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Qian Z, Wu F, Feng G, Lin W, Cai X, Wu J, Ke K, Ye Z, Xu G. A prognostic risk model based on lactate metabolism and transport-related lncRNAs for gastric adenocarcinoma. Biomarkers 2024; 29:211-221. [PMID: 38629165 DOI: 10.1080/1354750x.2024.2341411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 04/04/2024] [Indexed: 05/15/2024]
Abstract
BACKGROUND Increased lactate levels and metastasis in tumours are strongly associated with dismal outcomes. But prognostic value of lactate metabolism and transport-related lncRNAs in gastric adenocarcinoma (GA) patients remains unaddressed. METHODS Gene expression data of GA were provided by The Cancer Genome Atlas. Lactate metabolism and transport-related gene data were accessed from GSEA. LncRNAs related to lactate metabolism and transport were identified by correlation analysis. A prognostic model was built by regression analysis. Validity of prognostic model was confirmed through survival analysis and receiver operating characteristic (ROC) curve. Immunity of each risk group was evaluated by immune correlation analysis .LncRNA-mRNA network was built by correlation analysis using Cytoscape software. RESULTS A 12-gene prognostic model based on lactate metabolism and transport-related lncRNAs was built in GA. Median riskscore was utilized to classify GA samples into high- and low-risk groups. Survival analysis and ROC curves demonstrated validity of prognostic model. Most immune checkpoint molecules and TIDE scores were lower in the low-risk group. LINC01303 and LINC01545 may be the key prognostic factors in patients with GA. CONCLUSION This study successfully built a prognostic model of lactate metabolism and transport-related lncRNAs in GA. The findings guide prognostic management of GA patients.
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Affiliation(s)
- Zhenyuan Qian
- General Surgery, Cancer Center, Department of Gastrointestinal and Pancreatic Surgery, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Fang Wu
- General Surgery, Cancer Center, Department of Gastrointestinal and Pancreatic Surgery, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Guoqing Feng
- Department of General Surgery, Haining Traditional Chinese Medicine Hospital, Haining, Jiaxing, Zhejiang, China
| | - Wenfa Lin
- Zhejiang Chinese Medicine University, Hangzhou, Zhejiang, China
| | - Xufan Cai
- Zhejiang Chinese Medicine University, Hangzhou, Zhejiang, China
| | - Jianzhang Wu
- General Surgery, Cancer Center, Department of Gastrointestinal and Pancreatic Surgery, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Kun Ke
- General Surgery, Cancer Center, Department of Gastrointestinal and Pancreatic Surgery, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Zaiyuan Ye
- General Surgery, Cancer Center, Department of Gastrointestinal and Pancreatic Surgery, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Guoxi Xu
- Department of Gastrointestinal Surgery, Jinjiang Municipal Hospital, Jinjiang, Quanzhou, Fujian, China
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Zhao W, Li Y, Cheng H, Wang M, Zhang Z, Cai M, Zhao C, Xi X, Zhao X, Zhao W, Yang Y, Shao R. Myofibrillogenesis Regulator-1 Regulates the Ubiquitin Lysosomal Pathway of Notch3 Intracellular Domain Through E3 Ubiquitin-Protein Ligase Itchy Homolog in the Metastasis of Non-Small Cell Lung Cancer. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2306472. [PMID: 38342606 PMCID: PMC11022719 DOI: 10.1002/advs.202306472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 12/28/2023] [Indexed: 02/13/2024]
Abstract
Myofibrillogenesis regulator-1 (MR-1) is a multifunctional protein involved in the development of various human tumors. The study is the first to report the promoting effect of MR-1 on the development and metastasis of non-small cell lung cancer (NSCLC). MR-1 is upregulated in NSCLC and positively associated with poor prognosis. The overexpression of MR-1 promotes the metastasis of NSCLC cells by stabilizing the expression of Notch3-ICD (NICD3) in the cytoplasm through enrichment analysis, in vitro and in vivo experimental researches. And Notch3 signaling can upregulate many genes related to metastasis. The stabilizing effect of MR-1 on NICD3 is achieved through the mono-ubiquitin lysosomal pathway and the specific E3 ubiquitin ligase is Itchy homolog (ITCH). There is a certain interaction between MR-1 and NICD3. Elevated MR-1 can affect the level of ITCH phosphorylation, reduce its E3 enzyme activity, and thus lead to reduce the ubiquitination and degradation of NICD3. Interference with the interaction between MR-1 and NICD3 can increase the degradation of NICD3 and impair the metastatic ability of NSCLC cells, which is a previously overlooked treatment option in NSCLC. In summary, interference with the interaction between MR-1 and NICD3 in the progression of lung cancer may be a promising therapeutic target.
