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Bora JR, Mahalakshmi R. Photoradical-Mediated Catalyst-Independent Protein Cross-Link with Unusual Fluorescence Properties. Chembiochem 2023; 24:e202300380. [PMID: 37232210 PMCID: PMC7615464 DOI: 10.1002/cbic.202300380] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 05/25/2023] [Accepted: 05/26/2023] [Indexed: 05/27/2023]
Abstract
Photo-actively modified natural amino acids have served as lucrative probes for precise mapping of the dynamics, interaction networks, and turnover of cytosolic proteins both in vivo and ex vivo. In our attempts to extend the utility of photoreactive reporters to map the molecular characteristics of vital membrane proteins, we carried out site-selective incorporation of 7-fluoro-indole in the human mitochondrial outer membrane protein VDAC2 (voltage-dependent anion channel isoform 2), with the aim of generating Trp-Phe/Tyr cross-links. Prolonged irradiation at 282 nm provided us with a surprisingly unusual fluorophore that displayed sizably red-shifted excitation (λex-max =280 nm→360 nm) and emission (λem-max =330 nm→430 nm) spectra that was reversible with organic solvents. By measuring the kinetics of the photo-activated cross-linking with a library of hVDAC2 variants, we demonstrate that formation of this unusual fluorophore is kinetically retarded, independent of tryptophan, and is site-specific. Using other membrane (Tom40 and Sam50) and cytosolic (MscR and DNA Pol I) proteins, we additionally show that formation of this fluorophore is protein-independent. Our findings reveal the photoradical-mediated accumulation of reversible tyrosine cross-links, with unusual fluorescent properties. Our findings have immediate applications in protein biochemistry and UV-mediated protein aggregation and cellular damage, opening avenues for formulating therapeutics that prolong cell viability in humans.
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Affiliation(s)
- Jinam Ravindra Bora
- Molecular Biophysics Laboratory Department of Biological Sciences Indian Institute of Science Education and Research Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh (India)
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory Department of Biological Sciences Indian Institute of Science Education and Research Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh (India)
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2
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Li JY, Zhao Y, Gong S, Wang MM, Liu X, He QM, Li YQ, Huang SY, Qiao H, Tan XR, Ye ML, Zhu XH, He SW, Li Q, Liang YL, Chen KL, Huang SW, Li QJ, Ma J, Liu N. TRIM21 inhibits irradiation-induced mitochondrial DNA release and impairs antitumour immunity in nasopharyngeal carcinoma tumour models. Nat Commun 2023; 14:865. [PMID: 36797289 PMCID: PMC9935546 DOI: 10.1038/s41467-023-36523-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 02/02/2023] [Indexed: 02/18/2023] Open
Abstract
Although radiotherapy can promote antitumour immunity, the mechanisms underlying this phenomenon remain unclear. Here, we demonstrate that the expression of the E3 ubiquitin ligase, tumour cell-intrinsic tripartite motif-containing 21 (TRIM21) in tumours, is inversely associated with the response to radiation and CD8+ T cell-mediated antitumour immunity in nasopharyngeal carcinoma (NPC). Knockout of TRIM21 modulates the cGAS/STING cytosolic DNA sensing pathway, potentiates the antigen-presenting capacity of NPC cells, and activates cytotoxic T cell-mediated antitumour immunity in response to radiation. Mechanistically, TRIM21 promotes the degradation of the mitochondrial voltage-dependent anion-selective channel protein 2 (VDAC2) via K48-linked ubiquitination, which inhibits pore formation by VDAC2 oligomers for mitochondrial DNA (mtDNA) release, thereby inhibiting type-I interferon responses following radiation exposure. In patients with NPC, high TRIM21 expression was associated with poor prognosis and early tumour relapse after radiotherapy. Our findings reveal a critical role of TRIM21 in radiation-induced antitumour immunity, providing potential targets for improving the efficacy of radiotherapy in patients with NPC.
