Role of Cyclophilin on Amyloid Formation and Protein Disaggregation

Abstract

Oligomers and fibrils of protein and peptides are implicated in memory storage, neurotransmission and formation of amyloid diseases. It is believed that partially misfolded/folded states are trapped in a certain conformation and it eventually leads to formation of larger and more stable fibrillar aggregates. Recently, our laboratory demonstrated that AdK-aggregate could be disaggregated by cyclophilin CyP (LdCyP) in an isomerase- independent fashion, resulting in reactivation [Ref. 1]. We also observed the formation of elongated fibrils when lysozyme was co-incubated with cyclophilin [Ref. 2]. Very recently we tested the self aggregation process of insulin in the presence and absence of cyclophilin. The formation of insulin fiber was confirmed by ThT fluorescence assay when insulin was incubated in acidic condition at 65oC. However, co-incubation with cyclophilin, hinder the formation of amyloid fiber. Cyclophilin also showed potential to disaggregate amyloid aggregate of insulin. Cyclophilin itself was not formed amyloid fibril upon incubation for 50 days. TEM images, however, indicated formations of amorphous type of aggregates upon prolong incubation for several days at 65 oC. In our study, possibly, cyclophilin, helped to preserve the insulin native structure intact even at high temperature and did not allow it to partially unfold that may initiate the amyloid formation. Ref. 1. Mukherjee, D ; Patra, H ; Laskar, A ; Dasgupta, A ; Maiti, NC and Datta, AK, Archives Biochem. Biophys. 2013, 537, 82-90 Ref. 2. Das S., Pal U., Das S. and Maiti N.C. , Journal of Proteins and Proteomics, 4(2), 129-137, 2013.