Bio

Bio


Kun-Che (Gary) Chang was born in Kaohsiung, Taiwan. He received his B.S. in Life Science from National Dong Hwa University (Taiwan) in 2006 and his M.S. in Biotechnology from National Tsing Hua University (Taiwan) in 2008. After graduated, he did his military service at Ministry of the Interior, Taiwan for 1 year. After worked at National Taiwan University for 1 year, he transited to University of Minnesota, Dept. of Pharmacology as a research assistant from 2010 to 2011. He joined the Toxicology PhD program at University of Colorado and chose Dr. J. Mark Petrash?s lab for his doctoral training at Dept. of Ophthalmology. He obtained his PhD degree focusing on prevention of ocular inflammation in 2015. Then he joined Dr. Jeffrey Goldberg's lab's for his post-doctoral training at Dept. of Ophthalmology, Stanford University in 2016.

Honors & Awards


  • JNS Travel Award, The 41th Annual Meeting of the Japan Neuroscience Society (2018)
  • NEI-T32 awardee, Stanford Vision Research Training Program (2018-2019)
  • ARVO Travel Grant, The 2018 annual meeting of the Association for Research in Vision and Ophthalmology (2018)
  • Harold C. Heim Awards for Excellence in Graduate Research, University of Colorado Denver, Skaggs School of Pharmacy and Pharmaceutical Sciences (2015)
  • Award for best poster of vision sciences class, University of Colorado Denver Anschutz Medical Campus 29th Annual Student Research Forum (2014)
  • Trainee Award, The 17th International Workshop on the Enzymology and Molecular Biology of Carbonyl Metabolism (2014)
  • Award for School of Medicine Class of 2017 Poster Choice, University of Colorado Denver Anschutz Medical Campus 28th Annual Student Research Forum (2013)
  • C. Werner and Kitty Hirs Research Award, Graduate School at Anschutz Medical Campus, University of Colorado (2013, 2014, 2015)
  • MWSOT Student Travel Award, The 30th Annual Regional Meeting of the Mountain West Society of Toxicology (2012)
  • Book Aroma Award, National Dong Hwa University (2003, 2004)

Professional Education


  • Doctor of Philosophy, University of Colorado Denver (2015)
  • Master of Science, National Tsinghua University (2008)
  • Bachelor of Science, National Dong Hwa University (2006)

Stanford Advisors


Publications

All Publications


  • Retinal Cell Fate Specification. Trends in neurosciences Wu, S., Chang, K. C., Goldberg, J. L. 2018; 41 (4): 165?67

    Abstract

    How are different neural cell types generated from progenitor cells? In 1990, Turner et al. used new lineage tracing techniques to show that different cells in the mammalian retina share their progenitor origin. The findings established a key step toward our understanding of how multipotent progenitor cells give rise to complex circuitry in the retina.

    View details for DOI 10.1016/j.tins.2018.02.002

    View details for PubMedID 29602333

  • Induced Pluripotent Stem Cells Promote Retinal Ganglion Cell Survival After Transplant. Investigative ophthalmology & visual science Wu, S., Chang, K. C., Nahmou, M., Goldberg, J. L. 2018; 59 (3): 1571?76

    Abstract

    The purpose of this study was to characterize whether induced pluripotent stem cells (iPSCs) affect survival of grafted retinal ganglion cells (RGCs) after transplantation.For in vitro studies, human iPSCs were either directly cocultured with mouse RGCs or plated in hanging inserts in RGC cultures for 1 week. For ex vivo studies, RGCs and iPSCs were seeded onto the inner surface of an adult rat retina explant and cultured for 1 week. For in vivo studies, RGCs and iPSCs were intravitreally coinjected into an adult rat eye 1 week before examining retinas by explant and immunostaining.A dose-dependent increase in RGC survival was observed in RGC-iPSC direct cocultures, and RGC-iPSC indirect cocultures showed a similar RGC protective effect, but to a lesser extent than in direct coculture. Enhanced RGC survival was also identified in RGC-iPSC cotransplantations to adult retinas ex vivo and in vivo. In addition, RGCs with iPSC cotransplantation extended significantly longer neurites than RGC-only transplants.Human iPSCs promote transplanted RGC survival and neurite extension. This effect may be mediated at least partially through secretion of diffusible neuroprotective factors.

