N. P. Kantserova

Proteases of the calpain family: Structure and functions

Results of studies presented in recent papers and personal data related to investigation of structure, classification, phylogeny of calcium-dependent peptidases or calpains have been analyzed. The most extensively studied functions of calpains in cell activity have been examined. Some not yet resolved questions concerned with the biological role of a great number of proteins of the calpain family have been defined.

Proteinases of the calpain family in water invertebrates and fishes

Activity of Ca2+-dependent proteinases, or calpains (EC 3.4.22.17), was estimated in a wide range of aquatic invertebrates (Oligochaeta, Hirudinea, Crustacea, Insecta, Gastropoda, Bivalvia) and vertebrates (Osteichthyes). Detected molecular properties of calpains from the tissues of different species allow the consideration of the complications of calpain structural organization and regulatory mechanisms in invertebrates and vertebrates from a comparative-evolutionary perspective. Certain conclusions can be drawn about changes in the functional role of this proteolytic system in cell metabolism.

Intracellular protein degradation in the development of the atlantic salmon Salmo salar L.

Through the example of the Atlantic salmon Salmo salar L. we provide here the quick details on the universal and specific features of the proteolytic apparatus in the skeletal muscles of fish. Among the numerous muscle tissue proteases, the most comprehensively studied are those which determine the protein degradation levels in the efficiently growing and developing muscles of the salmon juveniles and by this way regulate the protein accumulation rates in muscles and the overall growth processes in the organism, namely, the lysosomal cathepsins B and D and calcium-dependent proteases (calpains). We have detected the age-related differences in the activity of the intracellullar proteases in salmon muscles, which suggest the important role of the proteolysis regulation in growth and the specific role for the certain proteolytic enzymes. For example, we have obtained data indicating the negative correlation between the cathepsin D and calpains activity levels in muscle tissue and the weight gain rate in the salmon of different age groups. The detected positive correlation between the cathepsin B activity and the morphometric indices in juvenile fish is apparently indicative of the key role of this enzyme in the metabolism of proteins of the predominantly nonmyofibrillar nature.

Effect of copper and cadmium ions on heart function and calpain activity in blue mussel Mytilus edulis

The heart rate and calpain activity of blue mussels Mytilus edulis from the sublittoral zone, exposed to different levels of water-borne copper and cadmium, was investigated in a long-term experiment. The content of cadmium and copper in the blue mussel was determined using flame and graphite Atomic absorption spectroscopy. The observed concentrations ranged from 2.5 to 89.1 μg/g dry weight for cadmium and from 6.1 to 51.0 μg/g dry weight for copper in the control and highest concentration, respectively. Initially, increase in cardiac activity in response to copper and Cadmium exposure was observed under all pollutant concentrations (5–250 and 10–500 μg/L, respectively). The calpain-like activity in gills and hepatopancreas of the mussels treated with metals changed in dose- and time-dependent manner: from a sharp rise at the 250 μg/L concentration of copper on the first day to a significant decrease under the effect of Cadmium in the concentration of 500 μg/L on the third day of the experiment. These results suggest that: (i) heart rate oscillation may reflect active adaptation of blue mussels to contamination and (ii) animals have different sensitivity to copper and Cadmium according to the role of the metals in the mussels’ life activity.

Biochemical response of blue mussels Mytilus edulis L. from the white sea to rapid changes in ambient temperature

The effect of rapid changes in ambient temperature on the biochemical profile of the blue mussel, Mytilus edulis L., was studied under aquarian conditions. It was shown that modifications in the content of reserve and structural lipids and their fatty acids, activity of lysosomal enzymes (β-glycosidase, cathepsins B and D), cytosolic calcium-dependent proteases (calpains) and phase II enzymes of xenobiotic transformation (glutathione S-transferase) reflect a nonspecific compensatory response of bivalves to the stress-inducing effect of environmental factors and indicate a metabolic rearrangement which occurs in mussels within the first hours of temperature changes. High initial level of glutathione S-transferase activity in control mussels as well as elevation of glutathione concentration during experiment may promote favorable recovery of mussels from the hypometabolic state.