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Affiliation(s)
- Jun-Yan Li
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Yin Zhao
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Sha Gong
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Miao-Miao Wang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Xu Liu
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Qing-Mei He
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Ying-Qin Li
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Sheng-Yan Huang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Han Qiao
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Xi-Rong Tan
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Ming-Liang Ye
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Xun-Hua Zhu
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Shi-Wei He
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Qian Li
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Ye-Lin Liang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Kai-Lin Chen
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Sai-Wei Huang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Qing-Jie Li
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China
| | - Jun Ma
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China. .,Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.
| | - Na Liu
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, 510060, Guangzhou, P.R. China.
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Comparing the Effects of Concord Grape ( Vitis labrusca L.) Puree, Juice, and Pomace on Intestinal Morphology, Functionality, and Bacterial Populations In Vivo ( Gallus gallus). Nutrients 2022; 14:nu14173539. [PMID: 36079797 PMCID: PMC9460804 DOI: 10.3390/nu14173539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/22/2022] [Accepted: 08/25/2022] [Indexed: 12/20/2022] Open
Abstract
This is a preliminary study evaluating the effect of different fractions of Concord grapes (Vitis labrusca L.) on the brush border membrane (BBM) morphology, duodenal gene expression, and specific gut bacterial populations. For this study, we utilized a unique intraamniotic approach, wherein, the test substances are administered into the amnion of the Gallus gallus egg (on day 17). The embryo orally consumes the amniotic fluid along with the injected test substance before the hatch. We randomly divided ~50 fertilized eggs into 5 groups including 6% grape (juice, puree, and pomace) along with controls (no injection and diluent—H2O). The grape juice was prepared by crushing the grapes; the grape residues were used as pomace. The grape puree included the grape skin, endocarp, mesocarp, and juice but not the seeds. On day 21, the hatch day, the blood, pectoral muscle, liver, duodenum, and large intestine were harvested. Our results showed no significant differences in blood glucose, pectoral glycogen level, or body weight. However, significant (p < 0.05) differences in duodenal and liver gene expression were observed between the treatment groups. The grape puree treatment resulted in higher Clostridium numbers and lower Bifidobacterium numbers when compared to all other groups. In summary, the dietary consumption of grape polyphenols has the potential to beneficially modulate aspects of intestinal health provided their concentration is limited.
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Yang L, Wang H, Lu W, Yang G, Lin Z, Chen R, Li H. Quantitative proteomic analysis of oxaliplatin induced peripheral neurotoxicity. J Proteomics 2022; 266:104682. [PMID: 35830924 DOI: 10.1016/j.jprot.2022.104682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/19/2022] [Accepted: 07/06/2022] [Indexed: 10/17/2022]
Abstract
Oxaliplatin (OXA)-induced peripheral neurotoxicity (OIPN) is a high-incidence and dose-dependent adverse reaction during OXA treatment. Its underlying mechanisms remain unclear, and no effective treatment or prevention therapies are currently available. Here, we employed a data independent acquisition (DIA)-based quantitative proteomic strategy to investigate the global proteome alterations in the dorsal root ganglion (DRG) tissues from mice injected with OXA for different periods. We identified 1128 differentially regulated proteins that were divided into six subclusters according to their alteration trends. Interestingly, these proteins were involved in cellular processes such as cell cycle, ribosomal stress, metabolism, and ion transport. In addition, OXA administration induced abundance changes of ion channels and proteins associated with mitochondrial function and reactive oxygen species production. Furthermore, we investigated the effects of diroximel fumarate (DRF), an FDA-approved oral fumarate drug for the treatment of relapsing forms of multiple sclerosis. Our findings showed that DRF could effectively ameliorate symptoms of OIPN and reduce the level of oxidative stress in mice. Taken together, our study systematically mapped the proteome alteration associated with the neural toxicity of OXA, and the findings could be leveraged to better understand the mechanisms of OIPN and to develop more effect treatment therapies. SIGNIFICANCE: Oxaliplatin (OXA)-induced peripheral neurotoxicity (OIPN) is a high-incidence and dose-dependent adverse reaction with unclear mechanism. Here we employed a data independent acquisition (DIA)-based quantitative proteomic strategy to explore the proteome changes in dorsal root ganglion (DRG) tissues from mice treated by OXA. The findings provided novel insights regarding the mechanisms of OIPN. For example, our data showed that OXA induced a broad disturbance in metabolism, particularly in glycolysis and amino acid metabolism. Additionally, we observed abundance changes of many ion channels and proteins associated with mitochondrial function and reactive oxygen species production. Furthermore, this study provided the first evidence for the possibility of repositioning diroximel fumarate (DRF) for treating OIPN.
