Jagged/Notch signalling is required for a subset of TGFβ1 responses in human kidney epithelial cells.
The Jagged/Notch pathway has been implicated in TGFβ1 responses in epithelial cells in diabetic nephropathy and other fibrotic conditions in vivo. Here, we identify that Jagged/Notch signalling is required for a subset of TGFβ1-stimulated gene responses in human kidney epithelial cells in vitro. TGFβ1 treatment of HK-2 and RPTEC cells for 24h increased Jagged1 (a Notch ligand) and Hes1 (a Notch target) mRNA. This response was inhibited by co-incubation with Compound E, an inhibitor of γ-secretase (GSI), an enzyme required for Notch receptor cleavage and transcription regulation. In both cell types, TGFβ1-responsive genes associated with epithelial-mesenchymal transition such as E-cadherin and vimentin were also affected by γ-secretase inhibition, but other TGFβ1 targets such as connective tissue growth factor (CTGF) and thrombospondin-1 (THBS1) were not. TGFβ1-induced changes in Jagged1 expression preceded EMT-associated gene changes, and co-incubation with GSI altered TGFβ1-induced changes in cell shape and cytoskeleton. Transfection of cells with the activated, cleaved form of Notch (NICD) triggered decreased expression of E-cadherin in the absence of TGFβ1, but did not affect α-smooth muscle actin expression, suggesting differential requirements for Notch signalling within the TGFβ1-responsive gene subset. Increased Jagged1 expression upon TGFβ1 exposure required Smad3 signalling, and was also regulated by PI3K and ERK. These data suggest that Jagged/Notch signalling is required for a subset of TGFβ1-responsive genes, and that complex signalling pathways are involved in the crosstalk between TGFβ1 and Notch cascades in kidney epithelia.
Nyhan
Kristine C
KC
UCD Diabetes Research Centre, School of Medicine and Medical Science, UCD Conway Institute, University College Dublin, Belfield Dublin 4, Ireland.
Faherty
Noel
N
Murray
Gregg
G
Cooey
Laurence Berubé
LB
Godson
Catherine
C
Crean
John K
JK
Brazil
Derek P
DP
D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D000072100:Jagged-1 Protein; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D016133:Polymerase Chain Reaction; D051880:Receptors, Notch / Q000378:metabolism*; D000072099:Serrate-Jagged Proteins; D015398:Signal Transduction; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; C000606273:JAG1 protein, human; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; D051880:Receptors, Notch; D000072099:Serrate-Jagged Proteins; D053773:Transforming Growth Factor beta1