Emerging role of mitophagy in human diseases and physiology

( Jee-hyun Um ),( Jeanho Yun ) 생화학분자생물학회 2017 BMB Reports Vol.50 No.6

Mitophagy is a process of selective removal of damaged or unnecessary mitochondria using autophagic machinery. Mitophagy plays an essential role in maintaining mitochondrial quality control and homeostasis. Mitochondrial dysfunctions and defective mitophagy in neurodegenerative diseases, cancer, and metabolic diseases indicate a close link between human disease and mitophagy. Furthermore, recent studies showing the involvement of mitophagy in differentiation and development, suggest that mitophagy may play a more active role in controlling cellular functions. A better understanding of mitophagy will provide insights about human disease and offer novel chance for treatment. This review mainly focuses on the recent implications for mitophagy in human diseases and normal physiology. [BMB Reports 2017; 50(6): 299-307]

Selective induction of mitophagy using an isoquinoline alkaloid CD1-012 improves mitochondrial dysfunction and cognitive impairment in Alzheimer’s disease model

Jee-Hyun Um,Dong Jin Shin,Young Yeon Kim,Dae Jin Jung,Jong Hyun Cho,Jeanho Yun 한국실험동물학회 2021 한국실험동물학회 학술발표대회 논문집 Vol.2021 No.7

Mitophagy, a selective degradation of damaged mitochondria, plays a central role in maintaining mitochondria quality control. Previous studies showed a decrease in mitophagy activity is closely related to neurodegenerative diseases including Alzheimer’s disease. Increasing mitophagy is now considered a promising strategy for the treatment of neurodegenerative diseases. However, mitophagy inducer that is effective enough to treat disease and has low toxicity is very limited. Using previously developed mitophagy assay system and single compound library from medicinal plants, we have identified isoquinoline alkaloid PA17 as a mitophagy inducers. Through chemical optimization, we developed CD1-012 that is tens of times more active in promoting mitophagy activity. CD1-012 treatment was not induced a collapse of mitochondria membrane potential and an increase of mitochondrial ROS level, indicating that CD1-012 is not act as mitochondria toxin. In addition, analysis of subcellular organelle proteins revealed that CD1-012 specifically induces degradation of mitochondria. Administration of CD1-012 to APPswd/PS2 Alzheimer’s disease mouse model for four weeks significantly improved cognition defects evidenced by Morris water maze test. More importantly, mitochondria dysfunction in hippocampus of APPswd/PS2 mouse model was also significantly rescued upon CD1-012 treatment. Taken together, our results suggest that induction of mitophagy is promising strategy for the treatment of Alzheimer’s disease and CD1-012 is a potential candidate for mitophagy-based medicine. This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (2016R1A5A2007009) and by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare and Ministry of science and ICT, Republic of Korea (HU21C0107).

Increased and correlated nuclear factor-kappa B and Ku autoantigen activities are associated with development of multidrug resistance

Um, Jee Hyun,Kang, Chi Dug,Lee, Bok Gun,Kim, Dong Wan,Chung, Byung Seon,Kim, Sun Hee 부산대학교 유전공학연구소 2001 분자생물학 연구보 Vol.17 No.-

In this syudy, we investigated possible engagement of NF-κB and Ku autoantigen (Ku) activation in development of multidrug resistance (MDR) and circumvention of MDR by modulation of NF-κB and Ku. The NF-κB activity and NF-κB p65 subunit level were constitutively higher in MDR cells than in drug-sensitive parental cells. Interestingly, a faster running NF-κB DNA binding complex was identified as Ku, a DNA binding complex was identified as Ku, a DNA damage sensor and a key double strand break repair protein, and was positively correlated with the NF-κB-transfected cells. Also both NF-κB and Ku activities were activated or inhibited by treatment with etoposide (VP-16) MG-132 (a proteasome inhibitor), respectively. Furthermore, PKA inhibitor suppressed markedly the constitutive and drug-induced activities of NF-κB and Ku in MDR cells and subsequently potentiated the cytotoxic activity of antivancer drugs. Our results proposed that the NF-κB and Ku activation could be one of multi-factorial MDR mechanism, and PKA inhibitor, likely via inhibition of NF-κB and Ku activities, could enhance the effectiveness of anticancer drugs against MDR cells with high activities of NF-κB and Ku. Oncogene (2001) 20, 6048-6056.

