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Gu Z, Xie D, Ding R, Huang C, Qiu Y. GPR173 agonist phoenixin 20 promotes osteoblastic differentiation of MC3T3-E1 cells. Aging (Albany NY) 2020; 13:4976-4985. [PMID: 33196456 PMCID: PMC7950309 DOI: 10.18632/aging.103717] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/29/2020] [Indexed: 11/25/2022]
Abstract
Osteogenic differentiation is critical to bone homeostasis, and its imbalance plays a key role in the progression of osteoporosis. Osteoblast cells are responsible for synthesizing new bone tissue, and understanding how to control osteoblastic differentiation is vital to the treatment of osteoporosis. Herein, we show that GPR173 signaling is involved in the regulation of osteoblastic differentiation in MC3T3-E1 cells. Our data reveals that GPR173 is abundantly expressed in MC3T3-E1 cells, and its expression is inducible upon the introduction of osteogenic media. The activation of GPR173 by its selective agonist phoenixin 20 induces the expression of several osteoblast signature genes including collagen type 1 alpha 1 (Col-I), osteocalcin (OCN), alkaline phosphatase (ALP) as well as increased matrix mineralization and ALP activity, suggesting that the activation of GPR173 promotes osteoblastic differentiation. Moreover, we show that the effect of phoenixin 20 is mediated by its induction on the key regulator runt-Related Transcription Factor 2 (Runx2). Mechanistically, we display that the action of phoenixin 20 requires the activation of MAPK kinase p38, and deactivation of p38 by its inhibitor SB203580 weakens the phoenixin 20-mediated induction of RUNX-2, ALP, and matrix mineralization. Silencing of GPR173 attenuates phoenixin 20-mediated osteoblastic differentiation, indicating its dependence on the receptor. Collectively, our study reveals a new role of GPR173 and its agonist phoenixin 20 in osteoblastic differentiation.
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Affiliation(s)
- Zhengtao Gu
- Department of Treatment Center for Traumatic Injuries, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, Academy of Orthopedics of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province, China
| | - Denghui Xie
- Division of Joint Surgery, Department of Orthopedics, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, Academy of Orthopedics of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province, China
| | - Rui Ding
- Division of Spine Surgery, Section II, Department of Orthopedics, Academy of Orthopedics of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province, China
| | - Caiqiang Huang
- Division of Spine Surgery, Section II, Department of Orthopedics, Academy of Orthopedics of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province, China
| | - Yiyan Qiu
- Division of Spine Surgery, Section II, Department of Orthopedics, Academy of Orthopedics of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province, China
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2
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Masud AJ, Kastaniotis AJ, Rahman MT, Autio KJ, Hiltunen JK. Mitochondrial acyl carrier protein (ACP) at the interface of metabolic state sensing and mitochondrial function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:118540. [PMID: 31473256 DOI: 10.1016/j.bbamcr.2019.118540] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/23/2019] [Accepted: 08/27/2019] [Indexed: 12/20/2022]
Abstract
Acyl carrier protein (ACP) is a principal partner in the cytosolic and mitochondrial fatty acid synthesis (FAS) pathways. The active form holo-ACP serves as FAS platform, using its 4'-phosphopantetheine group to present covalently attached FAS intermediates to the enzymes responsible for the acyl chain elongation process. Mitochondrial unacylated holo-ACP is a component of mammalian mitoribosomes, and acylated ACP species participate as interaction partners in several ACP-LYRM (leucine-tyrosine-arginine motif)-protein heterodimers that act either as assembly factors or subunits of the electron transport chain and Fe-S cluster assembly complexes. Moreover, octanoyl-ACP provides the C8 backbone for endogenous lipoic acid synthesis. Accumulating evidence suggests that mtFAS-generated acyl-ACPs act as signaling molecules in an intramitochondrial metabolic state sensing circuit, coordinating mitochondrial acetyl-CoA levels with mitochondrial respiration, Fe-S cluster biogenesis and protein lipoylation.
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Affiliation(s)
- Ali J Masud
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | | | - M Tanvir Rahman
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Kaija J Autio
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - J Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.
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3
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Rathore A, Chu Q, Tan D, Martinez TF, Donaldson CJ, Diedrich JK, Yates JR, Saghatelian A. MIEF1 Microprotein Regulates Mitochondrial Translation. Biochemistry 2018; 57:5564-5575. [PMID: 30215512 DOI: 10.1021/acs.biochem.8b00726] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recent technological advances led to the discovery of hundreds to thousands of peptides and small proteins (microproteins) encoded by small open reading frames (smORFs). Characterization of new microproteins demonstrates their role in fundamental biological processes and highlights the value in discovering and characterizing more microproteins. The elucidation of microprotein-protein interactions (MPIs) is useful for determining the biochemical and cellular roles of microproteins. In this study, we characterize the protein interaction partners of mitochondrial elongation factor 1 microprotein (MIEF1-MP) using a proximity labeling strategy that relies on APEX2. MIEF1-MP localizes to the mitochondrial matrix where it interacts with the mitochondrial ribosome (mitoribosome). Functional studies demonstrate that MIEF1-MP regulates mitochondrial translation via its binding to the mitoribosome. Loss of MIEF1-MP decreases the mitochondrial translation rate, while an elevated level of MIEF1-MP increases the translation rate. The identification of MIEF1-MP reveals a new gene involved in this process.