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Affiliation(s)
- Linlin Yang
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Hua Wang
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Wanting Lu
- General Surgery Department and Neurology Department, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Beijing 100053, China
| | - Gangqi Yang
- General Surgery Department and Neurology Department, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Beijing 100053, China
| | - Zian Lin
- Ministry of Education Key Laboratory of Analytical Science for Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Ruibing Chen
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China.
| | - Hongyan Li
- General Surgery Department and Neurology Department, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Beijing 100053, China.
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Abstract
Mitochondria have been recognized as key organelles in cardiac physiology and are potential targets for clinical interventions to improve cardiac function. Mitochondrial dysfunction has been accepted as a major contributor to the development of heart failure. The main function of mitochondria is to meet the high energy demands of the heart by oxidative metabolism. Ionic homeostasis in mitochondria directly regulates oxidative metabolism, and any disruption in ionic homeostasis causes mitochondrial dysfunction and eventually contractile failure. The mitochondrial ionic homeostasis is closely coupled with inner mitochondrial membrane potential. To regulate and maintain ionic homeostasis, mitochondrial membranes are equipped with ion transporting proteins. Ion transport mechanisms involving several different ion channels and transporters are highly efficient and dynamic, thus helping to maintain the ionic homeostasis of ions as well as their salts present in the mitochondrial matrix. In recent years, several novel proteins have been identified on the mitochondrial membranes and these proteins are actively being pursued in research for roles in the organ as well as organelle physiology. In this article, the role of mitochondrial ion channels in cardiac function is reviewed. In recent times, the major focus of the mitochondrial ion channel field is to establish molecular identities as well as assigning specific functions to them. Given the diversity of mitochondrial ion channels and their unique roles in cardiac function, they present novel and viable therapeutic targets for cardiac diseases.
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Affiliation(s)
- Harpreet Singh
- Department of Physiology and Cell Biology, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, Ohio
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6
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Khan A, Kuriachan G, Mahalakshmi R. Cellular Interactome of Mitochondrial Voltage-Dependent Anion Channels: Oligomerization and Channel (Mis)Regulation. ACS Chem Neurosci 2021; 12:3497-3515. [PMID: 34503333 DOI: 10.1021/acschemneuro.1c00429] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Voltage-dependent anion channels (VDACs) of the outer mitochondrial membrane are known conventionally as metabolite flux proteins. However, research findings in the past decade have revealed the multifaceted regulatory roles of VDACs, from governing cellular physiology and mitochondria-mediated apoptosis to directly regulating debilitating cancers and neurodegenerative diseases. VDACs achieve these diverse functions by establishing isoform-dependent stereospecific interactomes in the cell with the cytosolic constituents and endoplasmic reticulum complexes, and the machinery of the mitochondrial compartments. VDACs are now increasingly recognized as regulatory hubs of the cell. Not surprisingly, even the transient misregulation of VDACs results directly in mitochondrial dysfunction. Additionally, human VDACs are now implicated in interaction with aggregation-prone cytosolic proteins, including Aβ, tau, and α-synuclein, contributing directly to the onset of Alzheimer's and Parkinson's diseases. Deducing the interaction dynamics and mechanisms can lead to VDAC-targeted peptide-based therapeutics that can alleviate neurodegenerative states. This review succinctly presents the latest findings of the VDAC interactome, and the mode(s) of VDAC-dependent regulation of biochemical physiology. We also discuss the relevance of VDACs in pathophysiological states and aggregation-associated diseases and address how VDACs will facilitate the development of next-generation precision medicines.
