Publications by authors named "Young Hoon Sung"

89 Publications

The Genetic Basis of Reporter Mouse Strains.

Adv Exp Med Biol 2021 ;1310:551-564

Department of Medical Science and Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Genetically engineered mouse (GEM) models have been revolutionizing the biomedical studies on deciphering the physiological roles of genes in vivo. In addition to deactivating a gene in mice, diverse strategies have been created to monitor gene expressions and molecular dynamics of specific proteins in vivo. Although gene targeting in mouse embryonic stem (ES) cells was essential for the precise engineering of the mouse genome over almost three decades, this process is a time-consuming, expensive, and laborious one. These days, new technologies that directly apply engineered endonucleases, such as zinc-finger nucleases (ZFNs), Transcription Activator-Like Effector (TALE) Nucleases (TALENs), and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system, into the mouse zygotes are enabling us to rapidly replace conventional gene targeting in mouse ES cells. In this chapter, we will describe the principles of reporter mouse strains and the recent advances in generating them using engineered endonucleases.
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http://dx.doi.org/10.1007/978-981-33-6064-8_21DOI Listing
April 2021

Interpretation of XIAP Variants of Uncertain Significance in Paediatric Patients with Refractory Crohn's Disease.

J Crohns Colitis 2021 Aug;15(8):1291-1304

Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.

Background And Aims: Mutations in XIAP can lead to the development of treatment-refractory severe paediatric Crohn's disease [CD], for which haematopoietic stem cell transplantation is the primary therapeutic option. The interpretation of variants of uncertain significance [VUSs] in XIAP needs to be scrutinized.

Methods: Targeted next-generation sequencing was performed for 33 male paediatric patients with refractory CD admitted at a tertiary referral hospital. To obtain functional data, biomolecular cell assays and supercomputing molecular dynamics simulations were performed.

Results: Nine unrelated male patients harboured hemizygous XIAP variants. Four known pathogenic variants and one novel pathogenic variant [p.Lys168Serfs*12] were identified in five patients, and two novel VUSs [p.Gly205del and p.Pro260Ser] and one known VUS [p.Glu350del] were identified in the remaining four. Among children with VUSs, only the subject with p.Gly205del exhibited defective NOD2 signalling. Using molecular dynamics simulation, we determined that the altered backbone torsional energy of C203 in XIAP of p.G205del was ~2 kcal/mol, suggesting loss of zinc binding in the mutant XIAP protein and poor coordination between the mutant XIAP and RIP2 proteins. Elevated auto-ubiquitination of zinc-depleted p.G205del XIAP protein resulted in XIAP protein deficiency.

Conclusion: A high prevalence of XIAP deficiency was noted among children with refractory CD. Advanced functional studies decreased the subjectivity in the case-level interpretation of XIAP VUSs and directed consideration of haematopoietic stem cell transplantation.
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http://dx.doi.org/10.1093/ecco-jcc/jjab013DOI Listing
August 2021

Multiplex gene targeting in the mouse embryo using a Cas9-Cpf1 hybrid guide RNA.

Biochem Biophys Res Commun 2021 02 6;539:48-55. Epub 2021 Jan 6.

Department of Convergence Medicine, Asan Institutes for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea; Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea. Electronic address:

CRISPR-Cas systems, including Cas9 and Cpf1 (Cas12a), are promising tools for generating gene knockout mouse models. Unlike Cas9, Cpf1 can generate multiple crRNAs from a single concatemeric crRNA precursor, which is favorable for multiplex gene editing. Recently, a hybrid guide RNA (hgRNA) system employing both Cas9 and Cpf1 was developed for multiplex gene editing. As the crRNA of Cpf1 was linked to the 3' end of the sgRNA for Cas9, it can be split into separate guide RNAs by Cpf1. To examine whether this Cas9-Cpf1 hybrid system is suitable for multiplex gene knockouts in the mouse embryo, we generated an hgRNA that simultaneously targets the mouse Il10ra gene by Cas9 and mouse Dr3 (or Tnfrsf25, death receptor3) gene by Cpf1. The expression of hgRNA from a single promoter induced significant indels at each gene in cultured mouse cells upon the co-expression of both Cas9 and Cpf1. Interestingly, the hgRNA exhibited comparable Cas9-mediated indel activity without Cpf1 expression. Similarly, when the hgRNA was co-microinjected with both Cas9 and Cpf1 mRNAs into mouse zygotes at the pronuclear stage, founder mice were generated harboring mutations in both the Il10ra and Dr3 genes. However, when Cas9 mRNA was used alone without Cpf1 mRNA, the mouse Il10ra gene targeting was significantly decreased. These results indicate that the hgRNA system is a possible tool for multiplex gene targeting in the mouse embryo.
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http://dx.doi.org/10.1016/j.bbrc.2020.12.072DOI Listing
February 2021

The emotional dance with depression: A longitudinal investigation of OULA® for depression in women.

J Bodyw Mov Ther 2020 Oct 13;24(4):413-422. Epub 2020 Jun 13.

Department of Mathematical Sciences, Montana State University, PO Box 172400, Bozeman, MT, USA. Electronic address:

The primary purpose of this pilot study was to evaluate OULA®, a dance fitness program with a strong emphasis on processing emotions through dance, as an intervention for depression in women diagnosed with major or persistent depressive disorders. 53 women were eligible for participation. Women attended OULA® for 12 weeks and then abstained from OULA® during week 13. For the primary outcome, depression severity was measured using the Hamilton Depression Rating Scale (HAM-D), and secondary outcomes were measured using the Beck Anxiety Index (BAI) and the Subjective Happiness Scale (SHS). After the abstinence week, women were offered 3-months of optional additional OULA®. HAM-D, BAI and SHS scores were collected at weeks 2, 4, 5-14 and at the end of the 3-month optional OULA® phase. Results from linear mixed effects repeated models show that during the 12-week intervention period and at week 26, HAM-D scores significantly decrease each week compared to baseline. Further, BAI scores significantly decrease starting at week 5 and through the end of the intervention period and at week 26. Moreover, SHS scores increased significantly for four of the weeks during the intervention period and at week 26. The results from this study suggest that OULA® may be a useful intervention for decreasing depression and anxiety severity in women with depression but may not be helpful for improving subjective happiness.
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http://dx.doi.org/10.1016/j.jbmt.2020.05.007DOI Listing
October 2020

Type VI collagen and its cleavage product, endotrophin, cooperatively regulate the adipogenic and lipolytic capacity of adipocytes.