Basic, HCC basic : O-029 ; Enhanced inactivation of immortalized hepatic stellate cell line by the synergistic effect of combination of HMG CoA reductase inhibitor and selective COX-2 inhibitor

( Jee Won Hwang ),( Hyung Joon Yim ),( Hyun Jung Lee ),( Sun Jae Lee ),( Eileen L Yoon ),( Sang Jun Suh ),( Ji Hoon Kim ),( Jong Eun Yeon ),( Soon Ho Um ),( Kwan Soo Byun ) 대한간학회 2012 춘·추계 학술대회 (KASL) Vol.2012 No.-

Department of Internal Medicine, Division of Gastroenterology and Hepatology, Korea University College of Medicine Background: Hepatic stellate cells (HSCs) are a major fibrogenic cell type that contributes to collagen accumulation during chronic liver disease. The NS-398 (a selective COX-2 inhibitor) is a potential drug of chemoprevention and treatment of liver fibrosis by inhibiting HSC activation. The simvastatin (a HMG CoA reductase inhibitor) revert the myofibroblasts-like phenotype of HSC towards a more quiescent phenotype. We investigated the anti-fibrotic and pro-apoptotic mechanisms in synergistic effects of both drugs as using the human hepatic stellate cell line. Methods: The immortalized human hepatic stellate cell line, LX-2 was cultured. The cells were treated with control, simvastatin, NS-398, and combination of simvastatin and NS-398 for 24 and 48 hours. Cellular DNA synthesis was evaluated by measuring BrdU incorporation. Expression of proteins including cell cycle regulators such as p21, cyclinD1 and Akt, NF-kB, caspase-3, caspase-9 as apoptotic factors, α -smooth muscle actin (α-SMA) were measured in Western blot analysis. Results: In BrdU-proliferation assay, combination of two drugs effectively inhibited the proliferation rate compared to monotherapy. The combination of two drugs resulted in a greater decrease of procaspase-3, -9, Akt and NF-kB than monotherapy depend on the concentration of two drugs. In addition, the combination of NS-398 and simvastatin significantly promote the inactivation of HSCs by reducing the amounts of α-SMA protein. Conclusions: We suggested that both of two drugs have synergistic effects that anti-proliferative, pro-apoptotic and anti-fibrotic effects on activated HSCs. The mechanism of synergistic pro-apoptotic effect seems to be mediated through inhibition of NF-kB/Akt pathway and caspase activity.

Characterization of Expressed Sequence Tags (EST) Sequences from Normalized Full Length Enriched cDNA Library of Perilla frutescens

Jee Young Park,Nam Hoon Kim,Jonghoon Lee,Hong Il Choi,Yun Sun Lee,Shailendra Karki,Nur Kholilatul Izzah,Sampath Perumal,Ju Yeon Jeong,Jun Ki Lee,Hyun-Seung Park,Seung Duk Um,Sang-Haeng Choi,Hong-Seog 한국작물학회 2010 한국작물학회 학술발표대회 논문집 Vol.2010 No.04

Perilla is a genus as a member of the mint family Lamiaceae which is known to contain lots of volatile metabolite. Perilla has been called as ‘deulkae’ indicating ‘wild sesame’ that means it has been maintained in Korea with long history. It has been very friendly used as edible oil and as fresh leaf vegetable. Perilla oil is valued for its medicinal benefit because it contains best amounts of unsaturated fatty acids, especially for the alpha-linolenic acid, known to omega-3 fatty acid, among all of the plant oils. It also include many beneficial phytochemicals. However, little study is conducted on their genetics. Here, we announce construction of well normalized and full length enriched-perilla cDNA library from a whole plant of one cultivar ‘Youngho-deulkae’ and their sequence characterization to provide useful resources for genetics, breeding and metabolite engineering. By sequencing of 5,760 cDNA clones, we 5,438 high quality EST sequences. Sequence trimming and assembly resulted 3,995 unigenes which consists 1,004 contigs and 2,991 singletones. Unigenes that showed little homology at the DNA sequence level with known genes in other plants even though they showed similarity at the protein domain level based on BLASTN, BLASTX, and TBLASTX. This study may provide good resources for initiation of further genomics, comparative genomics, functional genomics such as metabolic engineering and molecular breeding.

