Inverse relationship between hSHBG affinity for testosterone and hSHBG concentration revealed by surface plasmon resonance

cited By 4International audienceA wide range of human sex hormone-binding globulin (hSHBG) affinity constants for testosterone (KAₕSHBG) has been reported in literature. To bring new insight on the KAₕSHBG value, we implemented a study of the molecular interactions occurring between testosterone and its plasma transport proteins by using surface plasmon resonance. The immobilization on the sensorchip of a testosterone derivative was performed by an oligoethylene glycol linker. For different plasmas with hSHBG concentrations, an assessment of the KAₕSHBG was obtained from a set of sensorgrams and curve-fitting these data. We observed that KAₕSHBG decreased, from at least two decades, when the plasma hSHBG concentration increased from 4.4 to 680 nmol/L. Our study shows a wide biological variability of KAₕSHBG that is related to the hSHBG concentration. These unexpected results may have a physiological significance and question the validity of current methods that are recommended for calculating free testosterone concentrations to evaluate androgen disorders in humans. © 2014 Elsevier Ireland Ltd

Multimodal imaging Gd-nanoparticles functionalized with Pittsburgh compound B or a nanobody for amyloid plaques targeting

International audienceGadolinium-based nanoparticles were functionalized with either the Pittsburgh compound B or a nanobody (B10AP) in order to create multimodal tools for an early diagnosis of amyloidoses.MATERIALS & METHODS:The ability of the functionalized nanoparticles to target amyloid fibrils made of β-amyloid peptide, amylin or Val30Met-mutated transthyretin formed in vitro or from pathological tissues was investigated by a range of spectroscopic and biophysics techniques including fluorescence microscopy.RESULTS:Nanoparticles functionalized by both probes efficiently interacted with the three types of amyloid fibrils, with KD values in 10 micromolar and 10 nanomolar range for, respectively, Pittsburgh compound B and B10AP nanoparticles. Moreover, they allowed the detection of amyloid deposits on pathological tissues.CONCLUSION:Such functionalized nanoparticles could represent promising flexible and multimodal imaging tools for the early diagnostic of amyloid diseases, in other words, Alzheimer's disease, Type 2 diabetes mellitus and the familial amyloidotic polyneuropathy

Imaging of Dysfunctional Elastogenesis in Atherosclerosis Using an Improved Gadolinium-Based Tetrameric MRI Probe Targeted to Tropoelastin

[Image: see text] Dysfunctional elastin turnover plays a major role in the progression of atherosclerotic plaques. Failure of tropoelastin cross-linking into mature elastin leads to the accumulation of tropoelastin within the growing plaque, increasing its instability. Here we present Gd(4)-TESMA, an MRI contrast agent specifically designed for molecular imaging of tropoelastin within plaques. Gd(4)-TESMA is a tetrameric probe composed of a tropoelastin-binding peptide (the VVGS-peptide) conjugated with four Gd(III)-DOTA-monoamide chelates. It shows a relaxivity per molecule of 34.0 ± 0.8 mM(–1) s(–1) (20 MHz, 298 K, pH 7.2), a good binding affinity to tropoelastin (K(D) = 41 ± 12 μM), and a serum half-life longer than 2 h. Gd(4)-TESMA accumulates specifically in atherosclerotic plaques in the ApoE(–/–) murine model of plaque progression, with 2 h persistence of contrast enhancement. As compared to the monomeric counterpart (Gd-TESMA), the tetrameric Gd(4)-TESMA probe shows a clear advantage regarding both sensitivity and imaging time window, allowing for a better characterization of atherosclerotic plaques

Synthesis and characterization of multimodal Gd-Nanoparticles vectorized for Amyloidosis diagnosis, and their affinity evaluation using Biacore.

International audienceAmyloidosis is a systemic disorder in which proteins form insoluble aggregates (or fibrils) in extracellular tissues. Depending of the protein nature and its deposition area, this accumulation could lead to different pathologies. In this project, we focus on three kind of amyloidosis forms: i) Amyloid Aβ, ii) Islet Amyloid PolyPeptide IAPP, iii) Transthyretin TTR, which are respectively responsible of Alzheimer Disease, type II diabetes and finely cardiomyopathy and polyneuropathy. We are investigating two different strategies to target the fibrils: i) Camelid heavy chain antibody fragment (or Nanobody)[1], ii) Peptides derived from the protein responsible of the aggregate

Synthesis and characterization of multimodal Gd-Nanoparticles vectorized for Amyloidosis diagnosis, and their affinity evaluation using Biacore.

