Systemic amyloidosis derived from EFEMP1 in a captive Tsushima leopard cat

In animals, most cases of systemic amyloidosis are of amyloid A type, and the other types of systemic amyloidoses are rare. This study analyzed systemic amyloidosis in a 15-year-old female Tsushima leopard cat. Amyloid deposits strongly positive for Congo red staining were observed in the arterial walls as well as the interstitium in multiple organs. Mass spectrometry–based proteomic analysis with laser microdissection of amyloid deposits identified epidermal growth factor–containing fibulin-like extracellular matrix protein 1 (EFEMP1) as a prime amyloidogenic protein candidate. Immunohistochemistry showed that the amyloid deposits were positive for the N-terminal region of EFEMP1. From these results, the present case was diagnosed as EFEMP1-derived amyloidosis. It is the first such case in an animal. EFEMP1-derived amyloidosis in humans has recently been reported as a systemic amyloidosis, and it is known as an age-related venous amyloidosis. The present case showed different characteristics from human EFEMP1-derived amyloidosis, including the amyloid deposition sites and the amyloidogenic region of the EFEMP1 protein, suggesting a different pathogenesis between Tsushima leopard cat and human EFEMP1-derived amyloidosis.

Is It Possible to Create Antimicrobial Peptides Based on the Amyloidogenic Sequence of Ribosomal S1 Protein of P. aeruginosa?

The development and testing of new antimicrobial peptides (AMPs) represent an important milestone toward the development of new antimicrobial drugs that can inhibit the growth of pathogens and multidrug-resistant microorganisms such as Pseudomonas aeruginosa, Gram-negative bacteria. Most AMPs achieve these goals through mechanisms that disrupt the normal permeability of the cell membrane, which ultimately leads to the death of the pathogenic cell. Here, we developed a unique combination of a membrane penetrating peptide and peptides prone to amyloidogenesis to create hybrid peptide: “cell penetrating peptide + linker + amyloidogenic peptide”. We evaluated the antimicrobial effects of two peptides that were developed from sequences with different propensities for amyloid formation. Among the two hybrid peptides, one was found with antibacterial activity comparable to antibiotic gentamicin sulfate. Our peptides showed no toxicity to eukaryotic cells. In addition, we evaluated the effect on the antimicrobial properties of amino acid substitutions in the non-amyloidogenic region of peptides. We compared the results with data on the predicted secondary structure, hydrophobicity, and antimicrobial properties of the original and modified peptides. In conclusion, our study demonstrates the promise of hybrid peptides based on amyloidogenic regions of the ribosomal S1 protein for the development of new antimicrobial drugs against P. aeruginosa.

Rationally Designed Bicyclic Peptides Prevent the Conversion of Aβ42 Assemblies Into Fibrillar Structures

There is great interest in drug discovery programs targeted at the aggregation of the 42-residue form of the amyloid β peptide (Aβ42), since this molecular process is closely associated with Alzheimer’s disease. The use of bicyclic peptides may offer novel opportunities for the effective modification of Aβ42 aggregation and the inhibition of its cytotoxicity, as these compounds combine the molecular recognition ability of antibodies with a relatively small size of about 2 kD. Here, to pursue this approach, we rationally designed a panel of six bicyclic peptides targeting various epitopes along the sequence of Aβ42 to scan its most amyloidogenic region (residues 13–42). Our kinetic analysis and structural studies revealed that at sub-stoichiometric concentrations the designed bicyclic peptides induce a delay in the condensation of Aβ42 and the subsequent transition to a fibrillar state, while at higher concentrations they inhibit such transition. We thus suggest that designed bicyclic peptides can be employed to inhibit amyloid formation by redirecting the aggregation process toward amorphous assemblies.

Dangerous Stops: Nonsense Mutations Can Dramatically Increase Frequency of Prion Conversion

Amyloid formation is associated with many incurable diseases. For some of these, sporadic cases are much more common than familial ones. Some reports point to the role of somatic cell mosaicism in these cases via origination of amyloids in a limited number of cells, which can then spread through tissues. However, specific types of sporadic mutations responsible for such effects are unknown. In order to identify mutations capable of increasing the de novo appearance of amyloids, we searched for such mutants in the yeast prionogenic protein Sup35. We introduced to yeast cells an additional copy of the SUP35 gene with mutated amyloidogenic domain and observed that some nonsense mutations increased the incidence of prions by several orders of magnitude. This effect was related to exposure at the C-terminus of an internal amyloidogenic region of Sup35. We also discovered that SUP35 mRNA could undergo splicing, although inefficiently, causing appearance of a shortened Sup35 isoform lacking its functional domain, which was also highly prionogenic. Our data suggest that truncated forms of amyloidogenic proteins, resulting from nonsense mutations or alternative splicing in rare somatic cells, might initiate spontaneous localized formation of amyloids, which can then spread, resulting in sporadic amyloid disease.

Impact of SDS surfactant on the interactions of Cu2+ ions with the amyloidogenic region of human prion protein

In this work, we focused on Cu2+ interaction with the hPrP fragment spanning residues 91–127 in the presence of micelles formed by the anionic surfactant sodium dodecyl sulfate.