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Journal of Nanobiotechnology Oct 2017Due to their natural tendency to self-assemble, proteins and peptides are important components for organic nanotechnology. One particular class of peptides of recent...
BACKGROUND
Due to their natural tendency to self-assemble, proteins and peptides are important components for organic nanotechnology. One particular class of peptides of recent interest is those that form amyloid fibrils, as this self-assembly results in extremely strong, stable quasi-one-dimensional structures which can be used to organise a wide range of cargo species including proteins and oligonucleotides. However, assembly of peptides already conjugated to proteins is limited to cargo species that do not interfere sterically with the assembly process or misfold under the harsh conditions often used for assembly. Therefore, a general method is needed to conjugate proteins and other molecules to amyloid fibrils after the fibrils have self-assembled.
RESULTS
Here we have designed an amyloidogenic peptide based on the TTR105-115 fragment of transthyretin to form fibrils that display an alkyne functionality, important for bioorthogonal chemical reactions, on their surface. The fibrils were formed and reacted both with an azide-containing amino acid and with an azide-functionalised dye by the Huisgen cycloaddition, one of the class of "click" reactions. Mass spectrometry and total internal reflection fluorescence optical microscopy were used to show that peptides incorporated into the fibrils reacted with the azide while maintaining the structure of the fibril. These click-functionalised amyloid fibrils have a variety of potential uses in materials and as scaffolds for bionanotechnology.
DISCUSSION
Although previous studies have produced peptides that can both form amyloid fibrils and undergo "click"-type reactions, this is the first example of amyloid fibrils that can undergo such a reaction after they have been formed. Our approach has the advantage that self-assembly takes place before click functionalization rather than pre-functionalised building blocks self-assembling. Therefore, the molecules used to functionalise the fibril do not themselves have to be exposed to harsh, amyloid-forming conditions. This means that a wider range of proteins can be used as ligands in this process. For instance, the fibrils can be functionalised with a green fluorescent protein that retains its fluorescence after it is attached to the fibrils, whereas this protein loses its fluorescence if it is exposed to the conditions used for aggregation.
Topics: Alkynes; Amino Acid Sequence; Amyloid; Azides; Click Chemistry; Green Fluorescent Proteins; Nanotechnology; Peptides; Prealbumin
PubMed: 28985740
DOI: 10.1186/s12951-017-0300-7 -
Biochemistry Aug 2018β-Amyloid (Aβ) aggregation is causally linked to Alzheimer's disease. On the basis of in vitro and transgenic animal studies, transthyretin (TTR) is hypothesized to...
β-Amyloid (Aβ) aggregation is causally linked to Alzheimer's disease. On the basis of in vitro and transgenic animal studies, transthyretin (TTR) is hypothesized to provide neuroprotection against Aβ toxicity by binding to Aβ and inhibiting its aggregation. TTR is a homotetrameric protein that circulates in blood and cerebrospinal fluid; its normal physiological role is as a carrier for thyroxine and retinol-binding protein (RBP). RBP forms a complex with retinol, and the holoprotein (hRBP) binds with high affinity to TTR. In this study, the role of TTR ligands in TTR-mediated inhibition of Aβ aggregation was investigated. hRBP strongly reduced the ability of TTR to inhibit Aβ aggregation. The effect was not due to competition between Aβ and hRBP for binding to TTR, as Aβ bound equally well to TTR-hRBP complexes and TTR. hRBP is known to stabilize the TTR tetrameric structure. We show that Aβ partially destabilizes TTR and that hRBP counteracts this destabilization. Taken together, our results support a mechanism wherein TTR-mediated inhibition of Aβ aggregation requires not only TTR-Aβ binding but also destabilization of TTR quaternary structure.
Topics: Amyloid beta-Peptides; Humans; Ligands; Peptide Fragments; Prealbumin; Protein Binding; Protein Multimerization; Protein Structure, Quaternary; Retinol-Binding Proteins
PubMed: 30024734
DOI: 10.1021/acs.biochem.8b00517 -
PloS One 2022Serum prealbumin level is slightly higher, whereas albumin is lower in peritoneal dialysis (PD) than hemodialysis (HD) patients. It is unknown whether albumin to...
