Search Results (3)

Tropomodulin (Tmod) is an actin-binding protein that interacts with tropomyosin and the actin filament at the pointed end. The influence of Tmod on the thin filament activation in the myocardium is not clear. We studied the interactions of Tmod1 and Tmod4 with the cardiac tropomyosin isoforms Tpm1.1 and Tpm1.2 using size-exclusion chromatography, a pull-down assay, and cross-linking with glutaraldehyde. We found that Tmod1 and Tmod4 form complexes with both Tpm1.1 and Tpm1.2, indicating durable interactions between these proteins. The effects of both Tmods on the actin–myosin interaction were studied using an in vitro motility assay. Tmod did not affect the sliding velocity of bare F-actin. Tmod1 slightly dose-dependently decreased the sliding velocity of F-actin–Tpm1.1 filaments and had no effect on the velocity of F-actin–Tpm1.2 filaments. With ventricular myosin, Tmod1 reduced the calcium sensitivity of the sliding velocity of thin filaments containing Tpm1.1 but did not affect it with filaments containing Tpm1.2. With atrial myosin, Tmod1 decreased the calcium sensitivity of the sliding velocities of thin filaments containing both Tpm1.1 and Tpm1.2. We can conclude that Tmod takes part in the regulation of actin–myosin interactions in the myocardium through interactions with Tpm. The effect of Tmod on the activation of thin filaments depends on the protein isoforms. Full article

The objective of the study was to evaluate the profile of serum autoantibodies and their diagnostic and pathogenetic significance in ovarian endometrioma (OEM) and deep infiltrative endometriosis (DIE). The study enrolled 74 patients with endometriosis (Group 1), including 53 patients with OEM (Subgroup 1a); 21 patients with DIE without ovarian lesions (Subgroup 1b); and 27 patients without endometriosis (Group 2). The diagnosis was confirmed by laparoscopic surgery and histologic examination of resected tissues. Antibodies (M, G) to tropomyosin 3 (TPM), tropomodulin 3 (TMOD), α-enolase (ENO), estradiol (E2), progesterone (PG), and human chorionic gonadotropin (hCG) were identified in blood serum using modified ELISA. In endometriosis, antibodies to endometrial antigens, hormones, and ENO were detected more often than antiphospholipid and antinuclear antibodies. Higher levels of IgM to TPM, hCG, E2, and PG and IgG to TMOD, ENO, E2, and hCG were found in Subgroup 1a compared to Group 2. IgM to TPM, hCG, E2, PG, and IgG to E2 and ENO had a high diagnostic value for OEM (AUC > 0.7), with antibodies to TPM having the highest sensitivity and specificity (73.6% and 81.5%). In Subgroup 1b, only the levels of IgM to TPM and hCG were higher than in Group 2. These antibodies had a high diagnostic value for DIE. Thus, endometriosis is associated with autoantibodies to endometrial antigens, α-enolase, steroid, and gonadotropic hormones. A wider spectrum of antibodies is detected in OEM than in DIE. These antibodies have a high diagnostic value for OEM and DIE and potential pathogenetic significance for endometriosis and associated infertility. Full article

Dendritic spines are actin-rich protrusions that receive a signal from the axon at the synapse. Remodeling of cytoskeletal actin is tightly connected to dendritic spine morphology-mediated synaptic plasticity of the neuron. Remodeling of cytoskeletal actin is required for the formation, development, maturation, and reorganization of dendritic spines. Actin filaments are highly dynamic structures with slow-growing/pointed and fast-growing/barbed ends. Very few studies have been conducted on the role of pointed-end binding proteins in the regulation of dendritic spine morphology. In this study, we evaluated the role played by tropomodulin 2 (Tmod2)—a brain-specific isoform, on the dendritic spine re-organization. Tmod2 regulates actin nucleation and polymerization by binding to the pointed end via actin and tropomyosin (Tpm) binding sites. We studied the effects of Tmod2 overexpression in primary hippocampal neurons on spine morphology using confocal microscopy and image analysis. Tmod2 overexpression decreased the spine number and increased spine length. Destroying Tpm-binding ability increased the number of shaft synapses and thin spine motility. Eliminating the actin-binding abilities of Tmod2 increased the number of mushroom spines. Tpm-mediated pointed-end binding decreased F-actin depolymerization, which may positively affect spine stabilization; the nucleation ability of Tmod2 appeared to increase shaft synapses. Full article