Difference between revisions of "Part:BBa K1993003"

Latest revision as of 18:00, 23 October 2020

CXCR4

Chemokine receptors are receptors found on the surface of certain cells that interact with chemokines. They have a 7-transmembrane (7-TM) structure and couple to G-protein for signal transduction within a cell. [1] (Figure 1) Following interaction with their specific chemokine ligands, chemokine receptors trigger a flux intracellular calcium (Ca2+) ions, initiate chemotaxis and guide the cell to a desired location. (Figure 2)

Figure 1. typical structure of a chemokine receptor.

Figure 2. the mechanism of interaction between a chemokine and a chemokine receptor.

Under the circumstances of inflammation, various kinds of cytokines, including chemokines, are released by the lesions. Guided by the chemokines, cells expressing chemokine receptors move towards the lesions where they can function better.[2] What’s more, different diseases would release different pools of chemokines, which would recruit different effector cells. See our disease table-chemokine

Based on the chemotaxis theory, in order to enhance the homing ability of our marvelous mesenchymal stem cells (MSCs) due to lack of enough chemokine receptors on their cell surface, we, SYSU-MEDICINE, had constructed a series of chemokine receptors that corresponding to different inflammatory diseases as far as possible. Among which, CXCL12 is a significant chemokine (CXCR4 is its chemokine receptor) in Inflammatory Bowel Disease(IBD) and Experimental Allergic Encephalomyelitis(EAE). See our disease table-chemokine

We acquired this gene from peripheral mononuclear blood cells (PMBCs) and purified it. (Figure 3) Then we constructed it under the control of EF-1α by Gateway technology. (Figure 4)

Figure 3 Purification of CXCR4

Figure 4 EF-1α-CXCR4.

We introduced that plasmid into MSCs and tested the expression of CXCR4 in MSCs on mRNA and protein level (Figure 5, Figure 6)

Figure 5. Relative mRNA Level of CXCR4

Figure 6. Western Blot of CXCR4.

Then, we tested the chemotaxis of engineered MSCs by conducting Transwell assay against CXCL12. To our excitement, our engineered MSCs had improved their homing ability with chemokine receptor CXCR4(Figure 7,Figure8).

Figure 7, Figure 8: Tanswell Assay of CXCR4.

MIT_MAHE 2020

Summary

CXCR4 is a G-protein-coupled seven transmembrane receptor that was originally cloned as an orphan chemokine receptor and was known as LESTR or fusin. It is expressed on the cell surface of most leukocytes, including all B cells, and monocytes and most T lymphocyte subsets, but just weakly on NK cells. It is also expressed on nonhematopoietic cells such as endothelial cells and epithelial cells, and adult stem cells such as fibrocytes and circulating progenitor epithelial cells. CXCR4 is also an essential cofactor for T-tropic HIV-1 and HIV-2 env-mediated fusion and entry into CD4+ lymphocytes.

References

[1]Allen, Samantha J.; Crown, Susan E.; Handel, Tracy M. (2007-01-01). "Chemokine: receptor structure, interactions, and antagonism". Annual Review of Immunology. 25: 787–820.

[2] Griffith J W, Sokol C L, Luster A D. Chemokines and chemokine receptors: positioning cells for host defense and immunity.[J]. Annual Review of Immunology, 2014, 32(1):659-702.

[3] Trentin J. J. (1978). Hemopoietic microenvironments. Transplantation proceedings, 10(1), 77–82.

[4] Schofield R. (1978). The relationship between the spleen colony-forming cell and the haemopoietic stem cell. Blood cells, 4(1-2), 7–25.

[5] Tavassoli M, Yoffey JM: Bone Marrow Structure and Function. New York, Alan R Liss Inc,. 1983 https://doi.org/10.1111/j.1600-0609.1984.tb01701.x

[6] Wilson, A., & Trumpp, A. (2006). Bone-marrow haematopoietic-stem-cell niches. Nature reviews. Immunology, 6(2), 93–106. https://doi.org/10.1038/nri1779 Sequence and Features