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Moncan M, Rakhsh-Khorshid H, Eriksson LA, Samali A, Gorman AM. Insights into the structure and function of the RNA ligase RtcB. Cell Mol Life Sci 2023; 80:352. [PMID: 37935993 PMCID: PMC10630183 DOI: 10.1007/s00018-023-05001-5] [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: 08/10/2023] [Revised: 09/19/2023] [Accepted: 10/11/2023] [Indexed: 11/09/2023]
Abstract
To be functional, some RNAs require a processing step involving splicing events. Each splicing event necessitates an RNA ligation step. RNA ligation is a process that can be achieved with various intermediaries such as self-catalysing RNAs, 5'-3' and 3'-5' RNA ligases. While several types of RNA ligation mechanisms occur in human, RtcB is the only 3'-5' RNA ligase identified in human cells to date. RtcB RNA ligation activity is well known to be essential for the splicing of XBP1, an essential transcription factor of the unfolded protein response; as well as for the maturation of specific intron-containing tRNAs. As such, RtcB is a core factor in protein synthesis and homeostasis. Taking advantage of the high homology between RtcB orthologues in archaea, bacteria and eukaryotes, this review will provide an introduction to the structure of RtcB and the mechanism of 3'-5' RNA ligation. This analysis is followed by a description of the mechanisms regulating RtcB activity and localisation, its known partners and its various functions from bacteria to human with a specific focus on human cancer.
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Affiliation(s)
- Matthieu Moncan
- Apoptosis Research Centre, University of Galway, Galway, Ireland
- School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Hassan Rakhsh-Khorshid
- Apoptosis Research Centre, University of Galway, Galway, Ireland
- School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Leif A Eriksson
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30, Göteborg, Sweden
| | - Afshin Samali
- Apoptosis Research Centre, University of Galway, Galway, Ireland
- School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
- CÚRAM SFI Research Centre for Medical Devices, University of Galway, Galway, Ireland
| | - Adrienne M Gorman
- Apoptosis Research Centre, University of Galway, Galway, Ireland.
- School of Biological and Chemical Sciences, University of Galway, Galway, Ireland.
- CÚRAM SFI Research Centre for Medical Devices, University of Galway, Galway, Ireland.
- Biomedical Sciences, Upper Newcastle, University of Galway, Galway, H91 W2TY, Ireland.
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2
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Francis D, Burguete AS, Ghabrial AS. Regulation of Archease by the mTOR-vATPase axis. Development 2022; 149:dev200908. [PMID: 36111596 PMCID: PMC9641670 DOI: 10.1242/dev.200908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 08/23/2022] [Indexed: 01/19/2023]
Abstract
Larval terminal cells of the Drosophila tracheal system generate extensive branched tubes, requiring a huge increase in apical membrane. We discovered that terminal cells compromised for apical membrane expansion - mTOR-vATPase axis and apical polarity mutants - were invaded by the neighboring stalk cell. The invading cell grows and branches, replacing the original single intercellular junction between stalk and terminal cell with multiple intercellular junctions. Here, we characterize disjointed, a mutation in the same phenotypic class. We find that disjointed encodes Drosophila Archease, which is required for the RNA ligase (RtcB) function that is essential for tRNA maturation and for endoplasmic reticulum stress-regulated nonconventional splicing of Xbp1 mRNA. We show that the steady-state subcellular localization of Archease is principally nuclear and dependent upon TOR-vATPase activity. In tracheal cells mutant for Rheb or vATPase loci, Archease localization shifted dramatically from nucleus to cytoplasm. Further, we found that blocking tRNA maturation by knockdown of tRNAseZ also induced compensatory branching. Taken together, these data suggest that the TOR-vATPase axis promotes apical membrane growth in part through nuclear localization of Archease, where Archease is required for tRNA maturation.
