Thapsigargin-induced Ca2+ increase inhibits TGFβ1-mediated Smad2 transcriptional responses via Ca2+/calmodulin-dependent protein kinase II.
Transforming growth factor β (TGFβ) signalling plays important roles in a variety of tissues and cell types. Impaired TGFβ signalling contributes to several pathologies, including cancer, fibrosis as well as neurodegenerative diseases. TGFβ receptor type I-mediated phosphorylation of Smad2, the formation of the Smad2-Smad4 complex and translocation to the nucleus are critical steps of the TGFβ signalling pathway. Here, we demonstrate that thapsigargin-mediated increase of intracellular Ca(2+) concentrations inhibited TGFβ1-induced Smad2 transcriptional activity in the oligodendroglial cell line OLI-neu. We provide evidence that thapsigargin treatment dramatically reduced the nuclear translocation of Smad2 after TGFβ1 treatment but had no effect on its phosphorylation at Ser465/467. Moreover, using Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) inhibitors and a constitutively active CaMKII mutant, we provide evidence that the observed inhibition of TGFβ signalling in OLI-neu cells was strongly dependent on Ca(2+)-mediated CaMKII activation. In summary, this study clearly shows that the TGFβ1-induced Smad2 nuclear translocation is negatively regulated by intracellular Ca(2+) in OLI-neu cells and that increased intracellular Ca(2+) concentrations block Smad2-mediated transcription of TGFβ target genes. These results underline the importance of intracellular Ca(2+) for the regulation of TGFβ signalling.
Ming
Ming
M
Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, and Shanghai Jiao Tong University School of Medicine, Shanghai, PR China.
Manzini
Ivan
I
Le
Weidong
W
Krieglstein
Kerstin
K
Spittau
Björn
B
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002460:Cell Line; D004791:Enzyme Inhibitors; D006801:Humans; D009836:Oligodendroglia / Q000166:cytology; D010766:Phosphorylation; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology*; D014158:Transcription, Genetic; D053773:Transforming Growth Factor beta1 / Q000235:genetics* / Q000378:metabolism
D004791:Enzyme Inhibitors; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1; D019284:Thapsigargin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002118:Calcium