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1.
Orphanet J Rare Dis ; 19(1): 323, 2024 Sep 06.
Article in English | MEDLINE | ID: mdl-39242501

ABSTRACT

BACKGROUND: Variant transthyretin amyloidosis (ATTRv) is a rare multisystemic disorder caused by mutations in the transthyretin (TTR) gene. The aim of the present work was to describe the clinical profile of asymptomatic carriers (AC) and Coutinho stage 1 ATTRv patients in Spain. METHODS: National, multicentre, cross-sectional study that included 86 AC and 19 patients diagnosed in the previous 12 months to enrolment. Clinical and demographical data, TTR gene mutations, red flags anamnesis, neurological and cardiological assessments were collected. RESULTS: The mean age of patients was 56.8 years at onset and 58.6 years at diagnosis; 53% of patients and 51% of AC were from non-endemic areas. Val50Met was the most frequent mutation in both groups. Neuropathy impairment score data (mean 17.7 ± 20.5) and small-fibre function in lower limbs assessed with SUDOSCAN revealed that patients were diagnosed at early stages of neurological impairment. Peripheral polyneuropathy (84.2%), autonomic neuropathy (73.7%), cardiac (63.2%) and gastrointestinal (47.4%) alterations were the most common symptoms in patients. Autonomic neuropathy, gastrointestinal impairment, carpal tunnel syndrome, cardiac and ocular alterations were potentially related to ATTRv in the AC group. CONCLUSIONS: The EMPATIa study provides a detailed description of AC and Coutinho stage 1 ATTRv patients across Spain, confirming the multisystemic clinical profile of the disease. This study reveals a diagnosis delay around 1.8 years, highlighting the importance of a profound disease awareness to reach a diagnose in earlier stages of neurological impairment.


Subject(s)
Amyloid Neuropathies, Familial , Prealbumin , Humans , Amyloid Neuropathies, Familial/genetics , Middle Aged , Male , Female , Spain , Cross-Sectional Studies , Prealbumin/genetics , Aged , Mutation/genetics , Adult
2.
Sci Rep ; 14(1): 20508, 2024 09 03.
Article in English | MEDLINE | ID: mdl-39227655

ABSTRACT

The pathophysiology of variant transthyretin (TTR) amyloidosis (ATTRv) is associated with destabilizing mutations in the TTR tetramer. However, why TTR with a wild-type genetic sequence misfolds and aggregates in wild-type transthyretin amyloidosis (ATTRwt) is unknown. Here, we evaluate kinetic TTR stability with a newly developed ELISA system in combination with urea-induced protein denaturation. Compared with that in control patients, endogenous TTR in patients with wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) exhibited thermodynamic instability, indicating that circulating TTR instability may be associated with the pathogenesis of ATTRwt as well as ATTRv. Our findings provide new insight into the underlying mechanisms of ATTRwt.


Subject(s)
Amyloid Neuropathies, Familial , Cardiomyopathies , Prealbumin , Humans , Prealbumin/genetics , Prealbumin/metabolism , Amyloid Neuropathies, Familial/genetics , Amyloid Neuropathies, Familial/metabolism , Cardiomyopathies/genetics , Cardiomyopathies/metabolism , Male , Female , Aged , Middle Aged , Protein Stability , Mutation , Kinetics
3.
Sci Rep ; 14(1): 18281, 2024 08 07.
Article in English | MEDLINE | ID: mdl-39112608

ABSTRACT

Hereditary transthyretin (ATTRv) amyloidosis is a rare, adult-onset, progressive, multisystemic condition caused by TTR pathogenic variants. Reliable biomarkers are needed to allow early diagnosis and to monitor disease severity and progression. We measured serum concentrations of growth differentiation factor-15 (GDF-15) and uromodulin (Umod) in ATTRv patients to evaluate correlations with standard markers of disease severity (FAP stage and PND score). Blood samples were collected from 16 patients diagnosed with ATTRv amyloidosis and a verified TTR variant and from 26 healthy controls. ATTRv patients were stratified by clinical phenotype (neurologic vs. mixed), genotype (V30M vs. non-V30M), and disease severity. We found significantly higher levels of serum GDF-15 in ATTRv patients compared with controls. Mean serum Umod levels were significantly lower in patients with ATTRv than controls. A positive correlation was found between serum Umod and estimated glomerular filtration rate (eGFR), while an inverse correlation was found with cystatin C levels. Conversely, GDF-15 showed a negative correlation with eGFR, and a direct correlation with cystatin C levels. No correlation was demonstrated between GDF-15 or Umod levels and traditional cardiac biomarkers. The results identify alteration of serum levels of GDF-15 and Umod in ATTRv amyloidosis.