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Affiliation(s)
- Deanne Francis
- College of Public Health, Medical and Veterinary Sciences, Division of Tropical Health and Medicine, Department of Biomedicine and Molecular and Cell Biology, James Cook University, Douglas, QLD 4811, Australia
| | - Alondra S. Burguete
- Department of Biomedicine and Molecular and Cell Biology, The Motor Neuron Center, Columbia University Medical Center, VP&S 5th floor, New York, NY 10032, USA
| | - Amin S. Ghabrial
- Department of Pathology and Cell Biology, Columbia University Medical Center, 630 168th Street, Vagellos Physicians and Surgeons 14-401L, New York, NY 10032, USA
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3
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Li X, Sun S, Appathurai S, Sundaram A, Plumb R, Mariappan M. A Molecular Mechanism for Turning Off IRE1α Signaling during Endoplasmic Reticulum Stress. Cell Rep 2020; 33:108563. [PMID: 33378667 PMCID: PMC7809255 DOI: 10.1016/j.celrep.2020.108563] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 09/14/2020] [Accepted: 12/06/2020] [Indexed: 12/15/2022] Open
Abstract
Misfolded proteins in the endoplasmic reticulum (ER) activate IRE1α endoribonuclease in mammalian cells, which mediates XBP1 mRNA splicing to produce an active transcription factor. This promotes the expression of specific genes to alleviate ER stress, thereby attenuating IRE1α. Although sustained activation of IRE1α is linked to human diseases, it is not clear how IRE1α is attenuated during ER stress. Here, we identify that Sec63 is a subunit of the previously identified IRE1α/Sec61 translocon complex. We find that Sec63 recruits and activates BiP ATPase through its luminal J-domain to bind onto IRE1α. This leads to inhibition of higher-order oligomerization and attenuation of IRE1α RNase activity during prolonged ER stress. In Sec63-deficient cells, IRE1α remains activated for a long period of time despite the presence of excess BiP in the ER. Thus, our data suggest that the Sec61 translocon bridges IRE1α with Sec63/BiP to regulate the dynamics of IRE1α signaling in cells. The stress sensor IRE1α is attenuated during prolonged ER stress by a poorly understood mechanism. Li et al. show that IRE1α forms a complex with the Sec61/Sec63 translocon in cells. Sec63 mediates BiP binding to IRE1α and thereby inhibits IRE1α oligomerization and attenuates IRE1α signaling during prolonged ER stress.
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Affiliation(s)
- Xia Li
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, Yale West Campus, West Haven, CT 06516, USA
| | - Sha Sun
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, Yale West Campus, West Haven, CT 06516, USA
| | - Suhila Appathurai
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, Yale West Campus, West Haven, CT 06516, USA
| | - Arunkumar Sundaram
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, Yale West Campus, West Haven, CT 06516, USA
| | - Rachel Plumb
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, Yale West Campus, West Haven, CT 06516, USA
| | - Malaiyalam Mariappan
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, Yale West Campus, West Haven, CT 06516, USA.
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4
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Bashir S, Banday M, Qadri O, Bashir A, Hilal N, Nida-I-Fatima, Rader S, Fazili KM. The molecular mechanism and functional diversity of UPR signaling sensor IRE1. Life Sci 2020; 265:118740. [PMID: 33188833 DOI: 10.1016/j.lfs.2020.118740] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/03/2020] [Accepted: 11/06/2020] [Indexed: 02/06/2023]
Abstract
The endoplasmic reticulum is primarily responsible for protein folding and maturation. However, the organelle is subject to varied stress conditions from time to time, which lead to the activation of a signaling program known as the Unfolded Protein Response (UPR) pathway. This pathway, upon sensing any disturbance in the protein-folding milieu sends signals to the nucleus and cytoplasm in order to restore homeostasis. One of the prime UPR signaling sensors is Inositol-requiring enzyme 1 (IRE1); an ER membrane embedded protein with dual enzyme activities, kinase and endoribonuclease. The ribonuclease activity of IRE1 results in Xbp1 splicing in mammals or Hac1 splicing in yeast. However, IRE1 can switch its substrate specificity to the mRNAs that are co-transnationally transported to the ER, a phenomenon known as Regulated IRE1 Dependent Decay (RIDD). IRE1 is also reported to act as a principal molecule that coordinates with other proteins and signaling pathways, which in turn might be responsible for its regulation. The current review highlights studies on IRE1 explaining the structural features and molecular mechanism behind its ribonuclease outputs. The emphasis is also laid on the molecular effectors, which directly or indirectly interact with IRE1 to either modulate its function or connect it to other pathways. This is important in understanding the functional pleiotropy of IRE1, by which it can switch its activity from pro-survival to pro-apoptotic, thus determining the fate of cells.
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Affiliation(s)
- Samirul Bashir
- Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Mariam Banday
- Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Ozaira Qadri
- Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Arif Bashir
- Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Nazia Hilal
- Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Nida-I-Fatima
- Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Stephen Rader
- Department of Chemistry, University of Northern British Columbia, Prince George, BC, Canada
| | - Khalid Majid Fazili
- Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, India.
