Design and redesign journey of a drug for transthyretin amyloidosis

The misfolding and subsequent aggregation of proteins into amyloid fibrils underlie the onset of a variety of human disorders collectively known as amyloidosis.Transthyretin(TTR)is one of the>30 amyloidogenic proteins identified to date and is associated with a group of highly debilitating and life-threatening disorders called TTR amyloidosis(ATTR).ATTR comprises senile systemic amyloidosis,which is linked to wild-type(WT)TTR aggregation,and hereditary ATTR,a dominantly inherited disorder caused by the deposition of one of over 130 TTR genetic variants.Senile systemic amyloidosis is a prevalent age-related amyloidosis,affecting up to 25%of the population over 80 years of age,and is characterized by the build-up of TTR fibrils in the myocardium.Regarding hereditary ATTR,the clinical presentation is highly heterogeneous,primarily affecting the peripheral nervous system(familial amyloid polyneuropathy-FAP)or the heart(familial amyloid cardiomyopathy).In rare cases,aggregation develops in the central nervous system,giving rise to a phenotype known as familial leptomeningeal amyloidosis(Carroll et al.,2022).

Small molecules to target tau amyloid aggregation

Protein aggregation has been linked with many neurodegenerative diseases,such as Alzheimer’s disease(AD)or Parkinson’s disease.AD belongs to a group of heterogeneous and incurable neurodegenerative disorders collectively known as tauopathies.They comprise frontotemporal dementia,Pick’s disease,or corticobasal degeneration,among others.The symptomatology varies with the specific tau protein variant involved and the affected brain region or cell type.However,they share a common neuropathological hallmark-the formation of proteinaceous deposits named neurofibrillary tangles.Neurofibrillary tangles,primarily composed of aggregated tau(Zhang et al.,2022),disrupt normal neuronal functions,leading to cell death and cognitive decline.

Small molecules to prevent the neurodegeneration caused by α-synuclein aggregation

Parkinson’s disease (PD) is a neurodegenerative disorder belonging to a group of human pathologies known as synucleinopathies,which includes multiple system atrophy or dementia with Lewy bodies (Spillantini et al.,1998).These diseases share a common neuropathological feature,the presence ofα-synuclein (α-Syn) deposits,although they differ in the cellular and anatomical compartment in whichα-Syn inclusions accumulate.PD affects more than 1% of people over 60 years of age,thus being the second most prevalent neurodegenerative disease in the world and the most common synucleinopathy.

LL-37 and CsgC exemplify the crosstalk between anti-amyloid, antimicrobial, and anti-biofilm protein activities

Protein misfolding and aggregation into amyloid fibrils is the main pathological hallmark of neurodegenerative diseases,including Alzheimer’s,Parkinson’s,Huntington’s,and prion diseases(Chiti and Dobson,2017).These insoluble fibrillar deposits possess a common structure characterized by a cross-β-sheet conformation in which β-strands run transversely to the fiber axis and form an intermolecular network of hydrogen bonds.

Inducing α-synuclein compaction: a new strategy for inhibiting α-synuclein aggregation?

Proteins might misfold during translation and folding or even once they are in their native states, due to stochastic fluctuations, destabilizing mutations or cellular stress. Aberrant protein species are usually detected and either refolded or cleared by the protein quality control machinery (Ciechanover and Kwon, 2015). When misfolded protein conformers cannot be degraded, they tend to self-assemble to form aggregates, a characteristic of many neurodegenerative diseases.

Prion-like domain disease-causing mutations and misregulation of alternative splicing relevance in limb-girdle muscular dystrophy (LGMD) 1G

Human prion-like proteins often correspond to nucleic acid binding proteins,displaying both globular domains and long intrinsically disordered regions(IDRs)(Harrison and Shorter,2017).Their IDRs are of low complexity and resemble in amino acid composition to the disordered yeast prion domains,being usually enriched in Gln and Asn residues and depleted in hydrophobic and charged residues.Accordingly,these sequence stretches are named prion-like domains(PrLDs).Prion-like proteins can aggregate into amyloid fibrils,which can accommodate incoming protein monomers,propagating thus the polymeric fold,both processes being。

One ring is sufficient to inhibit α-synuclein aggregation

Parkinson's disease,the second most prevalent neurodegenerative disorder worldwide,is characterized by a progressive loss of dopaminergic neurons in substantia nigra pars compacta,causing motor symptoms.This disorder's main hallmark is the formation of intraneuronal protein inclusions,named Lewy bodies and neurites.The major component of these arrangements is α-synuclein,an intrinsically disordered and soluble protein that,in pathological conditions,can form toxic and cell-to-cell transmissible amyloid structures.Preventing α-synuclein aggregation has attracted significant effort in the search for a disease-modifying therapy for Parkinson's disease.Small molecules like Synu Clean-D,epigallocatechin gallate,trodusquemine,or anle138 b exemplify this therapeutic potential.Here,we describe a subset of compounds containing a single aromatic ring,like dopamine,ZPDm,gallic acid,or entacapone,which act as molecular chaperones against α-synuclein aggregation.The simplicity of their structures contrasts with the complexity of the aggregation process,yet the block efficiently α-synuclein assembly into amyloid fibrils,in many cases,redirecting the reaction towards the formation of non-toxic off-pathway oligomers.Moreover,some of these compounds can disentangle mature α-synuclein amyloid fibrils.Their simple structures allow structure-activity relationship analysis to elucidate the role of different functional groups in the inhibition of α-synuclein aggregation and fibril dismantling,making them informative lead scaffolds for the rational development of efficient drugs.