Subject(s)
Amyloid Neuropathies, Familial , Biomarkers , Growth Differentiation Factor 15 , Humans , Male , Female , Biomarkers/blood , Middle Aged , Growth Differentiation Factor 15/blood , Pilot Projects , Amyloid Neuropathies, Familial/blood , Amyloid Neuropathies, Familial/diagnosis , Amyloid Neuropathies, Familial/genetics , Aged , Uromodulin/blood , Uromodulin/genetics , Prealbumin/genetics , Prealbumin/metabolism , Adult , Glomerular Filtration Rate , Case-Control Studies , Cystatin C/blood
4.
Proc Natl Acad Sci U S A ; 121(34): e2315007121, 2024 Aug 20.
Article in English | MEDLINE | ID: mdl-39133861

ABSTRACT

Kinetic stability is thought to be an attribute of proteins that require a long lifetime, such as the transporter of thyroxine and holo retinol-binding protein or transthyretin (TTR) functioning in the bloodstream, cerebrospinal fluid, and vitreous humor. TTR evolved from ancestral enzymes known as TTR-related proteins (TRPs). Here, we develop a rate-expansion approach that allows unfolding rates to be measured directly at low denaturant concentration, revealing that kinetic stability exists in the Escherichia coli TRP (EcTRP), even though the enzyme structure is more energetically frustrated and has a more mutation-sensitive folding mechanism than human TTR. Thus, the ancient tetrameric enzyme may already have been poised to mutate into a kinetically stable human transporter. An extensive mutational study that exchanges residues at key sites within the TTR and EcTRP dimer-dimer interface shows that tyrosine 111, replaced by a threonine in TTR, is the gatekeeper of frustration in EcTRP because it is critical for function. Frustration, virtually absent in TTR, occurs at multiple sites in EcTRP and even cooperatively for certain pairs of mutations. We present evidence that evolution at the C terminus of TTR was a compensatory event to maintain the preexisting kinetic stability while reducing frustration and sensitivity to mutation. We propose an "overcompensation" pathway from EcTRPs to functional hybrids to modern TTRs that is consistent with the biophysics discussed here. An alternative plausible pathway is also presented.


Subject(s)
Prealbumin , Prealbumin/metabolism , Prealbumin/chemistry , Prealbumin/genetics , Humans , Kinetics , Protein Unfolding , Escherichia coli/metabolism , Escherichia coli/genetics , Protein Folding , Models, Molecular , Protein Stability , Mutation , Escherichia coli Proteins/metabolism , Escherichia coli Proteins/chemistry , Escherichia coli Proteins/genetics , Protein Denaturation
5.
Protein Sci ; 33(9): e5101, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39149996

ABSTRACT

Aberrant formation and deposition of human transthyretin (TTR) aggregates causes transthyretin amyloidosis. To initialize aggregation, transthyretin tetramers must first dissociate into monomers that partially unfold to promote entry into the aggregation pathway. The native TTR tetramer (T) is stabilized by docking of the F87 sidechain into an interfacial cavity enclosed by several hydrophobic residues including A120. We have previously shown that an alternative tetramer (T*) with mispacked F87 sidechains is more prone to dissociation and aggregation than the native T state. However, the molecular basis for the reduced stability in T* remains unclear. Here we report characterization of the A120L mutant, where steric hindrance is introduced into the F87 binding site. The x-ray structure of A120L shows that the F87 sidechain is displaced from its docking site across the subunit interface. In A120S, a naturally occurring pathogenic mutant that is less aggregation-prone than A120L, the F87 sidechain is correctly docked, as in the native TTR tetramer. Nevertheless, 19F-NMR aggregation assays show an elevated population of a monomeric aggregation intermediate in A120S relative to a control containing the native A120, due to accelerated tetramer dissociation and slowed monomer tetramerization. The mispacking of the F87 sidechain is associated with enhanced exchange dynamics for interfacial residues. At 298 K, the T* populations of various naturally occurring mutants fall between 4% and 7% (ΔG ~ 1.5-1.9 kcal/mol), consistent with the free energy change expected for undocking and solvent exposure of one of the four F87 sidechains in the tetramer (ΔG ~ 1.6 kcal/mol). Our data provide a molecular-level picture of the likely universal F87 sidechain mispacking in tetrameric TTR that promotes interfacial conformational dynamics and increases aggregation propensity.


