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Abstract
The ERK1 and ERK2 (ERK1/2) cascade is a central signaling pathway activated by a wide variety of extracellular agents that transmit the messages of G Protein Coupled Receptors (GPCRs) and Receptor Tyrosine Kinases (RTKs). Being such a central pathway, the activity of the cascade is well regulated, including by dynamic changes of the subcellular localization of components of the ERK1/2 cascade. In resting cells, ERK1/2 are localized in the cytosol due to their interactions with different anchoring proteins. After stimulation, ERK1/2 are phosphorylated by MEK1/2 on their regulatory TEY motif, which permits their detachment from the anchoring proteins. This detachment exposes ERK1/2 to additional phosphorylation on two serine residues (SPS motif) within the nuclear translocation signal (NTS) of the kinases. This additional phosphorylation allows ERK1/2 to interact with importin7, which consequently promotes their translocation to the nucleus. More studies are still required in order to better understand the mechanism and consequence of the nuclear translocation of ERK1/2. In this chapter, we describe some of the techniques used to study nuclear translocation of ERK1/2 in mammalian cells. We briefly mention methods such as digitonin permeabilization and cellular fractionation, as well as overexpression of reporter constructs. More thoroughly, we describe immunofluorescence, immunoprecipitation, and proximity ligation assay (PLA) approaches that are routinely used in our laboratory. Hopefully, the increase of knowledge based on these methods will open more opportunities for the identification of new therapeutic targets for diseases where the ERK1/2 cascade is dysregulated, such as cancer, neurodegenerative diseases, and diabetes.
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Affiliation(s)
- Denise A Berti
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Rony Seger
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot, 76100, Israel.
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Liu C, Cheng A, Wang M, Chen S, Jia R, Zhu D, Liu M, Sun K, Yang Q, Chen X. Characterization of nucleocytoplasmic shuttling and intracellular localization signals in Duck Enteritis Virus UL54. Biochimie 2016; 127:86-94. [PMID: 27157269 DOI: 10.1016/j.biochi.2016.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 05/03/2016] [Indexed: 10/21/2022]
Abstract
Duck Enteritis virus (DEV) UL54 is a homolog of herpes simplex virus-1 (HSV-1) trafficking protein ICP27, which plays an essential role in infection. In this study, DEV UL54 shuttling between the nucleus and cytoplasm was verified with a heterokaryon assay. One predicted nuclear export sequence (NES) (339-348 aa) was shown to be functional and chromosomal region maintenance 1 (CRM1)-dependent; however, the insensitivity of UL54 to Leptomycin B (LMB) and NES mutation suggests that other mechanisms are responsible for the observed nuclear export. Next, three non-classical nuclear localization sequences (NLSs), referred to as NLS1 (105-122 aa), NLS2 (169-192 aa) and NLS3 (257-274 aa), were identified. Furthermore, a recombinant DEV with the UL54 NLSs deleted (DEV- UL54 mNLSs) was constructed and showed that UL54 NLSs moderately affected DEV growth.
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Affiliation(s)
- Chaoyue Liu
- Avian Diseases Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China
| | - Anchun Cheng
- Avian Diseases Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China.
| | - Mingshu Wang
- Avian Diseases Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China.
