The recombinant mouse TREM2 protein with an N-terminal 6xHis-tag is produced in E. coli. The extracellular domain of the TREM2 encoding gene (19-171aa), fused with the His-tag sequence, is cloned into an expression vector and transformed into the E. coli cells. The positive E. coli cells are selected and cultured for protein expression. After that, these cells undergo lysis, releasing the expressed TREM2 protein. The 6xHis-tagged recombinant TREM2 protein is purified using nickel affinity chromatography. SDS-PAGE assesses its purity, exceeding 90%.
The TREM2 protein is a membrane glycoprotein primarily found on microglia in the brain. TREM2 plays a crucial role in modulating microglial function, including phagocytosis of apoptotic neurons and the clearance of amyloid plaques in conditions like Alzheimer's disease [1]. Studies have shown that alterations in TREM2 expression, such as the Trem2 R47H variant, can lead to changes in microglial function and pathology, impacting processes like microgliosis and clustering around amyloid plaques [2][3]. Additionally, TREM2 deficiency has been linked to exacerbated neuroinflammation and impaired synaptic function in mouse models [4][5].
Research has also highlighted the importance of TREM2 in maintaining neuronal health, as Trem2 depletion in microglia can lead to low phagocytic activity and impaired clearance of apoptotic neurons [5]. Conversely, elevated levels of TREM2 have been shown to inhibit inflammatory responses and promote neuronal survival [5]. Furthermore, TREM2 mutations, such as the Y38C mutation, have been associated with impaired neuronal synapses in adult mice [6].
References:
[1] J. Satoh, H. Tabunoki, T. Ishida, S. Yagishita, K. Jinnai, N. Futamuraet al., Immunohistochemical characterization of microglia in nasu‐hakola disease brains, Neuropathology, vol. 31, no. 4, p. 363-375, 2010. https://doi.org/10.1111/j.1440-1789.2010.01174.x
[2] P. Cheng-Hathaway, E. Reed-Geaghan, T. Jay, B. Casali, S. Bemiller, S. Puntambekaret al., The trem2 r47h variant confers loss-of-function-like phenotypes in alzheimer’s disease, Molecular Neurodegeneration, vol. 13, no. 1, 2018. https://doi.org/10.1186/s13024-018-0262-8
[3] X. Xiang, T. Piers, B. Wefers, K. Zhu, A. Mallach, B. Brunneret al., The trem2 r47h alzheimer’s risk variant impairs splicing and reduces trem2 mrna and protein in mice but not in humans, Molecular Neurodegeneration, vol. 13, no. 1, 2018. https://doi.org/10.1186/s13024-018-0280-6
[4] H. Shin, Z. Jin, H. An, K. Park, J. Lee, S. Leeet al., Lipocalin-2 deficiency reduces hepatic and hippocampal triggering receptor expressed on myeloid cells-2 expressions in high-fat diet/streptozotocin-induced diabetic mice, Brain Sciences, vol. 12, no. 7, p. 878, 2022. https://doi.org/10.3390/brainsci12070878
[5] A. Liu, M. Chu, & Y. Wang, Up-regulation of trem2 inhibits hippocampal neuronal apoptosis and alleviates oxidative stress in epilepsy via the pi3k/akt pathway in mice, Neuroscience Bulletin, vol. 35, no. 3, p. 471-485, 2019. https://doi.org/10.1007/s12264-018-0324-5
[6] V. Jadhav, P. Lin, T. Pennington, G. Prisco, A. Jannu, G. Xuet al., Trem2 y38c mutation and loss of trem2 impairs neuronal synapses in adult mice,, 2020. https://doi.org/10.21203/rs.3.rs-33900/v2
