The L441P Mutation of Cystic Fibrosis Transmembrane conductance Regulator and its Molecular Pathogenic Mechanisms in a Korean Patient with Cystic Fibrosis

Gee, Heon Yung,Kim, Chang Keun,Kim, So Won,Lee, Ji Hyun,Kim, Jeong-Ho,Kim, Kyung Hwan,Lee, Min Goo The Korean Academy of Medical Sciences 2010 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.25 No.1

<P>Cystic fibrosis (CF) is an autosomal recessive disorder usually found in populations of white Caucasian descent. CF is caused by mutations in the Cystic Fibrosis Transmembrane conductance Regulator (<I>CFTR</I>) gene. A 5-yr-old Korean girl was admitted complaining of coughing and greenish sputum. Chest radiographs and computed tomographic (CT) scan revealed diffuse bronchiectasis in both lungs. The patient had chronic diarrhea and poor weight gain, and the abdominal pancreaticobiliary CT scan revealed atrophy of the pancreas. Finally, CF was confirmed by the repeated analysis of the quantitative pilocarpine iontophoresis test. The chloride concentration of sweat samples taken from both forearms of the pateint was an average of 88.7 mM/L (normal value <40 mM/L). After a comprehensive search for mutations in the <I>CFTR</I> gene, the patient was found to carry the non-synonymous L441P mutation in one allele. Molecular physiologic analysis of the L441P mutation of CFTR revealed that the L441P mutation completely abolished the CFTR Cl<SUP>-</SUP> channel activity by disrupting proper protein folding and membrane trafficking of CFTR protein. These results confirmed the pathogenicity of the L441P mutation of CFTR circulating in the Korean population. The possibility of CF should be suspected in patients with chronic bronchiectasis, although the frequency of CF is relatively rare in East Asia.</P>

Rescue of ΔF508-CFTR Trafficking via a GRASP-Dependent Unconventional Secretion Pathway

Gee, Heon ,Yung,Noh, Shin ,Hye,Tang, Bor ,Luen,Kim, Kyung ,Hwan,Lee, Min ,Goo Elsevier 2011 Cell Vol.146 No.5

<P><B>Summary</B></P><P>The most prevalent disease-causing mutation of CFTR is the deletion of Phe508 (ΔF508), which leads to defects in conventional Golgi-mediated exocytosis and cell surface expression. We report that ΔF508-CFTR surface expression can be rescued in vitro and in vivo by directing it to an unconventional GRASP-dependent secretion pathway. An integrated molecular and physiological analysis indicates that mechanisms associated with ER stress induce cell surface trafficking of the ER core-glycosylated wild-type and ΔF508-CFTR via the GRASP-dependent pathway. Phosphorylation of a specific site of GRASP and the PDZ-based interaction between GRASP and CFTR are critical for this unconventional surface trafficking. Remarkably, transgenic expression of GRASP in ΔF508-CFTR mice restores CFTR function and rescues mouse survival without apparent toxicity. These findings provide insight into how unconventional protein secretion is activated, and offer a potential therapeutic strategy for the treatment of cystic fibrosis and perhaps diseases stemming from other misfolded proteins.</P> <P><B>Graphical Abstract</B></P><P><ce:figure id='dfig1'></ce:figure></P><P><B>Highlights</B></P><P>► Mechanisms associated with ER stress activate unconventional protein secretion ► The GRASP-dependent pathway traffics core-glycosylated CFTR to the cell surface ► GRASP specifically associates with CFTR by a PDZ-based mechanism ► GRASP rescues the defects of ΔF508-CFTR in HEK293 cells and mice</P> <P>The common cystic fibrosis mutant of CFTR becomes functional and can reverse disease symptoms in mice when transported to the cell surface through a secretion pathway that bypasses the Golgi.</P>

Deep learning outperforms kidney organoid experts

( Seyoung Yu ),( Heon Yung Gee ) 대한신장학회 2023 Kidney Research and Clinical Practice Vol.42 No.1

작동유체가 양방향성 태양열 열다이오드의 열성능에 미치는 영향 분석

고영주(Ko Yung-Joo),현준호(Hyun Jun-Ho),이헌주(Lee Heon-Ju),천원기(Chun Won-Gee) 한국태양에너지학회 2007 한국태양에너지학회 학술대회논문집 Vol.- No.-

A series of experiments were conducted to investigate the effects of different working fluids on the behavior and thermal performance of a bi-directional solar thermodiode. The solar thermodiode was made up of two L-shaped loops mounted between a collector plate and a storage tank. Rotatable joints between the horizontal and inclined segments of the loops enable easy alteration of the direction of heat transfer. The loops and the tank were filled with a working fluid for effective heat transfer when the solar thermodiode was forwarded biased. Six different working fluids were tested with thermal conductivity values ranging from 0.1 to 0.56 W/m-℃, thermal expansion coefficient values ranging from 1.8 × 10⁻⁴ to 1.3 × 10⁻³ K⁻¹, and kinematic viscosity values ranging from 0.65 × 10⁻⁶ to 100 × 10⁻⁶ ㎡/s. The solar thermodiode was heated by a radiant heater consisting of 20 halogen lamps that generated a heat flux of about 1000 W/㎡ on the collector surface.

