The International Journal of Biochemistry & Cell Biology
Notch mediated epithelial to mesenchymal transformation is associated with increased expression of the Snail transcription factor
Introduction
Notch signalling pathways are known to play a key role in organ development, having a primary role in cell fate determination. Evidence suggests an integral involvement with the development and differentiation of the proximal tubule from the embryonic mesenchyme (Cheng and Kopan, 2005, Leimeister et al., 2003). More recent studies have demonstrated that a resident renal cell population with progenitor activity exists in adult kidneys, which strongly expresses members of the Notch signalling pathway (Challen et al., 2006). As the Notch pathway is highly expressed during organ regeneration in many tissues (Han et al., 2006, Turk et al., 2005, Adolphe and Wainwright, 2005, Raya et al., 2003, Kohler et al., 2004), and has been demonstrated to be present in the adult proximal tubule (Challen et al., 2006), it is suggested that the Notch pathway may be integrally involved with proximal tubular repair and regeneration.
However, activation of the Notch pathway has also been demonstrated to be involved in tumourigenesis, inducing numerous cellular functions including the development of epithelial to mesenchymal transition (EMT) (Leong and Karsan, 2006). A growing body of evidence suggests kidney proximal tubule epithelial cells (PTECs) undergo EMT to contribute to interstitial fibrosis in progressive renal disease (Iwano et al., 2002, Kalluri and Neilson, 2003, Zeisberg and Kalluri, 2004). Recently the process of EMT has been considered to be a process of ‘reverse embryogenesis’, with developmental genes such as gremlin being re-expressed in the fibrotic response in diabetic nephropathy (Roxburgh et al., 2006, Murphy et al., 2002). The consequence of EMT, i.e., the development of a migratory, invasive epithelial cell is an initial step in the development of renal fibrogenesis (Liu, 2004) and in tumour migration (Radtke and Raj, 2003). Hence the specific role of Notch in renal EMT resulting in interstitial fibrosis deserves exploration. Notch has been shown to promote EMT in the development of cardiac valves via repression of E-cadherin through upregulated Snail expression (Timmerman et al., 2004). However, to date the interaction between Notch1 and Snail in renal EMT has also not been explored.
In this study, we sought to delineate the role of the Notch and downstream Snail signalling pathway in the development of EMT in a human model of cultured proximal tubular cells.
Section snippets
Human primary tubular epithelial cell (PTEC) culture
Segments of renal cortex were obtained under aseptic conditions from 9 patients undergoing nephrectomy for small (<6 cm) tumours. Written informed consent was obtained from each patient before surgery, and ethics approval for the study was obtained from the Royal North Shore Hospital Human Research Ethics Committee. The method for isolation of primary culture of PTEC is previously described (Johnson et al., 1997). In brief, the kidney cortex remote from the tumour and confirmed histologically to
Effect of TGFβ1 ± AngII on Notch1 expression in human PTECs
Notch1 was minimally detected in control samples. Exposure of PTECs to TGFβ1 or TGFβ1 + AngII resulted in an increase in Notch1 expression of 1.9 ± 0.3-fold (*P < 0.05 vs. control) and 3.5 ± 0.2-fold respectively (#P < 0.005 vs. control and *P < 0.05 vs. TGFβ1; Fig. 1).
The role of Notch in the presence of TGFβ1 or TGFβ1 ± AngII on E-cadherin and α-SMA expression
E-cadherin is a Ca2+-dependent cell adhesion molecule that plays an important role in the development and maintenance of renal epithelial polarity. Loss of E-cadherin expression is considered to be one of the earliest changes in TGFβ1
Discussion
The present study demonstrates that Notch1 is integrally involved in the development of EMT in primary cultured human proximal tubular cells and hence is likely to participate in the development of renal fibrogenesis. Specifically, we have demonstrated that Notch1 is expressed when cells are induced to undergo EMT, that over-expression of Notch1 is in itself sufficient to induce EMT and that inhibition of activation of Notch signaling limits the development of EMT in well characterized in vitro
Conflict of interest
None declared.
