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  1. Article ; Online: Site-Specific Fluorescent Labeling, Single-Step Immunocytochemistry, and Delivery of Nanobodies into Living Cells.

    Gettemans, Jan

    Methods in molecular biology (Clifton, N.J.)

    2022  Volume 2446, Page(s) 373–393

    Abstract: The smallest natural antibody fragments currently available are single-domain antibodies obtained from camelid species and sharks (variable new antigen receptors). These molecules consist of a single amino acid chain of ~120 amino acids that adopts a ... ...

    Abstract The smallest natural antibody fragments currently available are single-domain antibodies obtained from camelid species and sharks (variable new antigen receptors). These molecules consist of a single amino acid chain of ~120 amino acids that adopts a typical immunoglobulin fold. Single-domain antibodies (nanobodies) are monovalent and can be isolated from immunized animals, from naïve libraries, or from synthetic libraries. Importantly, their complete DNA sequences are readily obtained by default, which greatly facilitates their rapid manipulation for various applications. Here, a PCR-based protocol for inserting a sortase A recognition sequence at the carboxy-terminus of a nanobody is described. Subsequently, a sortase A-catalyzed biochemical reaction results in tagging of the nanobody with a short carboxy-terminal amino acid sequence that carries a non-canonical residue (propargyl glycine). This allows click chemistry to be performed with an azido-derivatized fluorophore, with the ensuing fluorescent nanobody being covalently and site-specifically labeled. The labeled nanobody can be used directly for immunocytochemistry, omitting the classical secondary antibody step. Also described are methods for delivery of fluorescent nanobodies into the cytoplasm of mammalian cells by photoporation, a very low-toxicity approach involving laser light and graphene quantum dots. The combined protocol embodies a novel route for studying protein function in living cells at high resolution.
    MeSH term(s) Animals ; Antibodies ; Click Chemistry ; Fluorescent Dyes ; Immunohistochemistry ; Single-Domain Antibodies/chemistry
    Chemical Substances Antibodies ; Fluorescent Dyes ; Single-Domain Antibodies
    Language English
    Publishing date 2022-02-14
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1940-6029
    ISSN (online) 1940-6029
    DOI 10.1007/978-1-0716-2075-5_19
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Transforming nanobodies into high-precision tools for protein function analysis.

    Gettemans, Jan / De Dobbelaer, Brian

    American journal of physiology. Cell physiology

    2020  Volume 320, Issue 2, Page(s) C195–C215

    Abstract: Single-domain antibodies, derived from camelid heavy antibodies (nanobodies) or shark variable new antigen receptors, have attracted increasing attention in recent years due to their extremely versatile nature and the opportunities they offer for ... ...

    Abstract Single-domain antibodies, derived from camelid heavy antibodies (nanobodies) or shark variable new antigen receptors, have attracted increasing attention in recent years due to their extremely versatile nature and the opportunities they offer for downstream modification. Discovered more than three decades ago, these 120-amino acid (∼15-kDa) antibody fragments are known to bind their target with high specificity and affinity. Key features of nanobodies that make them very attractive include their single-domain nature, small size, and affordable high-level expression in prokaryotes, and their cDNAs are routinely obtained in the process of their isolation. This facilitates and stimulates new experimental approaches. Hence, it allows researchers to formulate new answers to complex biomedical questions. Through elementary PCR-based technologies and chemical modification strategies, their primary structure can be altered almost at leisure while retaining their specificity and biological activity, transforming them into highly tailored tools that meet the increasing demands of current-day biomedical research. In this review, various aspects of camelid nanobodies are expounded, including intracellular delivery in recombinant format for manipulation of, i.e., cytoplasmic targets, their derivatization to improve nanobody orientation as a capturing device, approaches to reversibly bind their target, their potential as protein-silencing devices in cells, the development of strategies to transfer nanobodies through the blood-brain barrier and their application in CAR-T experimentation. We also discuss some of their disadvantages and conclude with future prospects.
    MeSH term(s) Animals ; Antibodies/immunology ; Antibodies/metabolism ; Blood-Brain Barrier/immunology ; Blood-Brain Barrier/metabolism ; Cell Membrane/immunology ; Cell Membrane/metabolism ; Cytoplasm/immunology ; Cytoplasm/metabolism ; Humans ; Immunotherapy, Adoptive/methods ; Immunotherapy, Adoptive/trends ; Intracellular Space/immunology ; Intracellular Space/metabolism ; Proteins/physiology ; Single-Domain Antibodies/immunology ; Single-Domain Antibodies/metabolism
    Chemical Substances Antibodies ; Proteins ; Single-Domain Antibodies
    Language English
    Publishing date 2020-12-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 392098-7
    ISSN 1522-1563 ; 0363-6143
    ISSN (online) 1522-1563
    ISSN 0363-6143
    DOI 10.1152/ajpcell.00435.2020
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  3. Article ; Online: Major biotic stresses affecting maize production in Kenya and their implications for food security.