Subject(s)
Prealbumin , Prealbumin/chemistry , Prealbumin/genetics , Prealbumin/metabolism , Humans , Models, Molecular , Crystallography, X-Ray , Protein Conformation , Protein Multimerization , Protein Aggregates , Amyloid Neuropathies, Familial/genetics , Amyloid Neuropathies, Familial/metabolism , Binding Sites , Amino Acid Substitution
6.
Vascul Pharmacol ; 156: 107411, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39029855

ABSTRACT

INTRODUCTION: Tafamidis is a molecular chaperone that stabilizes the transthyretin (TTR) homo-tetramer, preventing its dissociation and consequent deposition as amyloid fibrils in organ tissues. Tafamidis reduces mortality and the incidence of hospitalization for cardiovascular causes in patients with TTR amyloid (ATTR) cardiomyopathy. As ATTR cardiomyopathy is associated with a high risk of thromboembolic complications, we hypothesized that tafamidis may have a direct ancillary anti-thrombotic effect. METHODS: Primary human aortic endothelial cells (HAECs) were treated with tafamidis at clinically relevant concentrations and with plasma of patients, before and after the initiation of treatment with tafamidis. The expression of TF was induced by incubation with Tumor Necrosis Factor α (TNFα). Intracellular expression of tissue factor (TF) was measured by western blot. TF activity was measured by a colorimetric assay. Gene expressions of TF were measured by quantitative polymerase chain reaction. RESULTS: Treatment with tafamidis dose-dependently reduced the expression and activity of TNFα-induced TF. This effect was confirmed in cells treated with patients' plasma. Signal Transducer and Activator of Transcription 3 (STAT3) phosphorylation was significantly inhibited by tafamidis. Incubation of HAECs with tafamidis and the STAT3 activator colivelin partially rescued the expression of TF. CONCLUSIONS: Treatment with tafamidis lowers the thrombotic potential in human primary endothelial cells by reducing TF expression and activity. This previously unknown off-target effect may provide a novel mechanistic explanation for the lower number of thromboembolic complications in ATTR cardiomyopathy patients treated with tafamidis.


Subject(s)
Amyloid Neuropathies, Familial , Benzoxazoles , Cardiomyopathies , Endothelial Cells , STAT3 Transcription Factor , Thromboplastin , Tumor Necrosis Factor-alpha , Humans , Cardiomyopathies/metabolism , Cardiomyopathies/drug therapy , Cardiomyopathies/prevention & control , Cardiomyopathies/pathology , Cardiomyopathies/genetics , Benzoxazoles/pharmacology , Endothelial Cells/metabolism , Endothelial Cells/drug effects , Endothelial Cells/pathology , Cells, Cultured , Amyloid Neuropathies, Familial/drug therapy , Amyloid Neuropathies, Familial/metabolism , Amyloid Neuropathies, Familial/genetics , Amyloid Neuropathies, Familial/pathology , Thromboplastin/metabolism , Thromboplastin/genetics , STAT3 Transcription Factor/metabolism , Tumor Necrosis Factor-alpha/metabolism , Fibrinolytic Agents/pharmacology , Phosphorylation , Dose-Response Relationship, Drug , Prealbumin/metabolism , Prealbumin/genetics , Male , Signal Transduction/drug effects , Female , Aorta/metabolism , Aorta/drug effects , Aorta/pathology , Aged , Middle Aged
7.
Physiol Rep ; 12(14): e16160, 2024 Jul.
Article in English | MEDLINE | ID: mdl-39039431

ABSTRACT

Decompression sickness (DCS) is a systemic syndrome that can occur after an environmental pressure reduction. Previously, we showed that the plasmatic tetrameric form of transthyretin (TTR) nearly disappeared in rats suffering DCS but not in asymptomatic ones. In this pilot study, we assessed whether the resistance to DCS could be associated with polymorphism of the gene of TTR. For this study, Sanger sequencing was performed on purified PCR products from the liver of 14-week-old male and female standard and DCS-resistant rats (n = 5 per group). Hepatic TTR mRNA expression was assessed by RT-qPCR in 18-19 week-old male and female standard and resistant rats (n = 6 per group). There is a synonymous single nucleotide polymorphism (SNP) on the third base of codon 46 (c.138 C > T). The thymine allele was present in 90% and 100% of males and females standard, respectively. However, this allele is present in only 30% of DCS-resistant males and females (p = 0.0002301). In the liver, there is a significant effect of the resistance to DCS (p = 0.043) and sex (p = 0.047) on TTR expression. Levels of TTR mRNA were lower in DCS-resistant animals. To conclude, DCS resistance might be associated with a SNP and a lower expression of TTR.


