration of steroidogenic proteins in ovarian cells. Methods: Adult female rats received BPA for 90 days by daily gavage at doses of 0, 0.001, or 0.1 mg/kg body weight. We determined serum levels of E2, testosterone (T), follicle-stimulating hormone (FSH), and luteinizing hormone (LH). We also analyzed the expressions of steroidogenic acute regulatory protein (StAR), P450 side-chain cleavage (P450scc), 3β-hydroxysteroid dehydrogenase isomerase (3β-HSD), and aromatase cytochrome P450 (P450arom) in the ovary. Results: Exposure to BPA significantly decreased E2 serum concentration, which was accompanied by augmented follicular atresia and luteal regression via increase of caspase-3-associated apoptosis in ovarian cells. After BPA exposure, P450arom and StAR protein levels were significantly decreased in granulosa cells and theca-interstitial (T-I) cells, respectively. However, P450scc and 3β-HSD protein levels remained unchanged. The increase in LH levels appeared to be associated with the decreased synthesis of T in T-I cells after BPA exposure via homeostatic positive feedback regulation. Conclusions: BPA exposure during adulthood can disturb the maintenance of normal ovarian functions by reducing E2. The steroidogenic proteins StAR and P450arom appear to be targeted by BPA. Source

Kim J.Y.,Dong - A University | Chung J.-Y.,Dong - A University | Lee S.G.,Dong - A University | Lee S.G.,Mitochondria Hub Regulation Center | And 12 more authors.
International Journal of Molecular Medicine

Taxanes are microtubule-stabilizing agents that have anticancer activity against several types of human solid tumors. Although the primary mechanism of action of these drugs is well understood, the signaling pathways that confer resistance to these agents in certain types of cancer remain poorly understood. In particular, the association of p53 with the mechanism(s) of taxane-mediated cell death is still controversial. In this study, we showed that p53 has a profound inhibitory effect on docetaxel (Doc)-induced apoptosis in prostate and colorectal cancer cells and that caspases play a critical role in this process. Doc induced prostate cancer cell apoptosis at high levels in p53-null PC3 cells, at intermediate levels in p53-mutant DU145 cells and at low levels in p53 wild-type LNCaP cells. While transient overexpression of p53 in PC3 cells suppressed Doc-induced apoptosis, knockdown of p53 in LNCaP cells increased apoptosis. This finding was further confirmed using an isogenic pair of colorectal cancer cell lines, HCT-116 p53-/-and p53+/+, indicating that p53 inhibits induction of apoptosis by Doc. To our knowledge, this is the first report describing that chemical or genetic knockout of p53 enhances the susceptibility of both prostate and colorectal cancer cells to Doc-induced apoptosis. These results may suggest an approach to stratify patients for regimens involving Doc. Source

Nam H.K.,Busan Medical Center | Lee S.J.,Busan Medical Center | Kim M.H.,Dong - A University | Rho J.H.,Mitochondria Hub Regulation Center | And 5 more authors.
American Journal of Nephrology

Background/Aim: Cyclosporine (CsA)-induced kidney injury is characterized by renal dysfunction with inflammatory cell infiltrations, apoptosis and fibrosis. Pleiotropic effects of statins may exert anti-inflammatory, antiapoptotic and antifibrotic actions beyond lipid control. The aim of this study is to investigate whether rosuvastatin (RUS) has anti-inflammatory, antiapoptotic and antifibrotic effects on chronic CsA-induced nephropathy in a rat model. Methods: Male Sprague-Dawley rats fed a low-sodium diet were divided into three treatment groups: control (0.9% saline injection), CsA (15 mg/kg/day by subcutaneous injection), CsA + RUS (10 mg/kg/day by gastric gavage). Renal function, CsA level and lipid levels were measured at the end of 4 weeks. The expression of ED-1, transforming growth factor-β1 (TGF-β1) and α-smooth muscle actin (α-SMA) for inflammation and fibrosis were examined by Western blot analysis. The expression levels of apoptosis-associated factors were examined by Western blot analysis. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase-mediated biotin nick end-labeling (TUNEL) method. Results: Kidney function was decreased in CsA-treated rats compared with controls, which was attenuated by RUS. RUS did not affect the lipid level or the blood CsA level. TUNEL staining showed that RUS inhibited CsA-induced tubular apoptosis. RUS decreased CsA-induced increased expression of Bax/Bcl-2 ratio. The expressions of ED-1, α-SMA, TGF-β1, Smad2/3, Smad4 and p-JNK were increased in CsA-treated rats, which were attenuated by RUS. Tubular atrophy and interstitial fibrosis in CsA-treated rats were attenuated by RUS supplementation. Conclusion: RUS supplementation attenuates proinflammatory and apoptosis-related factors and inhibits the fibrotic pathways including the smad-dependent and smad-independent pathways in a rat model of CsA-induced nephropathy. Copyright © 2012 S. Karger AG, Basel. Source

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