DOI
https://doi.org/10.25772/CFKC-0T68
Author ORCID Identifier
0009-0008-7496-9339
Defense Date
2025
Document Type
Thesis
Degree Name
Master of Science
Department
Microbiology & Immunology
First Advisor
Dr. Wook-Jin (Eddie) Chae
Second Advisor
Dr. Hisashi Harada
Third Advisor
Dr. Paula Bos
Abstract
Dickkopf1(DKK1) is a quintessential Wnt antagonist and immunomodulator in various inflammatory diseases. The underlying molecular mechanisms of DKK1-mediated immunomodulation remain elusive. Here, we identified TLR4 as a new receptor for DKK1 to activate NFκΒ pathway-mediated gene expression and pyroptosis via NLRP3 inflammasome in human and mouse macrophages.
DKK1 employed TLR4 to initiate NFκB signaling cascade via MyD88. MyD88-TAK1-NFκΒ pathway activation by DKK1 increased HIF1α, NFκB, and NLRP3 protein expression levels, leading to pyroptosis. Unlike LPS, DKK1 did not induce IRAK4 phosphorylation, while the interaction between MyD88 and IRAK4 was maintained for downstream signaling activation. DKK1 did not induce IRF3 phosphorylation in the nucleus and failed to induce IFNβ gene expression, indicating differential signaling from LPS. DKK1 primed macrophages via TLR4-MyD88, resulting in NLRP3 inflammasome-mediated pyroptosis via Caspase-1 and Gasdermin D maturation with various NLRP3 inflammasome activators, including Nigericin. Our results demonstrate that DKK1 is a novel endogenous priming ligand that augments differential NFκB pathway from LPS and NLRP3 inflammasome activation via TLR4 in mouse and human macrophages.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
4-10-2025