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Atomistic mapping of the Sclerostin-LRP6 binding interface using molecular dynamics simulation and essential
Mohammad Babelian1, Yalda Azghandi1, Faramarz Mehrnejad2
1Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
Summary
Sclerostin (SOST) inhibits LRP6 through stable interactions involving its loop 2 and C-terminal regions. This molecular mechanism explains SOST
Area of Science:
- Molecular biology
- Biochemistry
- Structural biology
Background:
- Sclerostin (SOST) is a key inhibitor of Wnt signaling, crucial for bone homeostasis.
- LRP6 is a central co-receptor in canonical Wnt beta-catenin signaling.
- SOST's high-affinity inhibition of LRP6 is a therapeutic target for osteoporosis, but its molecular details are not fully understood.
Purpose of the Study:
- To investigate the molecular mechanism of Sclerostin (SOST) inhibition of the LRP6 co-receptor.
- To elucidate the residue-level interactions and stability of the SOST-LRP6 E1E2 ectodomain complex in solution.
Main Methods:
- Atomistic molecular dynamics (MD) simulations of the human SOST-LRP6 E1E2 ectodomain complex.
- Analysis of residue-level interaction behavior and complex stability in solution.
Main Results:
- SOST engages LRP6 via two coordinated regions: loop 2 (with NAI motif) interacting with the E1 domain, and the C-terminal region (with HNQS motif) interacting with the E2 domain.
- These extended interactions explain the higher binding affinity of full-length SOST compared to truncated variants.
- An anchor-stabilized, dynamic interaction network maintains receptor engagement, with persistent loop 2/E1 and C-terminal/E2 contacts.
Conclusions:
- The study reveals a detailed molecular mechanism for SOST-mediated LRP6 inhibition.
- Understanding these interactions provides deeper insight into bone homeostasis and Wnt signaling pathways.
- This knowledge can inform the development of novel osteoporosis therapeutics targeting the SOST-LRP6 interaction.