| | - Shun Chen
- Avian Diseases Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China
| | - Renyong Jia
- Avian Diseases Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China
| | - Dekang Zhu
- Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China
| | - Mafeng Liu
- Avian Diseases Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China
| | - Kunfeng Sun
- Avian Diseases Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China
| | - Qiao Yang
- Avian Diseases Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China
| | - Xiaoyue Chen
- Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Wenjiang, Chengdu City, Sichuan, 611130, PR China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, 611130, PR China
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Influenza virus-induced caspase-dependent enlargement of nuclear pores promotes nuclear export of viral ribonucleoprotein complexes. J Virol 2015; 89:6009-21. [PMID: 25810542 DOI: 10.1128/jvi.03531-14] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 03/17/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Influenza A viruses (IAV) replicate their segmented RNA genome in the nucleus of infected cells and utilize caspase-dependent nucleocytoplasmic export mechanisms to transport newly formed ribonucleoprotein complexes (RNPs) to the site of infectious virion release at the plasma membrane. In this study, we obtained evidence that apoptotic caspase activation in IAV-infected cells is associated with the degradation of the nucleoporin Nup153, an integral subunit of the nuclear pore complex. Transmission electron microscopy studies revealed a distinct enlargement of nuclear pores in IAV-infected cells. Transient expression and subcellular accumulation studies of multimeric marker proteins in virus-infected cells provided additional evidence for increased nuclear pore diameters facilitating the translocation of large protein complexes across the nuclear membrane. Furthermore, caspase 3/7 inhibition data obtained in this study suggest that active, Crm1-dependent IAV RNP export mechanisms are increasingly complemented by passive, caspase-induced export mechanisms at later stages of infection. IMPORTANCE In contrast to the process seen with most other RNA viruses, influenza virus genome replication occurs in the nucleus (rather than the cytoplasm) of infected cells. Therefore, completion of the viral replication cycle critically depends on intracellular transport mechanisms that ensure the translocation of viral ribonucleoprotein (RNP) complexes across the nuclear membrane. Here, we demonstrate that virus-induced cellular caspase activities cause a widening of nuclear pores, thereby facilitating nucleocytoplasmic translocation processes and, possibly, promoting nuclear export of newly synthesized RNPs. These passive transport mechanisms are suggested to complement Crm1-dependent RNP export mechanisms known to occur at early stages of the replication cycle and may contribute to highly efficient production of infectious virus progeny at late stages of the viral replication cycle. The report provides an intriguing example of how influenza virus exploits cellular structures and regulatory pathways, including intracellular transport mechanisms, to complete its replication cycle and maximize the production of infectious virus progeny.
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Pyykkö I, Zou J, Zhang Y, Zhang W, Feng H, Kinnunen P. Nanoparticle based inner ear therapy. World J Otorhinolaryngol 2013; 3:114-133. [DOI: 10.5319/wjo.v3.i4.114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Revised: 08/22/2013] [Accepted: 10/18/2013] [Indexed: 02/06/2023] Open
Abstract
Synthetic nanoparticles can be used to carry drugs, genes, small interfering RNA (siRNA) and growth factors into the inner ear, to repair, restore and induce cellular regeneration. Nanoparticles (NPs) have been developed which are targetable to selected tissue, traceable in vivo, and equipped with controlled drug/gene release. The NPs are coated with a ‘stealth’ layer, and decorated with targeting ligands, markers, transfection agents and endosomal escape peptides. As payloads, genes such as the BDNF-gene, Math1-gene and Prestin-gene have been constructed and delivered in vitro. Short-hairpin RNA has been used in vitro to silence the negative regulator of Math1, the inhibitors of differentiation and DNA binding. In order to facilitate the passage of cargo from the middle ear to the inner ear, the oval window transports gadolinium chelate more efficiently than the round window and is the key element in introducing therapeutic agents into the vestibule and cochlea. Depending upon the type of NPs, different migration and cellular internalization pathways are employed, and optimal carriers should be designed depending on the cargo. The use of NPs as drug/gene/siRNA carriers is fascinating and can also be used as an intraoperative adjunct to cochlear implantation to attract the peripheral processes of the cochlear nerve.
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Liou JS, Liu BR, Martin AL, Huang YW, Chiang HJ, Lee HJ. Protein transduction in human cells is enhanced by cell-penetrating peptides fused with an endosomolytic HA2 sequence. Peptides 2012; 37:273-84. [PMID: 22898256 PMCID: PMC9616647 DOI: 10.1016/j.peptides.2012.07.019] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 07/21/2012] [Accepted: 07/23/2012] [Indexed: 11/21/2022]
Abstract
Endocytosis has been proposed as one of the primary mechanisms for cellular entry of cell-penetrating peptides (CPPs) and their cargoes. However, a major limitation of endocytic pathway is entrapment of the CPP-cargo in intracellular vesicles from which the cargo must escape into the cytoplasm to exert its biological activity. Here we demonstrate that a CPP tagged with an endosomolytic fusion peptide derived from the influenza virus hemagglutinin-2 (HA2) remarkably enhances the cytosolic delivery of proteins in human A549 cells. To determine the endosome-disruptive effects, recombinant DNA plasmids containing coding sequences of HA2, CPPs and red fluorescent proteins (RFPs) were constructed. The fusion proteins were purified from plasmid-transformed Escherichia coli, and their effects on protein transduction were examined using live cell imaging and flow cytometry. Our data indicate that endocytosis is the major route for cellular internalization of CPP-HA2-tagged RFP. Mechanistic studies revealed that the fusogenic HA2 peptide dramatically facilitates CPP-mediated protein entry through the release of endocytosed RFPs from endosomes into the cytoplasm. Furthermore, incorporating the HA2 fusion peptide of the CPP-HA2 fusion protein improved cytosolic uptake without causing cytotoxicity. These findings strongly suggest that the CPP-HA2 tag could be an efficient and safe carrier that overcomes endosomal entrapment of delivered therapeutic drugs.
