In
molecular biology, an intrabody (from
intracellular and antibody) is an antibody that works within the cell to bind to an intracellular
protein.[1] Due to the lack of a reliable mechanism for bringing antibodies into a living cell from the extracellular environment, this typically requires the expression of the antibody within the target cell, which can be accomplished in transgenic animals[2] or by
gene therapy. As a result, intrabodies are defined as antibodies that have been modified for intracellular localization, and the term has rapidly come to be used even when antibodies are produced in
prokaryotes or other non-target cells.[3] This term can apply to several types of
protein targeting: the antibody may remain in the
cytoplasm, or it may have a
nuclear localization signal,[4] or it may undergo
cotranslational translocation across the membrane into the lumen of the
endoplasmic reticulum, provided that it is retained in that compartment through a
KDEL sequence.[5]
Because naturally occurring antibodies are optimised to be secreted from the cell, cytosolic intrabodies require special alterations, including the use of single-chain antibodies (
scFvs), modification of immunoglobulin VL domains for hyperstability,[6] selection of antibodies resistant to the more reducing cytosolic environment,[7] or expression as a fusion protein with
maltose binding protein or other stable intracellular proteins.[8] Such optimizations have improved the stability and structure of intrabodies, allowing the publication of a variety of promising applications against
hepatitis B,[9]avian influenza,[10]prion diseases,[11]inflammation,[12]Parkinson's disease,[13] and
Huntington's disease.[14] Optimizations required for cytosolic intrabodies are not needed for ER retained intrabodies, which fold in the compartment in which antibodies are naturally produced. Since the 1990s ER intrabodies have been used in various research areas to knock down membrane proteins and secreted proteins. [15]
References
^Chen, SY; Bagley, J; Marasco, WA (1994). "Intracellular antibodies as a new class of therapeutic molecules for gene therapy". Human Gene Therapy. 5 (5): 595–601.
doi:
10.1089/hum.1994.5.5-595.
PMID7914435.
^Cohen, PA; Mani, JC; Lane, DP (1998). "Characterization of a new intrabody directed against the N-terminal region of human p53". Oncogene. 17 (19): 2445–56.
doi:
10.1038/sj.onc.1202190.
PMID9824155.
^Cohen, PA; Mani, JC; Lane, DP (1998). "Characterization of a new intrabody directed against the N-terminal region of human p53". Oncogene. 17 (19): 2445–56.
doi:
10.1038/sj.onc.1202190.
PMID9824155.
^Auf Der Maur, A; Escher, D; Barberis, A (2001). "Antigen-independent selection of stable intracellular single-chain antibodies". FEBS Letters. 508 (3): 407–12.
doi:
10.1016/S0014-5793(01)03101-5.
PMID11728462.
^Shaki-Loewenstein, S; Zfania, R; Hyland, S; Wels, WS; Benhar, I (2005). "A universal strategy for stable intracellular antibodies". Journal of Immunological Methods. 303 (1–2): 19–39.
doi:
10.1016/j.jim.2005.05.004.
PMID16045924.
^Serruys, B; Van Houtte, F; Verbrugghe, P; Leroux-Roels, G; Vanlandschoot, P (2009). "Llama-derived single-domain intrabodies inhibit secretion of hepatitis B virions in mice". Hepatology. 49 (1): 39–49.
doi:
10.1002/hep.22609.
PMID19085971.
^Mukhtar, MM; Li, S; Li, W; Wan, T; Mu, Y; Wei, W; Kang, L; Rasool, ST; et al. (2009). "Single-chain intracellular antibodies inhibit influenza virus replication by disrupting interaction of proteins involved in viral replication and transcription". The International Journal of Biochemistry & Cell Biology. 41 (3): 554–60.
doi:
10.1016/j.biocel.2008.07.001.
PMID18687409.
^Filesi, I; Cardinale, A; Mattei, S; Biocca, S (2007). "Selective re-routing of prion protein to proteasomes and alteration of its vesicular secretion prevent PrP(Sc) formation". Journal of Neurochemistry. 101 (6): 1516–26.
doi:
10.1111/j.1471-4159.2006.04439.x.
PMID17542810.
^Strebe, N; Guse, A; Schüngel, M; Schirrmann, T; Hafner, M; Jostock, T; Hust, M; Müller, W; Dübel, S (2009). "Functional knockdown of VCAM-1 at the posttranslational level with ER retained antibodies". Journal of Immunological Methods. 341 (1–2): 30–40.
doi:
10.1016/j.jim.2008.10.012.
PMID19038261.
^Cardinale, A; Biocca, S (2008). "The potential of intracellular antibodies for therapeutic targeting of protein-misfolding diseases". Trends in Molecular Medicine. 14 (9): 373–80.
doi:
10.1016/j.molmed.2008.07.004.
PMID18693139.