Subject(s)
Decompression Sickness , Liver , Polymorphism, Single Nucleotide , Prealbumin , Animals , Female , Male , Rats , Decompression Sickness/genetics , Decompression Sickness/metabolism , Disease Resistance/genetics , Liver/metabolism , Pilot Projects , Prealbumin/genetics , Prealbumin/metabolism , Rats, Wistar , RNA, Messenger/metabolism , RNA, Messenger/genetics
8.
Orphanet J Rare Dis ; 19(1): 273, 2024 Jul 20.
Article in English | MEDLINE | ID: mdl-39033298

ABSTRACT

BACKGROUND: Transthyretin amyloidosis (ATTR) is a multisystem disease caused by the deposition of fibrillar protein in organs and tissues. ATTR genotypes and phenotypes are highly heterogeneous. We present data on physical signs and symptoms, cardiac and neurological assessments and genetic profile of patients enrolled in the Transthyretin Cardiac Amyloidosis Registry of the State of São Paulo, Brazil. RESULTS: Six hundred-forty-four patients were enrolled, 505 with the variant form (ATTRv) and 139 with wild-type (ATTRwt). Eleven different mutations were detected, the most common being Val50Met (47.5%) and V142Ile (39.2%). Overall, more than half of the patients presented cardiac involvement, and the difference in this proportion between the ATTRv and ATTRwt groups was significant (43.9 vs. 89.9%; p < 0.001). The prevalence of the neurological phenotype also differed between ATTRv and ATTRwt (56.8 vs. 31.7%; p < 0.001). The mixed phenotype was found in 25.6% of the population, without a significant difference between ATTRv and ATTRwt groups. A group of patients remained asymptomatic (10.4%), with a lower proportion of asymptomatic ATTRwt patients. CONCLUSIONS: This study details the clinical and genetic spectrum of patients with ATTR in São Paulo, Brazil. This preliminary analysis highlights the considerable phenotypic heterogeneity of neurological and cardiac manifestations in patients with variant and wild-type ATTR.


Subject(s)
Amyloid Neuropathies, Familial , Prealbumin , Humans , Amyloid Neuropathies, Familial/genetics , Amyloid Neuropathies, Familial/pathology , Brazil , Male , Female , Middle Aged , Aged , Prealbumin/genetics , Prealbumin/metabolism , Mutation/genetics , Registries , Adult , Genotype , Phenotype
9.
J Am Soc Mass Spectrom ; 35(8): 1854-1864, 2024 Aug 07.
Article in English | MEDLINE | ID: mdl-39057193

ABSTRACT

Transthyretin (TTR), a 56 kDa homotetramer that is involved in the transport of thyroxine and retinol, has been linked to amyloidosis through disassembly of tetramers to form monomers, dimers, and trimers that then reassemble into higher order oligomers and/or fibrils. Hybrid TTR (hTTR) tetramers are found in heterozygous individuals that express both wild type TTR (wt-TTR) and mutant TTR (mTTR) forms of the protein, and these states display increased rates of amyloidosis. Here we monitor subunit exchange (SUE) reactions involving homomeric and mixed tetramers using high resolution native mass spectrometry (nMS). Our results show evidence that differences in TTR primary structure alter tetramer stabilities, and hTTR products can form spontaneously by SUE reactions. In addition, we find that solution temperature has strong effects on TTR tetramer stabilities and formation of SUE products. Lower temperatures promote formation of hTTR tetramers containing L55P and V30M subunits, whereas small effects on the formation of hTTR tetramers containing F87A and T119M subunits are observed. We hypothesize that the observed temperature dependent stabilities and subsequent SUE behavior are a result of perturbations to the network of "two kinds of water": hydrating and structure stabilizing water molecules (Spyrakis et al. J. Med. Chem. 2017, 60 (16), 6781-6827; Xu et al. Soft Matter 2012, 8, 324-336) that stabilize wt-TTR and mTTR tetramers. The results presented in this work illustrate the utility of high resolution nMS for studies of the structures, stabilities, and dynamics of protein complexes that directly influence SUE reactions.


