Identification of Giant Isoforms of Obscurin in Rat Striated Muscles Using Polyclonal Antibodies.

Using produced polyclonal antibodies specific to the N-terminal sequence (residues 61-298) of rat obscurin, we investigated the isoform composition of this protein in 4 striated muscles: myocardium of the left ventricle, diaphragm, skeletal m. gastrocnemius (containing mainly fast fibers), and m. soleus (containing mainly slow fibers).

The effect of apolipoprotein A-I and perfluorocarbon emulsion on the production of specific antibodies in mice.

Adjuvants are often required to improve the potentially low immunogenicity of vaccines. In this study, it is proposed to use an emulsion based on fluorocarbons as an adjuvant. Since this emulsion adsorbs only a small range of proteins, apolipoprotein A-I (ApoAI) was used as an anchor.

Inhibition of Histone Deacetylases 4 and 5 Reduces Titin Proteolysis and Prevents Reduction of TTN Gene Expression in Atrophied Rat Soleus Muscle after Seven-Day Hindlimb Unloading.

The effect of HDACs 4 and 5 on the level of atrophy, calpain-1 and titin content, and TTN gene expression in rat soleus after 7-day gravitational unloading (hindlimb suspension model) was studied. The development of atrophic changes induced by gravitational unloading in rat soleus was accompanied by an increase in the calpain-1 content, an increase in titin proteolysis, and a decrease in the mRNA content of the protein. Inhibition of HDACs 4 and 5 did not eliminate the development of unloading-induced atrophy but significantly prevented proteolysis of titin and the decrease in the TTN gene expression.

Predominant synthesis of giant myofibrillar proteins in striated muscles of the long-tailed ground squirrel Urocitellus undulatus during interbout arousal.

Molecular mechanisms underlying muscle-mass retention during hibernation have been extensively discussed in recent years. This work tested the assumption that protein synthesis hyperactivation during interbout arousal of the long-tailed ground squirrel Urocitellus undulatus should be accompanied by increased calpain-1 activity in striated muscles. Calpain-1 is known to be autolysed and activated in parallel.

Inhibition of Histone Deacetylase 1 Prevents the Decrease in Titin (Connectin) Content and Development of Atrophy in Rat m. soleus after 3-Day Hindlimb Unloading.

We studied the effect of histone deacetylase 1 (HDAC1) inhibition on titin content and expression of TTN gene in rat m. soleus after 3-day gravitational unloading. Male Wistar rats weighing 210±10 g were randomly divided into 3 groups: control, 3-day hindlimb suspension, and 3-day hindlimb suspension and injection of HDAC1 inhibitor CI-994 (1 mg/kg/day).

Effect of L-Arginine on Titin Expression in Rat Soleus Muscle After Hindlimb Unloading.

Nitric oxide (NO), produced by NO-synthases via L-arginine oxidation, is an essential trigger for signaling processes involved in structural and metabolic changes in muscle fibers. Recently, it was shown that L-arginine administration prevented the decrease in levels of the muscle cytoskeletal proteins, desmin and dystrophin, in rat soleus muscle after 14 days of hindlimb unloading. Therefore, in this study, we investigated the effect of L-arginine administration on the degree of atrophy changes in the rat soleus muscles under unloading conditions, and on the content, gene expression, and phosphorylation level of titin, the giant protein of striated muscles, able to form a third type of myofilaments-elastic filaments.

[Differences in Titin and Nebulin Gene Expression in Skeletal Muscles of Rats Chronically Alcoholized by Different Methods].

This work studied the changes in the levels of the main proteins of the calpain system (μ-calpain, Ca^(2+)-dependent protease, and fragments of its autolysis, inhibitor calpastatin) and μ-calpain substrates (giant proteins of the sarcomere cytoskeleton, titin and nebulin) in skeletal muscle (m. gastrocnemius, m. soleus, m.

Increased Autolysis of μ-Calpain in Skeletal Muscles of Chronic Alcohol-Fed Rats.

Background: Proteolysis can proceed via several distinct pathways such as the lysosomal, calcium-dependent, and ubiquitin-proteasome-dependent pathways. Calpains are the main proteases that cleave a large variety of proteins, including the giant sarcomeric proteins, titin and nebulin. Chronic ethanol feeding for 6 weeks did not affect the activities of μ-calpain and m-calpain in the m.

Chronic Alcohol Intoxication Is Not Accompanied by an Increase in Calpain Proteolytic Activity in Cardiac Muscle of Rats.

Enzymatic activity of Ca2+-dependent calpain proteases as well as the content and gene expression of μ-calpain (activated by micromolar calcium ion concentrations), calpastatin (inhibitor of calpains), and titin (substrate for calpains) were investigated in cardiac muscles of rats subjected to chronic alcoholization for 3 and 6 months. There was no increase in the "heart weight/body weight" parameter indicating development of heart hypertrophy in the alcoholized rats, while a decreasing trend was observed for this parameter in the rats after 6-month modeling of alcoholic cardiomyopathy, which indicated development of atrophic changes in the myocardium. Fluorometric measurements conducted using the Calpain Activity Assay Kit did not reveal any changes in total calpain activity in protein extracts of cardiac muscles of the rats alcoholized for 3 and 6 months.

[On the Role of Titin Phosphorylation in Development of Muscular Atrophy].

From our earlier experiments on the study of changes in titin content and the level of its phosphorylation in skeletal muscles, atrophied during space flight, hibernation, and also because of the development of alcohol-induced lesions it has been suggested that an increase in the degree of titin phosphorylation results in increased proteolytic degradation of this protein, that contributes to the development of skeletal muscle atrophy.

Seasonal changes in isoform composition of giant proteins of thick and thin filaments and titin (connectin) phosphorylation level in striated muscles of bears (Ursidae, Mammalia).

Seasonal changes in the isoform composition of thick and thin filament proteins (titin, myosin heavy chains (MyHCs), nebulin), as well as in the phosphorylation level of titin in striated muscles of brown bear (Ursus arctos) and hibernating Himalayan black bear (Ursus thibetanus ussuricus) were studied. We found that the changes that lead to skeletal muscle atrophy in bears during hibernation are not accompanied by a decrease in the content of nebulin and intact titin-1 (T1) isoforms. However, a decrease (2.

Isoform composition and gene expression of thick and thin filament proteins in striated muscles of mice after 30-day space flight.

Changes in isoform composition, gene expression of titin and nebulin, and isoform composition of myosin heavy chains as well as changes in titin phosphorylation level in skeletal (m. gastrocnemius, m. tibialis anterior, and m.

Systematic analysis of tropomodulin/tropomyosin interactions uncovers fine-tuned binding specificity of intrinsically disordered proteins.

An intriguing regulatory mechanism is the ability of some proteins to recognize their binding partners in an isoform-specific manner. In this study we undertook a systematic analysis of the specificity of the tropomodulin (Tmod) interaction with tropomyosin (TM) to show that affinities of different Tmod isoforms to TM are isoform-dependent. Intrinsic disorder predictions, alignment of sequences, and circular dichroism were utilized to establish a structural basis for these isoform-specific interactions.