Inclusion bodies

Inclusion bodies are aggregates of specific types of protein found in neurons, and a number of tissue cells including red blood cells, bacteria, viruses, and plants. Inclusion bodies of aggregations of multiple proteins are also found in muscle cells affected by inclusion body myositis and hereditary inclusion body myopathy.[1]

Inclusion bodies in neurons may accumulate in the cytoplasm or nucleus, and are associated with many neurodegenerative diseases.[2] Inclusion bodies in neurodegenerative diseases are aggregates of misfolded proteins (aggresomes) and are hallmarks of many of these diseases, including Lewy bodies in dementia with Lewy bodies, and Parkinson's disease, neuroserpin inclusion bodies called Collins bodies in familial encephalopathy with neuroserpin inclusion bodies,[3] inclusion bodies in Huntington's disease, Papp–Lantos bodies in multiple system atrophy, and various inclusion bodies in frontotemporal dementia including Pick bodies.[4] Bunina bodies in motor neurons are a core feature of amyotrophic lateral sclerosis.[5]

Other usual cell inclusions are often temporary inclusions of accumulated proteins, fats, secretory granules, or other insoluble components.[6]

Inclusion bodies are found in bacteria as particles of aggregated protein. They have a higher density than many other cell components but are porous.[7] They typically represent sites of viral multiplication in a bacterium or a eukaryotic cell and usually consist of viral capsid proteins. Inclusion bodies contain very little host protein, ribosomal components, or DNA/RNA fragments. They often almost exclusively contain the over-expressed protein and aggregation and has been reported to be reversible. It has been suggested that inclusion bodies are dynamic structures formed by an unbalanced equilibrium between aggregated and soluble proteins of Escherichia coli. There is a growing body of information indicating that formation of inclusion bodies occurs as a result of intracellular accumulation of partially folded expressed proteins which aggregate through non-covalent hydrophobic or ionic interactions or a combination of both.[citation needed]

  1. ^ "Sporadic Inclusion Body Myositis". NORD (National Organization for Rare Disorders). Retrieved 12 March 2021.
  2. ^ Chung CG, Lee H, Lee SB (1 September 2018). "Mechanisms of protein toxicity in neurodegenerative diseases". Cellular and Molecular Life Sciences. 75 (17): 3159–3180. doi:10.1007/s00018-018-2854-4. PMC 6063327. PMID 29947927.
  3. ^ "Encephalopathy, familial, with neuroserpin inclusion bodies (Concept Id: C1858680) – MedGen – NCBI". www.ncbi.nlm.nih.gov. Retrieved 6 April 2021.
  4. ^ Cruts M, Gijselinck I, van der Zee J, Engelborghs S, Wils H, Pirici D, Rademakers R, Vandenberghe R, Dermaut B, Martin JJ, van Duijn C, Peeters K, Sciot R, Santens P, De Pooter T, Mattheijssens M, Van den Broeck M, Cuijt I, Vennekens K, De Deyn PP, Kumar-Singh S, Van Broeckhoven C (24 August 2006). "Null mutations in progranulin cause ubiquitin-positive frontotemporal dementia linked to chromosome 17q21". Nature. 442 (7105): 920–4. Bibcode:2006Natur.442..920C. doi:10.1038/nature05017. PMID 16862115. S2CID 4423699.
  5. ^ Hardiman O, Al-Chalabi A, Chio A (5 October 2017). "Amyotrophic lateral sclerosis" (PDF). Nature Reviews. Disease Primers. 3: 17071. doi:10.1038/nrdp.2017.71. PMID 28980624. S2CID 1002680.
  6. ^ Dorland's illustrated medical dictionary (32 ed.). Philadelphia, PA: Saunders/Elsevier. 2012. p. 928. ISBN 9781416062578.
  7. ^ Singh SM, Panda AK (1 April 2005). "Solubilization and refolding of bacterial inclusion body proteins". Journal of Bioscience and Bioengineering. 99 (4): 303–310. doi:10.1263/jbb.99.303. PMID 16233795. S2CID 24807019. Inclusion bodies are dense electron-refractile particles of aggregated protein found in both the cytoplasmic and periplasmic spaces of E. coli during high-level expression of heterologous protein. It is generally assumed that high level expression of non-native protein (higher than 2% of cellular protein) and highly hydrophobic protein is more prone to lead to accumulation as inclusion bodies in E. coli. In the case of proteins having disulfide bonds, formation of protein aggregates as inclusion bodies is anticipated since the reducing environment of bacterial cytosol inhibits the formation of disulfide bonds. The diameter of spherical bacterial inclusion bodies varies from 0.5–1.3 μm and the protein aggregates have either an amorphous or paracrystalline nature depending on the localization. Inclusion bodies have higher density (~1.3 mg ml−1) than many of the cellular components, and thus can be easily separated by high-speed centrifugation after cell disruption. Inclusion bodies, despite being dense particles, are highly hydrated and have a porous architecture.