Basic, HCC basic : O-029 ; Enhanced inactivation of immortalized hepatic stellate cell line by the synergistic effect of combination of HMG CoA reductase inhibitor and selective COX-2 inhibitor

( Jee Won Hwang ),( Hyung Joon Yim ),( Hyun Jung Lee ),( Sun Jae Lee ),( Eileen L. Yoon ),( Sang Jun Suh ),( Ji Hoon Kim ),( Jong Eun Yeon ),( Soon Ho Um ),( Kwan Soo Byun ) 대한간학회 2012 춘·추계 학술대회 (KASL) Vol.2012 No.1

Background: Hepatic stellate cells (HSCs) are a major fibrogenic cell type that contributes to collagen accumulation during chronic liver disease. The NS-398 (a selective COX-2 inhibitor) is a potential drug of chemoprevention and treatment of liver fibrosis by inhibiting HSC activation. The simvastatin (a HMG CoA reductase inhibitor) revert the myofibroblasts-like phenotype of HSC towards a more quiescent phenotype. We investigated the anti-fibrotic and pro-apoptotic mechanisms in synergistic effects of both drugs as using the human hepatic stellate cell line. Methods: The immortalized human hepatic stellate cell line, LX-2 was cultured. The cells were treated with control, simvastatin, NS-398, and combination of simvastatin and NS-398 for 24 and 48 hours. Cellular DNA synthesis was evaluated by measuring BrdU incorporation. Expression of proteins including cell cycle regulators such as p21, cyclinD1 and Akt, NF-kB, caspase-3, caspase-9 as apoptotic factors, α -smooth muscle actin (α-SMA) were measured in Western blot analysis. Results: In BrdU-proliferation assay, combination of two drugs effectively inhibited the proliferation rate compared to monotherapy. The combination of two drugs resulted in a greater decrease of procaspase-3, -9, Akt and NF-kB than monotherapy depend on the concentration of two drugs. In addition, the combination of NS-398 and simvastatin significantly promote the inactivation of HSCs by reducing the amounts of α-SMA protein. Conclusions: We suggested that both of two drugs have synergistic effects that anti-proliferative, pro-apoptotic and anti-fibrotic effects on activated HSCs. The mechanism of synergistic pro-apoptotic effect seems to be mediated through inhibition of NF-kB/Akt pathway and caspase activity.

Hepatocyte-specific Prominin-1 protects against liver injury-induced fibrosis by stabilizing SMAD7

Lee Hyun,Yu Dong-Min,Bahn Myeong-Suk,Kwon Young-Jae,Um Min Jee,Yoon Seo Yeon,Kim Ki-Tae,Lee Myoung-Woo,Jo Sung-Je,Lee Sungsoo,Koo Seung-Hoi,Jung Ki Hoon,Lee Jae-Seon,Ko Young-Gyu 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Prominin-1 (PROM1), also known as CD133, is expressed in hepatic progenitor cells (HPCs) and cholangiocytes of the fibrotic liver. In this study, we show that PROM1 is upregulated in the plasma membrane of fibrotic hepatocytes. Hepatocellular expression of PROM1 was also demonstrated in mice (Prom1CreER; R26TdTom) in which cells expressed TdTom under control of the Prom1 promoter. To understand the role of hepatocellular PROM1 in liver fibrosis, global and liver-specific Prom1-deficient mice were analyzed after bile duct ligation (BDL). BDL-induced liver fibrosis was aggravated with increased phosphorylation of SMAD2/3 and decreased levels of SMAD7 by global or liver-specific Prom1 deficiency but not by cholangiocyte-specific Prom1 deficiency. Indeed, PROM1 prevented SMURF2-induced SMAD7 ubiquitination and degradation by interfering with the molecular association of SMAD7 with SMURF2. We also demonstrated that hepatocyte-specific overexpression of SMAD7 ameliorated BDL-induced liver fibrosis in liver-specific Prom1-deficient mice. Thus, we conclude that PROM1 is necessary for the negative regulation of TGFβ signaling during liver fibrosis.

The Mst1/2-BNIP3 axis is required for mitophagy induction and neuronal viability under mitochondrial stress

Jeong Dae Jin,Um Jee-Hyun,Kim Young Yeon,Shin Dong Jin,Im Sangwoo,Lee Kang-Min,Lee Yun-Hee,Lim Dae-sik,Kim Donghoon,Yun Jeanho 생화학분자생물학회 2024 Experimental and molecular medicine Vol.56 No.-

Mitophagy induction upon mitochondrial stress is critical for maintaining mitochondrial homeostasis and cellular function. Here, we found that Mst1/2 (Stk3/4), key regulators of the Hippo pathway, are required for the induction of mitophagy under various mitochondrial stress conditions. Knockdown of Mst1/2 or pharmacological inhibition by XMU-MP-1 treatment led to impaired mitophagy induction upon CCCP and DFP treatment. Mechanistically, Mst1/2 induces mitophagy independently of the PINK1-Parkin pathway and the canonical Hippo pathway. Moreover, our results suggest the essential involvement of BNIP3 in Mst1/2-mediated mitophagy induction upon mitochondrial stress. Notably, Mst1/2 knockdown diminishes mitophagy induction, exacerbates mitochondrial dysfunction, and reduces cellular survival upon neurotoxic stress in both SH-SY5Y cells and Drosophila models. Conversely, Mst1 and Mst2 expression enhances mitophagy induction and cell survival. In addition, AAV-mediated Mst1 expression reduced the loss of TH-positive neurons, ameliorated behavioral deficits, and improved mitochondrial function in an MPTP-induced Parkinson’s disease mouse model. Our findings reveal the Mst1/2-BNIP3 regulatory axis as a novel mediator of mitophagy induction under conditions of mitochondrial stress and suggest that Mst1/2 play a pivotal role in maintaining mitochondrial function and neuronal viability in response to neurotoxic treatment.