    View details for DOI 10.1167/iovs.17-23648

    View details for PubMedID 29625481

    View details for PubMedCentralID PMC5863687

  • Novel Regulatory Mechanisms for the SoxC Transcriptional Network Required for Visual Pathway Development JOURNAL OF NEUROSCIENCE Chang, K., Hertz, J., Zhang, X., Jin, X., Shaw, P., Derosa, B. A., Li, J. Y., Venugopalan, P., Valenzuela, D. A., Patel, R. D., Russano, K. R., Alshamekh, S. A., Sun, C., Tenerelli, K., Li, C., Velmeshev, D., Cheng, Y., Boyce, T. M., Dreyfuss, A., Uddin, M. S., Muller, K. J., Dykxhoorn, D. M., Goldberg, J. L. 2017; 37 (19): 4967-4981

    Abstract

    What pathways specify retinal ganglion cell (RGC) fate in the developing retina? Here we report on mechanisms by which a molecular pathway involving Sox4/Sox11 is required for RGC differentiation and for optic nerve formation in mice in vivo, and is sufficient to differentiate human induced pluripotent stem cells into electrophysiologically active RGCs. These data place Sox4 downstream of RE1 silencing transcription factor (REST) in regulating RGC fate, and further describe a newly identified, Sox4-regulated SUMOylation site in Sox11, which suppresses Sox11's nuclear localization and its ability to promote RGC differentiation, providing a mechanism for the SoxC familial compensation observed here and elsewhere in the nervous system. These data define novel regulatory mechanisms for this SoxC molecular network, and suggest pro-RGC molecular approaches for cell replacement-based therapies for glaucoma and other optic neuropathies.SIGNIFICANCE STATEMENTGlaucoma is the most common cause of blindness worldwide and along with other optic neuropathies is characterized by loss of retinal ganglion cells (RGCs). Unfortunately, vision and RGC loss are irreversible, and lead to bilateral blindness in around 14% of all diagnosed patients. Differentiating and transplanting RGC-like cells derived from stem cells have the potential to replace neurons that have already been lost and thereby restore visual function. These data uncover new mechanisms of retinal progenitor cell (RPC)- and human stem cell-to-RGC fate specification, and take a significant step towards understanding neuronal and retinal development and ultimately cell transplant therapy.

    View details for DOI 10.1523/JNEUROSCI.3430-13.2017

    View details for Web of Science ID 000401118600010

    View details for PubMedID 28411269

  • Influence of aldose reductase on epithelial-to-mesenchymal transition signaling in lens epithelial cells. Chemico-biological interactions Chang, K. C., Shieh, B., Petrash, J. M. 2017

    Abstract

    Cataract is the most frequent cause of blindness worldwide and is treated by surgical removal of the opaque lens to restore the light path to the retina. While cataract surgery is a safe procedure, some patients develop a complication of the surgery involving opacification and wrinkling of the posterior lens capsule. This process, called posterior capsule opacification (PCO), requires a second clinical treatment that can in turn lead to additional complications. Prevention of PCO is a current unmet need in the vision care enterprise. The pathogenesis of PCO involves the transition of lens epithelial cells to a mesenchymal phenotype, designated epithelial-to-mesenchymal transition (EMT). Our previous studies showed that transgenic mice designed for overexpression of human aldose reductase developed lens defects reminiscent of PCO. In the current study, we evaluated the impact of aldose reductase (AR) on expression of expression of EMT markers in the lens. Primary lens epithelial cells from AR-transgenic mice showed downregulated expression of Foxe3 and Pax6 and increased expression of ?-SMA, fibronectin and snail, a pattern of gene expression typical of cells undergoing EMT. A role for AR in these changes was further confirmed when we observed that they could be normalized by treatment of cells with Sorbinil, an AR inhibitor. Smad-dependent and Smad-independent pathways are known to contribute to EMT. Interestingly, AR overexpression induced ERK but not Smad-2 activation. These results suggest that elevation of AR may lead to activation of ERK signaling and thus play a role in TGF-?/Smad independent induction of EMT in lens epithelial cells.

    View details for DOI 10.1016/j.cbi.2017.01.017

    View details for PubMedID 28137510

  • SoxC transcription factors in retinal development and regeneration. Neural regeneration research Chang, K. C., Hertz, J. 2017; 12 (7): 1048?51