Metabolism 2021 01 12;114:154430. Epub 2020 Nov 12.

Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea. Electronic address:

Objective: Obesity-induced adipose tissue remodeling is closely associated with systemic insulin resistance. However, the mechanistic involvement of adipocyte-derived extracellular matrix proteins under pathophysiological conditions remains unclear. Our aim was to investigate the distinctive contributions of each chain of type VI collagens (Col6) and its cleavage protein endotrophin to adipocyte functions and insulin sensitivity.

Methods: Col6 comprises three alpha chains: Col6a1, Col6a2, and Col6a3. We generated Col6a1-, Col6a2-, and Col6a3-deficient 3T3-L1 adipocytes using the CRISPR-Cas9 system as well as a novel Col6a3-deficient (Col6a3KO) mouse model for loss-of-function studies. Adenoviral-endotrophin and adipocyte-specific doxycycline-inducible endotrophin transgenic mice were utilized for the gain-of-function analysis.

Results: The holo-Col6 fibrils were found to be required for mature adipocyte differentiation. Only Col6a3-deficient 3T3-L1 adipocytes showed decreased inflammation and basal adipocyte lipolysis and prevented ER-stress-induced insulin resistance. Consistently, Col6a3KO mice showed decreased adipocyte size and fat mass of epididymal adipose tissues due to a defect in adipogenic and lipolytic capacity of adipocytes. Beyond the structural role of Col6a3, overexpression of endotrophin in obese mice further augmented insulin resistance, which was tightly associated with a significant increase in lipolysis, inflammation, and cellular apoptosis in adipose tissues, whereas this showed a limited effect on adipogenesis.

Conclusions: These novel findings corroborate our previous observations suggesting that adipose tissue extracellular matrix regulates adipocyte function and insulin sensitivity in pathophysiological conditions. Mechanistically, holo-Col6 fibrils and their signaling derivative endotrophin govern adipocyte function independently of their role as structural supports via MAPK signaling pathways, and the latter could be an important metabolic effector in obesity-related metabolic diseases.
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http://dx.doi.org/10.1016/j.metabol.2020.154430DOI Listing
January 2021

Association between ARID2 and RAS-MAPK pathway in intellectual disability and short stature.

J Med Genet 2020 Oct 13. Epub 2020 Oct 13.

Medical Genetics Center, Asan Medical Center, Seoul, Republic of Korea

Background: ARID2 belongs to the Switch/sucrose non-fermenting complex, in which the genetic defects have been found in patients with dysmorphism, short stature and intellectual disability (ID). As the phenotypes of patients with mutations partially overlap with those of RASopathy, this study evaluated the biochemical association between ARID2 and RAS-MAPK pathway.

Methods: The phenotypes of 22 patients with either an heterozygous mutation or haploinsufficiency were reviewed. Comprehensive molecular analyses were performed using somatic and induced pluripotent stem cells (iPSCs) of a patient with haploinsufficiency as well as using the mouse model of haploinsufficiency by CRISPR/Cas9 gene editing.

Results: The phenotypic characteristics of deficiency include RASopathy, Coffin-Lowy syndrome or Coffin-Siris syndrome or undefined syndromic ID. Transient knockout HeLa cells using an shRNA increased ERK1 and ERK2 phosphorylation. Impaired neuronal differentiation with enhanced RAS-MAPK activity was observed in patient-iPSCs. In addition, haploinsufficient mice exhibited reduced body size and learning/memory deficit. haploinsufficiency was associated with reduced IFITM1 expression, which interacts with caveolin-1 (CAV-1) and inhibits ERK activation.

Discussion: haploinsufficiency is associated with enhanced RAS-MAPK activity, leading to reduced IFITM1 and CAV-1 expression, thereby increasing ERK activity. This altered interaction might lead to abnormal neuronal development and a short stature.
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http://dx.doi.org/10.1136/jmedgenet-2020-107111DOI Listing
October 2020

Impaired AKT signaling and lung tumorigenesis by PIERCE1 ablation in KRAS-mutant non-small cell lung cancer.

Oncogene 2020 09 29;39(36):5876-5887. Epub 2020 Jul 29.

Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea.

KRAS-mutant non-small cell lung cancer (NSCLC) is a major lung cancer subtype that leads to many cancer-related deaths worldwide. Although numerous studies on KRAS-mutant type NSCLC have been conducted, new oncogenic or tumor suppressive genes need to be detected because a large proportion of NSCLC patients does not respond to currently used therapeutics. Here, we show the tumor-promoting function of a cell cycle-related protein, PIERCE1, in KRAS-mutant NSCLC. Mechanistically, PIERCE1 depletion inhibits cell growth and AKT phosphorylation (pAKT) at S473, which is particularly observed in KRAS-mutant lung cancers. Analyses of AKT-related genes using microarray, immunoblotting, and real-time quantitative PCR indicated that PIERCE1 negatively regulates the gene expression of the AKT suppressor, TRIB3, through the CHOP pathway, which is a key regulatory pathway for TRIB3 expression. Similarly, in vivo analyses of PIERCE1 depletion in the KRAS mutation-related lung cancer mouse models revealed the suppressive effect of PIERCE1 knockout in urethane- and KRAS-induced lung tumorigenesis with decreased pAKT levels observed in the tumors. Tissue microarrays of human lung cancers indicated the expression of PIERCE1 in 83% of lung cancers and its correlation with pAKT expression. Thus, we illustrate how PIERCE1 depletion may serve as a therapeutic strategy against KRAS-mutant NSCLC and propose the clinical benefit of PIERCE1.
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http://dx.doi.org/10.1038/s41388-020-01399-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7471098PMC
September 2020

Tumor-derived exosomal miR-619-5p promotes tumor angiogenesis and metastasis through the inhibition of RCAN1.4.

Cancer Lett 2020 04 28;475:2-13. Epub 2020 Jan 28.

