Unveiling the Interplay between the TLR4/MD2 Complex and HSP70 in the Human Cardiovascular System: A Computational...

Area of Science:

• Immunology
• Cardiovascular Biology
• Molecular Biology

Background:

• Cardiovascular diseases (CVDs) involve complex mechanisms, with the innate immune system, particularly Toll-like receptor 4 (TLR4), implicated due to its interaction with endogenous molecules.
• The Heat-shock protein 70 (HSP70) family is of interest in cardiovascular tissues, potentially exhibiting dual effects via TLR4 pathways.
• The hypothesis of HSP70 family members acting as TLR4 ligands is gaining acceptance, but direct structural evidence and the role of the co-adaptor MD2 remain unclear.

Purpose of the Study:

• To investigate the interplay between the TLR4/MD2 complex and HSP70 family members within the human cardiovascular system.
• To propose a putative interaction model for these protein complexes.
• To explore the potential role of MD2 in HSP70 and TLR4 complexation.

Main Methods:

• Transcriptomic data analysis to assess correlated expression levels of TLR4, MD2, and HSP70 family members in cardiovascular tissues.
• Molecular docking simulations to model the interaction between HSP70 (ATP-bound vs. ADP-bound states) and the TLR4/MD2 complex.
• Proximity ligation assay to experimentally validate the interaction between HSP70 and TLR4 in cells, assessing the influence of ATP and MD2.

Main Results:

• Compelling evidence of correlated expression between TLR4, MD2, and HSP70 family members, especially in heart tissue.
• Molecular docking revealed a significantly better docking score for ATP-bound HSP70 interacting with the TLR4/MD2 complex compared to ADP-bound HSP70.
• Experimental data showed increased formation of fluorescent spots (indicating complexation) for HSP70 and TLR4 in ATP-stimulated cells, suggesting MD2's requirement for this interaction.

Conclusions:

• This study provides strong evidence for the interaction between HSP70 family members and the TLR4/MD2 complex in the human cardiovascular system.
• The ATP-bound state of HSP70 appears to favor binding to the TLR4/MD2 complex, with MD2 potentially playing a crucial role in this interaction.
• The findings offer a computational and experimental basis for future in vivo studies on the role of HSP70-TLR4/MD2 interplay in cardiovascular health and disease.