BACKGROUND
Serum prealbumin level is slightly higher, whereas albumin is lower in peritoneal dialysis (PD) than hemodialysis (HD) patients. It is unknown whether albumin to prealbumin ratio (APR) is associated with mortality risk among PD patients. This study aimed to evaluate the clinical implications of APR and its prediction value on long-term outcomes of PD patients.
METHODS
The study population were prevalent PD patients at a tertiary hospital. Based on APR, a total of 220 PD patients were divided into 3 groups: group 1: top tertile, median APR: 121.1; IQR:109.5-131.9 (n = 73, male: 37%; age: 59±13); group 2: middle tertile, median APR: 97.1; IQR 93.5-100.0 (n = 73, male:37%; age: 54±14), and group3: bottom tertile, median APR: 81.3; IQR:76.8-85.0 (n = 74, male:38%; 54±11). Patients were followed up for a maximum of 5 years. Outcome of interest was all-cause mortality.
RESULTS
Group 1 was characterized by older age, higher prevalence of diabetes, lower nPCR, higher Davies score and hs-CRP level. APR positively correlated to hs-CRP (β = 0.149, p = 0.045), but negatively correlated to nPCR (β = -0.161, p = 0.034). Hyperprealbuminemia, accounting for 0%, 23.3%, and 82.4% in groups 1,2, and 3, was associated with a lower risk for mortality (HR:0.41, 95%CI = 0.23-0.73). The cumulative survival is significantly lower in group 1 than the other two groups. By multivariable Cox regression, APR (HR:1.02; 95%CI:1.01-1.03) was found to be an independent predictor of long-term mortality.
CONCLUSION
PD patients with high APR are characterized by having more comorbidities and marked malnutrition-inflammation status, and are associated with long-term mortality, whereas hyperprealbuminemia and lower APR are favorable prognostic factors.
Topics: Adult; Aged; Humans; Male; Middle Aged; C-Reactive Protein; Kidney Failure, Chronic; Peritoneal Dialysis; Prealbumin; Prognosis; Renal Dialysis; Female
PubMed: 36346823
DOI: 10.1371/journal.pone.0276159 -
Journal of Molecular Biology Aug 2012Transthyretin (TTR) is one of the many proteins that are known to misfold and aggregate (i.e., undergo amyloidogenesis) in vivo. The process of TTR amyloidogenesis... (Review)
Review
Transthyretin (TTR) is one of the many proteins that are known to misfold and aggregate (i.e., undergo amyloidogenesis) in vivo. The process of TTR amyloidogenesis causes nervous system and/or heart pathology. While several of these maladies are associated with mutations that destabilize the native TTR quaternary and/or tertiary structure, wild-type TTR amyloidogenesis also leads to the degeneration of postmitotic tissue. Over the past 20 years, much has been learned about the factors that influence the propensity of TTR to aggregate. This biophysical information led to the development of a therapeutic strategy, termed "kinetic stabilization," to prevent TTR amyloidogenesis. This strategy afforded the drug tafamidis which was recently approved by the European Medicines Agency for the treatment of TTR familial amyloid polyneuropathy, the most common familial TTR amyloid disease. Tafamidis is the first and currently the only medication approved to treat TTR familial amyloid polyneuropathy. Here we review the biophysical basis for the kinetic stabilization strategy and the structure-based drug design effort that led to this first-in-class pharmacologic agent.
Topics: Amyloidosis; Animals; Drug Approval; Humans; Kinetics; Models, Molecular; Prealbumin; Protein Conformation
PubMed: 22244854
DOI: 10.1016/j.jmb.2011.12.060 -
Proceedings of the Japan Academy.... 2010The authors reviewed contribution of Kumamoto University group to the progress of the studies on transthyretin (TTR)-related familial amyloidotic polyneuropathy... (Review)
Review
The authors reviewed contribution of Kumamoto University group to the progress of the studies on transthyretin (TTR)-related familial amyloidotic polyneuropathy (TTR-related FAP) for 42 years (from 1967 to 2009). Andrade (1952) first described a large group of patients with FAP in Portugal and Araki et al. (1967) in second discovered similar FAP patients in Arao, Kumamoto, Japan. Owing to progress in biochemical and molecular genetic analyses, FAP is now believed to occur worldwide. As of today, reports of about 100 different points of single or two mutations, or a deletion in the transthyretin (TTR) gene, have been published. The authors' group has made pioneer works for study of FAP in the world. The focus on therapy in amylodosis will increase sharply as an impetus in near future, and successful treatments are expected.