    Abstract

    Glaucoma and other optic neuropathies result in optic nerve degeneration and the loss of retinal ganglion cells (RGCs) through complex signaling pathways. Although the mechanisms that regulate RGC development remain unclear, uncovering novel developmental pathways may support new strategies to regenerate the optic nerve or replace RGCs. Here we review recent studies that provide strong evidence that the Sry-related high-mobility-group C (SoxC) subfamily of transcription factors (TFs) are necessary and sufficient for axon guidance and RGC fate specification. These findings also uncover novel SoxC-dependent mechanisms that serve as master regulators during important steps of RGC development. For example, we review work showing that SoxC TFs regulate RGC axon guidance and direction through the optic chiasm towards their appropriate targets in the brain. We also review work demonstrating that Sox11 subcellular localization is, in part, controlled through small ubiquitin-like post-translational modifier (SUMO) and suggest compensatory cross-talk between Sox4 and Sox11. Furthermore, Sox4 overexpression is shown to positively drive RGC differentiation in human induced pluripotent stem cells (hiPSCs). Finally, we discuss how these findings may contribute to the advancement of regenerative and cell-based therapies to treat glaucoma and other optic nerve neuropathies.

    View details for DOI 10.4103/1673-5374.211178

    View details for PubMedID 28852381

    View details for PubMedCentralID PMC5558478

  • Characterization of Emodin as a Therapeutic Agent for Diabetic Cataract JOURNAL OF NATURAL PRODUCTS Chang, K., Li, L., Sanborn, T. M., Shieh, B., Lenhart, P., Ammar, D., LaBarbera, D. V., Petrash, J. M. 2016; 79 (5): 1439-1444

    Abstract

    Aldose reductase (AR) in the lens plays an important role in the pathogenesis of diabetic cataract (DC) by contributing to osmotic and oxidative stress associated with accelerated glucose metabolism through the polyol pathway. Therefore, inhibition of AR in the lens may hold the key to prevent DC formation. Emodin, a bioactive compound isolated from plants, has been implicated as a therapy for diabetes. However, its inhibitory activity against AR remains unclear. Our results showed that emodin has good selectively inhibitory activity against AR (IC50 = 2.69 ▒ 0.90 ?M) but not other aldo-keto reductases and is stable at 37 ░C for at least 7 days. Enzyme kinetic studies demonstrated an uncompetitive inhibition against AR with a corresponding inhibition constant of 2.113 ▒ 0.095 ?M. In in vivo studies, oral administration of emodin reduced the incidence and severity of morphological markers of cataract in lenses of AR transgenic mice. Computational modeling of the AR-NADP(+)-emodin ternary complex indicated that the 3-hydroxy group of emodin plays an essential role by interacting with Ser302 through hydrogen bonding in the specificity pocket of AR. All the findings above provide encouraging evidence for emodin as a potential therapeutic agent to prevent cataract in diabetic patients.

    View details for DOI 10.1021/acs.jnatprod.6b00185

    View details for Web of Science ID 000377150900027

    View details for PubMedID 27140653

  • Aldose reductase mediates retinal microglia activation BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS Chang, K., Shieh, B., Petrash, J. M. 2016; 473 (2): 565-571

    Abstract

    Retinal microglia (RMG) are one of the major immune cells in charge of surveillance of inflammatory responses in the eye. In the absence of an inflammatory stimulus, RMG reside predominately in the ganglion layer and inner or outer plexiform layers. However, under stress RMG become activated and migrate into the inner nuclear layer (INL) or outer nuclear layer (ONL). Activated RMG in cell culture secrete pro-inflammatory cytokines in a manner sensitive to downregulation by aldose reductase inhibitors. In this study, we utilized CX3CR1(GFP) mice carrying AR mutant alleles to evaluate the role of AR on RMG activation and migration inávivo. When tested on an AR(WT) background, IP injection of LPS induced RMG activation and migration into the INL and ONL. However, this phenomenon was largely prevented by AR inhibitors or in AR null mice, or was exacerbated in transgenic mice that over-express AR. LPS-induced increases in ocular levels of TNF-? and CX3CL-1 in WT mice were substantially lower in AR null mice or were reduced by AR inhibitor treatment. These studies demonstrate that AR expression in RMG may contribute to the proinflammatory phenotypes common to various eye diseases such as uveitis and diabetic retinopathy.