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Affiliation(s)
- Wenxia Zhao
- NHC Key Laboratory of Antibiotic Bioengineering, Laboratory of OncologyInstitute of Medicinal Biotechnology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing100050BeijingP. R. China
| | - Yang Li
- NHC Key Laboratory of Antibiotic Bioengineering, Laboratory of OncologyInstitute of Medicinal Biotechnology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing100050BeijingP. R. China
| | - Hanzeng Cheng
- Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia MedicaPeking Union Medical College and Chinese Academy of Medical SciencesBeijing100050P. R. China
| | - Mengyan Wang
- NHC Key Laboratory of Antibiotic Bioengineering, Laboratory of OncologyInstitute of Medicinal Biotechnology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing100050BeijingP. R. China
- Zhujiang HospitalSouthern Medical UniversityGuangzhouGuangdong510280P. R. China
| | - Zhishuo Zhang
- Department of EmergencyXinhua HospitalShanghai Jiaotong University School of MedicineShanghai200092P. R. China
- Department of Organ Transplantation and Hepatobiliary SurgeryThe First Hospital of China Medical UniversityShenyangLiaoning110001P. R. China
| | - Meilian Cai
- NHC Key Laboratory of Antibiotic Bioengineering, Laboratory of OncologyInstitute of Medicinal Biotechnology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing100050BeijingP. R. China
| | - Cong Zhao
- NHC Key Laboratory of Antibiotic Bioengineering, Laboratory of OncologyInstitute of Medicinal Biotechnology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing100050BeijingP. R. China
| | - Xiaoming Xi
- NHC Key Laboratory of Antibiotic Bioengineering, Laboratory of OncologyInstitute of Medicinal Biotechnology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing100050BeijingP. R. China
| | - Xiaojun Zhao
- NHC Key Laboratory of Antibiotic Bioengineering, Laboratory of OncologyInstitute of Medicinal Biotechnology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing100050BeijingP. R. China
| | - Wuli Zhao
- NHC Key Laboratory of Antibiotic Bioengineering, Laboratory of OncologyInstitute of Medicinal Biotechnology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing100050BeijingP. R. China
| | - Yajun Yang
- Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia MedicaPeking Union Medical College and Chinese Academy of Medical SciencesBeijing100050P. R. China
| | - Rongguang Shao
- NHC Key Laboratory of Antibiotic Bioengineering, Laboratory of OncologyInstitute of Medicinal Biotechnology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing100050BeijingP. R. China
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Jiang R, Zhou Y, Gao Q, Han L, Hong Z. ZC3H4 governs epithelial cell migration through ROCK/p-PYK2/p-MLC2 pathway in silica-induced pulmonary fibrosis. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2023; 104:104301. [PMID: 37866415 DOI: 10.1016/j.etap.2023.104301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 10/03/2023] [Accepted: 10/18/2023] [Indexed: 10/24/2023]
Abstract
BACKGROUND Increased epithelial migration capacity is a key step accompanying epithelial-mesenchymal transition (EMT). Our lab has described that ZC3H4 mediated EMT in silicosis. Here, we aimed to explore the mechanisms of ZC3H4 by which to stimulate epithelial cell migration. METHODS Silicon dioxide (SiO2)-induced pulmonary fibrosis (PF) animal models were administered by intratracheal instillation in C57BL/6 J mice. Pathological analysis and 2D migration assay were established to uncover the pulmonary fibrotic lesions and epithelial cell migration, respectively. Inhibitors targeting ROCK/p-PYK2/p-MLC2 and CRISPR/Cas9 plasmids targeting ZC3H4 were administrated to explore the signaling pathways. RESULTS 1) SiO2 upregulated epithelial migration in pulmonary fibrotic lesions. 2) ZC3H4 modulated SiO2-induced epithelial migration. 3) ZC3H4 governed epithelial migration through ROCK/p-PYK2/p-MLC2 signaling pathway. CONCLUSIONS ZC3H4 regulates epithelial migration through the ROCK/p-PYK2/p-MLC2 signaling pathway, providing the possibility that molecular drugs targeting ZC3H4-overexpression may exert effects on pulmonary fibrosis induced by silica.
