The presence and organization of intermediate filament (IF) proteins in petaloid coelomocytes from two species of echinoderms, the sea urchin Strongylocentrotus droebachiensis and the sea cucumber Cucumaria frondosa, were studied. Two monoclonal antibodies (IFA and Ah6) and one polyclonal antibody (W3-1) that together recognize invertebrate as well as vertebrate IF proteins were used to probe coelomocytes by immunofluorescence and immunoblotting methods. All three antibodies cross-reacted with a single M(r) 68 000 sea urchin lamin, as well as two putative lamin isoforms of approximately M(r) 70 000 and 68 000 in sea cucumber coelomocytes. Both IFA and Ah6 labeled granular material in the cytoplasm of sea urchin coelomocytes; by contrast, IFA labeling revealed a striking network of reticular material irregularly arrayed within the central regions of the sea cucumber coelomocyte cytoplasm. In addition, foci of Ah6-positive material were present in coelomocyte nuclei from both species. Comparison of immunoblotting patterns among whole cell and isolated nuclear preparations suggest that the cytoplasmic IF-like material is composed of M(r) 46 000 and 58 000 polypeptides, while M(r) 215 000 and 185 000 proteins are candidates for the immunoreactive nuclear foci. Further study of the functions of these non-filamentous arrays of IF proteins may furnish valuable insights into the evolution of IF function within vertebrate cells, particularly with respect to certain cytoplasmic and nuclear regulatory functions with which IF proteins have been speculated to be involved. (C) 2000 Elsevier Science Inc.
|Original language||English (US)|
|Number of pages||14|
|Journal||Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology|
|State||Published - 2000|
Bibliographical noteFunding Information:
The author gratefully acknowledges the stimulating input of Dr John Henson in discussions of echinoderm coelomocyte cytoskeletal organization and function, as well as his help with some of the microscopy. This work was made possible by a New Investigator Award from the Mount Desert Island Biological Laboratory, Salsbury Cove, ME.
Copyright 2020 Elsevier B.V., All rights reserved.
- Intermediate filaments
- Nuclear matrix
- Sea cucumber
- Sea urchin