    Njeru, Faith / Wambua, Angeline / Muge, Edward / Haesaert, Geert / Gettemans, Jan / Misinzo, Gerald

    PeerJ

    2023  Volume 11, Page(s) e15685

    Abstract: Maize ( ...

    Abstract Maize (
    MeSH term(s) Zea mays ; Kenya ; Plant Diseases ; Stress, Physiological ; Food Security ; Necrosis
    Language English
    Publishing date 2023-11-30
    Publishing country United States
    Document type Review ; Journal Article
    ZDB-ID 2703241-3
    ISSN 2167-8359 ; 2167-8359
    ISSN (online) 2167-8359
    ISSN 2167-8359
    DOI 10.7717/peerj.15685
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: An AKT2-specific nanobody that targets the hydrophobic motif induces cell cycle arrest, autophagy and loss of focal adhesions in MDA-MB-231 cells.

    Merckaert, Tijs / Zwaenepoel, Olivier / Gevaert, Kris / Gettemans, Jan

    Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie

    2020  Volume 133, Page(s) 111055

    Abstract: The AKT kinase family is a high-profile target for cancer therapy. Despite their high degree of homology the three AKT isoforms (AKT1, AKT2 and AKT3) are non-redundant and can even have opposing functions. Small-molecule AKT inhibitors affect all three ... ...

    Abstract The AKT kinase family is a high-profile target for cancer therapy. Despite their high degree of homology the three AKT isoforms (AKT1, AKT2 and AKT3) are non-redundant and can even have opposing functions. Small-molecule AKT inhibitors affect all three isoforms which severely limits their usefulness as research tool or therapeutic. Using AKT2-specific nanobodies we examined the function of endogenous AKT2 in breast cancer cells. Two AKT2 nanobodies (Nb8 and Nb9) modulate AKT2 and reduce MDA-MB-231 cell viability/proliferation. Nb8 binds the AKT2 hydrophobic motif and reduces IGF-1-induced phosphorylation of this site. This nanobody also affects the phosphorylation and/or expression levels of a wide range of proteins downstream of AKT, resulting in a G0/G1 cell cycle arrest, the induction of autophagy, a reduction in focal adhesion count and loss of stress fibers. While cell cycle progression is likely to be regulated by more than one isoform, our results indicate that both the effects on autophagy and the cytoskeleton are specific to AKT2. By using an isoform-specific nanobody we were able to map a part of the AKT2 pathway. Our results confirm AKT2 and the hydrophobic motif as targets for cancer therapy. Nb8 can be used as a research tool to study AKT2 signalling events and aid in the design of an AKT2-specific inhibitor.
    MeSH term(s) Amino Acid Motifs ; Antineoplastic Agents, Immunological/pharmacology ; Autophagy/drug effects ; Breast Neoplasms/drug therapy ; Breast Neoplasms/enzymology ; Breast Neoplasms/immunology ; Breast Neoplasms/pathology ; Cell Cycle Checkpoints/drug effects ; Cell Line, Tumor ; Female ; Focal Adhesions/drug effects ; Focal Adhesions/enzymology ; Focal Adhesions/immunology ; Focal Adhesions/pathology ; Humans ; Hydrophobic and Hydrophilic Interactions ; Insulin-Like Growth Factor I/metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-akt/antagonists & inhibitors ; Proto-Oncogene Proteins c-akt/immunology ; Proto-Oncogene Proteins c-akt/metabolism ; Signal Transduction ; Single-Domain Antibodies/pharmacology
    Chemical Substances Antineoplastic Agents, Immunological ; IGF1 protein, human ; Single-Domain Antibodies ; Insulin-Like Growth Factor I (67763-96-6) ; AKT2 protein, human (EC 2.7.11.1) ; Proto-Oncogene Proteins c-akt (EC 2.7.11.1)
    Language English
    Publishing date 2020-12-07
    Publishing country France
    Document type Journal Article
    ZDB-ID 392415-4
    ISSN 1950-6007 ; 0753-3322 ; 0300-0893
    ISSN (online) 1950-6007
    ISSN 0753-3322 ; 0300-0893
    DOI 10.1016/j.biopha.2020.111055
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Development and characterization of protein kinase B/AKT isoform-specific nanobodies.

