n-(n-(3-5-difluorophenacetyl)alanyl)phenylglycine-tert-butyl-ester and Acute-Kidney-Injury

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

This study aims to investigate the role of Notch pathway in the renal ischemia/reperfusion injury (IRI)-associated inflammation and apoptosis.. Male Sprague-Dawley rats were divided into three groups: normal saline (NS)-treated sham rats, NS-treated ischemia/reperfusion (I/R) rats, and N-[N-(3,5-difluorophenacetyl-l-alanyl)]-S-phenylglycine t-butyl ester (DAPT) (a γ-secretase inhibitor) treated I/R rats. I/R rat model underwent nephrectomy of the right kidney and was subjected to 60 min of left renal pedicle occlusion followed by 24 h, 48 h, and 72 h of reperfusion, respectively. The levels of creatinine, urea nitrogen (BUN), interleukin (IL)-6, tumor necrosis factor (TNF)-α in serum samples and urinary N-acety-β-d-glucosaminidase (NAG) were assayed. Histological examinations were performed. The protein expression of Notch2, hairy/enhancer of split 1 (hes-1), NF-κB2, monocyte chemoattractant protein (MCP)-1, B-cell lymphoma 2 (bcl-2), and bcl-2-associated X (bax) were detected and the degree of apoptosis of tubular cells was evaluated.. Renal IR induced severe tubular damage, caused significant increases in the Scr, BUN, IL-6, TNF-α, urinary NAG, Notch2, hes-1, NF-κB2, MCP-1, ratio of tubule cells apoptosis, and reduction in the ratio of bcl-2 to bax. However, DAPT treatment significantly reduced the level of Scr, BUN, IL-6, TNF-α, and NAG. Thus, I/R activates Notch2/hes-1 signaling and DAPT treatment can ameliorate the severity of tubular damage after renal IRI, lower the expression of NF-κB2, MCP-1, and bax protein, increase the expression of bcl-2 protein, and reduce the ratio of terminal 2-deoxyuridine 5-triphosphate nick end-labeling-positive cells.. Notch signaling plays an important role in the renal IRI-associated inflammation and apoptosis. DAPT can protect against IRI through partly suppressing inflammation and apoptosis, which could constitute a new target for AKI.

Topics: Acute Kidney Injury; Amyloid Precursor Protein Secretases; Animals; Apoptosis; Basic Helix-Loop-Helix Transcription Factors; bcl-2-Associated X Protein; Cytokines; Dipeptides; Epithelial Cells; Homeodomain Proteins; In Situ Nick-End Labeling; Inflammation; Kidney; Kidney Function Tests; Male; NF-kappa B; Rats; Rats, Sprague-Dawley; Receptor, Notch2; Reperfusion Injury; Signal Transduction; Transcription Factor HES-1