Department of Convergence Medicine, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, 05505, South Korea. Electronic address:

Tumor-derived exosomes (TEXs) contain enriched miRNAs that act as novel non-invasive biomarkers for cancer diagnosis and play a role in cancer progression. We investigated the exosomal miRNAs that affect cancer progression in non-small cell lung cancer (NSCLC) and identified the specific molecules involved. We identified that specific miRNAs in NSCLC cell-released exosomes can modulate angiogenesis, among which miR-619-5p was the most potent inducer. RCAN1.4 was identified as a target of miR-619-5p and its suppression promoted angiogenesis. Furthermore, the suppression of RCAN1.4 induced cell proliferation and metastasis in NSCLC cells. In patients with NSCLC, the level of RCAN1.4 expression was significantly lower, and that of miR-619-5p significantly higher, in tumor than normal lung tissues. miR-619-5p expression was higher than normal in exosomes isolated from the plasma of NSCLC patients. Finally, hypoxic conditions induced miR-619-5p upload into NSCLC cell-derived exosomes. Our findings indicate that exosomal miR-619-5p promotes the growth and metastasis of NSCLCs by regulating RCAN1.4 and can serve as a diagnostic indicator for these lung cancers.
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http://dx.doi.org/10.1016/j.canlet.2020.01.023DOI Listing
April 2020

Exosomal PD-L1 promotes tumor growth through immune escape in non-small cell lung cancer.

Exp Mol Med 2019 08 9;51(8):1-13. Epub 2019 Aug 9.

Department of Convergence Medicine, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, 05505, South Korea.

Programmed cell death protein-1/programmed cell death ligand-1 (PD-1/PD-L1) pathway blockade is a promising new cancer therapy. Although PD-1/PD-L1 treatment has yielded clinical benefits in several types of cancer, further studies are required to clarify predictive biomarkers for drug efficacy and to understand the fundamental mechanism of PD-1/PD-L1 interaction between host and tumor cells. Here, we show that exosomes derived from lung cancer cells express PD-L1 and play a role in immune escape by reducing T-cell activity and promoting tumor growth. The abundance of PD-L1 on exosomes represented the quantity of PD-L1 expression on cell surfaces. Exosomes containing PD-L1 inhibited interferon-gamma (IFN-γ) secretion by Jurkat T cells. IFN-γ secretion was restored by PD-L1 knockout or masking on the exosomes. Both forced expression of PD-L1 on cells without PD-L1 and treatment with exosomes containing PD-L1 enhanced tumor growth in vivo. PD-L1 was present on exosomes isolated from the plasma of patients with non-small cell lung cancer, and its abundance in exosomes was correlated with PD-L1 positivity in tumor tissues. Exosomes can impair immune functions by reducing cytokine production and inducing apoptosis in CD8 T cells. Our findings indicate that tumor-derived exosomes expressing PD-L1 may be an important mediator of tumor immune escape.
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http://dx.doi.org/10.1038/s12276-019-0295-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6802663PMC
August 2019

Association between altitude, prescription opioid misuse, and fatal overdoses.

Addict Behav Rep 2019 Jun 18;9:100167. Epub 2019 Feb 18.

Department of Psychiatry, University of Utah School of Medicine, 383 Colorow Drive, Salt Lake City, UT, 84108, United States.

Objective: Prescription opioid misuse and fatal overdoses have increased significantly over the last two decades. Living at altitude has been linked to greater reward benefits of other drugs of abuse, and living at altitude may also exacerbate the respiratory depression linked to opioid use. Therefore, we examined the relationships between living at altitude, and prescription opioid misuse and fatal overdoses.

Method: State-level past year rates of prescription opioid misuse were retrieved from the Substance Abuse and Mental Health Services Administration. County-level overdose data were extracted from the Centers for Disease Control and Prevention. Multiple linear regression models were fit to determine the relationship between average state elevation and state rates of opioid misuse. Logistic regression models were fit to determine the relationship between county elevation and county-level fatal opioid overdose prevalence.

Results: After controlling for state opioid prescribing rates and other confounders, we identified a significant positive association between mean state altitude and state-level opioid misuse rates for women, but not men. We also found a significant positive association between county-level altitude and prevalence of fatal opioid overdose.

Conclusions: Living at altitude is thus demographically associated with increasing rates of misuse of prescription opioids, as well as of cocaine and methamphetamine. Animal studies suggest that the hypobaric hypoxia exposure involved with living at altitude may disrupt brain neurochemistry, to increase reward benefits of drugs of abuse. This increased misuse of both stimulants and opioids may increase likelihood of overdose at altitude, with overdoses by opioid use also potentially facilitated by altitude-related hypoxia.
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http://dx.doi.org/10.1016/j.abrep.2019.100167DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6542744PMC
June 2019

Cerebral bioenergetic differences measured by phosphorus-31 magnetic resonance spectroscopy between bipolar disorder and healthy subjects living in two different regions suggesting possible effects of altitude.

Psychiatry Clin Neurosci 2019 Sep 3;73(9):581-589. Epub 2019 Jul 3.

Department of Psychiatry, University of Utah, Salt Lake City, USA.

Aim: Increased oxidative stress in cerebral mitochondria may follow exposure to the systemic hypobaric hypoxia associated with residing at higher altitudes. Because mitochondrial dysfunction is implicated in bipolar disorder (BD) pathophysiology, this may impact the cerebral bioenergetics in BD. In this study, we evaluated the cerebral bioenergetics of BD and healthy control (HC) subjects at two sites, located at sea level and at moderate altitude.

Methods: Forty-three veterans with BD and 33 HC veterans were recruited in Boston (n = 22) and Salt Lake City (SLC; n = 54). Levels of phosphocreatine, β nucleoside triphosphate (βNTP), inorganic phosphate, and pH over total phosphate (TP) were measured using phosphorus-31 magnetic resonance spectroscopy in the following brain regions: anterior cingulate cortex and posterior occipital cortex, as well as bilateral prefrontal and occipitoparietal (OP) white matter (WM).

Results: A significant main effect of site was found in βNTP/TP (Boston > SLC) and phosphocreatine/TP (Boston < SLC) in most cortical and WM regions, and inorganic phosphate/TP (Boston < SLC) in OP regions. A main effect analysis of BD diagnosis demonstrated a lower pH in posterior occipital cortex and right OP WM and a lower βNTP/TP in right prefrontal WM in BD subjects, compared to HC subjects.

Conclusion: The study showed that there were cerebral bioenergetic differences in both BD and HC veteran participants at two different sites, which may be partly explained by altitude difference. Future studies are needed to replicate these results in order to elucidate the dysfunctional mitochondrial changes that occur in response to hypobaric hypoxia.
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http://dx.doi.org/10.1111/pcn.12893DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6771782PMC
September 2019

Development of a Pde6b Gene Knockout Rat Model for Studies of Degenerative Retinal Diseases.

