Plasma and cellular fibronectin: distinct and independent functions during tissue repair

Fibronectin (FN) is a ubiquitous extracellular matrix (ECM) glycoprotein that plays vital roles during tissue repair. The plasma form of FN circulates in the blood, and upon tissue injury, is incorporated into fibrin clots to exert effects on platelet function and to mediate hemostasis. Cellular FN is then synthesized and assembled by cells as they migrate into the clot to reconstitute damaged tissue. The assembly of FN into a complex three-dimensional matrix during physiological repair plays a key role not only as a structural scaffold, but also as a regulator of cell function during this stage of tissue repair. FN fibrillogenesis is a complex, stepwise process that is strictly regulated by a multitude of factors. During fibrosis, there is excessive deposition of ECM, of which FN is one of the major components. Aberrant FN-matrix assembly is a major contributing factor to the switch from normal tissue repair to misregulated fibrosis. Understanding the mechanisms involved in FN assembly and how these interplay with cellular, fibrotic and immune responses may reveal targets for the future development of therapies to regulate aberrant tissue-repair processes

Homocysteine-induced cardiomyocyte apoptosis and plasma membrane flip-flop are independent of S-adenosylhomocysteine: a crucial role for nuclear p47(phox).

Item does not contain fulltextWe previously found that homocysteine (Hcy) induced plasma membrane flip-flop, apoptosis, and necrosis in cardiomyocytes. Inactivation of flippase by Hcy induced membrane flip-flop, while apoptosis was induced via a NOX2-dependent mechanism. It has been suggested that S-adenosylhomocysteine (SAH) is the main causative factor in hyperhomocysteinemia (HHC)-induced pathogenesis of cardiovascular disease. Therefore, we evaluated whether the observed cytotoxic effect of Hcy in cardiomyocytes is SAH dependent. Rat cardiomyoblasts (H9c2 cells) were treated under different conditions: (1) non-treated control (1.5 nM intracellular SAH with 2.8 muM extracellular L -Hcy), (2) incubation with 50 muM adenosine-2,3-dialdehyde (ADA resulting in 83.5 nM intracellular SAH, and 1.6 muM extracellular L -Hcy), (3) incubation with 2.5 mM D, L -Hcy (resulting in 68 nM intracellular SAH and 1513 muM extracellular L -Hcy) with or without 10 muM reactive oxygen species (ROS)-inhibitor apocynin, and (4) incubation with 100 nM, 10 muM, and 100 muM SAH. We then determined the effect on annexin V/propodium iodide positivity, flippase activity, caspase-3 activity, intracellular NOX2 and p47(phox) expression and localization, and nuclear ROS production. In contrast to Hcy, ADA did not induce apoptosis, necrosis, or membrane flip-flop. Remarkably, both ADA and Hcy induced a significant increase in nuclear NOX2 expression. However, in contrast to ADA, Hcy additionally induced nuclear p47(phox) expression, increased nuclear ROS production, and inactivated flippase. Incubation with SAH did not have an effect on cell viability, nor on flippase activity, nor on nuclear NOX2-, p47phox expression or nuclear ROS production. HHC-induced membrane flip-flop and apoptosis in cardiomyocytes is due to increased Hcy levels and not primarily related to increased intracellular SAH, which plays a crucial role in nuclear p47(phox) translocation and subsequent ROS production.1 december 201

Formin Homology 2 Domain Containing 3 (FHOD3) Is a Genetic Basis for Hypertrophic Cardiomyopathy

BACKGROUND: The genetic cause of hypertrophic cardiomyopathy remains unexplained in a substantial proportion of cases. Formin homology 2 domain containing 3 (FHOD3) may have a role in the pathogenesis of cardiac hypertrophy but has not been implicated in hypertrophic cardiomyopathy. OBJECTIVES: This study sought to investigate the relation between FHOD3 mutations and the development of hypertrophic cardiomyopathy. METHODS: FHOD3 was sequenced by massive parallel sequencing in 3,189 hypertrophic cardiomyopathy unrelated probands and 2,777 patients with no evidence of cardiomyopathy (disease control subjects). The authors evaluated protein-altering candidate variants in FHOD3 for cosegregation, clinical characteristics, and outcomes. RESULTS: The authors identified 94 candidate variants in 132 probands. The variants' frequencies were significantly higher in patients with hypertrophic cardiomyopathy (74 of 3,189 [2.32%]) than in disease control subjects (18 of 2,777 [0.65%]; p < 0.001) or in the gnomAD database (1,049 of 138,606 [0.76%]; p < 0.001). FHOD3 mutations cosegregated with hypertrophic cardiomyopathy in 17 families, with a combined logarithm of the odds score of 7.92, indicative of very strong segregation. One-half of the disease-causing variants were clustered in a small conserved coiled-coil domain (amino acids 622 to 655); odds ratio for hypertrophic cardiomyopathy was 21.8 versus disease control subjects (95% confidence interval: 1.3 to 37.9; p < 0.001) and 14.1 against gnomAD (95% confidence interval: 6.9 to 28.7; p < 0.001). Hypertrophic cardiomyopathy patients carrying (likely) pathogenic mutations in FHOD3 (n = 70) were diagnosed after age 30 years (mean 46.1 ± 18.7 years), and two-thirds (66%) were males. Of the patients, 82% had asymmetric septal hypertrophy (mean 18.8 ± 5 mm); left ventricular ejection fraction <50% was present in 14% and hypertrabeculation in 16%. Events were rare before age 30 years, with an annual cardiovascular death incidence of 1% during follow-up. CONCLUSIONS: FHOD3 is a novel disease gene in hypertrophic cardiomyopathy, accounting for approximately 1% to 2% of cases. The phenotype and the rate of cardiovascular events are similar to those reported in unselected cohorts. The FHOD3 gene should be routinely included in hypertrophic cardiomyopathy genetic testing panels

Cyclotides: Macrocyclic peptides with applications in drug design and agriculture

Cyclotides are disulfide-rich peptides from plants that are exceptionally stable as a result of their unique cyclic cystine knot structural motif. Their natural role is thought to be as plant defence agents, most notably against insect pests, but they also have potential applications in drug design and agriculture. This article identifies gaps in current knowledge on cyclotides and suggests future directions for research into this fascinating family of ultra-stable mini-proteins. © Springe