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Cofilins are small protein of the actin depolymerizing family. Actin polymerization/depolymerization is central to a number of critical cellular physiological tasks making cofilin a key protein for several physiological functions of the cell. Cofilin activity is mainly regulated by phosphorylation on serine residue 3 making this post-translational modification key to the regulation of myofilament integrity. In fact, in this form, the protein segregates in myocardial aggregates in human idiopathic dilated cardiomyopathy. Since myofilament network is an early target of oxidative stress we investigated the molecular changes induced by oxidation on cofilin isoforms and their interplay with the protein phosphorylation state to get insight on whether/how those changes may predispose to early protein aggregation. Using different and complementary approaches we characterized the aggregation properties of cofilin-2 and its phosphomimetic variant (S3D) in response to oxidative stress in silico, in vitro and on isolated cardiomyocytes. We found that the phosphorylated (inactive) form of cofilin-2 is mechanistically linked to the formation of an extended network of fibrillar structures induced by oxidative stress via the formation of a disulfide bond between Cys39 and Cys80. Such phosphorylation-dependent effect is likely controlled by changes in the hydrogen bonding network involving Cys39. We found that the sulfide ion inhibits the formation of such structures. This might represent the mechanism for the protective effect of the therapeutic agent Na2S on ischemic injury., Graphical abstract Image 1, Highlights • Cofilin changes the hydrogen bonding network involving Cys39 in its phosphorylated form. • This phosphorylation-dependent effect of oxidation promotes the formation of a disulfide bond between Cys39 and Cys80. • The formation of the Cys39 and Cys80 disulfide bond favors the formation of fibrillar aggregates. • The sulfide ion inhibits the formation of such structures.

The reported data are related to a research paper entitled "Phosphorylated cofilin-2 is more prone to oxidative modifications on Cys39 and favors amyloid fibril formation" [1] . Info about the formation and redox properties of the disulfide bridge of a protein is quite difficult to obtain and only in a few cases was it possible to observe a cyclic voltammetry (CV) signal [ 2 , 3 ]. Human cofilin-2 contains two cysteines (Cys39 and Cys80) which can be oxidized in suitable conditions and form a disulfide bridge [1] . For this purpose, CV measurements were carried out on human cofilin-2 WT and its mutant S3D immobilized on a gold electrode coated by an anionic self-assembled monolayer (SAM), after a pre-oxidation time which was fundamental for observing a CV signal relating to the oxidation/reduction process of the disulfide bridge of the proteins. The data include CV curves obtained with and without electrochemical pre-oxidation and after oxidation with H2O2. In addition, the plot of the cathodic peak current vs. electrochemical pre-oxidation time and the pH dependence of the formal potential (E°’) are reported. The data obtained by CV measurements were used to determine the time required to form the disulfide bridge for the immobilized proteins and, consequently, to observe the CV signal, to calculate the E°’ values and analyse the pH dependence of E°’. The electrochemical data were provided which will be useful for further electrochemical investigations regarding proteins bearing disulfide bridge(s) or cysteines prone to oxidation.

Background Recently, tangles and plaque-like aggregates have been identified in certain cases of dilated cardiomyopathy (DCM), traditionally labeled idiopathic (iDCM), where there is no specific diagnostic test or targeted therapy. This suggests a potential underlying cause for some of the iDCM cases. Objectives This study sought to identify the make-up of myocardial aggregates to understand the molecular mechanisms of these cases of DCM; this strategy has been central to understanding Alzheimer’s disease. Methods Aggregates were extracted from human iDCM samples with high congophilic reactivity (an indication of plaque presence), and the findings were validated in a larger cohort of samples. We tested the expression, distribution, and activity of cofilin in human tissue and generated a cardiac-specific knockout mouse model to investigate the functional impact of the human findings. We also modeled cofilin inactivity in vitro by using pharmacological and genetic gain- and loss-of-function approaches. Results Aggregates in human myocardium were enriched for cofilin-2, an actin-depolymerizing protein known to participate in neurodegenerative diseases and nemaline myopathy. Cofilin-2 was predominantly phosphorylated, rendering it inactive. Cardiac-specific haploinsufficiency of cofilin-2 in mice recapitulated the human disease’s morphological, functional, and structural phenotype. Pharmacological stimulation of cofilin-2 phosphorylation and genetic overexpression of the phosphomimetic protein promoted the accumulation of “stress-like” fibers and severely impaired cardiomyocyte contractility. Conclusions Our study provides the first biochemical characterization of prefibrillar myocardial aggregates in humans and the first report to link cofilin-2 to cardiomyopathy. The findings suggest a common pathogenetic mechanism connecting certain iDCMs and other chronic degenerative diseases, laying the groundwork for new therapeutic strategies.

