Reversible cAMP-induced translocation of cytoskeleton-associated 300- to 350-kDa proteins from nucleus to cytoplasm.
We previously reported that treatment of SV-3Y1 cells in an exponential growth state with 1 mM db-cAMP plus 1 mM theophylline induced reversible disappearance of nuclear dots stained by monoclonal anti-microtubule-associated protein (MAP)-1 antibody [T. Nakayama, K. Nishizawa, G. Kimura, and C. Sato (1986) Exp. Cell Res. 163, 246]. In the present study, we examined the relation between the intracellular localization and phosphorylation of 300- to 350-kDa proteins that are intracellular antigens for our anti-MAP-1 and -2 antibodies. Treatment with 1 mM db-cAMP plus 1 mM theophylline was found to result in a reversible decrease in immunofluorescent staining of the nucleus with polyclonal MAP-1 or -2 antibody, and a reversible increase in that of the cytoplasm. Simultaneous treatment with 2.5 microM colchicine, 2.5 microM colcemid, 20 microM putrescine, or 3 mM alpha-naphthyl phosphate in the presence of db-cAMP plus theophylline almost prevented this effect of db-cAMP plus theophylline. We examined the cytoplasmic and nuclear fractions by immunoperoxidase staining, immunoprecipitation, and 125I-protein A with anti-MAP-1 and -2 antibodies. Treatment with db-cAMP plus theophylline resulted in the increase of 300- to 350-kDa proteins in the cytoplasm and a decrease in the nucleus. This treatment also caused the dephosphorylation of 300- to 350-kDa proteins. The present research indicated that treatment with db-cAMP plus theophylline resulted in the reversible translocation of 300- to 350-kDa proteins from the nucleus to the cytoplasm accompanied by the dephosphorylation of these proteins.
Nakayama
T
T
Laboratory of Experimental Radiology, Aichi Cancer Center Research Institute, Nagoya, Japan.
Nishizawa
K
K
Sato
C
C
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D000242:Cyclic AMP / Q000494:pharmacology*; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D008970:Molecular Weight; D010766:Phosphorylation; D013806:Theophylline / Q000494:pharmacology
D003598:Cytoskeletal Proteins; D003994:Bucladesine; D013806:Theophylline; D000242:Cyclic AMP