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Affiliation(s)
- Annie Rathore
- Clayton Foundation Laboratories for Peptide Biology , The Salk Institute for Biological Studies , 10010 North Torrey Pines Road , La Jolla , California 92037 , United States.,Division of Biological Sciences , University of California, San Diego , 9500 Gilman Drive , La Jolla , California 92093 , United States
| | - Qian Chu
- Clayton Foundation Laboratories for Peptide Biology , The Salk Institute for Biological Studies , 10010 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Dan Tan
- Clayton Foundation Laboratories for Peptide Biology , The Salk Institute for Biological Studies , 10010 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Thomas F Martinez
- Clayton Foundation Laboratories for Peptide Biology , The Salk Institute for Biological Studies , 10010 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Cynthia J Donaldson
- Clayton Foundation Laboratories for Peptide Biology , The Salk Institute for Biological Studies , 10010 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Jolene K Diedrich
- Mass Spectrometry Core for Proteomics and Metabolomics , The Salk Institute for Biological Studies , 10010 North Torrey Pines Road , La Jolla , California 92037 , United States.,Department of Molecular Medicine , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - John R Yates
- Department of Molecular Medicine , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California 92037 , United States
| | - Alan Saghatelian
- Clayton Foundation Laboratories for Peptide Biology , The Salk Institute for Biological Studies , 10010 North Torrey Pines Road , La Jolla , California 92037 , United States
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4
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Jeong JH, Kim J, Kim J, Heo HR, Jeong JS, Ryu YJ, Hong Y, Han SS, Hong SH, Lee SJ, Kim WJ. ACN9 Regulates the Inflammatory Responses in Human Bronchial Epithelial Cells. Tuberc Respir Dis (Seoul) 2017; 80:247-254. [PMID: 28747957 PMCID: PMC5526951 DOI: 10.4046/trd.2017.80.3.247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 05/02/2017] [Accepted: 05/04/2017] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Airway epithelial cells are the first line of defense, against pathogens and environmental pollutants, in the lungs. Cellular stress by cadmium (Cd), resulting in airway inflammation, is assumed to be directly involved in tissue injury, linked to the development of lung cancer, and chronic obstructive pulmonary disease (COPD). We had earlier shown that ACN9 (chromosome 7q21), is a potential candidate gene for COPD, and identified significant interaction with smoking, based on genetic studies. However, the role of ACN9 in the inflammatory response, in the airway cells, has not yet been reported. METHODS We first checked the anatomical distribution of ACN9 in lung tissues, using mRNA in situ hybridization, and immunohistochemistry. Gene expression profiling in bronchial epithelial cells (BEAS-2B), was performed, after silencing ACN9. We further tested the roles of ACN9, in the intracellular mechanism, leading to Cd-induced production, of proinflammatory cytokines in BEAS-2B. RESULTS ACN9 was localized in lymphoid, and epithelial cells, of human lung tissues. ACN9 silencing, led to differential expression of 216 genes. Pathways of sensory perception to chemical stimuli, and cell surface receptor-linked signal transduction, were significantly enriched. ACN9 silencing, further increased the expression of proinflammatory cytokines, in BEAS-2B after Cd exposure. CONCLUSION Our findings suggest, that ACN9 may have a role, in the inflammatory response in the airway.