International audienceAmyloidosis is a systemic disorder in which proteins form insoluble aggregates (or fibrils) in extracellular tissues. Depending of the protein nature and its deposition area, this accumulation could lead to different pathologies. In this project, we focus on three kind of amyloidosis forms: i) Amyloid Aβ, ii) Islet Amyloid PolyPeptide IAPP, iii) Transthyretin TTR, which are respectively responsible of Alzheimer Disease, type II diabetes and finely cardiomyopathy and polyneuropathy. We are investigating two different strategies to target the fibrils: i) Camelid heavy chain antibody fragment (or Nanobody)[1], ii) Peptides derived from the protein responsible of the aggregate

Radiolabeled dendritic probes as tools for high in vivo tumor targeting: application to melanoma

International audienceIn bioimaging, targeting allows refining the diagnosis by improving the sensitivity and especially the specificity for an earlier diagnosis. Two 111In-radiolabeled dendritic nanoprobes (DPs) (In-111-2, In-111-3) and their model counterparts (In-111-1, In-111-4) are designed and assessed for in vitro and in vivo tumor targeting efficiency in a murine melanoma models. Tumor uptake is correlated to dendrimer multivalency and reaches values as high as 12.7 +/- 1.6% ID g(-1) at 4 h post intravenous injection for In-111-3 vs. 1.5 +/- 0.5% ID g(-1) for the unfunctionalized DP, and over 11% ID g(-1) for any tumor weight whatsoever

Small Molecule Inhibitors of ERCC1-XPF Protein-Protein Interaction Synergize Alkylating Agents in Cancer Cells

International audienceThe benefit of cancer chemotherapy based on alkylating agents is limited because of the action of DNA repair enzymes, which mitigate the damage induced by these agents. The interaction between the proteins ERCC1 and XPF involves two major components of the nucleotide excision repair pathway. Here, novel inhibitors of this interaction were identified by virtual screening based on available structures with use of the National Cancer Institute diversity set and a panel of DrugBank small molecules. Subsequently, experimental validation of the in silico screening was undertaken. Top hits were evaluated on A549 and HCT116 cancer cells. In particular, the compound labeled NSC 130813 [4-[(6-chloro-2-methoxy-9-acridinyl)amino]-2-[(4-methyl-1-piperazi nyl) methyl]] was shown to act synergistically with cisplatin and mitomycin C; to increase UVC-mediated cytotoxicity; to modify DNA repair as indicated by the staining of phosphorylated H2AX; and to disrupt interaction between ERCC1 and XPF in cells. In addition, using the Biacore technique, we showed that this compound interacts with the domain of XPF responsible for interaction with ERCC1. This study shows that small molecules targeting the protein-protein interaction of ERCC1 and XPF can be developed to enhance the effects of alkylating agents on cancer cells

Gd-nanoparticles functionalization with specific peptides for ß-amyloid plaques targeting

Amyloidoses are characterized by the extracellular deposition of insoluble fibrillar proteinaceous aggregates highly organized into cross-β structure and referred to as amyloid fibrils. Nowadays, the diagnosis of these diseases remains tedious and involves multiple examinations while an early and accurate protein typing is crucial for the patients' treatment. Routinely used neuroimaging techniques such as magnetic resonance imaging (MRI) and positron emission tomography (PET) using Pittsburgh compound B, [11C]PIB, provide structural information and allow to assess the amyloid burden, respectively, but cannot discriminate between different amyloid deposits. Therefore, the availability of efficient multimodal imaging nanoparticles targeting specific amyloid fibrils would provide a minimally-invasive imaging tool useful for amyloidoses typing and early diagnosis. In the present study, we have functionalized gadolinium-based MRI nanoparticles (AGuIX) with peptides highly specific for Aβ amyloid fibrils, LPFFD and KLVFF. The capacity of such nanoparticles grafted with peptide to discriminate among different amyloid proteins, was tested with Aβ(1–42) fibrils and with mutated-(V30M) transthyretin (TTR) fibrils

Development of gadolinium based nanoparticles having an affinity towards melanin

International audienceSmall Rigid Platforms (SRPs) are sub-5 nanometre gadolinium based nanoparticles that have been developed for multimodal imaging and theranostic applications. They are composed of a polysiloxane network surrounded by gadolinium chelates. A covalent coupling with quinoxaline derivatives has been performed. Such derivatives have proven their affinity for melanin frequently expressed in primary melanoma cases. Three different quinoxaline derivatives have been synthesised and coupled to the nanoparticles. The affinity of the grafted nanoparticles for melanin has then been shown in vitro by surface plasmon resonance on a homemade melanin grafted gold chip