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Affiliation(s)
- Rong Jiang
- Jiangsu Health Vocational College, Nanjing, Jiangsu Province, China
| | - Yichao Zhou
- Department of Occupation Disease Prevention and Cure, Changzhou Wujin District Center for Disease Control and Prevention, Changzhou, Jiangsu Province, China
| | - Qianqian Gao
- Department of Occupation Disease Prevention and Cure, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, Jiangsu Province, China; Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Lei Han
- Department of Occupation Disease Prevention and Cure, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, Jiangsu Province, China.
| | - Zhen Hong
- Jiangsu Health Vocational College, Nanjing, Jiangsu Province, China.
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Zhang Z, Fang T, Lv Y. A novel lactate metabolism-related signature predicts prognosis and tumor immune microenvironment of breast cancer. Front Genet 2022; 13:934830. [PMID: 36171887 PMCID: PMC9511350 DOI: 10.3389/fgene.2022.934830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 08/12/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Lactate, an intermediate product of glycolysis, has become an essential regulator of tumor maintenance, development, and metastasis. Lactate can drive tumors by changing the microenvironment of tumor cells. Because of lactate’s important role in cancer, we aim to find a novel prognostic signature based on lactate metabolism-related genes (LMRGs) of breast cancer (BC).Methods: RNA-sequencing data and clinical information of BC were enrolled from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. We obtained LMRGs from the Molecular Signature Database v7.4 and articles, and then we compared candidate genes with TCGA data to get differential genes. Univariate analysis and most minor absolute shrinkage and selector operator (LASSO) Cox regression were employed to filter prognostic genes. A novel lactate metabolism-related risk signature was constructed using a multivariate Cox regression analysis. The signature was validated by time-dependent ROC curve analyses and Kaplan–Meier analyses in TCGA and GEO cohorts. Then, we further investigated in depth the function of the model’s immune microenvironment.Results: We constructed a 3-LMRG-based risk signature. Kaplan–Meier curves confirmed that high-risk score subgroups had a worse prognosis in TCGA and GEO cohorts. Then a nomogram to predict the probability of survival for BC was constructed. We also performed Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway function analysis. The function analysis showed that the lactate metabolism-related signature was significantly related to immune response. A significant correlation was observed between prognostic LMRGs and tumor mutation burden, checkpoints, and immune cell infiltration. An mRNA–miRNA network was built to identify an miR-203a-3p/LDHD/LYRM7 regulatory axis in BC.Conclusion: In conclusion, we constructed a novel 3-LMRG signature and nomogram that can be used to predict the prognosis of BC patients. In addition, the signature is closely related to the immune microenvironment, which may provide new insight into future anticancer therapies.