Subject(s)
Prealbumin , Protein Multimerization , Water , Prealbumin/chemistry , Prealbumin/genetics , Prealbumin/metabolism , Water/chemistry , Humans , Protein Stability , Mutation , Mass Spectrometry/methods , Temperature , Models, Molecular
10.
Amyloid ; 31(3): 202-208, 2024 Sep.
Article in English | MEDLINE | ID: mdl-38946492

ABSTRACT

BACKGROUND: Genotyping and amyloid fibril detection in tissues are generally considered the diagnostic gold standard in transthyretin-related amyloidosis. Patients carry less stable TTR homotetramers prone to dissociation into non-native monomers, which rapidly self-assemble into oligomers and, ultimately, amyloid fibrils. Thus, the initial event of the amyloid cascade produces the smallest transthyretin species: the monomers. This creates engineering opportunities for diagnosis that remain unexplored. METHODS: We hypothesise that molecular sieving represents a promising method for isolating and concentrating trace TTR monomers from the tetramers present in plasma samples. Subsequently, immunodetection can be utilised to distinguish monomeric TTR from other low molecular weight proteins within the adsorbed fraction. A two-step assay was devised (ImmunoSieve assay), combining molecular sieving and immunodetection for sensing monomeric transthyretin. This assay was employed to analyse plasma microsamples from 10 individuals, including 5 pre-symptomatic carriers of TTR-V30M, the most prevalent amyloidosis-associated TTR variant worldwide, and 5 healthy controls. RESULTS: The ImmunoSieve assay enable sensitive detection of monomeric transthyretin in plasma microsamples. Moreover, the circulating monomeric TTR levels were significantly higher in carriers of amyloidogenic TTR mutation. CONCLUSIONS: Monomeric TTR can function as a biomarker for evaluating disease progression and assessing responses to therapies targeted at stabilising native TTR.


Subject(s)
Amyloid Neuropathies, Familial , Biomarkers , Prealbumin , Humans , Prealbumin/genetics , Prealbumin/metabolism , Amyloid Neuropathies, Familial/blood , Amyloid Neuropathies, Familial/genetics , Amyloid Neuropathies, Familial/diagnosis , Biomarkers/blood , Male , Female , Amyloid/blood , Amyloid/metabolism , Amyloid/genetics , Mutation
11.
Amyloid ; 31(3): 226-231, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39018203

ABSTRACT

AIMS: Transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressive disease that causes heart failure due to amyloid fibril deposition. Tafamidis was approved as the first causal treatment in 2020. We here report on real-world data in patients treated with tafamidis for at least 12 months according to the recently defined European Society for Cardiology (ESC) consensus criteria for disease progression. METHODS AND RESULTS: Three hundred and eight wildtype and 31 hereditary ATTR-CM patients were prospectively enrolled after first diagnosis of ATTR-CM and initiation of tafamidis 61 mg once daily treatment. After 12 months, significant deterioration in Karnofsky Index, estimated glomerular filtration rate (eGFR), N-terminal brain natriuretic peptide (NT-proBNP), septum thickness and left ventricular ejection fraction (LVEF) could be observed, significant disease progression was only detected in 25 patients (9%) using ESC consensus criteria. Mean survival time was 37 months with no differences between responders and non-responders. NT-proBNP was the only independent predictor for poor therapy response (p = .008). CONCLUSIONS: The majority of patients showed no significant disease progression according to the ESC consensus criteria after 12 months of therapy with tafamidis. However, at 12 months, treatment response based on the ESC consensus criteria was not associated with improved survival. Moreover, higher levels of NT-proBNP at diagnosis of ATTR-CM appears to predict poorer treatment response, confirming that timely initiation of therapy is advantageous.


Subject(s)
Amyloid Neuropathies, Familial , Benzoxazoles , Natriuretic Peptide, Brain , Humans , Amyloid Neuropathies, Familial/drug therapy , Amyloid Neuropathies, Familial/genetics , Amyloid Neuropathies, Familial/blood , Amyloid Neuropathies, Familial/pathology , Male , Female , Aged , Benzoxazoles/therapeutic use , Natriuretic Peptide, Brain/blood , Middle Aged , Peptide Fragments/blood , Cardiomyopathies/drug therapy , Aged, 80 and over , Disease Progression , Prospective Studies , Glomerular Filtration Rate , Prealbumin/genetics , Prealbumin/metabolism
12.
Commun Biol ; 7(1): 905, 2024 Jul 27.
Article in English | MEDLINE | ID: mdl-39068302

