The proteasomes of the sponges (Porifera): functioning in cell reaggregation of Halichondria panicea (Pallas, 1766)

• Main Author: Lavrov, Andrey
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: F1000Research 2017
• Subjects: White Sea
• Online Access: https://dx.doi.org/10.7490/f1000research.1114342.1; https://f1000research.com/slides/6-1042

Sponges (Porifera) is filter-feeding multicellular animals. Cells in the sponge body are in process of constant movement and transdifferentiation. One of the manifestations of sponge cell plasticity is the ability of the cell to reaggregate after animal tissue dissociation. This process can lead to the full reconstruction of intact sponge organization and is accompanied by cell dedifferentiations/transdifferentiations. Ubiquitin-proteasome system plays a crucial role in the regulation cell proteome homeostasis. This system should actively participate in the sponge cell reaggregation. The present study is aimed at the characterization of the proteasome system in the intact sponge tissue, cell suspension and multicellular aggregates at the different stages of the reaggregation in Halichondria panicea . The sponge collection and experiments with cell reaggregation were conducted on Pertsov White Sea Biological Station. The chymotrypsin-like (ChLA) and caspase-like activities (CLA) were measured in the homogenated samples by the hydrolysis of the fluorogenic oligopeptides Suc-LLVY-AMC and Z-LLG-АМС, respectively. The amount of the proteasome catalytic subunits β1, β5 and constitutive subunits α1,2,3,5,6,7, as well as the proteasome regulator РА700 was evaluated by Western-blotting. For the first time, the proteasome system was described in the most primitive metazoans – sponges. The ChLA of proteasomes of H. panicea demonstrate the high temperature lability and occurs at the temperature exceeding the animal physiological optimum. The ChLA and CLA of proteasomes in the cell suspension of H. panicea are lower than in intact tissues of the sponge. The amount of α-subunits and β5 subunit in the tissue is higher than in cell suspension. The proteasome regulator PA700 presented in cell suspension. The ChLA variations are accompanied only by the changes in the relative amount of β5 subunit, but not α-subunits. The ChLA increases in the multicellular aggregates at 3-5 days post dissociation. The intense histological reorganization of aggregates accompanied by cell dedifferentiations/transdifferentiations occurs at this period of cell reaggregation. The current study for the first time characterizes the functioning of ubiquitin-proteasome system in cold-water sponge H. panicea , as the representative of the lower metazoans.