Previously uncharacterized poly(N-isopropylacrylamide-acrylamide-allylamine)-coated magnetic nanoparticles (MNPs) were synthesized using silane-coated MNPs as a template for radical polymerization of N-isopropylacrylamide, acrylamide, and allylamine. Properties of these nanoparticles such as size, biocompatibility, drug loading efficiency, and drug release kinetics were evaluated in vitro for targeted and controlled drug delivery. Spherical core-shell nanoparticles with a diameter of 100 nm showed significantly lower systemic toxicity than did bare MNPs, as well as doxorubicin encapsulation efficiency of 72%, and significantly higher doxorubicin release at 41°C compared with 37°C, demonstrating their temperature sensitivity. Released drugs were also active in destroying prostate cancer cells (JHU31). Furthermore, the nanoparticle uptake by JHU31 cells was dependent on dose and incubation time, reaching saturation at 500 μg/mL and 4 hours, respectively. In addition, magnetic resonance imaging capabilities of the particles were observed using agarose platforms containing cells incubated with nanoparticles. Future work includes investigation of targeting capability and effectiveness of these nanoparticles in vivo using animal models.In this paper, previously uncharacterized magnetic nanoparticles were synthesized using silane-coated MNPs as a template for radical polymerization of N-isopropylacrylamide, acrylamide, and allylamine. Various properties of these nanoparticles were evaluated in vitro for targeted drug delivery.

Background Recently, tangles and plaque-like aggregates have been identified in certain cases of dilated cardiomyopathy (DCM). This suggests a potential underlying cause for the one-third of cases, traditionally labeled idiopathic (iDCM), where there is no specific diagnostic test or targeted therapy. Objectives This study sought to identify the make-up of myocardial aggregates to understand the molecular mechanisms of these cases of DCM; this strategy has been central to understanding Alzheimer's disease. Methods Aggregates were extracted from human iDCM samples with high congophilic reactivity (an indication of plaque presence), and the findings were validated in a larger cohort of samples. We tested the expression, distribution, and activity of cofilin in human tissue and generated a cardiac-specific knockout mouse model to investigate the functional impact of the human findings. We also modeled cofilin inactivity in vitro by using pharmacological and genetic gain- and loss-of-function approaches. Results Aggregates in human myocardium were enriched for cofilin-2, an actin-depolymerizing protein known to participate in neurodegenerative diseases and nemaline myopathy. Cofilin-2 was predominantly phosphorylated, rendering it inactive. Cardiac-specific haploinsufficiency of cofilin-2 in mice recapitulated the human disease's morphological, functional, and structural phenotype. Pharmacological stimulation of cofilin-2 phosphorylation and genetic overexpression of the phosphomimetic protein promoted the accumulation of "stress-like" fibers and severely impaired cardiomyocyte contractility. Conclusions Our study provides the first biochemical characterization of prefibrillar myocardial aggregates in humans and the first report to link cofilin-2 to cardiomyopathy. The findings suggest a common pathogenetic mechanism connecting certain iDCMs and other chronic degenerative diseases, laying the groundwork for new therapeutic strategies. © 2015 American College of Cardiology Foundation.