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Affiliation(s)
- Altmash Khan
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462066, India
| | - Gifty Kuriachan
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462066, India
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462066, India
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7
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Queralt-Martín M, Bergdoll L, Teijido O, Munshi N, Jacobs D, Kuszak AJ, Protchenko O, Reina S, Magrì A, De Pinto V, Bezrukov SM, Abramson J, Rostovtseva TK. A lower affinity to cytosolic proteins reveals VDAC3 isoform-specific role in mitochondrial biology. J Gen Physiol 2021; 152:133600. [PMID: 31935282 PMCID: PMC7062508 DOI: 10.1085/jgp.201912501] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/20/2019] [Indexed: 01/30/2023] Open
Abstract
Voltage-dependent anion channel (VDAC) is the major pathway for the transport of ions and metabolites across the mitochondrial outer membrane. Among the three known mammalian VDAC isoforms, VDAC3 is the least characterized, but unique functional roles have been proposed in cellular and animal models. Yet, a high-sequence similarity between VDAC1 and VDAC3 is indicative of a similar pore-forming structure. Here, we conclusively show that VDAC3 forms stable, highly conductive voltage-gated channels that, much like VDAC1, are weakly anion selective and facilitate metabolite exchange, but exhibit unique properties when interacting with the cytosolic proteins α-synuclein and tubulin. These two proteins are known to be potent regulators of VDAC1 and induce similar characteristic blockages (on the millisecond time scale) of VDAC3, but with 10- to 100-fold reduced on-rates and altered α-synuclein blocking times, indicative of an isoform-specific function. Through cysteine scanning mutagenesis, we found that VDAC3's cysteine residues regulate its interaction with α-synuclein, demonstrating VDAC3-unique functional properties and further highlighting a general molecular mechanism for VDAC isoform-specific regulation of mitochondrial bioenergetics.
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Affiliation(s)
- María Queralt-Martín
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Lucie Bergdoll
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA
| | - Oscar Teijido
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Nabill Munshi
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA
| | - Daniel Jacobs
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Adam J Kuszak
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Olga Protchenko
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Simona Reina
- Department of Biological, Geological and Environmental Sciences, University of Catania, Catania, Italy
| | - Andrea Magrì
- Department of Biological, Geological and Environmental Sciences, University of Catania, Catania, Italy
| | - Vito De Pinto
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Sergey M Bezrukov
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Jeff Abramson
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA
| | - Tatiana K Rostovtseva
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
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Srivastava SR, Mahalakshmi R. Evolutionary selection of a 19-stranded mitochondrial β-barrel scaffold bears structural and functional significance. J Biol Chem 2020; 295:14653-14665. [PMID: 32817169 PMCID: PMC7586230 DOI: 10.1074/jbc.ra120.014366] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 08/15/2020] [Indexed: 12/12/2022] Open
Abstract
Transmembrane β-barrels of eukaryotic outer mitochondrial membranes (OMMs) are major channels of communication between the cytosol and mitochondria and are indispensable for cellular homeostasis. A structurally intriguing exception to all known transmembrane β-barrels is the unique odd-stranded, i.e. 19-stranded, structures found solely in the OMM. The molecular origins of this 19-stranded structure and its associated functional significance are unclear. In humans, the most abundant OMM transporter is the voltage-dependent anion channel. Here, using the human voltage-dependent anion channel as our template scaffold, we designed and engineered odd- and even-stranded structures of smaller (V216, V217, V218) and larger (V220, V221) barrel diameters. Determination of the structure, dynamics, and energetics of these engineered structures in bilayer membranes reveals that the 19-stranded barrel surprisingly holds modest to low stability in a lipid-dependent manner. However, we demonstrate that this structurally metastable protein possesses superior voltage-gated channel regulation, efficient mitochondrial targeting, and in vivo cell survival, with lipid-modulated stability, all of which supersede the occurrence of a metastable 19-stranded scaffold. We propose that the unique structural adaptation of these transmembrane transporters exclusively in mitochondria bears strong evolutionary basis and is functionally significant for homeostasis.
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Affiliation(s)
- Shashank Ranjan Srivastava
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India.
