Phosphorylated cofilin-2 is more prone to oxidative modifications on Cys39 and favors amyloid fibril formation

Abstract

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 Na 2 S on ischemic injury.

DFT Simulation of the Water Molecule Interaction with the (00l) Surface of Montmorillonite

“…In the last two decades, smectites and, in general, clay minerals were employed as substrates for different and various fundamental and applied research involving biomolecules. For example, clays are able to condense, organize, and concentrate biomolecules of different kinds and sizes [15][16][17][18][19][20][21], and, if the clay substrates present both Brønsted and Lewis acid sites [22,23], they may also act as catalysts. Notwithstanding the important biotechnological applications of clay minerals, these types of studies are also of utmost interest in the field of prebiotic chemistry, i.e., in all the steps (selection, concentration, synthesis, and protection) that lead from the basic building blocks of life (amino acids, nucleotides, lipids) to functional macromolecules (peptides, RNA/DNA, membranes) and, eventually, to the first cell [24,25].…”

Computational and biochemical analyses reveal that cofilin-2 self assembles into amyloid-like structures and promotes the aggregation of other proteinaceous species: Pathogenic relevance to myopathies

“…The available literature suggests that cofilin-2, the muscle isoform of the ADF/cofilin family, is involved in the etiology of various pathological conditions, such as protein aggregate accumulations in cardiomyopathies [17]. Pignataro et al suggested that the phosphorylated cofilin-2 might form amyloid-like fibrillar structures, but only under pathophysiological conditions, such as oxidative distress [4]. However, the cofilin-2 amyloid formation under physiological conditions remains unexplored.…”

“…Previously, it was shown that phosphorylation of cofilin-2 promotes its aggregation under oxidative distress [4]. We asked whether the protein stability is affected by the phosphorylation of cofilin-2.…”

“…Despite highly identical sequences (~80% sequence identity) and similar affinities for G-actin and F-actin between the cofilins, cofilin-2 severs actin filaments more efficiently than cofilin-1 [2,3]. Moreover, cofilin-2 possesses only two cysteine residues, i.e., Cys-39 and Cys-80, while cofilin-1 has two additional cysteines at positions 139 and 147 [4]. Cofilin-2 has evolved its biochemical and cellular properties to regulate actin dynamics in sarcomeres [5].…”

“…Our recent finding revealed that cofilin-1 possesses an intrinsic propensity to form higher-order amyloidogenic fibrillar structures, and this amyloidogenesis is further aggravated by Cys-80 oxidation [20]. It has been divulged that the phosphorylated form of cofilin-2, under oxidative distress, forms fibrillar aggregates, which involves Cys-39 [4]. However, it is not yet clear whether cofilin-2 has an intrinsic property of amyloidogenesis under physiological conditions.…”