In vivo nuclear Ca2+-ATPase phosphorylation triggers intermediate size molecular transport to the nucleus.
Outer nuclear membrane is endowed with a SERCA type Ca(2+)-ATPase which pumps calcium into the nuclear envelope lumen and creates calcium stores. Variation in this calcium pool, among other things, regulates nuclear transport. The transport of Nuclear Localization Signal (NLS)-containing molecules into the nucleus is well established. Intermediate size molecules lacking an NLS translocate to the nucleus and its mechanism remains obscure. It is observed here that the treatment of HEK 293 cells in culture with dibutyryl cyclic AMP (db-cAMP) or forskolin (FK) triggered transport of Calcium Green 10 kDa dextran into the nucleus. Under similar conditions Fluo-3-AM accumulated around the nuclei. cAMP-dependent protein kinase phosphorylated 105 kDa nuclear Ca(2+)-ATPase (NCA) which served as a trigger for NLS-independent transport into the nucleus.
Gensburger
Claire
C
Centre de Neurochimie CNRS, 5 rue Blaise Pascal, Strasbourg Cedex 67084, France.
Freyermuth
Solange
S
Klein
Christian
C
Malviya
Anant N
AN
D021581:Active Transport, Cell Nucleus; D000252:Calcium-Transporting ATPases / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology* / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003911:Dextrans / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D018613:Microscopy, Confocal; D009930:Organic Chemicals; D010766:Phosphorylation
D003911:Dextrans; D005456:Fluorescent Dyes; D009930:Organic Chemicals; C071336:calcium green; D017868:Cyclic AMP-Dependent Protein Kinases; D000252:Calcium-Transporting ATPases