In diabetic nephropathy, connective tissue growth factor (CTGF) is upregulated and bone morphogenetic protein 7 (BMP-7) is downregulated. CTGF is known to inhibit BMP-4, but similar cross-talk between BMP-7 and CTGF has not been studied. In this study, it was hypothesized that CTGF acts as an inhibitor of BMP-7 signaling activity in diabetic nephropathy. Compared with diabetic wild-type CTGF ϩ/ϩ mice, diabetic CTGF ϩ/Ϫ mice had approximately 50% lower CTGF mRNA and protein, less severe albuminuria, no thickening of the glomerular basement membrane, and preserved matrix metalloproteinase (MMP) activity. Although the amount of BMP-7 mRNA was similar in the kidneys of diabetic CTGF ϩ/ϩ and CTGF ϩ/Ϫ mice, phosphorylation of the BMP signal transduction protein Smad1/5 and expression of the BMP target gene Id1 were lower in diabetic CTGF ϩ/ϩ mice.Moreover, renal Id1 mRNA expression correlated with albuminuria (R ϭ Ϫ0.86) and MMP activity (R ϭ 0.76). In normoglycemic mice, intraperitoneal injection of CTGF led to a decrease of pSmad1/5 in the renal cortex. In cultured renal glomerular and tubulointerstitial cells, CTGF diminished BMP-7 signaling activity, evidenced by lower levels of pSmad1/5, Id1 mRNA, and BMP-responsive elementluciferase activity. Co-immunoprecipitation, solid-phase binding assay, and surface plasmon resonance analysis showed that CTGF binds BMP-7 with high affinity (Kd approximately 14 nM). In conclusion, upregulation of CTGF inhibits BMP-7 signal transduction in the diabetic kidney and contributes to altered gene transcription, reduced MMP activity, glomerular basement membrane thickening, and albuminuria, all of which are hallmarks of diabetic nephropathy.
High‐performance adhesives are of great interest in view of industrial demand. We herein identify a straightforward synthetic strategy towards universal hydrogen‐bonded (H‐bonded) polymeric adhesives, using a side‐chain barbiturate (Ba) and Hamilton wedge (HW) functionalized copolymer. Starting from a rubbery copolymer containing thiolactone derivatives, Ba and HW moieties are tethered as pendant groups via an efficient one‐pot two‐step amine‐thiol‐bromo conjugation. Hetero‐complementary Ba/HW interactions thus yield H‐bonded supramolecular polymeric networks. In addition to an enhanced polymeric network integrity induced by specific Ba/HW association, the presence of individual Ba or HW moieties enables strong binding to a range of substrates, outstanding compared to commercial glues and reported adhesives.
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