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Ghosh S, Hom Choudhury S, Mukherjee K, Bhattacharyya SN. HuR-miRNA complex activates RAS GTPase RalA to facilitate endosome targeting and extracellular export of miRNAs. J Biol Chem 2024; 300:105750. [PMID: 38360271 PMCID: PMC10956062 DOI: 10.1016/j.jbc.2024.105750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 02/01/2024] [Accepted: 02/07/2024] [Indexed: 02/17/2024] Open
Abstract
Extracellular vesicles-mediated exchange of miRNA cargos between diverse types of mammalian cells is a major mechanism of controlling cellular miRNA levels and activity, thus regulating the expression of miRNA-target genes in both donor and recipient cells. Despite tremendous excitement related to extracellular vesicles-associated miRNAs as biomarkers or having therapeutic potential, the mechanism of selective packaging of miRNAs into endosomes and multivesicular bodies for subsequent extracellular export is poorly studied due to the lack of an in vitro assay system. Here, we have developed an in vitro assay with endosomes isolated from mammalian macrophage cells to follow miRNA packaging into endocytic organelles. The synthetic miRNAs, used in the assay, get imported inside the isolated endosomes during the in vitro reaction and become protected from RNase in a time- and concentration-dependent manner. The selective miRNA accumulation inside endosomes requires both ATP and GTP hydrolysis and the miRNA-binding protein HuR. The HuR-miRNA complex binds and stimulates the endosomal RalA GTPase to facilitate the import of miRNAs into endosomes and their subsequent export as part of the extracellular vesicles. The endosomal targeting of miRNAs is also very much dependent on the endosome maturation process that is controlled by Rab5 protein and ATP. In summary, we provide an in vitro method to aid in the investigation of the mechanism of miRNA packaging process for its export from mammalian macrophage cells.
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Affiliation(s)
- Syamantak Ghosh
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Sourav Hom Choudhury
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Kamalika Mukherjee
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India; Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center (UNMC), Nebraska, USA.
| | - Suvendra N Bhattacharyya
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India; Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center (UNMC), Nebraska, USA.
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Silva-Rodrigues JF, Patrício-Rodrigues CF, de Sousa-Xavier V, Augusto PM, Fernandes AC, Farinho AR, Martins JP, Teodoro RO. Peripheral axonal ensheathment is regulated by RalA GTPase and the exocyst complex. Development 2020; 147:dev.174540. [PMID: 31969325 DOI: 10.1242/dev.174540] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 01/14/2020] [Indexed: 12/21/2022]
Abstract
Axon ensheathment is fundamental for fast impulse conduction and the normal physiological functioning of the nervous system. Defects in axonal insulation lead to debilitating conditions, but, despite its importance, the molecular players responsible are poorly defined. Here, we identify RalA GTPase as a key player in axon ensheathment in Drosophila larval peripheral nerves. We demonstrate through genetic analysis that RalA action through the exocyst complex is required in wrapping glial cells to regulate their growth and development. We suggest that the RalA-exocyst pathway controls the targeting of secretory vesicles for membrane growth or for the secretion of a wrapping glia-derived factor that itself regulates growth. In summary, our findings provide a new molecular understanding of the process by which axons are ensheathed in vivo, a process that is crucial for normal neuronal function.
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Affiliation(s)
- Joana F Silva-Rodrigues
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Cátia F Patrício-Rodrigues
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Vicente de Sousa-Xavier
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Pedro M Augusto
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Ana C Fernandes
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Ana R Farinho
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - João P Martins
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal.,Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Rita O Teodoro
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
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Padavano J, Henkhaus RS, Chen H, Skovan BA, Cui H, Ignatenko NA. Mutant K-RAS Promotes Invasion and Metastasis in Pancreatic Cancer Through GTPase Signaling Pathways. Cancer Growth Metastasis 2015; 8:95-113. [PMID: 26512205 PMCID: PMC4612127 DOI: 10.4137/cgm.s29407] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 09/07/2015] [Accepted: 09/09/2015] [Indexed: 12/13/2022]
Abstract
Pancreatic ductal adenocarcinoma is one of the most aggressive malignancies, characterized by the local invasion into surrounding tissues and early metastasis to distant organs. Oncogenic mutations of the K-RAS gene occur in more than 90% of human pancreatic cancers. The goal of this study was to investigate the functional significance and downstream effectors of mutant K-RAS oncogene in the pancreatic cancer invasion and metastasis. We applied the homologous recombination technique to stably disrupt K-RAS oncogene in the human pancreatic cell line MiaPaCa-2, which carries the mutant K-RAS (G12C) oncogene in both alleles. Using in vitro assays, we found that clones with disrupted mutant K-RAS gene exhibited low RAS activity, reduced growth rates, increased sensitivity to the apoptosis inducing agents, and suppressed motility and invasiveness. In vivo assays showed that clones with decreased RAS activity had reduced tumor formation ability in mouse xenograft model and increased survival rates in the mouse orthotopic pancreatic cancer model. We further examined molecular pathways downstream of mutant K-RAS and identified RhoA GTP activating protein 5, caveolin-1, and RAS-like small GTPase A (RalA) as key effector molecules, which control mutant K-RAS-dependent migration and invasion in MiaPaCa-2 cells. Our study provides rational for targeting RhoA and RalA GTPase signaling pathways for inhibition of pancreatic cancer metastasis.
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Affiliation(s)
- Julianna Padavano
- Department of Biochemistry and Molecular Biophysics, Undergraduate Biology Research Program, University of Arizona, Tucson, Arizona, USA
| | - Rebecca S Henkhaus
- Cancer Biology Interdisciplinary Program, University of Arizona Cancer Center, Tucson, AZ, USA
| | - Hwudaurw Chen
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA
| | - Bethany A Skovan
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA
| | - Haiyan Cui
- University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA
| | - Natalia A Ignatenko
- Department of Cellular & Molecular Medicine, University of Arizona, Tucson, AZ, USA
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Nie C, Chen XW. Recycling of the insulin-responsive glucose transporter Glut4 regulated by the small GTPase RalA and the exocyst complex. Methods Cell Biol 2015; 130:307-18. [PMID: 26360042 DOI: 10.1016/bs.mcb.2015.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Endocytic recycling represents a major mechanism for continuous supply of molecules to the plasma membrane. Particularly, outbound trafficking of the recycling endosome (RE) or RE-derived vesicles can be upregulated by cellular signaling, through mobilization of specialized protein complexes acting as transport machineries. Therefore, biochemical and functional characterization of cell signaling molecules that operate multimeric protein complexes in membrane transport provides important insights to signaling-regulated trafficking events. In this chapter, we described biochemical approaches and reporter assays in differentiated adipocytes to determine the activity and function of the small GTPase RalA, which relays upstream insulin signaling to the exocyst complex that targets intracellular vesicles bearing the Glut4 transporter to the plasma membrane. The experimental design outlined in this chapter can be applied to other regulated transport events facilitated by the exocyst complex, as well as other GTPases that operate distinct transport complexes in specific physiological settings.
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