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9
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Dudko HV, Urban VA, Davidovskii AI, Veresov VG. Structure-based modeling of turnover of Bcl-2 family proteins bound to voltage-dependent anion channel 2 (VDAC2): Implications for the mechanisms of proapoptotic activation of Bak and Bax in vivo. Comput Biol Chem 2020; 85:107203. [DOI: 10.1016/j.compbiolchem.2020.107203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/31/2019] [Accepted: 01/13/2020] [Indexed: 12/15/2022]
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Novel insights into molecular mechanisms of Pseudourostyla cristata encystment using comparative transcriptomics. Sci Rep 2019; 9:19109. [PMID: 31836801 PMCID: PMC6911008 DOI: 10.1038/s41598-019-55608-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 11/20/2019] [Indexed: 12/17/2022] Open
Abstract
The encystment of many ciliates is an advanced survival strategy against adversity and the most important reason for ciliates existence worldwide. However, the molecular mechanism for the encystment of free-living ciliates is poorly understood. Here, we performed comparative transcriptomic analysis of dormant cysts and trophonts from Pseudourostyla cristata using transcriptomics, qRT-PCR and bioinformatic techniques. We identified 2565 differentially expressed unigenes between the dormant cysts and the trophonts. The total number of differentially expressed genes in GO database was 1752. The differential unigenes noted to the GO terms were 1993. These differential categories were mainly related to polyamine transport, pectin decomposition, cytoplasmic translation, ribosome, respiratory chain, ribosome structure, ion channel activity, and RNA ligation. A total of 224 different pathways were mapped. Among them, 184 pathways were upregulated, while 162 were downregulated. Further investigation showed that the calcium and AMPK signaling pathway had important induction effects on the encystment. In addition, FOXO and ubiquitin-mediated proteolysis signaling pathway jointly regulated the encystment. Based on these findings, we propose a hypothetical signaling network that regulates Pseudourostyla cristata encystment. Overall, these results provide deeper insights into the molecular mechanisms of ciliates encystment and adaptation to adverse environments.
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11
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Proteome Alterations in Equine Osteochondrotic Chondrocytes. Int J Mol Sci 2019; 20:ijms20246179. [PMID: 31817880 PMCID: PMC6940994 DOI: 10.3390/ijms20246179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 11/27/2019] [Accepted: 12/04/2019] [Indexed: 01/07/2023] Open
Abstract
Osteochondrosis is a failure of the endochondral ossification that affects developing joints in humans and several animal species. It is a localized idiopathic joint disorder characterized by focal chondronecrosis and growing cartilage retention, which can lead to the formation of fissures, subchondral bone cysts, or intra-articular fragments. Osteochondrosis is a complex multifactorial disease associated with extracellular matrix alterations and failure in chondrocyte differentiation, mainly due to genetic, biochemical, and nutritional factors, as well as traumas. This study describes the main proteomic alterations occurring in chondrocytes isolated from osteochondrotic cartilage fragments. A comparative analysis performed on equine osteochondrotic and healthy chondrocytes showed 26 protein species as differentially represented. In particular, quantitative changes in the extracellular matrix, cytoskeletal and chaperone proteins, and in cell adhesion and signaling molecules were observed in osteochondrotic cells, compared to healthy controls. Functional group analysis annotated most of these proteins in “growth plate and cartilage development”, while others were included in “glycolysis and gluconeogenesis”, “positive regulation of protein import”, “cell–cell adhesion mediator activity”, and “mitochondrion nucleoid”. These results may help to clarify some chondrocyte functional alterations that may play a significant role in determining the onset and progression of equine osteochondrosis and, being related, of human juvenile osteochondrosis.
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12
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Schmelter C, Fomo KN, Perumal N, Manicam C, Bell K, Pfeiffer N, Grus FH. Synthetic Polyclonal-Derived CDR Peptides as an Innovative Strategy in Glaucoma Therapy. J Clin Med 2019; 8:jcm8081222. [PMID: 31443184 PMCID: PMC6723090 DOI: 10.3390/jcm8081222] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/30/2019] [Accepted: 08/12/2019] [Indexed: 12/16/2022] Open
Abstract
The pathogenesis of glaucoma is strongly associated with the occurrence of autoimmune-mediated loss of retinal ganglion cells (RGCs) and additionally, recent evidence shows that specific antibody-derived signature peptides are significantly differentially expressed in sera of primary-open angle glaucoma patients (POAG) compared to healthy controls. Synthetically antibody-derived peptides can modulate various effector functions of the immune system and act as antimicrobial or antiviral molecules. In an ex vivo adolescent glaucoma model, this study, for the first time, demonstrates that polyclonal-derived complementarity-determining regions (CDRs) can significantly increase the survival rate of RGCs (p = 0.013). We subsequently performed affinity capture experiments that verified the mitochondrial serine protease HTRA2 (gene name: HTRA2) as a high-affinity retinal epitope target of CDR1 sequence motif ASGYTFTNYGLSWVR. Quantitative proteomic analysis of the CDR-treated retinal explants revealed increased expression of various anti-apoptotic and anti-oxidative proteins (e.g., VDAC2 and TXN) compared to untreated controls (p < 0.05) as well as decreased expression levels of cellular stress response markers (e.g., HSPE1 and HSP90AA1). Mitochondrial dysfunction, the protein ubiquitination pathway and oxidative phosphorylation were annotated as the most significantly affected signaling pathways and possibly can be traced back to the CDR-induced inhibition or modulation of the master regulator HTRA2. These findings emphasize the great potential of synthetic polyclonal-derived CDR peptides as therapeutic agents in future glaucoma therapy and provide an excellent basis for affinity-based biomarker discovery purposes.
