Wnt6 regulates epithelial cell differentiation and is dysregulated in renal fibrosis.
Diabetic nephropathy is the most common microvascular complication of diabetes mellitus, manifesting as mesangial expansion, glomerular basement membrane thickening, glomerular sclerosis, and progressive tubulointerstitial fibrosis leading to end-stage renal disease. Here we describe the functional characterization of Wnt6, whose expression is progressively lost in diabetic nephropathy and animal models of acute tubular injury and renal fibrosis. We have shown prominent Wnt6 and frizzled 7 (FzD7) expression in the mesonephros of the developing mouse kidney, suggesting a role for Wnt6 in epithelialization. Importantly, TCF/Lef reporter activity is also prominent in the mesonephros. Analysis of Wnt family members in human renal biopsies identified differential expression of Wnt6, correlating with severity of the disease. In animal models of tubular injury and fibrosis, loss of Wnt6 was evident. Wnt6 signals through the canonical pathway in renal epithelial cells as evidenced by increased phosphorylation of GSK3β (Ser9), nuclear accumulation of β-catenin and increased TCF/Lef transcriptional activity. FzD7 was identified as a putative receptor of Wnt6. In vitro Wnt6 expression leads to de novo tubulogenesis in renal epithelial cells grown in three-dimensional culture. Importantly, Wnt6 rescued epithelial cell dedifferentiation in response to transforming growth factor-β (TGF-β); Wnt6 reversed TGF-β-mediated increases in vimentin and loss of epithelial phenotype. Wnt6 inhibited TGF-β-mediated p65-NF-κB nuclear translocation, highlighting cross talk between the two pathways. The critical role of NF-κB in the regulation of vimentin expression was confirmed in both p65(-/-) and IKKα/β(-/-) embryonic fibroblasts. We propose that Wnt6 is involved in epithelialization and loss of Wnt6 expression contributes to the pathogenesis of renal fibrosis.
Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Research, UCD School of Biomolecular and Biomedical Science, Belfield, Dublin, Ireland;
Hayley
0000-0002-3302-0898
H
Beaton
Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Research, UCD School of Biomolecular and Biomedical Science, Belfield, Dublin, Ireland;
Darrell
D
Andrews
Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Research, UCD School of Biomolecular and Biomedical Science, Belfield, Dublin, Ireland;
Martin
M
Parsons
Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Research, UCD School of Biomolecular and Biomedical Science, Belfield, Dublin, Ireland;
Mary
M
Murphy
UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland;
Andrew
A
Gaffney
Nephrology Research Group, Centre for Public Health, Queens University Belfast, Royal Victoria Hospital, Belfast, United Kingdom; and.
David
D
Kavanagh
Nephrology Research Group, Centre for Public Health, Queens University Belfast, Royal Victoria Hospital, Belfast, United Kingdom; and.
Gareth J
GJ
McKay
Nephrology Research Group, Centre for Public Health, Queens University Belfast, Royal Victoria Hospital, Belfast, United Kingdom; and.
Alexander P
AP
Maxwell
UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland;
Cormac T
CT
Taylor
UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland;
Eoin P
EP
Cummins
UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland;
Catherine
C
Godson
UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland;
Debra F
DF
Higgins
Zoology Department, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland.
Paula
P
Murphy
Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Research, UCD School of Biomolecular and Biomedical Science, Belfield, Dublin, Ireland; john.crean@ucd.ie.
John
J
Crean
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D005355:Fibrosis; D051157:Frizzled Receptors; D000071679:Glycogen Synthase Kinase 3 beta / Q000235:genetics / Q000378:metabolism; D020672:I-kappa B Proteins / Q000235:genetics; D007668:Kidney / Q000196:embryology / Q000473:pathology*; D007674:Kidney Diseases / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology*; D007684:Kidney Tubules / Q000254:growth & development; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D011247:Pregnancy; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D051996:Transcription Factor RelA / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D014746:Vimentin / Q000096:biosynthesis; D051153:Wnt Proteins / Q000235:genetics* / Q000502:physiology*
D051157:Frizzled Receptors; C492041:Fzd7 protein, mouse; D020672:I-kappa B Proteins; D011518:Proto-Oncogene Proteins; D043562:Receptors, G-Protein-Coupled; D051996:Transcription Factor RelA; D016212:Transforming Growth Factor beta; D014746:Vimentin; D051153:Wnt Proteins; C095936:Wnt6 protein, mouse; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse
TGF-β; Wnt signaling; Wnt6; cell differentiation; epithelial cell; fibrosis; transforming growth factor-β