Unconventional protein secretion – new insights into the pathogenesis and therapeutic targets of human diseases

Kim, Jiyoon,Gee, Heon Yung,Lee, Min Goo The Company of Biologists Ltd. 2018 Journal of cell science Vol.131 No.12

<P>Most secretory proteins travel through a well-documented conventional secretion pathway involving the endoplasmic reticulum (ER) and the Golgi complex. However, recently, it has been shown that a significant number of proteins reach the plasma membrane or extracellular space via unconventional routes. Unconventional protein secretion (UPS) can be divided into two types: (i) the extracellular secretion of cytosolic proteins that do not bear a signal peptide (i.e. leaderless proteins) and (ii) the cell-surface trafficking of signal-peptide-containing transmembrane proteins via a route that bypasses the Golgi. Understanding the UPS pathways is not only important for elucidating the mechanisms of intracellular trafficking pathways but also has important ramifications for human health, because many of the proteins that are unconventionally secreted by mammalian cells and microorganisms are associated with human diseases, ranging from common inflammatory diseases to the lethal genetic disease of cystic fibrosis. Therefore, it is timely and appropriate to summarize and analyze the mechanisms of UPS involvement in disease pathogenesis, as they may be of use for the development of new therapeutic approaches. In this Review, we discuss the intracellular trafficking pathways of UPS cargos, particularly those related to human diseases. We also outline the disease mechanisms and the therapeutic potentials of new strategies for treating UPS-associated diseases.</P>

Specific autophagy and ESCRT components participate in the unconventional secretion of CFTR

Noh, Shin Hye,Gee, Heon Yung,Kim, Yonjung,Piao, He,Kim, Jiyoon,Kang, Chung Min,Lee, Gahyung,Mook-Jung, Inhee,Lee, Yangsin,Cho, Jin Won,Lee, Min Goo Informa UK (TaylorFrancis) 2018 AUTOPHAGY Vol.14 No.10

<P>The most common mutation in cystic fibrosis patients is a phenylalanine deletion at position 508 (Delta F508) in the CFTR (cystic fibrosis transmembrane conductance regulator) gene. This mutation impairs cell-surface trafficking of CFTR. During cellular stress, core-glycosylated CFTR Delta F508 is transported to the cell surface from the endoplasmic reticulum (ER) via an unconventional route that bypasses the Golgi. However, the mechanisms for this unconventional secretory pathway of CFTR are not well delineated. Here, we report that components of the macroautophagy/autophagy and ESCRT (endosomal sorting complex required for transport) pathways are involved in unconventional secretion of CFTR. In mammalian cells, we found that autophagic pathways were modulated by conditions that also stimulate unconventional secretion, namely ER stress and an ER-to-Golgi transport blockade. Additionally, we found that knockdown of early autophagy components, ATG5 and ATG7, and treatment with pharmacological autophagy inhibitors, wortmannin and 3-methyladenine, abolished the unconventional secretion of CFTR that had been stimulated by ER stress and an ER-to-Golgi blockade. Interestingly, immunoelectron microscopy revealed that GORASP2/GRASP55, which mediates unconventional CFTR trafficking, is present in multivesicular bodies (MVB) and autophagosomal structures under ER stress conditions. A custom small-interfering RNA screen of mammalian ESCRT proteins that mediate MVB biogenesis showed that silencing of some ESCRTs, including MVB12B, inhibited unconventional CFTR Delta F508 secretion. Furthermore, MVB12B overexpression partially rescued cell-surface expression and Cl- channel function of CFTR Delta F508. Taken together, these results suggest that components involved in early autophagosome formation and the ESCRT/MVB pathway play a key role in the stress-induced unconventional secretion of CFTR.</P>

Mutations in sphingosine-1-phosphate lyase cause nephrosis with ichthyosis and adrenal insufficiency

Lovric, Svjetlana,Goncalves, Sara,Gee, Heon Yung,Oskouian, Babak,Srinivas, Honnappa,Choi, Won-II,Shril, Shirlee,Ashraf, Shazia,Tan, Weizhen,Rao, Jia American Society for Clinical Investigation 2017 The Journal of clinical investigation Vol.127 No.3