    Merckaert, Tijs / Zwaenepoel, Olivier / Gevaert, Kris / Gettemans, Jan

    PloS one

    2020  Volume 15, Issue 10, Page(s) e0240554

    Abstract: The serine/threonine protein kinase AKT is frequently over-activated in cancer and is associated with poor prognosis. As a central node in the PI3K/AKT/mTOR pathway, which regulates various processes considered to be hallmarks of cancer, this kinase has ... ...

    Abstract The serine/threonine protein kinase AKT is frequently over-activated in cancer and is associated with poor prognosis. As a central node in the PI3K/AKT/mTOR pathway, which regulates various processes considered to be hallmarks of cancer, this kinase has become a prime target for cancer therapy. However, AKT has proven to be a highly complex target as it comes in three isoforms (AKT1, AKT2 and AKT3) which are highly homologous, yet non-redundant. The isoform-specific functions of the AKT kinases can be dependent on context (i.e. different types of cancer) and even opposed to one another. To date, there is no isoform-specific inhibitor available and no alternative to genetic approaches to study the function of a single AKT isoform. We have developed and characterized nanobodies that specifically interact with the AKT1 or AKT2 isoforms. These new tools should enable future studies of AKT1 and AKT2 isoform-specific functions. Furthermore, for both isoforms we obtained a nanobody that interferes with the AKT-PIP3-interaction, an essential step in the activation of the kinase. The nanobodies characterized in this study are a new stepping stone towards unravelling AKT isoform-specific signalling.
    MeSH term(s) Enzyme Activation ; Humans ; Protein Binding ; Protein Domains ; Protein Isoforms/metabolism ; Proto-Oncogene Proteins c-akt/metabolism ; Single-Domain Antibodies/metabolism
    Chemical Substances Protein Isoforms ; Single-Domain Antibodies ; AKT1 protein, human (EC 2.7.11.1) ; AKT2 protein, human (EC 2.7.11.1) ; Proto-Oncogene Proteins c-akt (EC 2.7.11.1)
    Language English
    Publishing date 2020-10-12
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2267670-3
    ISSN 1932-6203 ; 1932-6203
    ISSN (online) 1932-6203
    ISSN 1932-6203
    DOI 10.1371/journal.pone.0240554
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  6. Article ; Online: Alzheimer's Disease: A Systems View Provides a Unifying Explanation of Its Development.

