The HMGB1-CXCL12 heterocomplex and its interaction with CXCR4 as a target for tissue repair

Thesis

Reduced High Mobility Group Box 1 (HMGB1) protein binds to CXC Ligand 12 (CXCL12), signals through CXC Receptor 4 (CXCR4) to promote tissue regeneration and accelerates repair by transitioning stem and progenitor cells to GAlert. Therefore, administration of fully reduced HMGB1 (FR-HMGB1) could prove beneficial in clinical practice. However, local conversion of FR-HMGB1 to the disulfide form (DS-HMGB1) may result in deleterious inflammation through signalling via Toll-Like Receptors 2 and 4, and the Receptor for Advanced Glycation End Products (RAGE).

Engineering HMGB1 to eliminate these potentially deleterious properties requires knowledge on the mechanism of its interaction with CXCL12, for which there is sparse literature. I identified the residues involved in formation of the heterocomplex using a combination of peptide arrays, biolayer interferometry and nuclear magnetic resonance. With these, and the published literature on the interaction of HMGB1 with its proinflammatory receptors, I designed a panel of HMGB1 derivatives aimed at removing the deleterious activities. I identified a construct comprising two HMG B Boxes in tandem (DbB-HMGB1) which is unable to signal through either TLR-2 or TLR- 4 and has greatly decreased RAGE binding but retains regenerative activity equivalent to FR-HMGB1 in vivo and in vitro.

Authors: Viñals Guitart, Á

• DOI: 10.5287/ora-8n0moxj6o
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: HMGB1; CXCR4; DAMPs; CXCL12
• Subjects: Guided tissue regeneration; Mimetic design