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Affiliation(s)
- Ji-Sing Liou
- Department of Natural Resources and Environmental Studies, National Dong Hwa University, No. 1, Sec. 2, Da-Hsueh Road, Shoufeng, Hualien 97401, Taiwan
- Graduate Institute of Biotechnology, National Dong Hwa University, No. 1, Sec. 2, Da-Hsueh Road, Shoufeng, Hualien 97401, Taiwan
| | - Betty Revon Liu
- Department of Natural Resources and Environmental Studies, National Dong Hwa University, No. 1, Sec. 2, Da-Hsueh Road, Shoufeng, Hualien 97401, Taiwan
- Graduate Institute of Biotechnology, National Dong Hwa University, No. 1, Sec. 2, Da-Hsueh Road, Shoufeng, Hualien 97401, Taiwan
| | - Adam L. Martin
- Department of Biological Sciences and the cDNA Resources Center, Missouri University of Science and Technology, 206 Schrenk Hall, 400 West 11th Street, Rolla, MO 65409-1120, USA
| | - Yue-Wern Huang
- Department of Biological Sciences, Missouri University of Science and Technology, 105 Schrenk Hall, 400 West 11th Street, Rolla, MO 65409-1120, USA
| | - Huey-Jenn Chiang
- Graduate Institute of Biotechnology, National Dong Hwa University, No. 1, Sec. 2, Da-Hsueh Road, Shoufeng, Hualien 97401, Taiwan
| | - Han-Jung Lee
- Department of Natural Resources and Environmental Studies, National Dong Hwa University, No. 1, Sec. 2, Da-Hsueh Road, Shoufeng, Hualien 97401, Taiwan
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Xu D, Farmer A, Collett G, Grishin NV, Chook YM. Sequence and structural analyses of nuclear export signals in the NESdb database. Mol Biol Cell 2012; 23:3677-93. [PMID: 22833565 PMCID: PMC3442415 DOI: 10.1091/mbc.e12-01-0046] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 05/29/2012] [Accepted: 07/16/2012] [Indexed: 12/23/2022] Open
Abstract
We compiled >200 nuclear export signal (NES)-containing CRM1 cargoes in a database named NESdb. We analyzed the sequences and three-dimensional structures of natural, experimentally identified NESs and of false-positive NESs that were generated from the database in order to identify properties that might distinguish the two groups of sequences. Analyses of amino acid frequencies, sequence logos, and agreement with existing NES consensus sequences revealed strong preferences for the Φ1-X(3)-Φ2-X(2)-Φ3-X-Φ4 pattern and for negatively charged amino acids in the nonhydrophobic positions of experimentally identified NESs but not of false positives. Strong preferences against certain hydrophobic amino acids in the hydrophobic positions were also revealed. These findings led to a new and more precise NES consensus. More important, three-dimensional structures are now available for 68 NESs within 56 different cargo proteins. Analyses of these structures showed that experimentally identified NESs are more likely than the false positives to adopt α-helical conformations that transition to loops at their C-termini and more likely to be surface accessible within their protein domains or be present in disordered or unobserved parts of the structures. Such distinguishing features for real NESs might be useful in future NES prediction efforts. Finally, we also tested CRM1-binding of 40 NESs that were found in the 56 structures. We found that 16 of the NES peptides did not bind CRM1, hence illustrating how NESs are easily misidentified.
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Affiliation(s)
- Darui Xu
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
| | - Alicia Farmer
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
| | - Garen Collett
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
| | - Nick V. Grishin
- Howard Hughes Medical Institute and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
| | - Yuh Min Chook
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
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