ABSTRACT

ATTR amyloidosis results from the conversion of transthyretin into amyloid fibrils that deposit in tissues causing organ failure and death. This conversion is facilitated by mutations in ATTRv amyloidosis, or aging in ATTRwt amyloidosis. ATTRv amyloidosis exhibits extreme phenotypic variability, whereas ATTRwt amyloidosis presentation is consistent and predictable. Previously, we found unique structural variabilities in cardiac amyloid fibrils from polyneuropathic ATTRv-I84S patients. In contrast, cardiac fibrils from five genotypically different patients with cardiomyopathy or mixed phenotypes are structurally homogeneous. To understand fibril structure's impact on phenotype, it is necessary to study the fibrils from multiple patients sharing genotype and phenotype. Here we show the cryo-electron microscopy structures of fibrils extracted from four cardiomyopathic ATTRwt amyloidosis patients. Our study confirms that they share identical conformations with minimal structural variability, consistent with their homogenous clinical presentation. Our study contributes to the understanding of ATTR amyloidosis biopathology and calls for further studies.


Subject(s)
Amyloid , Cryoelectron Microscopy , Myocardium , Humans , Amyloid/metabolism , Amyloid/chemistry , Amyloid/ultrastructure , Myocardium/pathology , Myocardium/ultrastructure , Prealbumin/genetics , Prealbumin/metabolism , Prealbumin/chemistry , Amyloid Neuropathies, Familial/genetics , Amyloid Neuropathies, Familial/pathology , Male , Female , Middle Aged , Aged , Amyloidosis/metabolism , Amyloidosis/pathology , Amyloidosis/genetics , Mutation , Cardiomyopathies/genetics , Cardiomyopathies/pathology , Cardiomyopathies/metabolism
13.
Nat Commun ; 15(1): 6221, 2024 Jul 23.
Article in English | MEDLINE | ID: mdl-39043640

ABSTRACT

Transthyretin is a transport protein whose misfolding has been implicated in the development of cardiac amyloidosis. Here, we examine the clinical correlates of transthyretin levels, the differences in transthyretin levels according to the pathogenic V142I TTR variant carrier status, and the association of transthyretin levels with outcomes among 35,206 UK Biobank participants who underwent plasma profiling and were free from prevalent cardiovascular disease and chronic renal disease. Transthyretin levels are lower in females, decrease with increasing C-reactive protein levels, and increase with body mass index, systolic blood pressure, diastolic blood pressure, total cholesterol, albumin levels, triglyceride levels, and creatinine levels. V142I non-carriers [n = 35,167, mean: -0.1 (0.3)] have higher adjusted transthyretin levels compared with the carriers [n = 39, mean: -0.5 (0.3)] (p:<0.001). A standard deviation decrease in transthyretin levels increases the risk of heart failure [HRadj: 1.17 (95% Confidence Interval = 1.08-1.26)] and all-cause mortality [HRadj: 1.18 (95% Confidence Interval = 1.14-1.24)]. This study shows that individuals with low transthyretin levels, such as those carrying the V142I variant, are at a higher risk of heart failure and mortality.


Subject(s)
Biological Specimen Banks , Prealbumin , Humans , Female , Prealbumin/genetics , Prealbumin/metabolism , Male , United Kingdom/epidemiology , Middle Aged , Aged , Heart Failure/blood , Heart Failure/epidemiology , Heart Failure/mortality , C-Reactive Protein/metabolism , C-Reactive Protein/analysis , Adult , Blood Pressure , Body Mass Index , Risk Factors , UK Biobank
15.
J Mol Biol ; 436(16): 168673, 2024 Aug 15.
Article in English | MEDLINE | ID: mdl-38909653

ABSTRACT

The aggregation pathway of transthyretin (TTR) proceeds through rate-limiting dissociation of the tetramer (a dimer of dimers) and partial misfolding of the resulting monomer, which assembles into amyloid structures through a downhill polymerization mechanism. The structural features of the aggregation-prone monomeric intermediate are poorly understood. NMR relaxation dispersion offers a unique opportunity to characterize amyloidogenic intermediates when they exchange on favorable timescales with NMR-visible ground states. Here we use NMR to characterize the structure and conformational dynamics of the monomeric F87E mutant of human TTR. Chemical shifts derived from analysis of multinuclear relaxation dispersion data provide insights into the structure of a low-lying excited state that exchanges with the ground state of the F87E monomer at a rate of 3800 s-1. Disruption of the subunit interfaces of the TTR tetramer leads to destabilization of edge strands in both ß-sheets of the F87E monomer. Conformational fluctuations are propagated through the entire hydrogen bonding network of the DAGH ß-sheet, from the inner ß-strand H, which forms the strong dimer-dimer interface in the TTR tetramer, to outer strand D which is unfolded in TTR fibrils. Fluctuations are also propagated from the AB loop in the weak dimer-dimer interface to the EF helix, which undergoes structural remodeling in fibrils. The conformational fluctuations in both regions are enhanced at acidic pH where amyloid formation is most favorable. The relaxation dispersion data provide insights into the conformational dynamics of the amyloidogenic state of monomeric TTR that predispose it for structural remodeling and progression to amyloid fibrils.