Invest Ophthalmol Vis Sci 2019 04;60(5):1519-1526

Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Purpose: To describe the phenotypes of a newly developed Pde6b-deficient rat model of retinal degeneration.

Methods: Pde6b knockout rats were produced by CRISPR-Cpf1 technology. Pde6b knockout rats were evaluated for ocular abnormalities by comparison with wild-type eyes. Eyes were imaged using fundus photography and optical coherence tomography (OCT), stained by hematoxylin and eosin (H&E), and examined by TUNEL assay. Finally, eyes were functionally assessed by electroretinograms (ERGs).

Results: Pde6b knockout rats exhibited visible photoreceptor degeneration at 3 weeks of postnatal age. The fundus appearance of mutants was notable for pigmentary changes, vascular attenuation with an irregular vascular pattern, and outer retinal thinning, which resembled retinitis pigmentosa (RP) in humans. OCT showed profound retinal thinning in Pde6b knockout rats; the outer nuclear layer (ONL) was significantly thinner in Pde6b knockout rats, with relative preservation of the inner retina at 3 weeks of postnatal age. H&E staining confirmed extensive degeneration of the ONL, beginning at 3 weeks of postnatal age; no ONL remained in the retina by 16 weeks of postnatal age. Retinal sections of Pde6b knockout rats were highly positive for TUNEL, specifically in the ONL. In ERGs, Pde6b knockout rats showed no detectable a- or b-waves at 8 weeks of postnatal age.

Conclusions: The Pde6b knockout rat exhibits photoreceptor degeneration. It may provide a better model for experimental therapy for RP because of its slower progression and larger anatomic architecture than the corresponding mouse model. Further studies in this rat model may yield insights into effective therapies for human RP.
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http://dx.doi.org/10.1167/iovs.18-25556DOI Listing
April 2019

Knockout rat models mimicking human atherosclerosis created by Cpf1-mediated gene targeting.

Sci Rep 2019 02 22;9(1):2628. Epub 2019 Feb 22.

ConveRgence mEDIcine research cenTer (CREDIT), Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea.

The rat is a time-honored traditional experimental model animal, but its use is limited due to the difficulty of genetic modification. Although engineered endonucleases enable us to manipulate the rat genome, it is not known whether the newly identified endonuclease Cpf1 system is applicable to rats. Here we report the first application of CRISPR-Cpf1 in rats and investigate whether Apoe knockout rat can be used as an atherosclerosis model. We generated Apoe- and/or Ldlr-deficient rats via CRISPR-Cpf1 system, characterized by high efficiency, successful germline transmission, multiple gene targeting capacity, and minimal off-target effect. The resulting Apoe knockout rats displayed hyperlipidemia and aortic lesions. In partially ligated carotid arteries of rats and mice fed with high-fat diet, in contrast to Apoe knockout mice showing atherosclerotic lesions, Apoe knockout rats showed only adventitial immune infiltrates comprising T lymphocytes and mainly macrophages with no plaque. In addition, adventitial macrophage progenitor cells (AMPCs) were more abundant in Apoe knockout rats than in mice. Our data suggest that the Cpf1 system can target single or multiple genes efficiently and specifically in rats with genetic heritability and that Apoe knockout rats may help understand initial-stage atherosclerosis.
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http://dx.doi.org/10.1038/s41598-019-38732-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6385241PMC
February 2019

Microbiota-Derived Lactate Accelerates Intestinal Stem-Cell-Mediated Epithelial Development.

Cell Host Microbe 2018 12;24(6):833-846.e6

Mucosal Immunology Laboratory, Department of Convergence Medicine, University of Ulsan College of Medicine/Asan Medical Center, Seoul, Republic of Korea. Electronic address:

Symbionts play an indispensable role in gut homeostasis, but underlying mechanisms remain elusive. To clarify the role of lactic-acid-producing bacteria (LAB) on intestinal stem-cell (ISC)-mediated epithelial development, we fed mice with LAB-type symbionts such as Bifidobacterium and Lactobacillus spp. Here we show that administration of LAB-type symbionts significantly increased expansion of ISCs, Paneth cells, and goblet cells. Lactate stimulated ISC proliferation through Wnt/β-catenin signals of Paneth cells and intestinal stromal cells. Moreover, Lactobacillus plantarum strains lacking lactate dehydrogenase activity, which are deficient in lactate production, elicited less ISC proliferation. Pre-treatment with LAB-type symbionts or lactate protected mice in response to gut injury provoked by combined treatments with radiation and a chemotherapy drug. Impaired ISC-mediated epithelial development was found in mice deficient of the lactate G-protein-coupled receptor, Gpr81. Our results demonstrate that LAB-type symbiont-derived lactate plays a pivotal role in promoting ISC-mediated epithelial development in a Gpr81-dependent manner.
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http://dx.doi.org/10.1016/j.chom.2018.11.002DOI Listing
December 2018

Novel Compound Heterozygote Mutation in IL10RA in a Patient With Very Early-Onset Inflammatory Bowel Disease.

Inflamm Bowel Dis 2019 02;25(3):498-509

Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.

Background: Very early-onset inflammatory bowel disease (VEO-IBD) is often associated with monogenetic disorders. IL-10RA deficiency is one of the major causal mutations in VEO-IBD. Here, we aimed to identify the causal mutation associated with severe IBD in a 1-year-old patient, validate the pathogenicity of the mutation, and characterize the mutant protein.

Methods: To identify the causal mutation, targeted exome sequencing (ES) was performed using the genomic DNA from the patient. To validate the pathogenicity, IL-10RA functional tests were performed using the patient's peripheral blood mononuclear cells (PBMCs). Additionally, flow cytometry analysis, confocal microscopy on overexpressed green fluorescent protein-fused mutants, and computational analysis on the structures of IL-10RA proteins were performed.

Results: We identified a novel compound heterozygote mutation p.[Tyr91Cys];[Pro146Alafs*40] in the IL10RA gene of the patient. The missense variant p.Tyr91Cys was previously identified but not functionally tested, and a frameshift variant, p.Pro146Alafs*40, is novel and nonfunctional. PBMCs from the patient showed defective signal transducer and activator of transcription 3 activation. The p.Tyr91Cys mutant protein failed to properly localize on the plasma membrane. The p.Tyr91Cys mutation seems to disrupt the hydrophobic core structure surrounding the tyrosine 91 residue, causing structural instability.