    View details for DOI 10.1016/j.bbrc.2016.03.122

    View details for Web of Science ID 000374809700031

    View details for PubMedID 27033597

  • Aldose Reductase Mediates Transforming Growth Factor beta 2 (TGF-beta 2)-InducedMigration and Epithelial-To-Mesenchymal Transition of Lens-Derived Epithelial Cells INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Chang, K., Petrash, J. M. 2015; 56 (8): 4198-4210

    Abstract

    Cataract surgery involves removal of lens tissue, but is associated with a high complication rate due to regrowth of residual lens epithelial cells to produce posterior capsule opacification (PCO) and diminished visual acuity. As inhibitors of aldose reductase (AR) have been shown to suppress markers of PCO, our studies were designed to identify a role for AR in the pathogenesis of PCO.Sorbinil-mediated AR inhibition was determined by measuring sorbitol accumulation. Cell migration was measured using both transwell and scratch assays. Proteins in the SMAD signaling pathway were measured by Western blotting. The interactions of AR and SMADs were demonstrated by co-immunoprecipitation (Co-IP) and proximity ligation assay (PLA). Epithelial-to-mesenchymal transition (EMT) expression was measured by Western blot and quantitative PCR (q-PCR). Matrix metalloproteinase (MMP)-2 and MMP-9 activities were measured in conditioned medium by zymography.We observed that either Sorbinil-mediated AR inhibition or siRNA-mediated AR gene knockdown prevented migration of lens epithelial cells following exposure to TGF-?2. AR inhibition or AR knockdown reduced SMAD and MMP activation triggered by TGF-?2. In addition, we demonstrated AR inhibition or AR knockdown decreased TGF-?2-induced expression of EMT markers. Co-IP studies and PLA were used to demonstrate that AR and SMAD2 interact either directly or in close concert with additional factor(s) in a nonenzymatic manner.This study demonstrates that AR participates in the response of lens epithelial cells to TGF-?2. Our studies raise the possibility that AR inhibition may be effective in preventing development of PCO by disrupting the TGF-?2/SMAD pathway.

    View details for DOI 10.1167/iovs.15-16557

    View details for Web of Science ID 000362882700004

    View details for PubMedID 26132779

    View details for PubMedCentralID PMC4495811

  • Aldose reductase expression as a risk factor for cataract CHEMICO-BIOLOGICAL INTERACTIONS Snow, A., Shieh, B., Chang, K., Pal, A., Lenhart, P., Ammar, D., Ruzycki, P., Palla, S., Reddy, G. B., Petrash, J. M. 2015; 234: 247-253

    Abstract

    Aldose reductase (AR) is thought to play a role in the pathogenesis of diabetic eye diseases, including cataract and retinopathy. However, not all diabetics develop ocular complications. Paradoxically, some diabetics with poor metabolic control appear to be protected against retinopathy, while others with a history of excellent metabolic control develop severe complications. These observations indicate that one or more risk factors may influence the likelihood that an individual with diabetes will develop cataracts and/or retinopathy. We hypothesize that an elevated level of AR gene expression could confer higher risk for development of diabetic eye disease. To investigate this hypothesis, we examined the onset and severity of diabetes-induced cataract in transgenic mice, designated AR-TG, that were either heterozygous or homozygous for the human AR (AKR1B1) transgene construct. AR-TG mice homozygous for the transgene demonstrated a conditional cataract phenotype, whereby they developed lens vacuoles and cataract-associated structural changes only after induction of experimental diabetes; no such changes were observed in AR-TG heterozygotes or nontransgenic mice with or without experimental diabetes induction. We observed that nondiabetic AR-TG mice did not show lens structural changes even though they had lenticular sorbitol levels almost as high as the diabetic AR-TG lenses that showed early signs of cataract. Over-expression of AR led to increases in the ratio of activated to total levels of extracellular signal-regulated kinase (ERK1/2) and c-Jun N-terminal (JNK1/2), which are known to be involved in cell growth and apoptosis, respectively. After diabetes induction, AR-TG but not WT controls had decreased levels of phosphorylated as well as total ERK1/2 and JNK1/2 compared to their nondiabetic counterparts. These results indicate that high AR expression in the context of hyperglycemia and insulin deficiency may constitute a risk factor that could predispose the lens to disturbances in signaling through the ERK and JNK pathways and thereby alter the balance of cell growth and apoptosis that is critical to lens transparency and homeostasis.

    View details for DOI 10.1016/j.cbi.2014.12.017

    View details for Web of Science ID 000355044000029

    View details for PubMedID 25541468

  • Aldose reductase inhibition alleviates hyperglycemic effects on human retinal pigment epithelial cells CHEMICO-BIOLOGICAL INTERACTIONS Chang, K., Snow, A., LaBarbera, D. V., Petrash, J. M. 2015; 234: 254-260