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Riaz TA, Junjappa RP, Handigund M, Ferdous J, Kim HR, Chae HJ. Role of Endoplasmic Reticulum Stress Sensor IRE1α in Cellular Physiology, Calcium, ROS Signaling, and Metaflammation. Cells 2020; 9:E1160. [PMID: 32397116 PMCID: PMC7290600 DOI: 10.3390/cells9051160] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 04/27/2020] [Accepted: 05/06/2020] [Indexed: 12/14/2022] Open
Abstract
Inositol-requiring transmembrane kinase endoribonuclease-1α (IRE1α) is the most prominent and evolutionarily conserved unfolded protein response (UPR) signal transducer during endoplasmic reticulum functional upset (ER stress). A IRE1α signal pathway arbitrates yin and yang of cellular fate in objectionable conditions. It plays several roles in fundamental cellular physiology as well as in several pathological conditions such as diabetes, obesity, inflammation, cancer, neurodegeneration, and in many other diseases. Thus, further understanding of its molecular structure and mechanism of action during different cell insults helps in designing and developing better therapeutic strategies for the above-mentioned chronic diseases. In this review, recent insights into structure and mechanism of activation of IRE1α along with its complex regulating network were discussed in relation to their basic cellular physiological function. Addressing different binding partners that can modulate IRE1α function, UPRosome triggers different downstream pathways depending on the cellular backdrop. Furthermore, IRE1α are in normal cell activities outside the dominion of ER stress and activities under the weather of inflammation, diabetes, and obesity-related metaflammation. Thus, IRE1 as an ER stress sensor needs to be understood from a wider perspective for comprehensive functional meaning, which facilitates us with assembling future needs and therapeutic benefits.
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Affiliation(s)
- Thoufiqul Alam Riaz
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
| | - Raghu Patil Junjappa
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
| | - Mallikarjun Handigund
- Department of Laboratory Medicine, Jeonbuk National University, Medical School, Jeonju 54907, Korea;
| | - Jannatul Ferdous
- Department of Radiology and Research Institute of Clinical Medicine of Jeonbuk National University, Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju 54907, Korea;
| | - Hyung-Ryong Kim
- College of Dentistry, Dankook University, Cheonan 31116, Korea
| | - Han-Jung Chae
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
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Park CK, Horton NC. Structures, functions, and mechanisms of filament forming enzymes: a renaissance of enzyme filamentation. Biophys Rev 2019; 11:927-994. [PMID: 31734826 PMCID: PMC6874960 DOI: 10.1007/s12551-019-00602-6] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/24/2019] [Indexed: 12/19/2022] Open
Abstract
Filament formation by non-cytoskeletal enzymes has been known for decades, yet only relatively recently has its wide-spread role in enzyme regulation and biology come to be appreciated. This comprehensive review summarizes what is known for each enzyme confirmed to form filamentous structures in vitro, and for the many that are known only to form large self-assemblies within cells. For some enzymes, studies describing both the in vitro filamentous structures and cellular self-assembly formation are also known and described. Special attention is paid to the detailed structures of each type of enzyme filament, as well as the roles the structures play in enzyme regulation and in biology. Where it is known or hypothesized, the advantages conferred by enzyme filamentation are reviewed. Finally, the similarities, differences, and comparison to the SgrAI endonuclease system are also highlighted.
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Affiliation(s)
- Chad K. Park
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721 USA
| | - Nancy C. Horton
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721 USA
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Sicari D, Igbaria A, Chevet E. Control of Protein Homeostasis in the Early Secretory Pathway: Current Status and Challenges. Cells 2019; 8:E1347. [PMID: 31671908 PMCID: PMC6912474 DOI: 10.3390/cells8111347] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/21/2019] [Accepted: 10/23/2019] [Indexed: 12/20/2022] Open
Abstract
: Discrimination between properly folded proteins and those that do not reach this state is necessary for cells to achieve functionality. Eukaryotic cells have evolved several mechanisms to ensure secretory protein quality control, which allows efficiency and fidelity in protein production. Among the actors involved in such process, both endoplasmic reticulum (ER) and the Golgi complex play prominent roles in protein synthesis, biogenesis and secretion. ER and Golgi functions ensure that only properly folded proteins are allowed to flow through the secretory pathway while improperly folded proteins have to be eliminated to not impinge on cellular functions. Thus, complex quality control and degradation machineries are crucial to prevent the toxic accumulation of improperly folded proteins. However, in some instances, improperly folded proteins can escape the quality control systems thereby contributing to several human diseases. Herein, we summarize how the early secretory pathways copes with the accumulation of improperly folded proteins, and how insufficient handling can cause the development of several human diseases. Finally, we detail the genetic and pharmacologic approaches that could be used as potential therapeutic tools to treat these diseases.
