Tumor promoter induces reorganization of actin filaments and calspectin (fodrin or nonerythroid spectrin) in 3T3 cells.

AUTOR(ES)

Sobue, K

RESUMO

We have used immunofluorescence, differential-interference-contrast, and interference-reflection microscopy to examine the translocation of actin filaments and calspectin (fodrin or nonerythroid spectrin) in 3T3 cells induced by phorbol 12-myristate 13-acetate (PMA). The two cytoskeletal proteins were observed to localize in dot structures that corresponded to the cell-substratum contact sites (focal contact) of the cytoplasmic surface of the plasma membrane. The induction of these cytoskeletal changes was specific for tumor promoters. High-resolution microscopy revealed that calspectin was intensely concentrated in ring-like structures surrounding actin dots. It was also located within the areas of actin dots, but to a lesser extent. Trifluoperazine and other phenothiazine derivatives inhibited the formation of those dot structures that appeared after the addition of PMA. Some serine protease inhibitors were also demonstrated to influence cytoskeletal changes by PMA. Our results provide evidence that calspectin is closely associated with actin filaments in dot structures induced by PMA. Possible mechanisms for these cytoskeletal changes produced by PMA are discussed.

Documentos Relacionados

• Identification of a spectrin-like protein in nonerythroid cells.
• Expression of the beta subunit of spectrin in nonerythroid cells.
• Vasopressin induces selective desensitization of its mitogenic response in Swiss 3T3 cells.
• Human c-fgr induces a monocyte-specific enzyme in NIH 3T3 cells.
• Amplified expression of the HER2/ERBB2 oncogene induces resistance to tumor necrosis factor alpha in NIH 3T3 cells.