Topics: Amyloid Neuropathies, Familial; Cities; Humans; Japan; Liver Transplantation; Prealbumin; Prognosis
PubMed: 20689228
DOI: 10.2183/pjab.86.694 -
Structural polymorphism of amyloid fibrils in ATTR amyloidosis revealed by cryo-electron microscopy.Nature Communications Jan 2024ATTR amyloidosis is caused by the deposition of transthyretin in the form of amyloid fibrils in virtually every organ of the body, including the heart. This systemic...
ATTR amyloidosis is caused by the deposition of transthyretin in the form of amyloid fibrils in virtually every organ of the body, including the heart. This systemic deposition leads to a phenotypic variability that has not been molecularly explained yet. In brain amyloid conditions, previous studies suggest an association between clinical phenotype and the molecular structures of their amyloid fibrils. Here we investigate whether there is such an association in ATTRv amyloidosis patients carrying the mutation I84S. Using cryo-electron microscopy, we determined the structures of cardiac fibrils extracted from three ATTR amyloidosis patients carrying the ATTRv-I84S mutation, associated with a consistent clinical phenotype. We found that in each ATTRv-I84S patient, the cardiac fibrils exhibited different local conformations, and these variations can co-exist within the same fibril. Our finding suggests that one amyloid disease may associate with multiple fibril structures in systemic amyloidoses, calling for further studies.
Topics: Humans; Amyloid; Amyloid Neuropathies, Familial; Cryoelectron Microscopy; Prealbumin; Heart; Brain Diseases
PubMed: 38233397
DOI: 10.1038/s41467-024-44820-3 -
Journal of Biochemistry Jul 1986We cloned a genomic DNA fragment which covers the entire sequence of the mouse prealbumin gene and then studied the structure. The coding regions are separated into four... (Comparative Study)
Comparative Study
We cloned a genomic DNA fragment which covers the entire sequence of the mouse prealbumin gene and then studied the structure. The coding regions are separated into four exons by three introns, and these numbers, the sizes of the exons and the relative sites of the exon-intron junctions are all in complete agreement with those determined for the human gene. The sequences of four exons can be aligned perfectly with that of the previously determined mouse prealbumin cDNA. In addition to the exon regions, we found two highly conserved DNA regions between the mouse and human prealbumin genes, one in the 5'-flanking region of the gene and the other in the 3' end region of the first intron. These DNA regions contain several consensus glucocorticoid receptor-binding site sequences, and the latter also contains an enhancer sequence present in the immunoglobulin kappa-chain joining-constant kappa intron. RNA hybridizing to the mouse prealbumin cDNA was detected in the extracts from liver, brain, and kidney, but was not detected in testes, spleen, or heart. Little change was caused in the level of prealbumin mRNA in the liver by administration of dexamethasone to mice.
Topics: Animals; Base Sequence; Cloning, Molecular; DNA; DNA Restriction Enzymes; Genes; Humans; Mice; Nucleic Acid Hybridization; Prealbumin; Species Specificity; Tissue Distribution
PubMed: 3020014
DOI: 10.1093/oxfordjournals.jbchem.a121705 -
Human Gene Therapy Nov 2022Transthyretin amyloidosis (ATTR) is a progressive and fatal disease caused by transthyretin (TTR) amyloid fibril accumulation in tissues, which disrupts organ function....
Transthyretin amyloidosis (ATTR) is a progressive and fatal disease caused by transthyretin (TTR) amyloid fibril accumulation in tissues, which disrupts organ function. As the TTR protein is primarily synthesized by the liver, liver transplantation can cure familial ATTR but is not an option for the predominant age-related wild-type ATTR. Approved treatment approaches include TTR stabilizers and an RNA-interference therapeutic, but these require regular re-administration. Gene editing could represent an effective one-time treatment. We evaluated adeno-associated virus (AAV) vector-delivered, gene-editing meganucleases to reduce TTR levels. We used engineered meganucleases targeting two different sites within the gene. AAV vectors expressing TTR meganuclease transgenes were first tested in immunodeficient mice expressing the human sequence delivered using an AAV vector and then against the endogenous gene in rhesus macaques. Following a dose of 3 × 10 genome copies per kilogram, we detected on-target editing efficiency of up to 45% insertions and deletions (indels) in the TTR genomic DNA locus and >80% indels in RNA, with a concomitant decrease in serum TTR levels of >95% in macaques. The significant reduction in serum TTR levels following gene editing indicates that this approach could be an effective treatment for ATTR.