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Affiliation(s)
- Carsten Schmelter
- Department of Experimental and Translational Ophthalmology, University Medical Center, Johannes Gutenberg University, 55131 Mainz, Germany
| | - Kristian Nzogang Fomo
- Department of Experimental and Translational Ophthalmology, University Medical Center, Johannes Gutenberg University, 55131 Mainz, Germany
| | - Natarajan Perumal
- Department of Experimental and Translational Ophthalmology, University Medical Center, Johannes Gutenberg University, 55131 Mainz, Germany
| | - Caroline Manicam
- Department of Experimental and Translational Ophthalmology, University Medical Center, Johannes Gutenberg University, 55131 Mainz, Germany
| | - Katharina Bell
- Department of Experimental and Translational Ophthalmology, University Medical Center, Johannes Gutenberg University, 55131 Mainz, Germany
| | - Norbert Pfeiffer
- Department of Experimental and Translational Ophthalmology, University Medical Center, Johannes Gutenberg University, 55131 Mainz, Germany
| | - Franz H Grus
- Department of Experimental and Translational Ophthalmology, University Medical Center, Johannes Gutenberg University, 55131 Mainz, Germany.
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Gupta A, Mahalakshmi R. Helix-strand interaction regulates stability and aggregation of the human mitochondrial membrane protein channel VDAC3. J Gen Physiol 2019; 151:489-504. [PMID: 30674561 PMCID: PMC6445588 DOI: 10.1085/jgp.201812272] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/02/2019] [Indexed: 11/25/2022] Open
Abstract
Human mitochondrial VDACs bind amyloidogenic proteins, but do not intrinsically aggregate. Gupta and Mahalakshmi find that an interaction between the N-terminal α-helix and strands β7–β9 regulates VDAC aggregation and stability, providing a plausible mechanism for VDAC coaggregation in cells. Voltage-dependent anion channels (VDACs) are β-sheet–rich transmembrane β-barrels that are vital for metabolite transport across the mitochondrial membrane. Under cellular stress, human VDACs hetero-oligomerize and coaggregate with proteins that can form amyloidogenic and neurodegenerative deposits, implicating a role for VDACs in proteotoxicity. However, whether VDACs possess intrinsic interaction sites that can lead to protein aggregation is not known. Here, we couple a systematic thiol replacement strategy with far-UV circular dichroism spectropolarimetry and UV scattering spectroscopy to map aggregation-prone regions of human VDACs, using isoform 3 as our model VDAC. We show that the region comprising strands β7–β9 is highly aggregation prone. Further, we find that an α1–β7–β9 interaction (involving the hVDAC3 N-terminal α1 helix) can lower protein aggregation, whereas perturbations of this interaction promote VDAC aggregation. We also show that hVDAC3 aggregation proceeds via a partially unfolded structure. Our findings allow us to propose a plausible mechanism for the role of human VDACs in forming proteotoxic aggregates in the cell. The key target sites on VDACs—strands β7–β9—may be useful for developing VDAC aggregation inhibitors.