Subject(s)
Amyloid , Prealbumin , Protein Conformation , Prealbumin/chemistry , Prealbumin/metabolism , Prealbumin/genetics , Humans , Amyloid/chemistry , Amyloid/metabolism , Protein Multimerization , Models, Molecular , Hydrogen Bonding , Mutation , Nuclear Magnetic Resonance, Biomolecular
17.
Ann Neurol ; 96(3): 423-440, 2024 Sep.
Article in English | MEDLINE | ID: mdl-38923548

ABSTRACT

Amyloid neuropathy is caused by deposition of insoluble ß-pleated amyloid sheets in the peripheral nervous system. It is most common in: (1) light-chain amyloidosis, a clonal non-proliferative plasma cell disorder in which fragments of immunoglobulin, light or heavy chain, deposit in tissues, and (2) hereditary transthyretin (ATTRv) amyloidosis, a disorder caused by autosomal dominant mutations in the TTR gene resulting in mutated protein that has a higher tendency to misfold. Amyloid fibrils deposit in the endoneurium of peripheral nerves, often extensive in the dorsal root ganglia and sympathetic ganglia, leading to atrophy of Schwann cells in proximity to amyloid fibrils and blood-nerve barrier disruption. Clinically, amyloid neuropathy is manifested as a length-dependent sensory predominant neuropathy associated with generalized autonomic failure. Small unmyelinated nerves are involved early and prominently in early-onset Val30Met ATTRv, whereas other ATTRv and light-chain amyloidosis often present with large- and small-fiber involvement. Nerve conduction studies, quantitative sudomotor axon testing, and intraepidermal nerve fiber density are useful tools to evaluate denervation. Amyloid deposition can be demonstrated by tissue biopsy of the affected organ or surrogate site, as well as bone-avid radiotracer cardiac imaging. Treatment of light-chain amyloidosis has been revolutionized by monoclonal antibodies and stem cell transplantation with improved 5-year survival up to 77%. Novel gene therapy and transthyretin stabilizers have revolutionized treatment of ATTRv, improving the course of neuropathy (less change in the modified Neuropathy Impairment Score + 7 from baseline) and quality of life. With great progress in amyloidosis therapies, early diagnosis and presymptomatic testing for ATTRv family members has become paramount. ANN NEUROL 2024;96:423-440.


Subject(s)
Amyloid Neuropathies, Familial , Amyloid Neuropathies , Humans , Amyloid Neuropathies, Familial/therapy , Amyloid Neuropathies, Familial/genetics , Amyloid Neuropathies, Familial/physiopathology , Amyloid Neuropathies/therapy , Amyloid Neuropathies/genetics , Immunoglobulin Light-chain Amyloidosis/therapy , Immunoglobulin Light-chain Amyloidosis/genetics , Immunoglobulin Light-chain Amyloidosis/physiopathology , Amyloidosis/therapy , Amyloidosis/genetics , Prealbumin/genetics
18.
J Biol Chem ; 300(8): 107495, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38925327

ABSTRACT

Transthyretin (TTR) is an homotetrameric protein involved in the transport of thyroxine. More than 150 different mutations have been described in the TTR gene, several of them associated with familial amyloid cardiomyopathy. Recently, our group described a new variant of TTR in Brazil, namely A39D-TTR, which causes a severe cardiac condition. Position 39 is in the AB loop, a region of the protein that is located within the thyroxine-binding channels and is involved in tetramer formation. In the present study, we solved the structure and characterize the thermodynamic stability of this new variant of TTR using urea and high hydrostatic pressure. Interestingly, during the process of purification, A39D-TTR turned out to be a dimer and not a tetramer, a variation that might be explained by the close contact of the four aspartic acids at position 39, where they face each other inside the thyroxine channel. In the presence of subdenaturing concentrations of urea, bis-ANS binding and dynamic light scattering revealed A39D-TTR in the form of a molten-globule dimer. Co-expression of A39D and WT isoforms in the same bacterial cell did not produce heterodimers or heterotetramers, suggesting that somehow a negative charge at the AB loop precludes tetramer formation. A39D-TTR proved to be highly amyloidogenic, even at mildly acidic pH values where WT-TTR does not aggregate. Interestingly, despite being a dimer, aggregation of A39D-TTR was inhibited by diclofenac, which binds to the thyroxine channel in the tetramer, suggesting the existence of other pockets in A39D-TTR able to accommodate this molecule.


