n-(n-(3-5-difluorophenacetyl)alanyl)phenylglycine-tert-butyl-ester and Fibrosis

Notch is a key player in various developmental processes during the embryonic stage as well as in regulating tissue homeostasis, cell differentiation, and stem cell maintenance in adult life. Activation of Notch signaling occurs following Notch receptor-ligand interaction and subsequent enzymatic proteolysis by the gamma-secretase complex, resulting in the cytoplasmic release of a Notch intracellular domain, which translocates to the nucleus to initiate the downstream transcriptional machinery. Notch activation and its aberrant signaling have been broadly linked to the pathogenesis of cancer and some chronic inflammatory diseases resulting in pathologic fibrotic processes. This review focuses on the molecular basis of Notch-induced signaling and its interaction with other pathways to identify therapeutic targets. We also highlight current efforts to pharmacologically intervene in Notch signaling and discuss promising ongoing experimental and clinical studies.

Topics: Amyloid Precursor Protein Secretases; Animals; Anti-Inflammatory Agents; Antineoplastic Agents; Carcinogenesis; Clinical Trials as Topic; Fibrosis; Genes, Tumor Suppressor; Humans; Inflammation; Ligands; Neoplasms; Receptors, Notch; Signal Transduction

In order to investigate the role of the Notch signaling pathway in skeletal muscle fibrosis after nerve injury, 60 Sprague-Dawley rats were selected and divided randomly into a control and two experimental groups. Group A served as controls without any treatment. Rats in groups B were injected intraperitoneally with 0.2 mL PBS and those in group C were injected intraperitoneally with 0.2 mL PBS+100 μmol/L, 0.2 mL N-[N-(3,5-difluorophenacetyl)-l-alanyl]- S-phenylglycine t-butyl ester (DAPT, a gamma-secretase inhibitor that suppresses Notch signaling) respectively, on postoperative days 1, 3, 7, 10, and 14 in a model of denervation-induced skeletal muscle fibrosis by right sciatic nerve transection. Five rats from each group were euthanized on postoperative days 1, 7, 14, and 28 to collect the right gastrocnemii, and hematoxylin and eosin (HE) staining, immunohistochemistry test, real-time PCR, and Western blotting were performed to assess connective tissue hyperplasia and fibroblast density as well as expression of Notch 1, Jagged 1, and Notch downstream molecules Hes 1 and collagen I (COL I) on day 28. There was no significant difference in HE-stained fibroblast density between group B and C on postoperative day 1. However, fibroblast density was significantly higher in group B than in group C on postoperative days 7, 14, and 28. Notch 1, Jagged 1, Hes 1, and COL I proteins in the gastrocnemius were expressed at very low levels in group A but at high levels in group B. Expression levels of these proteins were significantly lower in group C than in group B (P<0.05), but they were higher in group C than in group A (P<0.05) on postoperative day 28. We are led to conclude that locking the Notch signaling pathway inhibits fibrosis progression of denervated skeletal muscle. Thus, it may be a new approach for treatment of fibrosis of denervated skeletal muscle.

Topics: Amyloid Precursor Protein Secretases; Animals; Collagen Type I; Dipeptides; Enzyme Inhibitors; Fibroblasts; Fibrosis; Gene Expression Regulation; Hamstring Muscles; Injections, Intraperitoneal; Jagged-1 Protein; Male; Muscle Denervation; Muscle, Skeletal; Rats; Rats, Sprague-Dawley; Receptor, Notch1; Sciatic Nerve; Signal Transduction; Transcription Factor HES-1

Relaxin (RLX) can prevent cardiac fibrosis. We aimed to investigate the possible mechanism and signal transduction pathway of RLX inhibiting cardiac fibrosis.. Isoproterenol (5 mg·kg(-1)·d(-1)) was used to establish the cardiac fibrosis model in rats, which were administered RLX. The cardiac function, related targets of cardiac fibrosis, and endothelial-mesenchymal transition (EndMT) were measured. Transforming growth factor β (TGF-β) was used to induce EndMT in human umbilical vein endothelial cells, which were pretreated with RLX, 200 ng·mL(-1), then with the inhibitor of Notch. Transwell cell migration was used to evaluate cell migration. CD31 and vimentin content was determined by immunofluorescence staining and Western blot analysis. Notch protein level was examined by Western blot analysis.. RLX improved cardiac function in rats with cardiac fibrosis; it reduced the content of collagen I and III, increased the microvascular density of the myocardium, and suppressed the EndMT in heart tissue. In vitro, RLX decreased the mobility of human umbilical vein endothelial cells induced by TGF-β, increased the expression of endothelial CD31, and decreased vimentin content. Compared to TGF-β and RLX co-culture alone, TGF-β + RLX + Notch inhibitor increased cell mobility and the EndMT, but decreased the levels of Notch-1, HES-1, and Jagged-1 proteins.. RLX may inhibit the cardiac fibrosis via EndMT by Notch-mediated signaling.

