Mechanistic studies of Metal Ion-Induced Transthyretin Misfolding and Toxic Oligomer Formation

Misfolding and aggregation of transthyretin (TTR) is implicated in numerous degenerative diseases, including cardiomyopathy and polyneuropathy (ATTR amyloidosis). Protein misfolding involves structural changes from native polypeptides to oligomeric intermediate states, which eventually form cross-β structured amyloid fibrils. Understanding the molecular mechanisms of misfolding and aggregation is critical for developing therapeutic strategies to prevent pathogenic misfolding processes. However, the precise mechanisms underlying misfolding and aggregation remain poorly understood. In addition, it is now widely recognized that prefibrillar species, especially misfolded oligomers, play pivotal roles in driving cellular dysfunction. Investigating structural transition from natively folded TTR to misfolded oligomers and characterizing misfolded oligomers would be essential for understanding the molecular basis of ATTR amyloidosis. Mounting evidence suggests that metal ions such as Zn²⁺ and Ca²⁺ play significant roles in protein misfolding and aggregation. These ions have been shown to accelerate TTR aggregation, and elevated levels have been observed in the tissues of ATTR patients. Precise roles of the metal ions in the misfolding and aggregation, particularly oligomer formation, have not been clearly understood. The proposed research program seeks to elucidate the molecular mechanisms by which TTR misfolds into toxic oligomers in the presence of metal ions. We will perform biophysical and computational analyses of metal ion binding to investigate the mechanisms underlying metal-induced misfolding into oligomers. Specific aims of the proposal are: (1) Investigating TTR misfolding and oligomer formation upon metal ion binding. (2) Elucidating the molecular mechanism of metal-induced TTR misfolding. Project Number: 1R15GM163276-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of General Medical Sciences (NIGMS) | Principal Investigator: KWANG HUN LIM | Institution: EAST CAROLINA UNIVERSITY, GREENVILLE, NC | Award Amount: $566,250 | Activity Code: R15 | Study Section: Macromolecular Structure and Function B Study Section[MSFB] View on NIH RePORTER: https://reporter.nih.gov/project-details/11291424