    Grobler, Corlia / van Tongeren, Marvi / Gettemans, Jan / Kell, Douglas B / Pretorius, Etheresia

    Journal of Alzheimer's disease : JAD

    2022  Volume 91, Issue 1, Page(s) 43–70

    Abstract: Alzheimer's disease (AD) is a debilitating neurodegenerative disorder affecting 50 million people globally. It is characterized by the presence of extracellular senile plaques and intracellular neurofibrillary tangles, consisting of amyloid-β and ... ...

    Abstract Alzheimer's disease (AD) is a debilitating neurodegenerative disorder affecting 50 million people globally. It is characterized by the presence of extracellular senile plaques and intracellular neurofibrillary tangles, consisting of amyloid-β and hyperphosphorylated tau proteins, respectively. Despite global research efforts, there is currently no cure available, due in part to an incomplete understanding of the disease pathogenesis. Numerous possible mechanisms, or hypotheses, explaining the origins of sporadic or late-onset AD have been proposed, including the amyloid-β, inflammatory, vascular, and infectious hypotheses. However, despite ample evidence, the failure of multiple trial drugs at the clinical stage illuminates the possible pitfalls of these hypotheses. Systems biology is a strategy which aims to elucidate the interactions between parts of a whole. Using this approach, the current paper shows how the four previously mentioned hypotheses of AD pathogenesis can be intricately connected. This approach allows for seemingly contradictory evidence to be unified in a system-focused explanation of sporadic AD development. Within this view, it is seen that infectious agents, such as P. gingivalis, may play a central role. The data presented here shows that when present, P. gingivalis or its virulence factors, such as gingipains, may induce or exacerbate pathologies underlying sporadic AD. This evidence supports the view that infectious agents, and specifically P. gingivalis, may be suitable treatment targets in AD.
    MeSH term(s) Humans ; Alzheimer Disease/pathology ; Amyloid beta-Peptides/metabolism ; Neurofibrillary Tangles/pathology ; tau Proteins/metabolism ; Plaque, Amyloid/pathology
    Chemical Substances Amyloid beta-Peptides ; tau Proteins
    Language English
    Publishing date 2022-11-28
    Publishing country Netherlands
    Document type Journal Article ; Review ; Research Support, Non-U.S. Gov't
    ZDB-ID 1440127-7
    ISSN 1875-8908 ; 1387-2877
    ISSN (online) 1875-8908
    ISSN 1387-2877
    DOI 10.3233/JAD-220720
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  7. Article: Nanobody Technology: A Versatile Toolkit for Microscopic Imaging, Protein-Protein Interaction Analysis, and Protein Function Exploration.

    Beghein, Els / Gettemans, Jan

    Frontiers in immunology

    2017  Volume 8, Page(s) 771

    Abstract: Over the last two decades, nanobodies or single-domain antibodies have found their way in research, diagnostics, and therapy. These antigen-binding fragments, derived from Camelid heavy chain only antibodies, possess remarkable characteristics that favor ...

    Abstract Over the last two decades, nanobodies or single-domain antibodies have found their way in research, diagnostics, and therapy. These antigen-binding fragments, derived from Camelid heavy chain only antibodies, possess remarkable characteristics that favor their use over conventional antibodies or fragments thereof, in selected areas of research. In this review, we assess the current status of nanobodies as research tools in diverse aspects of fundamental research. We discuss the use of nanobodies as detection reagents in fluorescence microscopy and focus on recent advances in super-resolution microscopy. Second, application of nanobody technology in investigating protein-protein interactions is reviewed, with emphasis on possible uses in mass spectrometry. Finally, we discuss the potential value of nanobodies in studying protein function, and we focus on their recently reported application in targeted protein degradation. Throughout the review, we highlight state-of-the-art engineering strategies that could expand nanobody versatility and we suggest future applications of the technology in the selected areas of fundamental research.
    Language English
    Publishing date 2017
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 2606827-8
    ISSN 1664-3224
    ISSN 1664-3224
    DOI 10.3389/fimmu.2017.00771
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  8. Article ; Online: Nb-induced stabilisation of p53 in HPV-infected cells.