    Abstract

    Chronic hyperglycemia is an important risk factor involved in the onset and progression of diabetic retinopathy (DR). Among other effectors, aldose reductase (AR) has been linked to the pathogenesis of this degenerative disease. The purpose of this study was to investigate whether the novel AR inhibitor, beta-glucogallin (BGG), can offer protection against various hyperglycemia-induced abnormalities in human adult retinal pigment epithelial (ARPE-19) cells. AR is an enzyme that contributes to cellular stress by production of reactive oxygen species (ROS) under high glucose conditions. A marked decrease in cell viability (from 100% to 78%) following long-term exposure (4 days) of RPE cells to high glucose (HG) was largely prevented by siRNA-mediated knockdown of AR gene expression (from 79% to 97%) or inhibition using sorbinil (from 66% to 86%). In HG, BGG decreased sorbitol accumulation (44%), ROS production (27%) as well as ER stress (22%). Additionally, we demonstrated that BGG prevented loss of mitochondrial membrane potential (MMP) under HG exposure. We also showed that AR inhibitor pretreatment reduced retinal microglia-induced apoptosis in APRE-19 cells. These results suggest that BGG may be useful as a therapeutic agent against retinal degeneration in the diabetic eye by preventing RPE cell death.

    View details for DOI 10.1016/j.cbi.2014.10.007

    View details for Web of Science ID 000355044000030

    View details for PubMedID 25451566

    View details for PubMedCentralID PMC4402120

  • Aldose Reductase Inhibition Prevents Endotoxin-Induced Inflammatory Responses in Retinal Microglia INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Chang, K., Ponder, J., LaBarbera, D. V., Petrash, J. M. 2014; 55 (5): 2853-2861

    Abstract

    Retinal microglia become activated in diabetes and produce pro-inflammatory molecules associated with changes in retinal vasculature and increased apoptosis of retinal neurons and glial cells. We sought to determine if the action of aldose reductase (AR), an enzyme linked to the pathogenesis of diabetic retinopathy, contributes to activation of microglial cells.Involvement of AR in the activation process was studied using primary cultures of retinal microglia (RMG) isolated from wild-type and AR-null mice, or in mouse macrophage cultures treated with either AR inhibitors or small interfering RNA (siRNA) directed to AR. Inflammatory cytokines were measured by ELISA. Cell migration was measured using a transwell assay. Gelatin zymography was used to detect active matrix metalloproteinase (MMP)-9, while RMG-induced apoptosis of adult retinal pigment epithelium (ARPE-19) cells was studied in a cell coculture system.Aldose reductase inhibition or genetic deficiency substantially reduced lipopolysacharide (LPS)-induced cytokine secretion from macrophages and RMG. Aldose reductase inhibition or deficiency also reduced the activation of MMP-9 and attenuated LPS-induced cell migration. Additionally, blockade of AR by sorbinil or through genetic means caused a reduction in the ability of activated RMG to induce apoptosis of ARPE-19 cells.These results demonstrate that the action of AR contributes to the activation of RMG. Inhibition of AR may be a therapeutic strategy to reduce inflammation associated with activation of RMG in disease.

    View details for DOI 10.1167/iovs.13-13487

    View details for Web of Science ID 000339484800006

    View details for PubMedID 24677107

    View details for PubMedCentralID PMC4010364

  • Design of an Amide N-Glycoside Derivative of beta-Glucogallin: A Stable, Potent, and Specific Inhibitor of Aldose Reductase JOURNAL OF MEDICINAL CHEMISTRY Li, L., Chang, K., Zhou, Y., Shieh, B., Ponder, J., Abraham, A. D., Ali, H., Snow, A., Petrash, J. M., LaBarbera, D. V. 2014; 57 (1): 71-77

    Abstract

    ?-Glucogallin (BGG), a major component of the Emblica officinalis medicinal plant, is a potent and selective inhibitor of aldose reductase (AKR1B1). New linkages (ether/triazole/amide) were introduced via high yielding, efficient syntheses to replace the labile ester, and an original two-step (90%) preparation of BGG was developed. Inhibition of AKR1B1was assessed in vitro and using transgenic lens organ cultures, which identified the amide linked glucoside (BGA) as a stable, potent, and selective therapeutic lead toward the treatment of diabetic eye disease.