Conclusions: Targeted ES and linkage analysis identified novel compound heterozygous mutations p.[Tyr91Cys];[Pro146Alafs*40] in the IL10RA gene of a child with severe VEO-IBD. p.Tyr91Cys proteins were functionally defective in IL-10RA signaling and failed to properly localize on the plasma membrane, probably due to its structural instability.
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http://dx.doi.org/10.1093/ibd/izy353DOI Listing
February 2019

Hypothalamic Macrophage Inducible Nitric Oxide Synthase Mediates Obesity-Associated Hypothalamic Inflammation.

Cell Rep 2018 10;25(4):934-946.e5

Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Ulsan College of Medicine, Seoul 05505, Korea. Electronic address:

Obesity-associated metabolic alterations are closely linked to low-grade inflammation in peripheral organs, in which macrophages play a central role. Using genetic labeling of myeloid lineage cells, we show that hypothalamic macrophages normally reside in the perivascular area and circumventricular organ median eminence. Chronic consumption of a high-fat diet (HFD) induces expansion of the monocyte-derived macrophage pool in the hypothalamic arcuate nucleus (ARC), which is significantly attributed to enhanced proliferation of macrophages. Notably, inducible nitric oxide synthase (iNOS) is robustly activated in ARC macrophages of HFD-fed obese mice. Hypothalamic macrophage iNOS inhibition completely abrogates macrophage accumulation and activation, proinflammatory cytokine overproduction, reactive astrogliosis, blood-brain-barrier permeability, and lipid accumulation in the ARC of obese mice. Moreover, central iNOS inhibition improves obesity-induced alterations in systemic glucose metabolism without affecting adiposity. Our findings suggest a critical role for hypothalamic macrophage-expressed iNOS in hypothalamic inflammation and abnormal glucose metabolism in cases of overnutrition-induced obesity.
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http://dx.doi.org/10.1016/j.celrep.2018.09.070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6284237PMC
October 2018

Efficacy of nano-particulated, water-soluble erlotinib against intracranial metastases of EGFR-mutant lung cancer.

Mol Oncol 2018 12 2;12(12):2182-2190. Epub 2018 Nov 2.

Department of Oncology, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, South Korea.

Central nervous system (CNS) metastasis is one of the serious complications of epidermal growth factor receptor (EGFR)-mutant lung cancer, which arises due to poor penetration of the brain-blood barrier by EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Although osimertinib, a third-generation EGFR-TKI, has efficacy against CNS metastases, further treatment modalities are still needed as some of these lesions do not respond to osimertinib, or undergo progression after an initial response to this drug if radiotherapy has already been conducted. Here, we investigated the efficacy of water-soluble erlotinib (NUFS-sErt) against these metastases. This agent was synthesized using a nano-particulation platform technology utilizing fat and supercritical fluid (NUFS™) to resolve the low solubility problem that typically prevents the creation of injectable forms of EGFR-TKIs. The average NUFS-sErt particle size was 236.4 nm, and it showed time-dependent dissolution in culture media. The effects of NUFS-sErt were similar to those of conventional erlotinib in terms of inhibiting the proliferation of EGFR-mutant lung cancer cells and suppressing EGFR signaling. In an intraperitoneal xenograft model of HCC827 cells, intraperitoneal administration of NUFS-sErt produced a dose-dependent inhibition of tumor growth and enhanced survival rate. Notably, the injection of NUFS-sErt into the brain ventricle caused significant tumor growth inhibition in an intracranial xenograft model. Hence, our current findings indicate that NUFS-sErt is a novel, water-soluble form of erlotinib that can be administered using intraventricular or intrathecal injections. The target cases would be patients with a progressive CNS metastasis and no other therapeutic options. This drug could also be given intravenously to patients with swallowing difficulties or an inability to ingest due to a medical condition.
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http://dx.doi.org/10.1002/1878-0261.12394DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6275278PMC
December 2018

Inhibition of euchromatin histone-lysine N-methyltransferase 2 sensitizes breast cancer cells to tumor necrosis factor-related apoptosis-inducing ligand through reactive oxygen species-mediated activating transcription factor 4-C/EBP homologous protein-death receptor 5 pathway activation.

Mol Carcinog 2018 11 19;57(11):1492-1506. Epub 2018 Jul 19.

ASAN Institute for Life Sciences, ASAN Medical Center, Seoul, Republic of Korea.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been characterized as an anti-cancer therapeutic agent with prominent cancer cell selectivity over normal cells. However, breast cancer cells are generally resistant to TRAIL, thus limiting its therapeutic potential. In this study, we found that BIX-01294, a selective inhibitor of euchromatin histone methyltransferase 2/G9a, is a strong TRAIL sensitizer in breast cancer cells. The combination of BIX-01294 and TRAIL decreased cell viability and led to an increase in the annexin V/propidium iodide-positive cell population, DNA fragmentation, and caspase activation. BIX-01294 markedly increased death receptor 5 (DR5) expression, while silencing of DR5 using small interfering RNAs abolished the TRAIL-sensitizing effect of BIX-01294. Specifically, BIX-01294 induced C/EBP homologous protein (CHOP)-mediated DR5 gene transcriptional activation and DR5 promoter activation was induced by upregulation of the protein kinase R-like endoplasmic reticulum kinase-mediated activating transcription factor 4 (ATF4). Moreover, inhibition of reactive oxygen species by N-acetyl-L-cysteine efficiently blocked BIX-01294-induced DR5 upregulation by inhibiting ATF4/CHOP expression, leading to diminished sensitization to TRAIL. These findings suggest that BIX-01294 sensitizes breast cancer cells to TRAIL by upregulating ATF4/CHOP-dependent DR5 expression with a reactive oxygen species-dependent manner. Furthermore, combination treatment with BIX-01294 and TRAIL suppressed tumor growth and induced apoptosis in vivo. In conclusion, we found that epigenetic regulation can contribute to the development of resistance to cancer therapeutics such as TRAIL, and further studies of unfolded protein responses and the associated epigenetic regulatory mechanisms may lead to the discovery of new molecular targets for effective cancer therapy.
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http://dx.doi.org/10.1002/mc.22872DOI Listing
November 2018

Generation of genetically-engineered animals using engineered endonucleases.

Arch Pharm Res 2018 Sep 17;41(9):885-897. Epub 2018 May 17.