Topics: Humans; Mice; Animals; Dependovirus; Macaca mulatta; Amyloid Neuropathies, Familial; Prealbumin; RNA
PubMed: 36375122
DOI: 10.1089/hum.2022.061 -
Journal of Neurochemistry Mar 2021The liver-derived, circulating transport protein transthyretin (TTR) is the cause of systemic hereditary (ATTRv) and wild-type (ATTRwt) amyloidosis. TTR stabilization...
The liver-derived, circulating transport protein transthyretin (TTR) is the cause of systemic hereditary (ATTRv) and wild-type (ATTRwt) amyloidosis. TTR stabilization and knockdown are approved therapies to mitigate the otherwise lethal disease course. To date, the variety in phenotypic penetrance is not fully understood. This systematic review summarizes the current literature on TTR pathophysiology with its therapeutic implications. Tetramer dissociation is the rate-limiting step of amyloidogenesis. Besides destabilizing TTR mutations, other genetic (RBP4, APCS, AR, ATX2, C1q, C3) and external (extracellular matrix, Schwann cell interaction) factors influence the type of onset and organ tropism. The approved small molecule tafamidis stabilizes the tetramer and significantly decelerates the clinical course. By sequence-specific mRNA knockdown, the approved small interfering RNA (siRNA) patisiran and antisense oligonucleotide (ASO) inotersen both significantly reduce plasma TTR levels and improve neuropathy and quality of life compared to placebo. With enhanced hepatic targeting capabilities, GalNac-conjugated siRNA and ASOs have recently entered phase III clinical trials. Bivalent TTR stabilizers occupy both binding groves in vitro, but have not been tested in trials so far. Tolcapone is another stabilizer with the potential to cross the blood-brain barrier, but its half-life is short and liver failure a potential side effect. Amyloid-directed antibodies and substances like doxycycline aim at reducing the amyloid load, however, none of the yet developed antibodies has successfully passed clinical trials. ATTR-amyloidosis has become a model disease for pathophysiology-based treatment. Further understanding of disease mechanisms will help to overcome the remaining limitations, including application burden, side effects, and blood-brain barrier permeability.
Topics: Amyloid; Amyloidosis, Familial; Animals; Gene Knockdown Techniques; Humans; Prealbumin
PubMed: 33155274
DOI: 10.1111/jnc.15233 -
Contrast Media & Molecular Imaging 2022The expression of TTR and apolipoprotein H (APOH) genes and their relationship with prognosis in patients with colorectal cancer (CRC) metastasis by using bioinformatics...
The expression of TTR and apolipoprotein H (APOH) genes and their relationship with prognosis in patients with colorectal cancer (CRC) metastasis by using bioinformatics analysis techniques are explored. The expression profiles of related genes in patients with CRC metastasis are retrieved from the Gene Expression Omnibus (GEO) database. The core genes transthyretin (TTR) and APOH are screened by constructing protein-protein interaction (PPI) network, and the corresponding patient data of 327 patients are extracted and included in the metastasis group. The TTR and APOH genes of 300 patients without CRC metastasis are screened and included in the control group. The relationship between the expression levels of TTR and APOH and the clinicopathological parameters of patients with CRC metastasis is analyzed. Kaplan-Meier survival curve is drawn to observe the influence of overexpression and low expression of TTR and APOH on the prognosis and survival of patients in the metastatic group. Receiver operating characteristic (ROC) curve is drawn to observe the prognostic efficacy of combined TTR and APOH detection in patients with CRC metastasis. The experimental results show that bioassay can confirm the close relationship between TTR, APOH, and patients with CRC metastasis. Regular detection of serum TTR and APOH expression can effectively assess the patient's condition and take measures to improve the prognosis of the patients.
Topics: Colorectal Neoplasms; Computational Biology; Gene Expression Regulation, Neoplastic; Humans; Prealbumin; Prognosis; beta 2-Glycoprotein I
PubMed: 36101808
DOI: 10.1155/2022/1121312