Acknowledgements
We would like to thank Prof. Paul Ling of the Dept. Molecular Virology and Microbiology at the Baylor College of Medicine, Houston, Texas, U.S. who generously supplied the Notch1-ICD vector (pJT111) and the department of urology of Royal North Shore hospital and Concord hospital for assisting in procuring the kidneys for primary culture.
References (42)
- et al.
The role of Notch signaling in specification of podocyte and proximal tubules within the developing mouse kidney
Kidney Int
(2005) - et al.
Dorsal-ventral pattern of Delta trafficking is established by a snail-tom-neuralized pathway
Dev Cell
(2006) - et al.
Molecular requirements for epithelial–mesenchymal transition during tumor progression
Curr Opin Cell Biol
(2005) - et al.
Human renal fibroblasts modulate proximal tubule cell growth and transport via the IGF-I axis
Kidney Int
(1997) - et al.
Expression of Notch pathway genes in the embryonic mouse metanephros suggests a role in proximal tubule development
Gene Expr Patterns
(2003) - et al.
Recent insights into the role of Notch signaling in tumorigenesis
Blood
(2006) - et al.
Dissection of key events in tubular epithelial to myofibroblast transition and its implications in renal interstitial fibrosis
Am J Pathol
(2001) - et al.
Pathways to improving skin regeneration
Expert Rev Mol Med
(2005) - et al.
Glycogen synthase kinase-3 is an endogenous inhibitor of Snail transcription: implications for the epithelial–mesenchymal transition
J Cell Biol
(2005) - et al.
The Snail genes as inducers of cell movement and survival: implications in development and cancer
Development
(2005)
Interactions of transforming growth factor-beta and angiotensin II in renal fibrosis
Hypertension
Snail activation disrupts tissue homeostasis and induces fibrosis in the adult kidney
EMBO J
Cell adhesion and signalling by cadherins and Ig-CAMs in cancer
Nat Rev Cancer
Kidney side population reveals multilineage potential and renal functional capacity but also cellular heterogeneity
J Am Soc Nephrol
Influence of connective tissue growth factor antisense oligonucleotide on angiotensin II-induced epithelial mesenchymal transition in HK2 cells
Acta Pharmacol Sin
Gamma-secretase activity is dispensable for mesenchyme-to-epithelium transition but required for podocyte and proximal tubule formation in developing mouse kidney
Development
Diverse cellular and molecular mechanisms contribute to epithelial plasticity and metastasis
Nat Rev Mol Cell Biol
Disruption of Ecadherin by Matrix Metalloproteinase directly mediates epithelial–mesenchymal transition in renal tubular epithelial cells
Am J Pathol
Local signals in stem cell-based bone marrow regeneration
Cell Res
Evidence that fibroblasts derive from epithelium during tissue fibrosis
J Clin Invest
Upregulation of MMP-9 in MDCK epithelial cell line in response to expression of the Snail transcription factor
J Cell Sci
Cited by (97)
MiR-26a-5p from HucMSC-derived extracellular vesicles inhibits epithelial mesenchymal transition by targeting Adam17 in silica-induced lung fibrosis
2023, Ecotoxicology and Environmental SafetyMicroRNA-34a inhibits epithelial-mesenchymal transition of lens epithelial cells by targeting Notch1
2019, Experimental Eye ResearchMAML1 regulates EMT markers expression through NOTCH-independent pathway in breast cancer cell line MCF7
2019, Biochemical and Biophysical Research CommunicationsZinc finger proteins and ATP-binding cassette transporter-dependent multidrug resistance
2024, European Journal of Clinical InvestigationTargeting the key players of phenotypic plasticity in cancer cells by phytochemicals
2024, Cancer and Metastasis ReviewsTumor cell plasticity in targeted therapy-induced resistance: mechanisms and new strategies
2023, Signal Transduction and Targeted Therapy