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Affiliation(s)
- Zhihao Zhang
- Department of Thyroid Breast Surgery, Xi’an NO. 3 Hospital, The Affiliated Hospital of Northwest University, Xi’an, China
| | - Tian Fang
- Department of Medical Oncology, Cancer Center, West China Hospital of Sichuan University, Chengdu, China
| | - Yonggang Lv
- Department of Thyroid Breast Surgery, Xi’an NO. 3 Hospital, The Affiliated Hospital of Northwest University, Xi’an, China
- *Correspondence: Yonggang Lv,
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Chen F, Zhang S, Liu T, Yuan L, Wang Y, Zhang G, Liang S. Preliminary study on pathogenic mechanism of first Chinese family with PNKD. Transl Neurosci 2022; 13:125-133. [PMID: 35795196 PMCID: PMC9186512 DOI: 10.1515/tnsci-2022-0222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/03/2022] [Accepted: 05/12/2022] [Indexed: 11/15/2022] Open
Abstract
Background The first Chinese family with paroxysmal non-kinesigenic dystonia (PNKD) was confirmed to harbour a PNKD mutation. However, the pathogenic mechanism of the PNKD-causing gene mutation was unclear. Methods Wild-type and mutant PNKD-L plasmids were prepared and transfected into the C6 cell line to study the distribution and stability of PNKD protein in C6 cells and its effect on the glutathione content. The blood and cerebrospinal fluid (CSF) of 3 PNKD patients and 3 healthy controls were collected. The differentially expressed proteins were identified using isobaric tags for relative and absolute quantitation. Furthermore, Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analyses were performed, and the protein–protein interaction network was constructed. Results Wild-type PNKD protein was mainly distributed in the membranes, whereas mutant PNKD protein was distributed throughout the C6 cells. After transfection with mutant PNKD-L plasmid, the glutathione content decreased significantly in C6 cells; the stability of the mutant PNKD protein was significantly low. There were 172 and 163 differentially expressed proteins in CSF and plasma, respectively, of PNKD patients and healthy controls. For these proteins, blood microparticle and complex activation (classical pathway) were the common GO enrichment term, and complex and coordination cascade pathway were the common KEGG enrichment pathway. Recombinant mothers against decapentaplegic homolog 4 (SMAD4) was one of the differentially expressed proteins; it exhibited a relationship with the aforementioned enrichment GO terms and KEGG pathway. Conclusion PNKD protein was mainly distributed in cell membranes. PNKD-L mutation affected subcellular localisation, PNKD protein stability, and glutathione content. SMAD4 was found to be a potential biomarker for PNKD diagnosis.
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Affiliation(s)
- Feng Chen
- Functional Neurosurgery Department, National Children’s Health Center of China, Beijing Children’s Hospital, Capital Medical University , No. 56, Nanlishi Road, Xicheng District , Beijing , 100045 , China
| | - Shaohui Zhang
- Neurosurgery Department, PLA General Hospital , No. 28 Fuxing Road, Haidian District , Beijing , 100853 , China
| | - Tinghong Liu
- Functional Neurosurgery Department, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China , No. 56, Nanlishi Road, Xicheng District , Beijing , 100045 , China
- Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing, China , No. 56, Nanlishi Road, Xicheng District , Beijing , 100045 , China
| | - Liu Yuan
- Functional Neurosurgery Department, National Children’s Health Center of China, Beijing Children’s Hospital, Capital Medical University , No. 56, Nanlishi Road, Xicheng District , Beijing , 100045 , China
| | - Yangshuo Wang
- Functional Neurosurgery Department, National Children’s Health Center of China, Beijing Children’s Hospital, Capital Medical University , No. 56, Nanlishi Road, Xicheng District , Beijing , 100045 , China
| | - Guojun Zhang
- Functional Neurosurgery Department, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China , No. 56, Nanlishi Road, Xicheng District , Beijing , 100045 , China
- Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing, China , No. 56, Nanlishi Road, Xicheng District , Beijing , 100045 , China
| | - Shuli Liang
- Functional Neurosurgery Department, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China , No. 56, Nanlishi Road, Xicheng District , Beijing , 100045 , China
- Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing, China , No. 56, Nanlishi Road, Xicheng District , Beijing , 100045 , China
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Ershov P, Kaluzhskiy L, Mezentsev Y, Yablokov E, Gnedenko O, Ivanov A. Enzymes in the Cholesterol Synthesis Pathway: Interactomics in the Cancer Context. Biomedicines 2021; 9:biomedicines9080895. [PMID: 34440098 PMCID: PMC8389681 DOI: 10.3390/biomedicines9080895] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 02/06/2023] Open
Abstract
A global protein interactome ensures the maintenance of regulatory, signaling and structural processes in cells, but at the same time, aberrations in the repertoire of protein-protein interactions usually cause a disease onset. Many metabolic enzymes catalyze multistage transformation of cholesterol precursors in the cholesterol biosynthesis pathway. Cancer-associated deregulation of these enzymes through various molecular mechanisms results in pathological cholesterol accumulation (its precursors) which can be disease risk factors. This work is aimed at systematization and bioinformatic analysis of the available interactomics data on seventeen enzymes in the cholesterol pathway, encoded by HMGCR, MVK, PMVK, MVD, FDPS, FDFT1, SQLE, LSS, DHCR24, CYP51A1, TM7SF2, MSMO1, NSDHL, HSD17B7, EBP, SC5D, DHCR7 genes. The spectrum of 165 unique and 21 common protein partners that physically interact with target enzymes was selected from several interatomic resources. Among them there were 47 modifying proteins from different protein kinases/phosphatases and ubiquitin-protein ligases/deubiquitinases families. A literature search, enrichment and gene co-expression analysis showed that about a quarter of the identified protein partners was associated with cancer hallmarks and over-represented in cancer pathways. Our results allow to update the current fundamental view on protein-protein interactions and regulatory aspects of the cholesterol synthesis enzymes and annotate of their sub-interactomes in term of possible involvement in cancers that will contribute to prioritization of protein targets for future drug development.
