RESUMO
Polyphosphate (polyP), a several billion-year-old biopolymer, is produced in every cell, tissue, and organism studied. Structurally extremely simple, polyP consists of long chains of covalently linked inorganic phosphate groups. We report here the surprising discovery that polyP shows a remarkable efficacy in accelerating amyloid fibril formation. We found that polyP serves as an effective nucleation source for various different amyloid proteins, ranging from bacterial CsgA to human α-synuclein, Aß1-40/42, and Tau. polyP-associated α-synuclein fibrils show distinct differences in seeding behavior, morphology, and fibril stability compared with fibrils formed in the absence of polyP. In vivo, the amyloid-stimulating and fibril-stabilizing effects of polyP have wide-reaching consequences, increasing the rate of biofilm formation in pathogenic bacteria and mitigating amyloid toxicity in differentiated neuroblastoma cells and C. elegans strains that serve as models for human folding diseases. These results suggest that we have discovered a conserved cytoprotective modifier of amyloidogenic processes.
Assuntos
Peptídeos beta-Amiloides/agonistas , Proteínas de Escherichia coli/agonistas , Fragmentos de Peptídeos/agonistas , Polifosfatos/farmacologia , alfa-Sinucleína/agonistas , Proteínas tau/agonistas , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/metabolismo , Animais , Animais Geneticamente Modificados , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Caenorhabditis elegans/efeitos dos fármacos , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Linhagem Celular Tumoral , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Expressão Gênica , Humanos , Cinética , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/metabolismo , Polifosfatos/química , Dobramento de Proteína/efeitos dos fármacos , alfa-Sinucleína/química , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismo , Proteínas tau/química , Proteínas tau/genética , Proteínas tau/metabolismoRESUMO
Over-expression of the Hsp70 molecular chaperone prevents protein aggregation and ameliorates neurodegenerative disease phenotypes in model systems. We identified an Hsp70 activator, MAL1-271, that reduces α-synuclein aggregation in a Parkinson's Disease model. We now report that MAL1-271 directly increases the ATPase activity of a eukaryotic Hsp70. Next, twelve MAL1-271 derivatives were synthesized and examined in a refined α-synuclein aggregation model as well as in an assay that monitors maturation of a disease-causing Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mutant, which is also linked to Hsp70 function. Compared to the control, MAL1-271 significantly increased the number of cells lacking α-synuclein inclusions and increased the steady-state levels of the CFTR mutant. We also found that a nitrile-containing MAL1-271 analog exhibited similar effects in both assays. None of the derivatives exhibited cellular toxicity at concentrations up to 100⯵m, nor were cellular stress response pathways induced. These data serve as a gateway for the continued development of a new class of Hsp70 agonists with efficacy in these and potentially other disease models.
Assuntos
Adenosina Trifosfatases/metabolismo , Ativadores de Enzimas/farmacologia , Ésteres/farmacologia , Proteínas de Choque Térmico HSP70/agonistas , Multimerização Proteica/efeitos dos fármacos , Pirimidinonas/farmacologia , Linhagem Celular Tumoral , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Ativadores de Enzimas/síntese química , Ativadores de Enzimas/química , Ativadores de Enzimas/toxicidade , Ésteres/síntese química , Ésteres/química , Ésteres/toxicidade , Células HEK293 , Proteínas de Choque Térmico HSP70/metabolismo , Humanos , Estrutura Molecular , Dobramento de Proteína/efeitos dos fármacos , Pirimidinonas/síntese química , Pirimidinonas/química , Pirimidinonas/toxicidade , Saccharomyces cerevisiae/enzimologia , Relação Estrutura-Atividade , alfa-Sinucleína/agonistas , alfa-Sinucleína/metabolismoRESUMO
Epidemiological evidence has shown associations between prevalence of Parkinson's disease (PD) and exposure to environmental pollutants, but the mechanisms of pathogensis are still unclear. The objective of this study is to investigate effects of methylmercury (MeHg) on a dopaminergic neuronal cell line, MN9D and compare that to 1-methyl-4-phenylpyridinium (MPP+), a well-established agent associated with pathogenesis of PD. MN9D cells were exposed to MeHg (1-10 µM) and MPP+ (10-400 µM) for 24 or 48 h. Our results showed that MeHg induced cell death dose-dependently. MeHg also decreased the release of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) similar to the effects of MPP+. There was an increase in DOPAC + HVA/DA ratio. At the same time, both MeHg and MPP+ decreased the synthesis of tyrosine hydroxylase and dopamine transporter at the mRNA and protein levels. Expression of the α-Synuclein (α-Syn), a hallmark neuropathological indicator of PD, was also up-regulated at the mRNA level but not at the protein level after both MeHg and MPP+ dosing. Monoamine oxidase-B activity was suppressed in all MeHg treatments and MPP+ (1 µM)-treated cells. These findings suggest that MeHg can disrupt the synthesis, the uptake of DA and the metabolism as well as alter the biology of α-Syn similar to MPP+. Exposure to MeHg may potentially be a risk factor for the development of PD.