    View details for DOI 10.1021/jm401311d

    View details for Web of Science ID 000329677800006

    View details for PubMedID 24341381

  • Beta-glucogallin reduces the expression of lipopolysaccharide-induced inflammatory markers by inhibition of aldose reductase in murine macrophages and ocular tissues CHEMICO-BIOLOGICAL INTERACTIONS Chang, K., Laffin, B., Ponder, J., Enzsoely, A., Nemeth, J., LaBarbera, D. V., Petrash, J. M. 2013; 202 (1-3): 283-287

    Abstract

    Aldose reductase (AR) catalyzes the reduction of toxic lipid aldehydes to their alcohol products and mediates inflammatory signals triggered by lipopolysaccharide (LPS). Beta-glucogallin (BGG), a recently described AR inhibitor, was purified from extracts of the Indian gooseberry (Emblica officinalis). In this study, we found that BGG showed low cytotoxicity in Raw264.7 murine macrophages and effectively inhibited AR activity as measured by a decrease in sorbitol accumulation. In addition, BGG-mediated inhibition of AR prevented LPS-induced activation of JNK and p38 and lowered ROS levels, which could inhibit LPS-induced apoptosis. Uveitis is a disease of the eye associated with chronic inflammation. In this study, we also demonstrated that treatment with BGG decreased the number of inflammatory cells that infiltrate the ocular media of mice with experimental uveitis. Accordingly, these results suggest BGG is a potential therapy for inflammatory diseases.

    View details for DOI 10.1016/j.cbi.2012.12.001

    View details for Web of Science ID 000317539500035

    View details for PubMedID 23247009

    View details for PubMedCentralID PMC3656825

  • Eicosapentaenoic acid and docosahexaenoic acid inhibit macrophage-induced gastric cancer cell migration by attenuating the expression of matrix metalloproteinase 10 JOURNAL OF NUTRITIONAL BIOCHEMISTRY Wu, M., Tsai, Y., Hua, K., Chang, K., Kuo, M., Lin, M. 2012; 23 (11): 1434-1439

    Abstract

    Uptake of docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) improves the treatment of cancer and reduces tumor-associated macrophage count. However, the mechanism of this relationship is still unclear. In this study, macrophages enhanced gastric cancer cell migration ability and induced the differentially expressed matrix metalloproteinase genes (MMP1, MMP3 and MMP10) of N87 as identified by polymerase chain reaction array. Furthermore, DHA and EPA inhibited macrophage-enhanced cancer cell migration and attenuated MMP10 at both the RNA and protein level. The suppression of MMP10 expression was further verified by zymography and antibody blocking experiments. Additionally, DHA and EPA attenuated expression of macrophage-activated extracellular-signal-regulated kinase (ERK) and signal transducers and activators of transcription 3 (STAT3) in cancer cells. Attenuation was verified by demonstrating blockade with specific inhibitors and thereby increased MMP10 expression. Accordingly, we hypothesized that macrophage enhances cancer cell migration through ERK and STAT3 phosphorylation and subsequent increased MMP10 expression and that DHA and EPA could attenuate these signals. These findings not only explain the beneficial effects of DHA/EPA, but also point to ERK/STAT3/MMP10 as the potential targets for gastric cancer treatment.

    View details for DOI 10.1016/j.jnutbio.2011.09.004

    View details for Web of Science ID 000310490000009

    View details for PubMedID 22285823

  • Cholesterol regulation of receptor-interacting protein 140 via microRNA-33 in inflammatory cytokine production FASEB JOURNAL Ho, P., Chang, K., Chuang, Y., Wei, L. 2011; 25 (5): 1758-1766

    Abstract

    Receptor interacting protein 140 (RIP140) is a nuclear receptor coregulator that affects a wide spectrum of biological processes. It is unclear whether and how the expression level of RIP140 can be modulated and whether RIP140 is involved in inflammatory diseases. Here, we examine how intracellular cholesterol regulates RIP140 expression, and we evaluate the effect of RIP140 expression on macrophage proinflammatory potential. Macrophages treated with modified low-density lipoprotein express higher RIP140 mRNA and protein levels. Consistently, simvastatin reduces RIP140 levels, which can be reversed by mevalonate. Moreover, a high-fat diet elevates RIP140 but lowers miR-33 levels in peritoneal macrophages, and increases the production of IL-1? and TNF-? in macrophages. Mechanistically, miR-33 targets RIP140 mRNA by recognizing its target located in a highly conserved sequence of the 3'-untranslated region (3'-UTR) of RIP140 mRNA. Consequentially, miR-33 reduces RIP140 coactivator activity for NF-?B, which is supported by the reduction in NF-?B reporter activity and the inflammatory potential in macrophages. This study uncovers a cholesterol-miR-33-RIP140 regulatory pathway that modulates the proinflammatory potential in macrophages in response to an alteration in the intracellular cholesterol status, and identifies RIP140 as a direct target of miR-33 that mediates simvastatin-triggered anti-inflammation.

