Phosphorylation Of Receptor-regulated Smads Research Articles

Abstract 3656: A multi-scale approach to quantitatively evaluate the SMAD signaling pathway

Abstract Angiogenesis and cell proliferation are fundamental biological processes whose pathologic states represent two hallmarks of cancer. Central to controlling both processes is the TGF-β/BMP signaling pathway, for which the SMAD proteins serve as major downstream effector molecules. Upon ligand-binding, TGF-β or BMP type I/II receptor heterotetramers phosphorylate receptor-regulated SMADs (R-SMADs). TGF-β-receptor binding leads to SMAD2/3 phosphorylation, whereas BMP-receptor binding induces phosphorylation of SMADs 1/5/8. Phosphorylated SMADs (pSMADs) then form a complex with the co-SMAD SMAD4 at which point they undergo nuclear translocation, where they function as transcriptional modulators of target genes. The magnitude of SMAD phosphorylation and functional output (e.g., stimulated angiogenesis or attenuated cell proliferation) depends on both the ligand concentration, as well as the duration of exposure. In this study, we quantitatively evaluate the phosphorylation states of R-SMADs, as well as their downstream biological effects at three different biological scales: 1) biochemical, 2) cellular, and 3) tissue/3D models. At the biochemical level, the temporal and dose-dependent phosphorylation of R-SMADs in response to growth factor stimulation can be quantified using a quantitative ELISA approach. Growth factor stimulation can be quantified at the cellular level by high content imaging of SMAD phosphorylation and nuclear translocation, while simultaneously monitoring cell proliferation rates. Lastly, high-resolution confocal imaging can be employed to observe developmental consequences of phospho-SMAD signaling using a HUVEC-based 3D angiogenesis model system. For Research Use Only. Not for use in diagnostic procedures. Citation Format: Ernest Heimsath, Lisa Arvidson, Reginaldo Prioli, Antony Wood. A multi-scale approach to quantitatively evaluate the SMAD signaling pathway. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3656.

하고초 추출물의 streptozotocin 유발 당뇨 랫트 사구체 손상 개선 효과

Prunella vulgaris, well-known traditional medicinal plant, is used for the cure of abscess, scrofula, hypertension and urinary diseases. Diabetic nephropathy is the most common cause of end-stage renal disease. The pathological characteristics of diabetic nephropathy are glomerular and tubular basement membrane thickening. The aim of the present study was to evaluate the effect of Prunella vulgaris, on diabetic glomerular injury in streptozotocin –induced diabetes rats. Diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin (STZ; 45 mg/kg) and confirmed by random glucose level higher than ≤ 300 mg/dL. The experimental rats were divided into five groups: control group (Male SD rats), STZ group (Male SD rats injected STZ), Aminoguanidine group (Male SD rats injected STZ + AG 100 mg/kg/day), Low dose group (Male SD rats injected STZ + APV 100 mg/kg/day), High dose group (Male SD rats injected STZ + APV 300 mg/kg/day). AG or APVs were administered once a day for 8 weeks. Body weight and food/water intake were measured every four weeks. At the end of study, the kidneys were collected and cut into pieces for immunohistochemistry and western blot analysis. Our study showed that body weight and water/food intake were no significant differences between untreated STZ-induced diabetic rat and APV treated-STZ rat. However, phosphorylation of receptor-regulated Smads (Smad3) was significantly decreased in APV treated-STZ rat as compared with the diabetic group. In addition, APV was improved nephrin level in kidney tissue. Therefore, we suggest that APV has a protective effect against STZ-induced diabetic glomerular injury.

The Aryl Hydrocarbon Receptor Ligand ITE Inhibits TGFβ1-Induced Human Myofibroblast Differentiation

Fibrosis can occur in any human tissue when the normal wound healing response is amplified. Such amplification results in fibroblast proliferation, myofibroblast differentiation, and excessive extracellular matrix deposition. Occurrence of these sequelae in organs such as the eye or lung can result in severe consequences to health. Unfortunately, medical treatment of fibrosis is limited by a lack of safe and effective therapies. These therapies may be developed by identifying agents that inhibit critical steps in fibrotic progression; one such step is myofibroblast differentiation triggered by transforming growth factor-β1 (TGFβ1). In this study, we demonstrate that TGFβ1-induced myofibroblast differentiation is blocked in human fibroblasts by a candidate endogenous aryl hydrocarbon receptor (AhR) ligand 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE). Our data show that ITE disrupts TGFβ1 signaling by inhibiting the nuclear translocation of Smad2/3/4. Although ITE functions as an AhR agonist, and biologically persistent AhR agonists, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin, cause severe toxic effects, ITE exhibits no toxicity. Interestingly, ITE effectively inhibits TGFβ1-driven myofibroblast differentiation in AhR(-/-) fibroblasts: Its ability to inhibit TGFβ1 signaling is AhR independent. As supported by the results of this study, the small molecule ITE inhibits myofibroblast differentiation and may be useful clinically as an antiscarring agent.

Smurf1 Interacts with Transforming Growth Factor-β Type I Receptor through Smad7 and Induces Receptor Degradation

Smad7 is an inhibitory Smad that acts as a negative regulator of signaling by the transforming growth factor-beta (TGF-beta) superfamily proteins. Smad7 is induced by TGF-beta, stably interacts with activated TGF-beta type I receptor (TbetaR-I), and interferes with the phosphorylation of receptor-regulated Smads. Here we show that Smurf1, an E3 ubiquitin ligase for bone morphogenetic protein-specific Smads, also interacts with Smad7 and induces Smad7 ubiquitination and translocation into the cytoplasm. In addition, Smurf1 associates with TbetaR-I via Smad7, with subsequent enhancement of turnover of TbetaR-I and Smad7. These results thus reveal a novel function of Smad7, i.e. induction of degradation of TbetaR-I through recruitment of an E3 ligase to the receptor.