Imaging of Dysfunctional Elastogenesis in Atherosclerosis Using an Improved Gadolinium-Based Tetrameric MRI Probe Targeted to Tropoelastin.
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ABSTRACT:
SUBMITTER: Capuana F
PROVIDER: S-EPMC8558862 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Tropoelastin, as the monomer unit of elastin, assembles into elastic fibers that impart strength and resilience to elastic tissues. Tropoelastin is also widely used to manufacture versatile materials with specific mechanical and biological properties. The assembly of tropoelastin into elastic fibers or biomaterials is crucially influenced by key submolecular regions and specific residues within these domains. In this work, we identify the functional contributions of two rarely occurring negatively charged residues, glutamate 345 in domain 19 and glutamate 414 in domain 21, in jointly maintaining the native conformation of the tropoelastin hinge, bridge and foot regions. Alanine substitution of E345 and/or E414 variably alters the positioning and interactive accessibility of these regions, as illustrated by nanostructural studies and detected by antibody and cell probes. These structural changes are associated with a lower propensity for monomer coacervation, cross-linking into morphologically and functionally atypical hydrogels, and markedly impaired and abnormal elastic fiber formation. Our work indicates the crucial significance of both E345 and E414 residues in modulating specific local structure and higher-order assembly of human tropoelastin.
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Project description:AimsDysfunctional matrix turnover is present at sites of abdominal aortic aneurysm (AAA) and leads to the accumulation of monomeric tropoelastin rather than cross-linked elastin. We used a gadolinium-based tropoelastin-specific magnetic resonance contrast agent (Gd-TESMA) to test whether quantifying regional tropoelastin turnover correlates with aortic expansion in a murine model. The binding of Gd-TESMA to excised human AAA was also assessed.Methods and resultsWe utilized the angiotensin II (Ang II)-infused apolipoprotein E gene knockout (ApoE-/-) murine model of aortic dilation and performed in vivo imaging of tropoelastin by administering Gd-TESMA followed by late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) and T1 mapping at 3 T, with subsequent ex vivo validation. In a cross-sectional study (n = 66; control = 11, infused = 55) we found that Gd-TESMA enhanced MRI was elevated and confined to dilated aortic segments (control: LGE=0.13 ± 0.04 mm2, control R1= 1.1 ± 0.05 s-1 vs. dilated LGE =1.0 ± 0.4 mm2, dilated R1 =2.4 ± 0.9 s-1) and was greater in segments with medium (8.0 ± 3.8 mm3) and large (10.4 ± 4.1 mm3) compared to small (3.6 ± 2.1 mm3) vessel volume. Furthermore, a proof-of-principle longitudinal study (n = 19) using Gd-TESMA enhanced MRI demonstrated a greater proportion of tropoelastin: elastin expression in dilating compared to non-dilating aortas, which correlated with the rate of aortic expansion. Treatment with pravastatin and aspirin (n = 10) did not reduce tropoelastin turnover (0.87 ± 0.3 mm2 vs. 1.0 ± 0.44 mm2) or aortic dilation (4.86 ± 2.44 mm3 vs. 4.0 ± 3.6 mm3). Importantly, Gd-TESMA-enhanced MRI identified accumulation of tropoelastin in excised human aneurysmal tissue (n = 4), which was confirmed histologically.ConclusionTropoelastin MRI identifies dysfunctional matrix remodelling that is specifically expressed in regions of aortic aneurysm or dissection and correlates with the development and rate of aortic expansion. Thus, it may provide an additive imaging marker to the serial assessment of luminal diameter for surveillance of patients at risk of or with established aortopathy.
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Project description:This study aimed to model formamide-based melting for the optimization of the sensitivity and specifcity of oligonucleotide probes in dignostic high-density microarrays. Formamide melting profiles of DNA oligonucleotides were obtained with a high-density microarray targeting 16S rRNA genes of Escherichia coli and Rhodobacter sphaeroides. One or two mismatched versions of perfect match probes were included on the array to systematically analyze the effect of formamide on mismatch stability and mismatch discrimination. A thermodynamics-based mathematical model of formamide denaturation was developed to predict the formamide melting profiles with sufficient accuracy to help with oligonucleotide design in microbial ecology applications. 16S rRNA sequences with GenBank accession codes U00006 ( E. coli ) and X53853 (R. sphaeroides) were used for probe design. The following oligonucleotide probe sets were used for the systematic analysis of the effect of formamide on probe-target hybrids (parenthetic information gives set name followed by the number of probes): 22-mer perfect match probes tiling the 16S rRNA gene of E. coli (TileE, n=1521), perfect match E.coli probes of variable length between 18 and 26 mers (Length, n=1045), E. coli probes with central single mismatches (OneM, n=1563), E. coli probes with single positional mismatches (PosM, n=4092), E. coli probes with single deletion mismatches (Gap, n=248), E. coli probes with single insertion mismatches (Insertion, n=248), E. coli probes with two separate mismatches (TwoM, n=1674), E. coli probes with central tandem mismatches (Tandem, n=558), and 22-mer perfect match probes tiling the 16S rRNA gene of R. sphaeroides. Also, a probe with no match to 16S rRNA genes was used as a background control. On the array, regular probes were replicated three times and the Nonsense probe ten times. See the manuscript of Yilmaz et al. for details.
2012-06-29 | E-GEOD-33021 | biostudies-arrayexpress
Project description:This study aimed to model formamide-based melting for the optimization of the sensitivity and specifcity of oligonucleotide probes in dignostic high-density microarrays. Formamide melting profiles of DNA oligonucleotides were obtained with a high-density microarray targeting 16S rRNA genes of Escherichia coli and Rhodobacter sphaeroides. One or two mismatched versions of perfect match probes were included on the array to systematically analyze the effect of formamide on mismatch stability and mismatch discrimination. A thermodynamics-based mathematical model of formamide denaturation was developed to predict the formamide melting profiles with sufficient accuracy to help with oligonucleotide design in microbial ecology applications.
2012-06-30 | GSE33021 | GEO