ИСТИНА

The key role in the proteome homeostasis in eukaryotic cells plays the ubiquitin- proteasome system (UPS) which determines the adaptive plasticity of multicellular organisms. Marine invertebrates of intertidal zones, in particular, Sponges (Porifera) are the unique model for studying the molecular mechanisms of adaptation. The aim of this research is to clarify the role of the proteasome pathway in regulating cellular proteome under dissociation and reaggregation processes in the sea cold-water sponges Halichondria panacea and Halisarca dujardini (Demospongiae, Pallas, 1766). Proteasomes of marine cold-water Sponges have not previously ex- plored. Sampling was carried out in the Kandalaksha Bay of the White Sea (66 ° 34 ‘N, 33 ° 08’ E). It was first investigated the chymotrypsin-like (ChLA) and caspase–like (CLA) proteasome activities by the level of hydrolysis of fluorogenic oligopeptide Suc-LLVY-AMC and Z-LLG-AMC, respectively, and proteasome subunits in clarified homogenates of cells and tissues of sea cold-water sponges Halichondria panacea and Halisarca dujardini. The oligopeptide hydrolysis rate is determined at 10 C and 37C. The specificity of the reaction established in experiments with the proteasome inhibitor MG-132 and lactacystin. The increase of the temperature (from 10 to 37 ° C) resulted in an increase of ChL of Halisarca dujardini tissues by 3.5 times, and in Halichondria panacea by 2 times, while in the ChLA of Halisarca dujardini dissociated cells by 7 times higher than Halichondria panacea dissociated cells. Under dissociation of tissue in the sponge cells heat shock protein HSP70 content and proteasome subunit alpha type and beta 5 and proteasome ChL are reduced. We found that chaperone system is activated, as well as changes in the structure and activity of the protea- some occur in the cell reaggregation processes in the studied cold-water marine sponges. In the process of reaggregation the relative abundance of proteins HSP70 chaperones and proteasome subunit alpha type varies significantly only in the period of intensive transformations and / or differentiation / dedifferentiation of cells in aggregates. We first established that a feature of proteasome of marine cold-water sponges Halichondria panacea and Halisarca dujardini is low of 26S proteasome forms, which indicates that their proteasome sys- tem focuses primarily on hydrolysis of non-ubiquitinated proteins. We used the method of the modified native electrophoresis to study not only the proteasome fractions and changes in the proteasome activities in clarified homogenates, but also to identify changes in the electrophoretic mobility of the 20S proteasome. In the disso- ciated cells and tissues of sponges are not detected 26S proteasome. The dissociated sponge cells increases the electrophoretic mobility of 20S proteasome forms, indicating that structural changes in the 20S proteasomes. The obtained results allow us to consider the induction of chaperone HSP70 and changes in the structure of the 20S proteasome as key mechanisms for adaptation and for the development of protective responses in Sponges and, possibly, other marine cold-water invertebrates. For the first time we received the original information proteasome system of multicellular organisms in the early stages of evolution. This work partly supported by RFBR grant 16-04-00454. Lyupina Y, Lavrov A, Erokhov P et al. Proteasome mechanism of adaptive plasticity of sea cold-water sponges [version 1; not peer reviewed]. F1000Research 2017, 6:1076 (poster) (doi: 10.7490/f1000research.1114376.1)