An amyloidogenic determinant in n‐terminal pro‐brain natriuretic peptide (nt‐probnp): Implications for cardiac amyloidoses

Abstract

Deposition of amyloid in the atria (isolated atrial/cardiac amyloid) is fairly common in the aging heart. It consists of amyloid fibrils, formed both by atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) and the precursor molecule of ANP, proANP. This study examines whether amyloidogenic determinants (short peptides/amyloid forming favoring regions) exist in the sequence of NT-proBNP, the N-terminal part of proBNP, and if these determinants form amyloid-like fibrils in vitro. We have predicted a possible amyloidogenic determinant in the sequence of the NT-proBNP, and we conclusively show, after its synthesis, that it forms amyloid-like fibrils in vitro, utilizing transmission electron microscopy, X-ray diffraction, attenuated total reflectance Fourier-transform infrared spectroscopy, and polarizing microscopy. Thus, for the first time, in this study, a possible biological role is attributed to a certain, specific part of this important cardiac prohormone/natriuretic peptide, which acts as an important biomarker indicative of heart failure. Its possible direct involvement in isolated cardiac amyloidosis, atrial fibrillation, and other types of cardiac amyloidoses is indicated and discussed. Since these cardiac hormones and their prohormones play key roles in cardiovascular homeostasis through natriuresis, diuresis, vasorelaxation, and inhibition of renin and aldosterone secretion (pathophysiology of hypertension and cardiovascular regulation), we also try to suggest these specific, short peptides as possible future structural targets of efforts toward inhibiting formation of natriuretic peptide(s) amyloid.

An N‐terminal pro‐atrial natriuretic peptide (NT‐proANP) ‘aggregation‐prone’ segment involved in isolated atrial amyloidosis

“…Therefore, an alternative approach may involve NT‐proANP forming early oligomers through coiled–coils and further polymerizing into atrial amyloid fibrillar structures, as a result of the self‐aggregation potential of the KLRALLT aggregation prone peptide. A similar process has recently been proposed to occur for the NT‐proBNP natriuretic pro‐hormone [26].…”

“…The predicted 'aggregation-prone' region of NT-proANP is marked with ''#'' under the sequence. The four underlined hydrophobic residues located at the N-terminal segment of NT-proANP (nominal residues 37-59), show heptad periodicities of hydrophobic residues, a coiled-coil motif (a motif capable of forming a superhelix of a-helices) [26,47]. with a 1% Congo red solution in distilled water (pH 5.75) for 20 min [30].…”

“…This aggregation‐prone peptide segment was synthesized (see Section 2) and here we present experimental results, verifying its strong aggregation propensity to form amyloid fibrils. It should be mentioned at this point that, a distantly homologous peptide, KMVLYTL, has also been determined to possess a strong aggregation propensity in the sequence of the N‐terminal pro‐brain natriuretic peptide (NT‐proBNP) [26]. An analysis of the physico‐chemical properties of both peptides is provided (see Supplementary Table 1 and Fig.…”

Exploring the ‘aggregation-prone’ core of human Cystatin C: A structural study

“…By its very definition the ''amyloid stretch hypothesis'' proposed that amyloid aggregation is actually driven by short fragments of misfolded proteins (Esteras-Chopo et al, 2005), and thus until today, scientists in structural biology have extensively been studying a great variety of amyloidogenic (or 'aggrega tion-prone') peptides Iconomidou et al, 2012;Louros et al, 2014;Teng and Eisenberg, 2009;Tenidis et al, 2000). These short amyloidogenic stretches of five or six amino acid residues do exhibit the potential to 'guide' amyloid fibril formation from a soluble globular domain (Lopez de la Paz and Serrano, 2004;Teng and Eisenberg, 2009).…”

Hidden Aggregation Hot-Spots on Human Apolipoprotein E: A Structural Study

“…In the context of the “amyloid stretch hypothesis”, which proposes that amyloidogenesis is actually driven by short fragments of misfolded proteins [45], scientists have extensively been studying a variety of short aggregation-prone stretches, with a potential to guide amyloid fibril formation from a soluble globular domain [46,47,48,49,50,51,52,53]. Based on this idea, many algorithms have been developed, in an attempt to extract the information of amyloidogenicity only from primary protein sequences [54].…”