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- PublicationBMP7-induced-Pten inhibits Akt and prevents renal fibrosisBone morphogenetic protein-7 (BMP-7) counteracts pro-fibrotic effects of TGFβ1 in cultured renal cells and protects from fibrosis in acute and chronic renal injury models. Using the unilateral ureteral obstruction (UUO) model of chronic renal fibrosis, we investigated the effect of exogenous-rhBMP-7 on pro-fibrotic signaling pathways mediated by TGFβ1 and hypoxia. Mice undergoing UUO were treated with vehicle or rhBMP-7 (300 μg/kg i.p.) every other day for eight days and kidneys analysed for markers of fibrosis and SMAD, MAPK, and PI3K signaling. In the kidney, collecting duct and tubular epithelial cells respond to BMP-7 via activation of SMAD1/5/8. Phosphorylation of SMAD1/5/8 was reduced in UUO kidneys from vehicle-treated animals yet maintained in UUO kidneys from BMP-7-treated animals, confirming renal bioactivity of exogenous rhBMP-7. BMP-7 inhibited Collagen Iα1 and Collagen IIIα1 gene expression and Collagen I protein accumulation, while increasing expression of Collagen IVα1 in UUO kidneys. Activation of SMAD2, SMAD3, ERK, p38 and PI3K/Akt signaling occurred during fibrogenesis and BMP-7 significantly attenuated SMAD3 and Akt signaling in vivo. Analysis of renal collecting duct (mIMCD) and tubular epithelial (HK-2) cells stimulated with TGFβ1 or hypoxia (1% oxygen) to activate Akt provided further evidence that BMP-7 specifically inhibited PI3K/Akt signaling. PTEN is a negative regulator of PI3K and BMP-7 increased PTEN expression in vivo and in vitro. These data demonstrate an important mechanism by which BMP-7 orchestrates renal protection through Akt inhibition and highlights Akt inhibitors as anti-fibrotic therapeutics
Scopus© Citations 53 563
- PublicationProtein disorder and short conserved motifs in disordered regions are enriched near the cytoplasmic side of single-pass transmembrane proteinsIntracellular juxtamembrane regions of transmembrane proteins play pivotal roles in cell signalling, mediated by protein-protein interactions. Disordered protein regions, and short conserved motifs within them, are emerging as key determinants of many such interactions. Here, we investigated whether disorder and conserved motifs are enriched in the juxtamembrane area of human single-pass transmembrane proteins. Conserved motifs were defined as short disordered regions that were much more conserved than the adjacent disordered residues. Human single-pass proteins had higher mean disorder in their cytoplasmic segments than their extracellular parts. Some, but not all, of this effect reflected the shorter length of the cytoplasmic tail. A peak of cytoplasmic disorder was seen at around 30 residues from the membrane. We noted a significant increase in the incidence of conserved motifs within the disordered regions at the same location, even after correcting for the extent of disorder. We conclude that elevated disorder within the cytoplasmic tail of many transmembrane proteins is likely to be associated with enrichment for signalling interactions mediated by conserved short motifs.
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