Changes of G-actin localisation in the mitotic spindle region or nucleus during mitosis and after heat shock: a histochemical study of G-actin in various cell lines with fluorescent labelled vitamin D-binding protein.
The presence and localisation of G-actin in various cell lines was studied using the highly G-actin specific, fluorescence-labelled vitamin D-binding protein. In various cell-types, pig kidney-derived cells (LLC-PK1), Chinese hamster ovary (CHO) cells, SV-40 transformed African green monkey kidney (COS) cells and human hepatoma (HepG2) cells, G-actin was only visible in the cytoplasm of interphase cells. However, in mitotic cells, depending on the mitotic phase, intense G-actin staining was found associated with the mitotic spindle (early mitosis) or overlapping the DNA-staining pattern (late mitosis). Also after heat shock (60-180 min at 43 degrees C), an intense nuclear staining of G-actin was observed. In LLC-PK1 cells, the increase of nuclear G-actin staining disappeared again after 24 h at 37 degrees C, but in COS, CHO and HepG2 cells, it was still present in the nucleus after 24 h at 37 degrees C, indicating that the process was not rapidly reversible in these cells; the increased nuclear G-actin was not associated with cell division. Comparison of the amount of G-actin present in the nucleus and in the cytosol before and after heat shock using Western blotting demonstrated that the total amount of G-actin in both nucleus and cytosol was unchanged after heat shock. This indicates that the increased G-actin staining is not a result of import of G-actin into the nucleus. These observations suggest a rearrangement of G-actin in the nucleus during both mitosis and heat shock, which may be due to changes in interaction of G-actin with chromosomes.
Meijerman
I
I
Division of Toxicology, Sylvius Laboratories, PO Box 9503, Leiden-Amsterdam Centre for Drug Research, Leiden University, 2300 RA, Leiden, Netherlands.
Blom
W M
WM
de Bont
H J
HJ
Mulder
G J
GJ
Nagelkerke
J F
JF
D000199:Actins / Q000032:analysis*; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism* / Q000528:radiation effects; D003520:Cyclophosphamide; D003599:Cytoskeleton / Q000528:radiation effects; D003600:Cytosol / Q000378:metabolism; D004247:DNA / Q000032:analysis; D004317:Doxorubicin; D005456:Fluorescent Dyes; D000882:Haplorhini; D006651:Histocytochemistry; D006358:Hot Temperature; D006801:Humans; D018613:Microscopy, Confocal; D008938:Mitosis; D011806:Quinolinium Compounds; D008941:Spindle Apparatus / Q000378:metabolism*; D013552:Swine; D013844:Thiazoles; D014407:Tumor Cells, Cultured; D014750:Vincristine; D014809:Vitamin D-Binding Protein
D000199:Actins; D005456:Fluorescent Dyes; D011806:Quinolinium Compounds; D013844:Thiazoles; D014809:Vitamin D-Binding Protein; C075295:1,1'-(4,4,7,7-tetramethyl-4,7-diazaundecamethylene)bis-4-(3-methyl-2,3-dihydro(benzo-1,3-thiazole)-2-methylidene)quinolinium; D014750:Vincristine; D004317:Doxorubicin; D003520:Cyclophosphamide; D004247:DNA