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Affiliation(s)
- Jae Hoon Jeong
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Jeeyoung Kim
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.,Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea
| | - Jeongwoon Kim
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.,Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea
| | - Hye-Ryeon Heo
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.,Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea
| | - Jin Seon Jeong
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Young-Joon Ryu
- Department of Pathology, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Yoonki Hong
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.,Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea
| | - Seon-Sook Han
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.,Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea
| | - Seok-Ho Hong
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.,Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea
| | - Seung-Joon Lee
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.,Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea
| | - Woo Jin Kim
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.,Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea
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Chen YM, Li X, Song GX, Liu M, Fan Y, Wu LJ, Li H, Zhang QJ, Liu YQ, Qian LM. Effect of LYRM1 knockdown on proliferation, apoptosis, differentiation and mitochondrial function in the P19 cell model of cardiac differentiation in vitro. J Bioenerg Biomembr 2016; 48:33-41. [PMID: 26759027 PMCID: PMC4733147 DOI: 10.1007/s10863-015-9638-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 12/17/2015] [Indexed: 12/15/2022]
Abstract
To explore the effects of LYRM1 knockdown on proliferation, apoptosis, differentiation and mitochondrial function in the embryonic carcinoma (P19) cell model of cardiac differentiation. Knockdown of LYRM1 using small interfering RNA (siRNA) was confirmed by quantitative real-time PCR. Cell Counting Kit-8(CCK-8) proliferation assays and cell cycle analysis demonstrated that LYRM1 gene silencing significantly inhibited P19 cell proliferation. Flow cytometry and measurement of their caspase-3 activities revealed that knockdown of LYRM1 increased P19 cell apoptosis. Observation of morphological changes using an inverted microscope and expression analysis of specific differentiation marker genes using quantitative real-time PCR and Western blotting revealed that knockdown of LYRM1 significantly inhibited the differentiation of P19 cells into cardiomyocytes. Furthermore, real-time quantitative PCR applied to detect mitochondrial DNA (mtDNA) copy number implied that there was no significant difference in the LYRM1 knockdown group compared with the control group. Cellular ATP production investigated by luciferase-based luminescence assay was dramatically decreased in differentiated cells transfected with LYRM1 RNAi. Fluorescence microscopy and flow cytometery were used to detect the reactive oxygen species (ROS) and the mitochondrial membrane potential (MMP) showed that the level of ROS was dramatically increased and MMP was obviously decreased in differentiated cells transfected with LYRM1 RNAi. Collectively, knockdown of LYRM1 promoted apoptosis and suppressed proliferation and differentiation in P19 cells. In addition, knockdown of LYRM1 induced mitochondrial impairment in P19 cells during differentiation, which was reflected by decreased ATP synthesis, lower MMP and increased ROS levels.
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Affiliation(s)
- Yu-Mei Chen
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, Jiangsu Province, People's Republic of China
| | - Xing Li
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, Jiangsu Province, People's Republic of China
| | - Gui-Xian Song
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, Jiangsu Province, People's Republic of China
| | - Ming Liu
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, Jiangsu Province, People's Republic of China
| | - Yi Fan
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, Jiangsu Province, People's Republic of China
| | - Li-Jie Wu
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, Jiangsu Province, People's Republic of China
| | - Hua Li
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, Jiangsu Province, People's Republic of China
| | - Qi-Jun Zhang
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, Jiangsu Province, People's Republic of China
| | - Yao-Qiu Liu
- Department of MICU, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Nanjing, 210029, China.
| | - Ling-Mei Qian
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, Jiangsu Province, People's Republic of China.
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6
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Zhang M, Qin ZY, Dai YM, Wang YM, Zhu GZ, Zhao YP, Ji CB, Zhu JG, Shi CM, Qiu J, Cao XG, Guo XR. Knockdown of LYRM1 rescues insulin resistance and mitochondrial dysfunction induced by FCCP in 3T3-L1 adipocytes. Cell Biochem Biophys 2015; 70:667-75. [PMID: 24771405 DOI: 10.1007/s12013-014-9971-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
LYR motif-containing 1 (LYRM1) was recently discovered to be involved in adipose tissue homeostasis and obesity-associated insulin resistance. We previously demonstrated that LYRM1 overexpression might contribute to insulin resistance and mitochondrial dysfunction. Additionally, knockdown of LYRM1 enhanced insulin sensitivity and mitochondrial function in 3T3-L1 adipocytes. We investigated whether knockdown of LYRM1 in 3T3-L1 adipocytes could rescue insulin resistance and mitochondrial dysfunction induced by the cyanide p-trifluoromethoxyphenyl-hydrazone (FCCP), a mitochondrion uncoupler, to further ascertain the mechanism by which LYRM1 is involved in obesity-associated insulin resistance. Incubation of 3T3-L1 adipocytes with 1 µM FCCP for 12 h decreased insulin-stimulated glucose uptake, reduced intracellular ATP synthesis, increased intracellular reactive oxygen species (ROS) production, impaired insulin-stimulated Glucose transporter type 4 (GLUT4) translocation, and diminished insulin-stimulated tyrosine phosphorylation of Insulin receptor substrate-1 (IRS-1) and serine phosphorylation of Protein Kinase B (Akt). Knockdown of LYRM1 restored insulin-stimulated glucose uptake, rescued intracellular ATP synthesis, reduced intracellular ROS production, restored insulin-stimulated GLUT4 translocation, and rescued insulin-stimulated tyrosine phosphorylation of IRS-1 and serine phosphorylation of Akt in FCCP-treated 3T3-L1 adipocytes. This study indicates that FCCP-induced mitochondrial dysfunction and insulin resistance are ameliorated by knockdown of LYRM1.