Modulation of Ca2+ dependent protease activity in fish and invertebrates by weak low-frequency magnetic fields

Results of experiments addressing the effects of weak low-frequency magnetic fields on intracellular Ca2+ dependent proteinases (calpains) from invertebrates and fish are discussed. Exposure of live animals to weak low-frequency magnetic fields with parameters chosen to induce the resonance of Ca2+ ions led to a significant decrease of calpain activity in the animals investigated. The physical factor studied also caused partial loss of activity in preparations of Ca2+ dependent proteinases obtained from invertebrates and fish. The phenomenon discovered is in accordance with the interference model of the effect of weak low-frequency magnetic fields on biological objects.

Degradation of skeletal muscle protein during growth and development of salmonid fish

Published data and the results of the authors’ own studies on the role of intracellular proteolytic enzymes and the metabolic and signaling processes regulated by these enzymes at certain stages of growth and development of salmonid fishes are analyzed in the present review. The major pathways of intracellular proteolysis relying on autophagy, proteasome activity, and calpain activity are considered, as well as the relative contribution of these pathways to proteolysis in skeletal muscle of the fish. Skeletal muscle accounts for more than half of the weight of the fish and undergoes the most significant changes due to the action of anabolic and catabolic signals. Special attention is paid to the intensity of protein degradation during the active growth period characterized by a high rate of protein synthesis and metabolism in fish, as well as to protein degradation during the reproductive period characterized by predomination of catabolic processes in contrast to the growth period. Skeletal muscle plays a unique role as a source of plastic and energy substrates in fish, and, therefore, the process of muscle protein degradation is regarded as a key mechanism for the regulation of growth intensity in juvenile salmon and for maintenance of viability and reproductive capacity of salmonid fish during the maturation of gametes, starvation, and migration related to spawning. The possibility of using a set of parameters of intracellular proteolysis to characterize the early development of salmonids is demonstrated in the review.

Correlation between the activity of intracellular Ca2+-dependent proteinase and the content of membrane lipid components in mussel, Mytilus edulis, upon accumulation of heavy metals

The correlation between the activity of calpains and the content of membrane lipid components in the organs of mussels, Mytilus edulis L., is shown in the aquarium experiment on studying the response of mussels to the action of copper and cadmium ions. This correlation is most likely explained by the effector activity of membrane lipid components (arachidonic acid and phosphatidylinositol) with respect to Ca2+-channels. Thus, the correlation between the membrane lipid composition and the functional activity of proteins, which is defined by the level of intracellular Ca2+, is found in the experiment.

Calcium-dependent proteinases of some invertebrates and fish

In comparative-evolutionary aspect, the experimental data are considered about activity, biochemical properties, and peculiarities of structural organization of proteins of the calpain family in some invertebrates and fish. Peculiarities of calpain-like proteins of invertebrates—the predecessors of calpains of higher animals are revealed. By the example of the studied taxa, there is traced complication of the structural organization and mechanisms of control of the calpain activities, which reflects stages of molecular evolution of the protein family.

Modulation of Ca2+-dependent proteolysis under the action of weak low-frequency magnetic fields

The study aimed to determine the molecular targets of magnetic fields in living objects. Timedependent effects of weak low-frequency magnetic fields tuned to the parametric resonance for calcium ions were studied on model organisms (fish, whelk). The dynamics of Ca2+-dependent proteinase activity under the exposure to magnetic fields with given parameters and minimal time of exposure in order to achieve inactivation of these proteinases was determined as well. As hyperactivation of Ca2+-dependent proteinases is a basis of degenerative pathology development, the therapeutic potential of weak low-frequency magnetic fields enabling the modulation of Ca2+-dependent proteinase activity is supported.