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El-Sisi MG, Radwan SM, Saeed AM, El-Mesallamy HO. Serum levels of FAK and some of its effectors in adult AML: correlation with prognostic factors and survival. Mol Cell Biochem 2021; 476:1949-1963. [PMID: 33507464 DOI: 10.1007/s11010-020-04030-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 12/22/2020] [Indexed: 11/28/2022]
Abstract
Focal adhesion kinase (FAK), human myofibrillogenesis regulator-1 (MR-1), ephrin receptor type A4 (EphA4), proto-oncogene tyrosine kinase Src (Src), and protein kinase C (PKC) are important markers in proliferation, survival, and migration in some cancers. However, the significance of each is still unclear in different malignancies, including acute myeloid leukemia (AML). Therefore, this study was conducted to investigate their serum levels in Egyptian adult de novo AML patients (n = 70) against healthy volunteers (n = 20). We managed to study the correlation between each pair and to investigate their association with diagnosis, prognosis, and survival. Serum levels were analyzed using enzyme-linked immunosorbent assay (ELISA). We found that FAK, MR-1, Src, and PKC serum levels were significantly higher in AML patients compared to control (p < 0.0001), and this was associated with significantly lower EphA4 level (p < 0.0001). Interestingly, we also observed a significant negative correlation of FAK (p = 0.027), MR-1 (p = 0.003), Src (p = 0.038), and PKC (p = 0.03) with patients' overall survival (OS) while there was a positive significant correlation between EphA4 and OS (p = 0.007). In conclusion, this study suggests that FAK, MR-1, EphA4, Src, and PKC may be used as early diagnostic and prognostic markers with high sensitivity and specificity in AML patients and thus may be incorporated into the patients' early diagnostic and prognostic panels.
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Affiliation(s)
- Mona G El-Sisi
- Biochemistry Department, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt
| | - Sara M Radwan
- Biochemistry Department, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt
| | - Alia M Saeed
- Department of Internal Medicine, Clinical Hematology and Oncology Division, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Hala O El-Mesallamy
- Biochemistry Department, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt. .,Faculty of Pharmacy, Sinai University, Sinai, Egypt.
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Functions of Cytochrome c oxidase Assembly Factors. Int J Mol Sci 2020; 21:ijms21197254. [PMID: 33008142 PMCID: PMC7582755 DOI: 10.3390/ijms21197254] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 09/23/2020] [Indexed: 12/22/2022] Open
Abstract
Cytochrome c oxidase is the terminal complex of eukaryotic oxidative phosphorylation in mitochondria. This process couples the reduction of electron carriers during metabolism to the reduction of molecular oxygen to water and translocation of protons from the internal mitochondrial matrix to the inter-membrane space. The electrochemical gradient formed is used to generate chemical energy in the form of adenosine triphosphate to power vital cellular processes. Cytochrome c oxidase and most oxidative phosphorylation complexes are the product of the nuclear and mitochondrial genomes. This poses a series of topological and temporal steps that must be completed to ensure efficient assembly of the functional enzyme. Many assembly factors have evolved to perform these steps for insertion of protein into the inner mitochondrial membrane, maturation of the polypeptide, incorporation of co-factors and prosthetic groups and to regulate this process. Much of the information about each of these assembly factors has been gleaned from use of the single cell eukaryote Saccharomyces cerevisiae and also mutations responsible for human disease. This review will focus on the assembly factors of cytochrome c oxidase to highlight some of the outstanding questions in the assembly of this vital enzyme complex.
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