<P>Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease cases. A mutation in 1 of over 40 monogenic genes can be detected in approximately 30% of individuals with SRNS whose symptoms manifest before 25 years of age. However, in many patients, the genetic etiology remains unknown. Here, we have performed whole exome sequencing to identify recessive causes of SRNS. In 7 families with SRNS and facultative ichthyosis, adrenal insufficiency, immunodeficiency, and neurological defects, we identified 9 different recessive mutations in SGPL1, which encodes sphingosine-1-phosphate (S1P) lyase. All mutations resulted in reduced or absent SGPL1 protein and/or enzyme activity. Overexpression of cDNA representing SGPL1 mutations resulted in subcellular mislocalization of SGPL1. Furthermore, expression of WT human SGPL1 rescued growth of SGPL1-deficient dpl1. yeast strains, whereas expression of disease-associated variants did not. Immunofluorescence revealed SGPL1 expression in mouse podocytes and mesangial cells. Knockdown of Sgpl1 in rat mesangial cells inhibited cell migration, which was partially rescued by VPC23109, an S1P receptor antagonist. In Drosophila, Sply mutants, which lack SGPL1, displayed a phenotype reminiscent of nephrotic syndrome in nephrocytes. WT Sply, but not the disease-associated variants, rescued this phenotype. Together, these results indicate that SGPL1 mutations cause a syndromic form of SRNS.</P>

A Small Molecule That Binds to an ATPase Domain of Hsc70 Promotes Membrane Trafficking of Mutant Cystic Fibrosis Transmembrane Conductance Regulator

Cho, Hyungseoph J.,Gee, Heon Yung,Baek, Kyung-Hwa,Ko, Sung-Kyun,Park, Jong-Moon,Lee, Hookeun,Kim, Nam-Doo,Lee, Min Goo,Shin, Injae American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.50

<P>Cystic fibrosis transmembrane conductance regulator (CFTR) is a cell-surface anion channel that permeates chloride and bicarbonate ions. The most frequent mutation of CFTR that causes cystic fibrosis is the deletion of phenylalanine at position 508 (δF508), which leads to defects in protein folding and cellular trafficking to the plasma membrane. The lack of the cell-surface CFTR results in a reduction in the lifespan due to chronic lung infection with progressive deterioration of lung function. Hsc70 plays a crucial role in degradation of mutant CFTR by the ubiquitin-proteasome system. To date, various Hsc70 inhibitors and transcription regulators have been tested to determine whether they correct the defective activity of mutant CFTR. However, they exhibited limited or questionable effects on restoring the chloride channel activity in cystic fibrosis cells. Herein, we show that a small molecule apoptozole (Az) has high cellular potency to promote membrane trafficking of mutant CFTR and its chloride channel activity in cystic fibrosis cells. Results from affinity chromatography and ATPase activity assay indicate that Az inhibits the ATPase activity of Hsc70 by binding to its ATPase domain. In addition, a ligand-directed protein labeling and molecular modeling studies also suggest the binding of Az to an ATPase domain, in particular, an ATP-binding pocket. It is proposed that Az suppresses ubiquitination of δF508-CFTR maybe by blocking interaction of the mutant with Hsc70 and CHIP, and, as a consequence, it enhances membrane trafficking of the mutant.</P>

Lactobacillus plantarum ameliorates NASH-related inflammation by upregulating l-arginine production

Kim Dong Yun,Park Jun Yong,Gee Heon Yung 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Lactobacillus is a probiotic with therapeutic potential for several diseases, including liver disease. However, the therapeutic effect of L. plantarum against nonalcoholic steatohepatitis (NASH) and its underlying mechanisms remain unelucidated. Therefore, we delineated the L. plantarum-mediated NASH regulation in a mouse model to understand its therapeutic effect. We used a choline-deficient high-fat diet (CD-HFD)-induced murine model that recapitulated the critical features of human metabolic syndrome and investigated the effect of L. plantarum on NASH pathogenesis using transcriptomic, metagenomic, and immunohistochemistry analyses. Validation experiments were performed using liver organoids and a murine model fed a methionine-choline-deficient (MCD) diet. L. plantarum treatment in mice significantly decreased liver inflammation and improved metabolic phenotypes, such as insulin tolerance and the hepatic lipid content, compared with those in the vehicle group. RNA-sequencing analysis revealed that L. plantarum treatment significantly downregulated inflammation-related pathways. Shotgun metagenomic analysis revealed that L-arginine biosynthesis-related microbial genes were significantly upregulated in the L. plantarum group. We also confirmed the elevated arginine levels in the serum of the L. plantarum group. We further used liver organoids and mice fed an MCD diet to demonstrate that L-arginine alone was sufficient to alleviate liver inflammation. Our data revealed a novel and counterintuitive therapeutic effect of L. plantarum on alleviating NASH-related liver inflammation by increasing circulating L-arginine.

The Therapeutic Effect of Lactobacillus Plantarum on Metabolic Phenotypes in Non-Alcoholic Fatty Liver Disease Mice Model

( Dong Yun Kim ),( Jae Seung Lee ),( Heon Yung Gee ),( Junyong Park ) 대한간학회 2021 춘·추계 학술대회 (KASL) Vol.2021 No.1