ConveRgence mEDIcine research cenTer (CREDIT), Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea.

The key to successful drug discovery and development is to find the most suitable animal model of human diseases for the preclinical studies. The recent emergence of engineered endonucleases is allowing for efficient and precise genome editing, which can be used to develop potentially useful animal models for human diseases. In particular, zinc finger nucleases, transcription activator-like effector nucleases, and the clustered regularly interspaced short palindromic repeat systems are revolutionizing the generation of diverse genetically-engineered experimental animals including mice, rats, rabbits, dogs, pigs, and even non-human primates that are commonly used for preclinical studies of the drug discovery. Here, we describe recent advances in engineered endonucleases and their application in various laboratory animals. We also discuss the importance of genome editing in animal models for more closely mimicking human diseases.
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http://dx.doi.org/10.1007/s12272-018-1037-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6153862PMC
September 2018

Discovery of a Potent and Mutant-Selective EGFR Inhibitor that Overcomes T790M-Mediated Resistance in Lung Cancer.

Target Oncol 2018 06;13(3):389-398

Department of Oncology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, 05505, South Korea.

Background: Despite remarkable activity in epidermal growth factor receptor (EGFR)-mutant lung cancer patients, the clinical efficacy of EGFR tyrosine kinase inhibitors (TKIs) is limited by the emergence of acquired resistance, which is mostly caused by a secondary T790M mutation. Fortunately, newly developed, mutant-selective EGFR-TKIs against T790M have been proven as an effective therapeutic approach although only osimertinib has received the FDA approval until now.

Objective: To determine the in vitro and in vivo efficacy of a new EGFR TKI, OBX1-012 in cells with mutant EGFR.

Methods: Effects of OBX1-012 on cellular viability and EGFR-related signaling were determined in EGFR-mutant non-small cell lung cancer (NSCLC) cells, including cells harboring T790M mutations. In addition, in vivo efficacy of OBX1-012 was evaluated in xenograft models.

Results: We report the discovery and preclinical assessment of another novel, mutant-selective EGFR-TKI, OBX1-012. Compared with other mutant-selective EGFR-TKIs such as olumitinib and osimertinib, it showed similar potency and selectivity for mutant EGFR. OBX1-012 treatment was highly effective against human EGFR-mutant lung cancer models with or without EGFR T790M, not only in vitro but also in vivo. However, OBX1-012 like other EGFR-TKIs failed to exhibit efficacy for the exon 20 insertion mutation or C797S mutation, which was generated by site-directed mutagenesis and stable transfection of Ba/F3 cells.

Conclusions: These results identify OBX1-012 as a highly effective, mutant-selective EGFR-TKI for the treatment of T790M-mediated resistance in NSCLC.
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http://dx.doi.org/10.1007/s11523-018-0568-zDOI Listing
June 2018

Discovery of a Potent and Mutant-Selective EGFR Inhibitor that Overcomes T790M-Mediated Resistance in Lung Cancer.

Target Oncol 2018 06;13(3):389-398

Department of Oncology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, 05505, South Korea.

Background: Despite remarkable activity in epidermal growth factor receptor (EGFR)-mutant lung cancer patients, the clinical efficacy of EGFR tyrosine kinase inhibitors (TKIs) is limited by the emergence of acquired resistance, which is mostly caused by a secondary T790M mutation. Fortunately, newly developed, mutant-selective EGFR-TKIs against T790M have been proven as an effective therapeutic approach although only osimertinib has received the FDA approval until now.

Objective: To determine the in vitro and in vivo efficacy of a new EGFR TKI, OBX1-012 in cells with mutant EGFR.

Methods: Effects of OBX1-012 on cellular viability and EGFR-related signaling were determined in EGFR-mutant non-small cell lung cancer (NSCLC) cells, including cells harboring T790M mutations. In addition, in vivo efficacy of OBX1-012 was evaluated in xenograft models.

Results: We report the discovery and preclinical assessment of another novel, mutant-selective EGFR-TKI, OBX1-012. Compared with other mutant-selective EGFR-TKIs such as olumitinib and osimertinib, it showed similar potency and selectivity for mutant EGFR. OBX1-012 treatment was highly effective against human EGFR-mutant lung cancer models with or without EGFR T790M, not only in vitro but also in vivo. However, OBX1-012 like other EGFR-TKIs failed to exhibit efficacy for the exon 20 insertion mutation or C797S mutation, which was generated by site-directed mutagenesis and stable transfection of Ba/F3 cells.

Conclusions: These results identify OBX1-012 as a highly effective, mutant-selective EGFR-TKI for the treatment of T790M-mediated resistance in NSCLC.
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http://dx.doi.org/10.1007/s11523-018-0568-zDOI Listing
June 2018

Preliminary Psychometric Evaluation of the Hamilton Depression Rating Scale in Methamphetamine Dependence.

J Dual Diagn 2017 Oct-Dec;13(4):305-311. Epub 2017 Aug 18.

d Department of Mathematical Sciences , Montana State University , Bozeman , Montana , USA.

Objective: The purpose of this study was to test the initial psychometric properties of the 17-item Hamilton Depression Rating Scale (HAM-D) in individuals with and without major depressive disorder who use methamphetamine. We used data from two completed studies and two ongoing clinical trials. The HAM-D has well established reliability and validity in a variety of populations. However, there are no published reports of reliability and validity of the HAM-D in a methamphetamine-using population.

Methods: HAM-D and depression status data were extracted from four separate studies for this psychometric assessment. Using these data, we evaluated three measures of construct validity: internal consistency, contrasted group validity, and factorial validity.

Results: We found potential concerns with the construct validity of the HAM-D in users of methamphetamine. Intercorrelations between items were primarily less than 0.20 and the Cronbach's alpha value in this sample was 0.58, indicating potential issues with internal consistency. The results of two-sample t-tests suggest concerns with contrasted group validity, as no significant difference in average scores were found for nine items. Consistent with previous studies, a principal component analysis indicates that the HAM-D is multidimensional.

Conclusions: The 17-item HAM-D might not reliably and validly measure depression severity in a methamphetamine-using population. Given our small sample, additional research is needed, though, to further test the psychometric properties of the HAM-D in individuals who use methamphetamine.
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http://dx.doi.org/10.1080/15504263.2017.1356493DOI Listing
July 2018

Use of a patterned current blocking layer to enhance the light output power of InGaN-based light-emitting diodes.