    View details for DOI 10.1096/fj.10-179267

    View details for Web of Science ID 000290023800031

    View details for PubMedID 21285396

  • Serum vascular endothelial growth factor-D levels correlate with cervical lymph node metastases in papillary thyroid carcinoma GROWTH FACTORS Lai, C., Chen, K., Hung, C., Kuo, S., Chang, Y., Lin, M., Chang, K., Wu, M. 2011; 29 (2-3): 57-62

    Abstract

    The aim of this multicenter study was to evaluate the clinical relevance of serum vascular endothelial growth factor-D (VEGF-D) in papillary thyroid carcinoma (PTC). This prospective study consisted of 74 patients with primary PTC and 15 patients with benign thyroid nodules treated from 2008 to 2009. VEGF-D concentration was compared with patient clinicopathologic features and lymph node metastases. There was no significant difference in mean serum VEGF-D levels between the PTC and benign thyroid nodule groups. Within the PTC group, serum VEGF-D levels were significantly higher in patients with lymph node metastases than in patients without metastases (241.92 vs. 213.89ápg/ml, respectively; Pá=á0.035). Receiver operating characteristic curve analysis revealed that preoperative serum VEGF-D levels were predictive of lymph node metastases in the patients >45 years. Serum VEGF-D level that was correlated with the presence of cervical lymph node metastases in PTC patients might be a useful prognostic indicator.

    View details for DOI 10.3109/08977194.2011.557373

    View details for Web of Science ID 000290407300002

    View details for PubMedID 21319951

  • Gefitinib-induced epidermal growth factor receptor-independent keratinocyte apoptosis is mediated by the JNK activation pathway BRITISH JOURNAL OF DERMATOLOGY Lu, P., Kuo, T., Chang, K., Chang, C., Chu, C. 2011; 164 (1): 38-46

    Abstract

    Gefitinib (ZD1839) is a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor with a significant antitumour effect on various cancers. Skin toxicity induced by gefitinib is common, and has been shown to be related to the inhibition of EGFR signalling pathways. However, other mechanisms may be involved in gefitinib-induced skin toxicity.To study the possible EGFR-independent mechanisms of gefitinib-induced skin toxicity.The human immortalized keratinocyte cell line HaCaT and human lung adenocarcinoma cell lines (A549 and PC9) were treated with different concentrations of gefitinib for 24, 48 and 72 h. Cell viability was measured by MTT assay [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] after EGFR gene silencing. The signalling pathways were investigated by immunoblot analysis. Keratinocyte apoptosis was evaluated by nuclear condensation and flow cytometric analysis.Gefitinib maintained its cytotoxicity to HaCaT cells after EGFR gene silencing, indicating that an EGFR-independent mechanism exists. Increased phosphorylation of p38 mitogen-activated protein kinase and JNK by gefitinib was observed in a dose-dependent manner in HaCaT cells. The JNK inhibitor, SP600125, attenuated the gefitinib-induced cytotoxicity and apoptosis of HaCaT cells. Immunohistochemical examination of patient specimens showed an increased expression of phosphorylated JNK in lesional epidermis compared with nonlesional epidermis.Gefitinib can induce keratinocyte apoptosis through an EGFR-independent JNK activation pathway.

    View details for DOI 10.1111/j.1365-2133.2010.10038.x

    View details for Web of Science ID 000285752000008

    View details for PubMedID 20846305

  • TNF-alpha Mediates Eosinophil Cationic Protein-induced Apoptosis in BEAS-2B Cells BMC CELL BIOLOGY Chang, K., Lo, C., Fan, T., Chang, M. D., Shu, C., Chang, C., Chung, C., Fang, S., Chao, C., Tsai, J., Lai, Y. 2010; 11

    Abstract

    Eosinophilic granulocytes are important for the human immune system. Many cationic proteins with cytotoxic activities, such as eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN), are released from activated eosinophils. ECP, with low RNase activity, is widely used as a biomarker for asthma. ECP inhibits cell viability and induces apoptosis to cells. However, the specific pathway underlying the mechanisms of ECP-induced cytotoxicity remains unclear. This study investigated ECP-induced apoptosis in bronchial epithelial BEAS-2B cells and elucidated the specific pathway during apoptosis.To address the mechanisms involved in ECP-induced apoptosis in human BEAS-2B cells, investigation was carried out using chromatin condensation, cleavage of poly (ADP-ribose) polymerase (PARP), sub-G1 distribution in cell cycle, annexin V labeling, and general or specific caspase inhibitors. Caspase-8-dependent apoptosis was demonstrated by cleavage of caspase-8 after recombinant ECP treatment, accompanied with elevated level of tumor necrosis factor alpha (TNF-alpha). Moreover, ECP-induced apoptosis was effectively inhibited in the presence of neutralizing anti-TNF-alpha antibody.In conclusion, our results have demonstrated that ECP increased TNF-alpha production in BEAS-2B cells and triggered apoptosis by caspase-8 activation through mitochondria-independent pathway.