Potentiation of chemosensitivity in multidrug-resistant human leukemia CEM cells by inhibition of DNA-dependent protein kinase using wortmannin

Kim, Sun-Hee,Um, Jee-Hyun,Kim, Dong-Wan,Kwon, Byung-Hyun,Kim, Dong-Wan,Chung, Byung-Seon,Kang, Chi-Dug Institute of Genetic Engineering Changwon National 2000 Gene and Protein Vol.4 No.-

DNA-dependent protein kinase (DNA-PK) is activated by DNA stand breaks and participates in DNA repair. Its regulatory subunit, Ku autoantigen, binds to DNA and recruits the catalytic subunit (DNA-PKcs). We show here a new role of DNA-PK in the development of multidrug resistance (MDR). The Ku-DNA binding activity, the levels of Ku70/Ku80 and DNA-PKcs in MDR variants, CEM/VLB_(10-2). CEM/VLB_(55-8) and CEM/VLB_100 were higher than those in their parental drug-sensitive CEM cells in a drug resistance-dependent fashion. Also, CEM/VLB_100 cells showed about 3-fold increase of DNA-PK enzyme activity as compared with CEM cells. Similar results were observed in another MDR cell line, FM3A/M mouse mammary carcinoma cells. Moreover, we observed the CEM/VLB_100 cells were about 11-fold sensitive to wortmannin, which inhibits DNA-PK, compared with the CEM cells, and sensitized the MDR cells when combined with either bleomycin or vincristine, but have a little effect on CEM cells. Wortmannin was shown to inhibit DNA-PK and Ku-DNA binding activity of CEM/VLB_100 cells dose dependently but had a little or no effect on their parental cells. Our results suggested that enhanced expression of DNA-PK participates in the development of MDR, and the use of DNA-PK inhibitors such as wortmannin is likely to improve the effectiveness of anticancer drugs and thus could partially overcome drug resistance in DMR cells, through its ability to inhibit Ku/DNA-PK activity. ⓒ 2000 Elsevier Science Ltd. All rights reserved.

Potentiation of chemosensitivity in multidrug-resistant human leukemia CEM cells by inhibition of DNA-dependent protein kinase using wortmannin

Kim, Sun-Hee,Um, Jee-Hyun,Kim, Dong-Won,Kwon, Byung-Hyun,Kim, Dong-Wan,Chung, Byung-Seon,kang, Chi-Dug 부산대학교 유전공학연구소 2000 분자생물학 연구보 Vol.16 No.-

DNA-dependent protein kinase (DNA_PK) is activated by DNA strand breaks and participates in DNA repair. Its regulatory subunit, Ku autoantigen, binds to DNA and recruits the catalytic subunit (DNA_PKcs). We show here a new role of DNA-PK in the development of multidrug resistance (MDR). The Ku-DNA binding activity, the levels of Ku70/Ku80 and DNA-PKcs in MDR variants. CEM/VLB_10-2. CEM/VLB_55-8 and CEM/VLB_100 were higher than those in their parental drug-sensitive CEM cells in a drug resistance-dependent fashion. Also, CEM/VLB_100 cells showed about 30fold increase of DNA-PK enzyme activity as compared with CEM cells. Similar results were observed in another MDR cell line, FM3A/M mouse mammary carcinoma cells. Moreover, we observed that CEM/VLB_100 cells were about 11-fold sensitive to wortmannin, which inhibits DNA-PK, compared with the CEM cells, and sensitized the MDR cells when combined with either bleomycin or vincristine, but have a little effect on CEM cells. Wortmannin was shown to inhibit DNA-PK and Ku-DNA binding activity in CEM/VLB_100 cells dose dependently but had a little or no effect on their parental cells. Our results suggested that enhanced expression of DNA-PK participates in the development of MDR, and the use of DNA-PK inhibitors such as wortmannin is likely to improve the effectiveness of anticancer drugs and thus could partially overvome drug resistance in MDR cells, through its ability to inhibit Ku/DNA-PK activity. ⓒ 2000 Elsevier Science Ltd. All rights reserved.