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Affiliation(s)
- Min Zhang
- State Key Laboratory of Reproductive Medicine, Nanjing Maternal and Child Health Hospital of Nanjing Medical University, Nanjing, 210004, China
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Angerer H. Eukaryotic LYR Proteins Interact with Mitochondrial Protein Complexes. BIOLOGY 2015; 4:133-50. [PMID: 25686363 PMCID: PMC4381221 DOI: 10.3390/biology4010133] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 02/04/2015] [Indexed: 01/18/2023]
Abstract
In eukaryotic cells, mitochondria host ancient essential bioenergetic and biosynthetic pathways. LYR (leucine/tyrosine/arginine) motif proteins (LYRMs) of the Complex1_LYR-like superfamily interact with protein complexes of bacterial origin. Many LYR proteins function as extra subunits (LYRM3 and LYRM6) or novel assembly factors (LYRM7, LYRM8, ACN9 and FMC1) of the oxidative phosphorylation (OXPHOS) core complexes. Structural insights into complex I accessory subunits LYRM6 and LYRM3 have been provided by analyses of EM and X-ray structures of complex I from bovine and the yeast Yarrowia lipolytica, respectively. Combined structural and biochemical studies revealed that LYRM6 resides at the matrix arm close to the ubiquinone reduction site. For LYRM3, a position at the distal proton-pumping membrane arm facing the matrix space is suggested. Both LYRMs are supposed to anchor an acyl-carrier protein (ACPM) independently to complex I. The function of this duplicated protein interaction of ACPM with respiratory complex I is still unknown. Analysis of protein-protein interaction screens, genetic analyses and predicted multi-domain LYRMs offer further clues on an interaction network and adaptor-like function of LYR proteins in mitochondria.
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Affiliation(s)
- Heike Angerer
- Goethe University Frankfurt, Medical School, Institute of Biochemistry II, Structural Bioenergetics Group, Max-von-Laue Street 9, Frankfurt am Main 60438, Germany.
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Majka SM, Miller HL, Helm KM, Acosta AS, Childs CR, Kong R, Klemm DJ. Analysis and isolation of adipocytes by flow cytometry. Methods Enzymol 2014; 537:281-96. [PMID: 24480352 DOI: 10.1016/b978-0-12-411619-1.00015-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Analysis and isolation of adipocytes via flow cytometry is particularly useful to study their biology. However, the adoption of this technology has often been hampered by the presence of stromal/vascular cells in adipocyte fractions prepared from collagenase-digested adipose tissue. Here, we describe a multistep staining method and gating strategy that effectively excludes stromal contaminants. Initially, we set a gate optimized to the size and internal complexity of adipocytes. Exclusion of cell aggregates is then performed based on fluorescence of a nuclear stain followed by positive selection to collect only those cell events containing lipid droplets. Lastly, negative selection of cells expressing stromal or vascular lineage markers removes any remaining stromal contaminants. These procedures are applicable to simple analysis of adipocytes and their subcellular constituents by flow cytometry as well as isolation of adipocytes by flow sorting.
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Affiliation(s)
- Susan M Majka
- Department of Medicine, Vanderbilt University, Nashville, Tennessee, USA
| | - Heidi L Miller
- Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Karen M Helm
- Cancer Center Flow Cytometry Core, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Alistaire S Acosta
- Cancer Center Flow Cytometry Core, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Christine R Childs
- Cancer Center Flow Cytometry Core, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | | | - Dwight J Klemm
- Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
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The superfamily of mitochondrial Complex1_LYR motif-containing (LYRM) proteins. Biochem Soc Trans 2013; 41:1335-41. [DOI: 10.1042/bst20130116] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Mitochondrial LYRM (leucine/tyrosine/arginine motif) proteins are members of the Complex1_LYR-like superfamily. Individual LYRM proteins have been identified as accessory subunits or assembly factors of mitochondrial OXPHOS (oxidative phosphorylation) complexes I, II, III and V respectively, and they play particular roles in the essential Fe–S cluster biogenesis and in acetate metabolism. LYRM proteins have been implicated in mitochondrial dysfunction, e.g. in the context of insulin resistance. However, the functional significance of the common LYRM is still unknown. Analysis of protein–protein interaction screens suggests that LYRM proteins form protein complexes with phylogenetically ancient proteins of bacterial origin. Interestingly, the mitochondrial FAS (fatty acid synthesis) type II acyl-carrier protein ACPM associates with some of the LYRM protein-containing complexes. Eukaryotic LYRM proteins interfere with mitochondrial homoeostasis and might function as adaptor-like ‘accessory factors’.
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