    View details for Web of Science ID 000274599300002

    View details for PubMedID 20089176

  • Control Mechanisms of Differential Translation of Hsp90 Isoforms in 9L Rat Gliosarcoma Cells JOURNAL OF CELLULAR BIOCHEMISTRY Lo, C., Chang, Y., Chao, C., Chang, M. D., Chang, K., Lai, Y. 2009; 107 (3): 418-427

    Abstract

    Although the differential expression of heat shcok proteins, Hsp90alpha and Hsp90beta was extensively studied in many kinds of cells, the post-transcriptional regulation of Hsp90 isoforms remains unclear. In control and GA-treated rat gliosarcoma cells, it has been reported that the translational efficiency of hsp90alpha is higher than hsp90beta. In this study, we present evidences identifying the roles for leaky scanning and 5'-UTR sequence in translational regulation of Hsp90beta. The result of in vitro transcription and translation (IVTT) experiment showed that hsp90alpha exhibited higher translation efficiency than hsp90beta. Sequence analysis revealed that there is an out-of-frame downstream AUG codon in hsp90beta gene. However, elimination of the downstream AUG by site-directly mutagenesis or introducing Kozak context sequence around the initiator AUG of hsp90beta open reading frame increased its translational efficiency, which indicated that leaky scanning might be a possible mechanism regulating hsp90beta. Furthermore, we also constructed a firefly luciferase reporter system to verify the effect of subsequent translation at the downstream out-of-frame AUG codon in 9L and A549 cells. Furthermore, it is believed that 5'-untranslated region (5'-UTR) also plays a significant role in translational control. We showed hsp90beta 5'-UTR gives rise to the reduction of the translation efficiency in IVTT experiment. Additionally, the reductive effect of hsp90beta 5'-UTR was further confirmed by luciferase reporter assay using truncated deletion analyses of 5'-UTR of hsp90beta. Our results support the hypothesis that ribosome leaky scanning mechanism and 5'-UTR sequence acts as negative regulators in hsp90beta mRNA.

    View details for DOI 10.1002/jcb.22138

    View details for Web of Science ID 000266872300006

    View details for PubMedID 19308988

  • Concerted actions of multiple transcription elements confer differential Transactivation of HSP90 isoforms in geldanamycin-treated 9L rat gliosarcoma cells JOURNAL OF CELLULAR BIOCHEMISTRY Chao, C., Sun, F., Wang, C., Lo, C., Chang, Y., Chang, K., Chang, M. D., Lai, Y. 2008; 104 (4): 1286-1296

    Abstract

    HSP90 chaperones are transducer proteins of many signaling pathways in cells. Using a highly specific inhibitor, geldanamycin (GA), an increasing number of the HSP90 client proteins have been identified. Nevertheless, there is little information on the differential transactivation of the two isoforms of the hsp90 genes, hsp90alpha and beta, in cells under stress conditions. Here, we demonstrate the differential expression of the HSP90 isoforms, HSP90alpha and beta, in rat gliosarcoma 9L cells using a modified SDS-PAGE system that allowed us to distinguish the isoforms. We subsequently assessed the transcriptional controls involving the transcription elements located in the promoter regions of the hsp90 genes. At the protein level, HSP90alpha is more responsive to GA in terms of rate of de novo synthesis and amount of accumulation, as shown by metabolic-labeling and Western-blotting analyses. Upregulation of the hsp90 genes was demonstrated by real-time qPCR. The promoter elements hsp90alpha-HSE2 and hsp90beta-HSE1 were also identified to be the major transcription elements involved in GA-activated gene expression, as shown by EMSA, whereas the results of supershift showed that the transcription factor HSF1 is also involved. Moreover, EMSA results of analysis of the GC box showed differences in both the initial amounts and inductive response of hsp90s transcripts, whereas analysis of the TATA box showed GA responsiveness in hsp90alpha only. Collectively, these results indicate that GA exerts its regulatory effects through transcription elements including heat-shock elements (HSEs), GC boxes and TATA boxes, resulting in differential transactivation of hsp90alpha and hsp90beta in rat gliosarcoma 9L cells.

    View details for DOI 10.1002/jcb.21705

    View details for Web of Science ID 000257567300014

    View details for PubMedID 18320580

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