The mammalian iris-ciliary complex affects organization and synthesis of cytoskeletal proteins of organ and tissue cultured lens epithelial cells.
A water soluble growth inhibitor was isolated from the mammalian ocular iris-ciliary complex. The molecular weight of this protein is 10 kD or lower as determined by ultrafiltration fractionation. The iris-ciliary (IC) complex water soluble protein(s) significantly inhibits synthesis of lower molecular weight proteins of the epithelial cells of the organ cultured mammalian ocular lens. It was also found that this inhibitory effect of IC is mediated via the structural organization of the lens. Monolayer cultures of the lens epithelial cells exposed to IC did not manifest any inhibition of their protein synthesis. Moreover, these tissue cultured lens epithelial (TCLE) cells showed a significant increase in their protein synthetic activities in response to the presence of IC factors in the culture medium. It is postulated that the IC activity is modulated via either the lens capsule, an extracellular matrix, or due to the specific organization of the intact lens. The specific effects of IC on the cytoskeletal organization and synthesis in the organ cultured lens epithelial (OCLE) and TCLE cells were also examined. Both groups, treated with IC factors, manifested significant alterations in their protein synthetic activities and cytoskeletal architecture. The 3H-leucine incorporation experiments showed that alpha-actin and alpha-tubulin synthesis is partially inhibited by IC factors in OCLE cells but vimentin synthesis is not, whereas in TCLE cells all of them showed increased synthesis in response to IC factors. Turnover rates of these proteins in both OCLE and TCLE cells were also computed. The immunofluorescence and microscopic evaluation of OCLE and TCLE cells exposed to IC factors illustrated significant alteration in the cytoarchitecture of the filaments. We demonstrate that an inhibitor(s) molecule of 10 kD or lower size isolated from IC inhibited protein synthesis of OCLE cells and stimulated protein synthesis in TCLE cells. The IC factor also affects the synthesis and organization of cytoskeletal filaments of both the OCLE and TCLE cells.
Banerjee
A
A
Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan 48201.
Emanuel
K
K
Parafina
J
J
Bagchi
M
M
D000199:Actins / Q000096:biosynthesis / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002924:Ciliary Body / Q000502:physiology*; D046508:Culture Techniques; D003598:Cytoskeletal Proteins / Q000096:biosynthesis* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004848:Epithelium / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006131:Growth Inhibitors / Q000502:physiology*; D007498:Iris / Q000502:physiology*; D007908:Lens, Crystalline / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D009924:Organ Culture Techniques; D011817:Rabbits; D014404:Tubulin / Q000096:biosynthesis / Q000378:metabolism; D014746:Vimentin / Q000096:biosynthesis / Q000378:metabolism
D000199:Actins; D003598:Cytoskeletal Proteins; D006131:Growth Inhibitors; D014404:Tubulin; D014746:Vimentin