TLR8 Overexpression Lysate

HEK293T cells in 10-cm dishes were transiently transfected with a non-lipid polymer transfection reagent specially designed and manufactured for large volume DNA transfection. Transfected cells were cultured for 48hrs before collection. The cells were lysed in modified RIPA buffer (25mM Tris-HCl pH7.6, 150mM NaCl, 1% NP-40, 1mM EDTA, 1xProteinase inhibitor cocktail mix, 1mM PMSF and 1mM Na3VO4, and then centrifuged to clarify the lysate. Protein concentration was measured by BCA protein assay kit.

Toll-like receptor 8 (TLR8) is a member of the TLR family of receptors that play a role in innate immune system activation and the recognition of pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) (1,2). TLRs are type I membrane receptors that can be expressed on either the cell surface or internally, on endosomes (1,2). TLR8 is an endosomal receptor and is activated by pathogenic single stranded (ss) RNA (1-3). TLR8 is located on the X chromosome and is expressed mostly in monocytes/macrophages, neutrophils, and myeloid dendritic cells (1-3). Structurally, TLR8 consists of an extracellular domain, a cysteine-rich region, and transmembrane domain, and a Toll/Interleukin-1 receptor homology (TIR) domain (3,4). The extracellular domain contains a N-terminal leucine rich repeat (LRRNT) and a C-terminal LRR (LRRCT) which have 26 LRRs between them, each approximately 20-30 amino acids (aa), and a Z-loop between LRR14 and LRR15 (3). The primary isoform of the human TLR8 is synthesized as a protein 1041 aa in length with a theoretical molecular weight of ~120 kDa (4).

TLR8 is highly similar to TLR7 and both pathways are mediated by the adapter protein MyD88 to signal through IFN regulatory factor 7 (IRF7) and nuclear factor (NF)-kappaB (1-3,5). However, TLR7 recognizes guanosine and GU-rich ssRNA, while TLR8 recognizes uridine and AU-rich sequences (2,5). TLR7/TLR8 agonists, including derivatives of the immunostimulatory imiquimod, have been shown to be a promising cancer therapy capable of providing anticancer signals to antigen presenting cells (APCs), with many agonists being tested in both pre-clinical and clinical trials (6). Similarly, studies suggest that agonists for TLR8, in combination with other individual TLR agonists and antagonists, may also be useful for treating inflammatory allergic diseases, such as allergic rhinitis (7).

References

1. Sakaniwa, K., & Shimizu, T. (2020). Targeting the innate immune receptor TLR8 using small-molecule agents. Acta crystallographica. Section D, Structural biology, 76(Pt 7). https://doi.org/10.1107/S2059798320006518

2. Cervantes, J. L., Weinerman, B., Basole, C., & Salazar, J. C. (2012). TLR8: the forgotten relative revindicated. Cellular & molecular immunology. https://doi.org/10.1038/cmi.2012.38

3. Ohto, U., Tanji, H., & Shimizu, T. (2014). Structure and function of toll-like receptor 8. Microbes and infection. https://doi.org/10.1016/j.micinf.2014.01.007

4. Uniprot (Q9NR97)

5. Jannuzzi, G. P., de Almeida, J., Paulo, L., de Almeida, S. R., & Ferreira, K. S. (2020). Intracellular PRRs Activation in Targeting the Immune Response Against Fungal Infections. Frontiers in cellular and infection microbiology. https://doi.org/10.3389/fcimb.2020.591970

6. Frega, G., Wu, Q., Le Naour, J., Vacchelli, E., Galluzzi, L., Kroemer, G., & Kepp, O. (2020). Trial Watch: experimental TLR7/TLR8 agonists for oncological indications. Oncoimmunology. https://doi.org/10.1080/2162402X.2020.1796002

7. Golshiri-Isfahani, A., Amizadeh, M., & Arababadi, M. K. (2018). The roles of toll like receptor 3, 7 and 8 in allergic rhinitis pathogenesis. Allergologia et immunopathologia. https://doi.org/10.1016/j.aller.2017.09.026

This product is for research use only and is not approved for use in humans or in clinical diagnosis. Lysates are guaranteed for 6 months from date of receipt.

Array NBP2-05618

• TLR8 Antibodies
• TLR8 ELISA Kits
• TLR8 Lysate
• TLR8 Proteins