    Steels, Anneleen / Vannevel, Laura / Zwaenepoel, Olivier / Gettemans, Jan

    Scientific reports

    2019  Volume 9, Issue 1, Page(s) 12680

    Abstract: Cervical cancer is caused by a persistent infection of the mucosal epithelia with high-risk human papilloma viruses (HPVs). The viral oncoprotein E6 is responsible for the inactivation of the tumour suppressor p53 and thus plays a crucial role in HPV- ... ...

    Abstract Cervical cancer is caused by a persistent infection of the mucosal epithelia with high-risk human papilloma viruses (HPVs). The viral oncoprotein E6 is responsible for the inactivation of the tumour suppressor p53 and thus plays a crucial role in HPV-induced tumorigenesis. The viral E6 protein forms a trimeric complex with the endogenous E3 ubiquitine ligase E6AP and the DNA-binding domain (DBD) of p53, which results in the polyubiquitination and proteasomal degradation of p53. We have developed nanobodies (Nbs) against the DBD of p53, which substantially stabilise p53 in HeLa cells. The observed effect is specific for HPV-infected cells, since similar effects were not seen for U2OS cells. Despite the fact that the stabilised p53 was strongly nuclear enriched, its tumour suppressive functions were hampered. We argue that the absence of a tumour suppressive effect is caused by inhibition of p53 transactivation in both HPV-infected and HPV-negative cells. The inactivation of the transcriptional activity of p53 was associated with an increased cellular proliferation and viability of HeLa cells. In conclusion, we demonstrate that p53 DBD Nbs positively affect protein stability whilst adversely affecting protein function, attesting to their ability to modulate protein properties in a very subtle manner.
    MeSH term(s) Cell Line, Tumor ; Cell Nucleus/metabolism ; Cell Proliferation/drug effects ; Female ; HeLa Cells ; Humans ; Papillomaviridae/physiology ; Protein Domains/immunology ; Protein Stability/drug effects ; Single-Domain Antibodies/immunology ; Single-Domain Antibodies/pharmacology ; Transcriptional Activation/drug effects ; Tumor Suppressor Protein p53/chemistry ; Tumor Suppressor Protein p53/immunology ; Tumor Suppressor Protein p53/metabolism ; Uterine Cervical Neoplasms/metabolism ; Uterine Cervical Neoplasms/pathology ; Vorinostat/pharmacology
    Chemical Substances Single-Domain Antibodies ; Tumor Suppressor Protein p53 ; Vorinostat (58IFB293JI)
    Language English
    Publishing date 2019-09-03
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-019-49061-9
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  9. Article ; Online: Use of Nanobodies to Localize Endogenous Cytoskeletal Proteins and to Determine Their Contribution to Cancer Cell Invasion by Using an ECM Degradation Assay.

    Van Audenhove, Isabel / Gettemans, Jan

    Methods in molecular biology (Clifton, N.J.)

    2016  Volume 1365, Page(s) 225–241

    Abstract: There are numerous ways to study actin cytoskeletal structures, and thereby identify the underlying mechanisms of organization and their regulating proteins. Traditional approaches make use of protein overexpression or siRNA. However to study or modulate ...