Subject(s)
Cardiomyopathies , Prealbumin , Protein Multimerization , Thermodynamics , Prealbumin/genetics , Prealbumin/chemistry , Prealbumin/metabolism , Humans , Cardiomyopathies/metabolism , Cardiomyopathies/genetics , Thyroxine/metabolism , Thyroxine/chemistry , Mutation, Missense , Amyloid/metabolism , Amyloid/chemistry , Amyloid/genetics , Amino Acid Substitution , Urea/chemistry , Urea/metabolism
19.
J Neurol ; 271(9): 5746-5761, 2024 Sep.
Article in English | MEDLINE | ID: mdl-38907862

ABSTRACT

Hereditary transthyretin-related amyloidosis (ATTRv amyloidosis) is a rare and progressively debilitating disease characterized by the deposition of transthyretin (TTR) amyloid fibrils in various organs and tissues, most commonly in the heart and peripheral nerves. This pathological deposition can lead to significant organ dysfunction and, ultimately, organ failure. ATTRv amyloidosis exhibits a broad range of clinical presentations, from purely neurological symptoms to purely cardiac manifestations, as well as mixed phenotypes which result from both neurological and cardiac implications. This wide phenotypical spectrum realistically challenges disease diagnosis and prognosis, especially in individuals without or with an unknown family history. Multiple factors are thought to contribute to this variability, including genetic, epigenetic, and even environmental influences. Understanding these factors is crucial, as they can significantly affect disease expression and progression. This review aims to summarize each of these contributing factors, to help elucidate the current knowledge on the phenotypical variability of ATTRv amyloidosis.


Subject(s)
Amyloid Neuropathies, Familial , Phenotype , Humans , Amyloid Neuropathies, Familial/genetics , Prealbumin/genetics
20.
Medicine (Baltimore) ; 103(26): e38767, 2024 Jun 28.
Article in English | MEDLINE | ID: mdl-38941378

ABSTRACT

Hereditary transthyretin-mediated amyloidosis (ATTRv amyloidosis), known as Corino de Andrade disease, is a rare neurodegenerative disorder with a significant global impact characterized by the misfolding of transthyretin (TTR) protein leading to amyloid aggregation, ATTRv amyloidosis, especially with polyneuropathy, poses a considerable challenge in managing its rapid progression and debilitating effects. This mini-review focuses on the recent advancements in the treatment landscape for ATTRv amyloidosis with polyneuropathy, specifically the RNA interference therapeutic Vutrisiran and the ligand-conjugated antisense oligonucleotide Eplontersen. We aim to provide a comprehensive overview of the mechanisms, current evidence from clinical trials, and future directions for these novel therapeutic agents. Vutrisiran and Eplontersen have demonstrated significant clinical efficacy in improving neuropathic impairment, quality of life, and serum TTR levels in various trials. The distinct mechanistic approaches of these therapies, coupled with their acceptable safety profiles, offer promising avenues for addressing the complexities of ATTRv amyloidosis with polyneuropathy. The introduction of Vutrisiran and Eplontersen marks a pivotal moment in the quest for effective therapies against ATTRv amyloidosis with polyneuropathy. While clinical evidence is promising, ongoing research is crucial to deepen mechanistic understanding and address research gaps. Future perspectives include the potential expansion of therapeutic options and a more inclusive approach to cater to the diverse needs of individuals globally. This mini-review provides valuable insights into the evolving landscape of ATTRv amyloidosis management and sets the stage for further exploration in this challenging domain.


Subject(s)
Amyloid Neuropathies, Familial , Polyneuropathies , Humans , Amyloid Neuropathies, Familial/genetics , Amyloid Neuropathies, Familial/therapy , Polyneuropathies/genetics , Oligonucleotides/therapeutic use , Oligonucleotides, Antisense/therapeutic use , Prealbumin/genetics , Quality of Life
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