Opt Express 2017 Jul;25(15):17556-17561

We employed a patterned current blocking layer (CBL) to enhance light output power of GaN-based light-emitting diodes (LEDs). Nanoimprint lithography (NIL) was used to form patterned CBLs (a diameter of 260 nm, a period of 600, and a height of 180 nm). LEDs (chip size: 300 × 800 µm) fabricated with no CBL, a conventional SiO CBL, and a patterned SiO CBL, respectively, exhibited forward-bias voltages of 3.02, 3.1 and 3.1 V at an injection current of 20 mA. The LEDs without and with CBLs gave series resistances of 9.8 and 11.0 Ω, respectively. The LEDs with a patterned SiO CBL yielded 39.6 and 11.9% higher light output powers at 20 mA, respectively, than the LEDs with no CBL and conventional SiO CBL. On the basis of emission images and angular transmittance results, the patterned CBL-induced output enhancement is attributed to the enhanced light extraction and current spreading.
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http://dx.doi.org/10.1364/OE.25.017556DOI Listing
July 2017

An Open-Label Pilot Study of Combined Augmentation With Creatine Monohydrate and 5-Hydroxytryptophan for Selective Serotonin Reuptake Inhibitor- or Serotonin-Norepinephrine Reuptake Inhibitor-Resistant Depression in Adult Women.

J Clin Psychopharmacol 2017 Oct;37(5):578-583

From the *Department of Psychiatry and †Brain Institute, University of Utah; and ‡Veterans Integrated Service Network 19 Mental Illness Research Education Clinical, Centers of Excellence, Salt Lake City Veterans Affairs Medical Center, Salt Lake City, UT.

Purpose: Many women with major depressive disorder (MDD) respond inadequately to standard treatments. Augmentation of conventional antidepressants with creatine monohydrate and 5-hydroxytryptophan (5-HTP) could correct deficits in serotonin production and brain bioenergetics associated with depression in women, yielding synergistic benefit. We describe an open-label study of 5-HTP and creatine augmentation in women with MDD who had failed selective serotonin reuptake inhibitor (SSRI) or serotonin-norepinephrine reuptake inhibitor (SNRI) monotherapy.

Methods: Fifteen women who were adequately adherent to an SSRI or SNRI and currently experiencing MDD, with a 17-item Hamilton Depression Rating Scale (HAM-D) score of 16 or higher, were treated with 5 g of creatine monohydrate daily and 100 mg of 5-HTP twice daily for 8 weeks, with 4 weeks of posttreatment follow-up. The primary outcome was change in mean HAM-D scores.

Results: Mean HAM-D scores declined from 18.9 (SD, 2.5) at pretreatment visits to 7.5 (SD, 4.4) (P < 0.00001), a decrease of 60%. Participants did not experience any serious treatment-related adverse events.

Conclusions: Combination treatment with creatine and 5-HTP may represent an effective augmentation strategy for women with SSRI- or SNRI-resistant depression. Given the limitations of this small, open-label trial, future study in randomized, placebo-controlled trials is warranted.
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http://dx.doi.org/10.1097/JCP.0000000000000754DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5578880PMC
October 2017

Superior Efficacy and Selectivity of Novel Small-Molecule Kinase Inhibitors of T790M-Mutant EGFR in Preclinical Models of Lung Cancer.

Cancer Res 2017 03 12;77(5):1200-1211. Epub 2017 Jan 12.

Department of Oncology, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea.

The clinical utility of approved EGFR small-molecule kinase inhibitors is plagued both by toxicity against wild-type EGFR and by metastatic progression in the central nervous system, a disease sanctuary site. Here, we report the discovery and preclinical efficacy of GNS-1486 and GNS-1481, two novel small-molecule EGFR kinase inhibitors that are selective for T790M-mutant isoforms of EGFR. Both agents were effective in multiple mouse xenograft models of human lung adenocarcinoma (T790M-positive or -negative), exhibiting less activity against wild-type EGFR than existing approved EGFR kinase inhibitors (including osimertinib). In addition, GNS-1486 showed superior potency against intracranial metastasis of EGFR-mutant lung adenocarcinoma. Our results offer a preclinical proof of concept for new EGFR kinase inhibitors with the potential to improve therapeutic index and efficacy against brain metastases in patients. .
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http://dx.doi.org/10.1158/0008-5472.CAN-16-2432DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5334209PMC
March 2017

Establishment of a Conditional Transgenic Mouse Model Recapitulating EML4-ALK-Positive Human Non-Small Cell Lung Cancer.

J Thorac Oncol 2017 03 9;12(3):491-500. Epub 2016 Nov 9.

Division of Medical Oncology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea. Electronic address:

Background: Anaplastic lymphoma receptor tyrosine kinase gene (ALK) fusion is a distinct molecular subclassification of NSCLC that is targeted by anaplastic lymphoma kinase (ALK) inhibitors. We established a transgenic mouse model that expresses tumors highly resembling human NSCLC harboring echinoderm microtubule associated protein like 4 gene (EML)-ALK fusion. We aimed to test an EML4-ALK transgenic mouse model as a platform for assessing the efficacy of ALK inhibitors and examining mechanisms of acquired resistance to ALK inhibitors.

Methods: Transgenic mouse lines harboring LoxP-STOP-LoxP-FLAGS-tagged human EML4-ALK (variant 1) transgene was established by using C57BL/6N mice. The transgenic mouse model with highly lung-specific, inducible expression of echinoderm microtubule associated protein like 4-ALK fusion protein was established by crossing the EML4-ALK transgenic mice with mice expressing Cre-estrogen receptor fusion protein under the control of surfactant protein C gene (SPC). Expression of EML4-ALK transgene was induced by intraperitoneally injecting mice with tamoxifen. When the lung tumor of the mice treated with the ALK inhibitor crizotinib for 2 weeks was measured, tumor shrinkage was observed.

Results: EML4-ALK tumor developed after 1 week of tamoxifen treatment. Echinoderm microtubule associated protein like 4-ALK was strongly expressed in the lung but not in other organs. ALK and FLAGS expressions were observed by immunohistochemistry. Treatment of EML4-ALK tumor-bearing mice with crizotinib for 2 weeks induced dramatic shrinkage of tumors with no signs of toxicity. Furthermore, prolonged treatment with crizotinib led to acquired resistance in tumors, resulting in regrowth and disease progression. The resistant tumor nodules revealed acquired ALK G1202R mutations.