    Abstract There are numerous ways to study actin cytoskeletal structures, and thereby identify the underlying mechanisms of organization and their regulating proteins. Traditional approaches make use of protein overexpression or siRNA. However to study or modulate resident endogenous proteins, complementary methods are required. Since the discovery of nanobodies in 1993, they have proven to represent interesting tools in a variety of applications due to their high affinity, solubility, and stability. Especially their intracellular functionality makes them ideally suited for the study of actin cytoskeletal regulation. Here we provide a protocol to clone nanobody cDNAs in frame with an EGFP or mCherry fluorescent tag. We explain how to transfect this fusion protein in eukaryotic (cancer) cells and how to perform immunofluorescence. This allows microscopic analysis of endogenous (cytoskeletal) proteins and gives insight into their endogenous localization. Moreover, we outline an extracellular matrix (ECM) degradation assay as an application of the general protocol. By seeding cells onto a fluorescently labeled gelatin matrix, degradation can be quantified by means of a matrix degradation index. This assay demonstrates the contribution of a protein during cancer cell invasiveness in vitro and the potential of a nanobody to inhibit this degradation through modulation of its target.
    MeSH term(s) Cytoskeletal Proteins/immunology ; Cytoskeletal Proteins/metabolism ; DNA, Complementary/genetics ; Extracellular Matrix/metabolism ; Fluorescent Antibody Technique ; Green Fluorescent Proteins/genetics ; HEK293 Cells ; HeLa Cells ; Humans ; Microscopy ; Neoplasm Invasiveness ; Protein Transport ; Single-Domain Antibodies/immunology ; Transfection
    Chemical Substances Cytoskeletal Proteins ; DNA, Complementary ; Single-Domain Antibodies ; enhanced green fluorescent protein ; Green Fluorescent Proteins (147336-22-9)
    Language English
    Publishing date 2016
    Publishing country United States
    Document type Journal Article
    ISSN 1940-6029
    ISSN (online) 1940-6029
    DOI 10.1007/978-1-4939-3124-8_12
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  10. Article ; Online: Nanobodies as Versatile Tools to Understand, Diagnose, Visualize and Treat Cancer.

    Van Audenhove, Isabel / Gettemans, Jan

    EBioMedicine

    2016  Volume 8, Page(s) 40–48

    Abstract: Since their discovery, nanobodies have been used extensively in the fields of research, diagnostics and therapy. These antigen binding fragments, originating from Camelid heavy-chain antibodies, possess unusual hallmarks in terms of (small) size, ... ...

    Abstract Since their discovery, nanobodies have been used extensively in the fields of research, diagnostics and therapy. These antigen binding fragments, originating from Camelid heavy-chain antibodies, possess unusual hallmarks in terms of (small) size, stability, solubility and specificity, hence allowing cost-effective production and sometimes outperforming monoclonal antibodies. In this review, we evaluate the current status of nanobodies to study, diagnose, visualize or inhibit cancer-specific proteins and processes. Nanobodies are highly adaptable tools for cancer research as they enable specific modulation of targets, enzymatic and non-enzymatic proteins alike. Molecular imaging studies benefit from the rapid, homogeneous tumor accumulation of nanobodies and their fast blood clearance, permitting previously unattainable fast tumor visualization. Moreover, they are endowed with considerable therapeutic potential as inhibitors of receptor-ligand pairs and deliverers of drugs or drug-loaded nanoparticles towards tumors. More in vivo and clinical studies are however eagerly awaited to unleash their full potential.
    MeSH term(s) Animals ; Biomarkers, Tumor/immunology ; Biomarkers, Tumor/metabolism ; Contrast Media/chemistry ; Drug Carriers/chemistry ; Humans ; Neoplasms/diagnosis ; Neoplasms/diagnostic imaging ; Neoplasms/drug therapy ; Neoplasms/pathology ; Protein Domains/immunology ; Receptors, Cell Surface/chemistry ; Receptors, Cell Surface/immunology ; Receptors, Cell Surface/metabolism ; Single-Domain Antibodies/immunology ; Single-Domain Antibodies/therapeutic use ; Tomography, Emission-Computed
    Chemical Substances Biomarkers, Tumor ; Contrast Media ; Drug Carriers ; Receptors, Cell Surface ; Single-Domain Antibodies
    Language English
    Publishing date 2016-04-30
    Publishing country Netherlands
    Document type Journal Article ; Review
    ZDB-ID 2851331-9
    ISSN 2352-3964
    ISSN (online) 2352-3964
    DOI 10.1016/j.ebiom.2016.04.028
    Database MEDical Literature Analysis and Retrieval System OnLINE

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