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Affiliation(s)
- Daria Sicari
- Proteostasis & Cancer Team INSERM U1242 « Chemistry, Oncogenesis Stress Signaling », Université de Rennes, CEDEX, 35042 Rennes, France.
- Centre de Lutte contre le Cancer Eugène Marquis, CEDEX, 35042 Rennes, France.
| | - Aeid Igbaria
- Proteostasis & Cancer Team INSERM U1242 « Chemistry, Oncogenesis Stress Signaling », Université de Rennes, CEDEX, 35042 Rennes, France.
- Centre de Lutte contre le Cancer Eugène Marquis, CEDEX, 35042 Rennes, France.
| | - Eric Chevet
- Proteostasis & Cancer Team INSERM U1242 « Chemistry, Oncogenesis Stress Signaling », Université de Rennes, CEDEX, 35042 Rennes, France.
- Centre de Lutte contre le Cancer Eugène Marquis, CEDEX, 35042 Rennes, France.
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8
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Li J, Yu Q, Zhang B, Xiao C, Ma T, Yi X, Liang C, Li M. Stress-associated endoplasmic reticulum protein 1 (SERP1) and Atg8 synergistically regulate unfolded protein response (UPR) that is independent on autophagy in Candida albicans. Int J Med Microbiol 2018; 308:378-386. [PMID: 29544880 DOI: 10.1016/j.ijmm.2018.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 02/28/2018] [Accepted: 03/05/2018] [Indexed: 01/07/2023] Open
Abstract
Cellular stresses could activate several response processes, such as the unfolded protein response (UPR), autophagy and oxidative stress response to restore cellular homeostasis or render cell death. Herein, we identified the Candida albicans stress-associated endoplasmic reticulum protein 1 (SERP1), also known as Ysy6, which was involved in endoplasmic reticulum (ER) stress response. We found that deletion of both SERP1/YSY6 and ATG8 led to hypersensitivity to tunicamycin (TN), and resulted in severe mitochondrial dysfunction under this stress. UPR reporting systems illustrated that the double mutation attenuated splicing of HAC1 mRNA, followed by decreased level of UPR activation. In addition, the atg8Δ/Δ ysy6Δ/Δ double mutant had normal autophagic degradation of the ER component Sec63 under ER stress, suggesting that SERP1/Ysy6 and Atg8 synergistically regulated UPR that is independent on autophagy. We also found that deletion of both SERP1/YSY6 and ATG8 caused the loss of virulence. This study reveals the important role of SERP1/Ysy6 and Atg8 in ER stress response and virulence in C. albicans.
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Affiliation(s)
- Jianrong Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin, PR China
| | - Qilin Yu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin, PR China
| | - Bing Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin, PR China
| | - Chenpeng Xiao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin, PR China
| | - Tianyu Ma
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin, PR China
| | - Xiao Yi
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin, PR China
| | - Chao Liang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin, PR China
| | - Mingchun Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin, PR China.
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Sundaram A, Plumb R, Appathurai S, Mariappan M. The Sec61 translocon limits IRE1α signaling during the unfolded protein response. eLife 2017; 6. [PMID: 28504640 PMCID: PMC5449187 DOI: 10.7554/elife.27187] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 05/13/2017] [Indexed: 01/08/2023] Open
Abstract
IRE1α is an endoplasmic reticulum (ER) localized endonuclease activated by misfolded proteins in the ER. Previously, we demonstrated that IRE1α forms a complex with the Sec61 translocon, to which its substrate XBP1u mRNA is recruited for cleavage during ER stress (Plumb et al., 2015). Here, we probe IRE1α complexes in cells with blue native PAGE immunoblotting. We find that IRE1α forms a hetero-oligomeric complex with the Sec61 translocon that is activated upon ER stress with little change in the complex. In addition, IRE1α oligomerization, activation, and inactivation during ER stress are regulated by Sec61. Loss of the IRE1α-Sec61 translocon interaction as well as severe ER stress conditions causes IRE1α to form higher-order oligomers that exhibit continuous activation and extended cleavage of XBP1u mRNA. Thus, we propose that the Sec61-IRE1α complex defines the extent of IRE1α activity and may determine cell fate decisions during ER stress conditions. DOI:http://dx.doi.org/10.7554/eLife.27187.001
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Affiliation(s)
- Arunkumar Sundaram
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States.,Advance Molecular Biology Lab, School of Health Sciences, University of Science Malaysia, Kubang Kerian, Malaysia
| | - Rachel Plumb
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
| | - Suhila Appathurai
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
| | - Malaiyalam Mariappan
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
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