title: Modulation of nucleocytosolic [Ca2+] gradient in smooth muscle by protein phosphorylation.
abstract: In resting DDT1MF-2 smooth muscle cells, the cytosolic free Ca2+ concentration ([Ca2+]c) was higher than the free Ca2+ concentration in the nucleus ([Ca2+]n). However, this nucleocytosolic [Ca2+] gradient was reversed by Ca2+ agonists like ATP or, as is shown here, by the epidermal growth factor (EGF). The ATP-induced reversal of the nucleocytosolic [Ca2+] gradient was blocked by stimulation of protein kinase C with phorbol 12-myristate 13-acetate or with the diacylglycerol kinase inhibitor R59949, or by inhibition of the Ser/Thr-specific protein phosphatases-1 and -2A with okadaic acid or calyculin A. Moreover, the magnitude of the ATP-induced reversal of the [Ca2+] gradient diminished during prolonged culture of the cells. The EGF-induced [Ca2+] rise in the cytosol and nucleus was blocked by okadaic acid and by the tyrosine kinase inhibitors herbimycin A and psi-tectorigenin. Our data suggest that the nucleocytosolic [Ca2+] gradient is modulated by (de)phosphorylation processes catalyzed by tyrosine protein kinases, by protein kinase C, and by Ser/Thr protein phosphatases-1 and -2A.
authors.affiliation: Physiological Laboratory, Faculty of Medicine, Katholieke Universiteit of Leuven, Gasthuisberg, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Himpens
authors.forename: H
authors.initials: H
authors.lastname: De Smedt
authors.forename: M
authors.initials: M
authors.lastname: Bollen
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D016227:Benzoquinones; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D003600:Cytosol / Q000378:metabolism; D019852:Diacylglycerol Kinase; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D004988:Ethers, Cyclic / Q000494:pharmacology; D006706:Homeostasis; D007700:Kinetics; D047029:Lactams, Macrocyclic; D007890:Leiomyosarcoma; D008387:Marine Toxins; D008647:Mesocricetus; D008954:Models, Biological; D009130:Muscle, Smooth / Q000378:metabolism*; D019319:Okadaic Acid; D010080:Oxazoles / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D010880:Piperidines / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology; D052999:Quinazolinones; D011809:Quinones / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D016227:Benzoquinones; D004988:Ethers, Cyclic; D047029:Lactams, Macrocyclic; D008387:Marine Toxins; D010080:Oxazoles; D010750:Phosphoproteins; D010880:Piperidines; D011799:Quinazolines; D052999:Quinazolinones; D011809:Quinones; C058544:R 59949; D005576:Colforsin; D019319:Okadaic Acid; D017828:Rifabutin; D004815:Epidermal Growth Factor; C020754:herbimycin; C059041:calyculin A; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D019852:Diacylglycerol Kinase; D011493:Protein Kinase C; D017027:Protein Tyrosine Phosphatases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium