Deciphering the Molecular Dance: Exploring the Dynamic Interplay Between Mouse Insulin B9-23 Peptides and their...

Area of Science:

• Immunology
• Biochemistry
• Structural Biology

Background:

• Type 1 diabetes stems from autoimmune destruction of pancreatic beta cells.
• Autoreactive T cells recognize specific insulin B-chain peptides, like B9-23, as antigens.
• Understanding the aggregation properties of these peptides is crucial for developing therapeutic strategies.

Purpose of the Study:

• To investigate the aggregation behavior of mouse insulin B9-23 peptides and their mutants.
• To explore the impact of these aggregation differences on interactions with epigallocatechin gallate (EGCG).
• To establish a correlation between peptide aggregation and anti-islet autoimmunity.

Main Methods:

• Characterization of mouse insulin 1 B9-23 (Ins1 B9-23), insulin 2 B9-23 (Ins2 B9-23), and mutants (Ins2 B9-23 Y16A, Ins2 B9-23 C19S).
• Utilized drift tube ion mobility spectrometry-mass spectrometry (DTIMS-MS).
• Employed transmission electron microscopy (TEM) and two-dimensional infrared spectroscopy (2D-IR).

Main Results:

• Ins1 B9-23 and Ins2 Y16A mutant showed rapid fibril formation.
• Ins2 B9-23 and Ins2 C19S mutant exhibited slower fibrillization with structural rearrangement.
• EGCG effectively disrupted fibrils of Ins1 B9-23 and Y16A mutant but not Ins2 B9-23 and C19S mutant.

Conclusions:

• Peptide aggregation behavior significantly influences interactions with amyloid inhibitors like EGCG.
• Distinct aggregation patterns of insulin B9-23 peptides correlate with divergent effects on anti-islet autoimmunity.
• These findings provide insights into the structural basis of autoimmune responses in Type 1 diabetes.