Conclusions: An EML4-ALK transgenic mouse model for study of drug resistance was successfully established with short duration of tumorigenesis. This model should be a strong preclinical model for testing efficacy of ALK TKIs, providing a useful tool for investigating the mechanisms of acquired resistance and pursuing novel treatment strategies in ALK-positive lung cancer.
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http://dx.doi.org/10.1016/j.jtho.2016.10.022DOI Listing
March 2017

PIERCE1 is critical for specification of left-right asymmetry in mice.

Sci Rep 2016 06 16;6:27932. Epub 2016 Jun 16.

Department of Biochemistry, College of Life Science and Biotechnology and Yonsei Laboratory Animal Research Center, Yonsei University, Seoul 03722, Republic of Korea.

The specification of left-right asymmetry of the visceral organs is precisely regulated. The earliest breakage of left-right symmetry occurs as the result of leftward flow generated by asymmetric beating of nodal cilia, which eventually induces asymmetric Nodal/Lefty/Pitx2 expression on the left side of the lateral plate mesoderm. PIERCE1 has been identified as a p53 target gene involved in the DNA damage response. In this study, we found that Pierce1-null mice exhibit severe laterality defects, including situs inversus totalis and heterotaxy with randomized situs and left and right isomerisms. The spectrum of laterality defects was closely correlated with randomized expression of Nodal and its downstream genes, Lefty1/2 and Pitx2. The phenotype of Pierce1-null mice most closely resembled that of mutant mice with impaired ciliogenesis and/or ciliary motility of the node. We also found the loss of asymmetric expression of Cerl2, the earliest flow-responding gene in the node of Pierce1-null embryos. The results suggest that Pierce1-null embryos have defects in generating a symmetry breaking signal including leftward nodal flow. This is the first report implicating a role for PIERCE1 in the symmetry-breaking step of left-right asymmetry specification.
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http://dx.doi.org/10.1038/srep27932DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4917697PMC
June 2016

Generation of knockout mice by Cpf1-mediated gene targeting.

Nat Biotechnol 2016 08 6;34(8):808-10. Epub 2016 Jun 6.

Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea.

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http://dx.doi.org/10.1038/nbt.3614DOI Listing
August 2016

Activation of the IGF1R pathway potentially mediates acquired resistance to mutant-selective 3rd-generation EGF receptor tyrosine kinase inhibitors in advanced non-small cell lung cancer.

Oncotarget 2016 Apr;7(16):22005-15

Department of Oncology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, Korea.

Mutant-selective, 3rd-generation EGFR-TKIs were recently developed to control lung cancer cells harboring T790M-mediated resistance. However, the development of resistance to these novel drugs seems inevitable. Thus, we investigated the mechanism of acquired resistance to the mutant-selective EGFR-TKI WZ4002. We established five WZ4002-resistant cells, derived from cells harboring both EGFR and T790M mutations by long-term exposure to increasing doses of WZ4002. Compared with the parental cells, all resistant cells showed 10-100-folds higher resistance to WZ4002, as well as cross-resistance to other mutant-selective inhibitors. Among them, three resistant cells (HCC827/WR, PC-9/WR and H1975/WR) showed dependency on EGFR signaling, but two other cells (PC-9/GR/WR and PC-9/ER/WR) were not. Notably, insulin-like growth factor-1 receptor (IGF1R) was aberrantly activated in PC-9/GR/WR cells in phospho-receptor tyrosine kinase array, consistently accompanied by loss of IGF binding protein-3 (IGFBP3). Down-regulation of IGF1R by shRNA, as well as inhibition of IGF1R activity either by AG-1024 (a small molecule IGF1R inhibitor) or BI 836845 (a monoclonal anti-IGF1/2 blocking antibody), restored the sensitivity to WZ4002 both in vitro and xenograft. Taken together, these results suggest that activation of the IGF1R pathway associated with IGFBP3 loss can induce an acquired resistance to the mutant-selective EGFR-TKI, WZ4002. Therefore, a combined therapy of IGF1R inhibitors and mutant-selective EGFR-TKIs might be a viable treatment strategy for overcoming acquired resistance.
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http://dx.doi.org/10.18632/oncotarget.8013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5008340PMC
April 2016

Creatine target engagement with brain bioenergetics: a dose-ranging phosphorus-31 magnetic resonance spectroscopy study of adolescent females with SSRI-resistant depression.

Amino Acids 2016 08 23;48(8):1941-54. Epub 2016 Feb 23.

Department of Psychiatry, University of Utah School of Medicine, 501 Chipeta Way, Salt Lake City, UT, 84108, USA.

Major depressive disorder (MDD) often begins during adolescence and is projected to become the leading cause of global disease burden by the year 2030. Yet, approximately 40 % of depressed adolescents fail to respond to standard antidepressant treatment with a selective serotonin reuptake inhibitor (SSRI). Converging evidence suggests that depression is related to brain mitochondrial dysfunction. Our previous studies of MDD in adult and adolescent females suggest that augmentation of SSRI pharmacotherapy with creatine monohydrate (CM) may improve MDD outcomes. Neuroimaging with phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS) can measure the high-energy phosphorus metabolites in vivo that reflect mitochondrial function. These include phosphocreatine (PCr), a substrate for the creatine kinase reaction that produces adenosine triphosphate. As part of the National Institute of Mental Health's experimental medicine initiative, we conducted a placebo-controlled dose-ranging study of adjunctive CM for adolescent females with SSRI-resistant MDD. Participants were randomized to receive placebo or CM 2, 4 or 10 g daily for 8 weeks. Pre- and post-treatment (31)P-MRS scans were used to measure frontal lobe PCr, to assess CM's target engagement with cerebral energy metabolism. Mean frontal lobe PCr increased by 4.6, 4.1 and 9.1 % in the 2, 4 and 10 g groups, respectively; in the placebo group, PCr fell by 0.7 %. There was no group difference in adverse events, weight gain or serum creatinine. Regression analysis of PCr and depression scores across the entire sample showed that frontal lobe PCr was inversely correlated with depression scores (p = 0.02). These results suggest that CM achieves target engagement with brain bioenergetics and that the target is correlated with a clinical signal. Further study of CM as a treatment for adolescent females with SSRI-resistant MDD is warranted.
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http://dx.doi.org/10.1007/s00726-016-2194-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4974294PMC
August 2016
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