Topics: Animals; Cardiomyopathies; Cell Movement; Cells, Cultured; Collagen; Dipeptides; Disease Models, Animal; Endothelial Cells; Epithelial-Mesenchymal Transition; Fibrosis; Human Umbilical Vein Endothelial Cells; Humans; Isoproterenol; Male; Myocardium; Neovascularization, Physiologic; Rats, Sprague-Dawley; Receptor, Notch1; Relaxin; Signal Transduction; Ventricular Function, Left

The aging kidney has a diminished regenerative potential and an increased tendency to develop tubular atrophy and fibrosis after acute injury. In this study, we found that activation of tubular epithelial Notch1 signaling was prolonged in the aging kidney after ischemia/reperfusion (IR) damage. To analyze the consequences of sustained Notch activation, we generated mice with conditional inducible expression of Notch1 intracellular domain (NICD) in proximal tubules. NICD kidneys were analyzed 1 and 4 wk after renal IR. Conditional NICD expression was associated with aggravated tubular damage, a fibrotic phenotype, and the expression of cellular senescence markers p21 and p16(INK4a). In wild-type mice pharmacological inhibition of Notch using the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) improved tubulo-interstitial damage and antagonized the prosenescent pathway activation after IR. In vitro, activation of Notch signaling with delta-like-ligand-4 caused prosenescent changes in tubular cells while inhibition with DAPT attenuated these changes. In conclusion, our data suggest that sustained epithelial Notch activation after IR might contribute to the inferior outcome of old kidneys after injury. Sustained epithelial activation of Notch is associated with a prosenescent phenotype and maladaptive repair.

Topics: Acute Kidney Injury; Adaptor Proteins, Signal Transducing; Aging; Animals; Calcium-Binding Proteins; Cellular Senescence; Dipeptides; Fibrosis; Intracellular Signaling Peptides and Proteins; Kidney Tubules; Kidney Tubules, Proximal; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Receptor, Notch1; Reperfusion Injury

Notch1 signaling controls the cardiac adaptation to stress. We therefore aimed to validate whether olmesartan, a widely used angiotensin II type 1 receptor blocker, ameliorates cardiac remodeling and dysfunction via delta-like ligand 4 (DLL4)/Notch1 pathway in mice with chronic pressure overload.. Cardiac pressure overload was produced by transverse aortic constriction (TAC). A total of 35 wide-type C57BL/6J mice were randomly divided into sham group, TAC group, TAC + olmesartan group, and TAC + olmsartan + DAPT group (DAPT: γ-secretase inhibitor, Notch signaling inhibitor). Saline (10 mL·kg(-1)·d(-1)) or the same volume of olmesartan liquor (3 mg·kg(-1) d(-1)) was administered by gavage, and DAPT (10 μmole·kg(-1)·d(-1)) by peritoneal injection. After 28 days of treatment, cardiac hemodynamics, echocardiography, and histology were evaluated, followed by quantitative polymerase chain reaction of fetal gene (ANP and SAA) expression. Notch1-related proteins and ERK1/2 were examined by western blot, and the serum level of angiotensin II was determined by means of enzyme-linked immunosorbent assay kits.. Persistent pressure overload-induced left ventricular hypertrophy, dysfunction, fibrosis, and microcirculation dysfunction, together with the upregulation of angiotensin II, ERK1/2, and fetal gene expression. By the activation of DLL4/Notch1, olmesartan decreased left ventricular hypertrophy and fibrosis, preserved cardiac function, and improved capillary density and coronary perfusion. All these curative effects were suppressed by pharmacological blockade of Notch signaling with DAPT.. Our findings identify a heretofore unknown pharmacological mechanism that olmesartan improves cardiac remodeling and function via DLL4/Notch1 pathway activation in mice with chronic pressure overload, which may present a new therapeutic target for hypertension.

Topics: Adaptor Proteins, Signal Transducing; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Calcium-Binding Proteins; Dipeptides; Disease Models, Animal; Fibrosis; Hypertrophy, Left Ventricular; Imidazoles; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Microcirculation; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Receptor, Notch1; Tetrazoles; Up-Regulation; Ventricular Dysfunction, Left; Ventricular Remodeling