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Affiliation(s)
- Ankit Gupta
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
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Srivastava SR, Zadafiya P, Mahalakshmi R. Hydrophobic Mismatch Modulates Stability and Plasticity of Human Mitochondrial VDAC2. Biophys J 2018; 115:2386-2394. [PMID: 30503532 PMCID: PMC6301912 DOI: 10.1016/j.bpj.2018.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/15/2018] [Accepted: 11/01/2018] [Indexed: 01/13/2023] Open
Abstract
The human mitochondrial outer membrane protein voltage-dependent anion channel isoform 2 (hVDAC2) is a β-barrel metabolite flux channel that is indispensable for cell survival. It is well established that physical forces imposed on a transmembrane protein by its surrounding lipid environment decide protein structure and stability. Yet, how the mitochondrial membrane and protein-lipid interplay together regulate hVDAC2 stability is unknown. Here, we combine experimental biophysical investigations of protein stability with all-atom molecular dynamics simulations to study the effect of the most abundant mitochondrial phosphocholine (PC) lipids on hVDAC2. We demonstrate experimentally that increasing the PC lipid acyl chain length from diC14:0 to diC18:0-PC has a nonlinear effect on the β-barrel. We show that protein stability is highest in diC16:0-PC, which exhibits a negative mismatch with the hVDAC2 barrel. Our simulations also reveal that structural rigidity of hVDAC2 is highest under optimal negative mismatch provided by diC16:0-PC bilayers. Further, we validate our observations by altering the physical properties of PC membranes indirectly using cholesterol. We propose that VDAC plasticity and stability in the mitochondrial outer membrane are modulated by physical properties of the bilayer.
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Affiliation(s)
- Shashank Ranjan Srivastava
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Punit Zadafiya
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India.
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Lella M, Mahalakshmi R. Direct Structural Annotation of Membrane Protein Aggregation Loci using Peptide-Based Reverse Mapping. J Phys Chem Lett 2018; 9:2967-2971. [PMID: 29763546 PMCID: PMC6005643 DOI: 10.1021/acs.jpclett.8b00953] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 05/15/2018] [Indexed: 06/08/2023]
Abstract
Membrane protein aggregation is associated with neurodegenerative diseases. Despite remarkable advances to map protein aggregation, molecular elements that drive the structural transition from functional to amyloidogenic β-sheet polymers remain elusive. Here, we report a simple and reliable reverse-mapping method to identify the molecular elements. We validate our approach by obtaining molecular details of aggregation loci of human β-barrel nanopore ion channels that are vital for cell survival. By coupling bottom-up synthesis with time-resolved aggregation kinetics and high-resolution imaging, we identify molecular elements that switch folded channels to polymeric β-rich aggregates. We prove that intrinsic protein aggregation and amyloidogenicity does not depend on total hydrophobicity but on single residue differences in the primary sequence. Our method offers effective strategies for sequence-based design of aggregation inhibitors in biomedicine for neurodegenerative diseases.
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Chaturvedi D, Mahalakshmi R. Transmembrane β-barrels: Evolution, folding and energetics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:2467-2482. [PMID: 28943271 DOI: 10.1016/j.bbamem.2017.09.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 09/16/2017] [Accepted: 09/19/2017] [Indexed: 12/23/2022]
Abstract
The biogenesis of transmembrane β-barrels (outer membrane proteins, or OMPs) is an elaborate multistep orchestration of the nascent polypeptide with translocases, barrel assembly machinery, and helper chaperone proteins. Several theories exist that describe the mechanism of chaperone-assisted OMP assembly in vivo and unassisted (spontaneous) folding in vitro. Structurally, OMPs of bacterial origin possess even-numbered strands, while mitochondrial β-barrels are even- and odd-stranded. Several underlying similarities between prokaryotic and eukaryotic β-barrels and their folding machinery are known; yet, the link in their evolutionary origin is unclear. While OMPs exhibit diversity in sequence and function, they share similar biophysical attributes and structure. Similarly, it is important to understand the intricate OMP assembly mechanism, particularly in eukaryotic β-barrels that have evolved to perform more complex functions. Here, we deliberate known facets of β-barrel evolution, folding, and stability, and attempt to highlight outstanding questions in β-barrel biogenesis and proteostasis.
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Affiliation(s)
- Deepti Chaturvedi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462066, India.
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462066, India.
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