Deubiquitinating enzyme USP11 promotes renal tubular cell senescence and fibrosis via inhibiting the ubiquitin degradation of TGF-β receptor II

TGF‑β/Smad signaling in chronic kidney disease: Exploring post‑translational regulatory perspectives (Review)

The TGF‑β/Smad signaling pathway plays a pivotal role in the onset of glomerular and tubulointerstitial fibrosis in chronic kidney disease (CKD). The present review delves into the intricate post‑translational modulation of this pathway and its implications in CKD. Specifically, the impact of the TGF‑β/Smad pathway on various biological processes was investigated, encompassing not only renal tubular epithelial cell apoptosis, inflammation, myofibroblast activation and cellular aging, but also its role in autophagy. Various post‑translational modifications (PTMs), including phosphorylation and ubiquitination, play a crucial role in modulating the intensity and persistence of the TGF‑β/Smad signaling pathway. They also dictate the functionality, stability and interactions of the TGF‑β/Smad components. The present review sheds light on recent findings regarding the impact of PTMs on TGF‑β receptors and Smads within the CKD landscape. In summary, a deeper insight into the post‑translational intricacies of TGF‑β/Smad signaling offers avenues for innovative therapeutic interventions to mitigate CKD progression. Ongoing research in this domain holds the potential to unveil powerful antifibrotic treatments, aiming to preserve renal integrity and function in patients with CKD.

E3 ligases and DUBs target ferroptosis: A potential therapeutic strategy for neurodegenerative diseases

Ferroptosis is a form of cell death mediated by iron and lipid peroxidation (LPO). Recent studies have provided compelling evidence to support the involvement of ferroptosis in the pathogenesis of various neurodegenerative diseases (NDDs), such as Alzheimer's disease (AD), Parkinson's disease (PD). Therefore, understanding the mechanisms that regulate ferroptosis in NDDs may improve disease management. Ferroptosis is regulated by multiple mechanisms, and different degradation pathways, including autophagy and the ubiquitinproteasome system (UPS), orchestrate the complex ferroptosis response by directly or indirectly regulating iron accumulation or lipid peroxidation. Ubiquitination plays a crucial role as a protein posttranslational modification in driving ferroptosis. Notably, E3 ubiquitin ligases (E3s) and deubiquitinating enzymes (DUBs) are key enzymes in the ubiquitin system, and their dysregulation is closely linked to the progression of NDDs. A growing body of evidence highlights the role of ubiquitin system enzymes in regulating ferroptosis sensitivity. However, reports on the interaction between ferroptosis and ubiquitin signaling in NDDs are scarce. In this review, we first provide a brief overview of the biological processes and roles of the UPS, summarize the core molecular mechanisms and potential biological functions of ferroptosis, and explore the pathophysiological relevance and therapeutic implications of ferroptosis in NDDs. In addition, reviewing the roles of E3s and DUBs in regulating ferroptosis in NDDs aims to provide new insights and strategies for the treatment of NDDs. These include E3- and DUB-targeted drugs and ferroptosis inhibitors, which can be used to prevent and ameliorate the progression of NDDs.

Senegenin Attenuates Pulmonary Fibrosis by Inhibiting Oxidative-Stress-Induced Epithelial Cell Senescence through Activation of the Sirt1/Pgc-1α Signaling Pathway

Idiopathic pulmonary fibrosis is a fatal interstitial lung disease for which effective drug therapies are lacking. Senegenin, an effective active compound from the traditional Chinese herb Polygala tenuifolia Willd, has been shown to have a wide range of pharmacological effects. In this study, we investigated the therapeutic effects of senegenin on pulmonary fibrosis and their associated mechanisms of action. We found that senegenin inhibited the senescence of epithelial cells and thus exerted anti-pulmonary-fibrosis effects by inhibiting oxidative stress. In addition, we found that senegenin promoted the expression of Sirt1 and Pgc-1α and that the antioxidative and antisenescent effects of senegenin were suppressed by specific silencing of the Sirt1 and Pgc-1α genes, respectively. Moreover, the senegenin-induced effects of antioxidation, antisenescence of epithelial cells, and antifibrosis were inhibited by treatment with Sirt1 inhibitors in vivo. Thus, the Sirt1/Pgc-1α pathway exerts its antifibrotic effect on lung fibrosis by mediating the antioxidative and antisenescent effects of senegenin.

The role of epithelial cells in fibrosis: Mechanisms and treatment

Fibrosis is a pathological process that affects multiple organs and is considered one of the major causes of morbidity and mortality in multiple diseases, resulting in an enormous disease burden. Current studies have focused on fibroblasts and myofibroblasts, which directly lead to imbalance in generation and degradation of extracellular matrix (ECM). In recent years, an increasing number of studies have focused on the role of epithelial cells in fibrosis. In some cases, epithelial cells are first exposed to external physicochemical stimuli that may directly drive collagen accumulation in the mesenchyme. In other cases, the source of stimulation is mainly immune cells and some cytokines, and epithelial cells are similarly altered in the process. In this review, we will focus on the multiple dynamic alterations involved in epithelial cells after injury and during fibrogenesis, discuss the association among them, and summarize some therapies targeting changed epithelial cells. Especially, epithelial mesenchymal transition (EMT) is the key central step, which is closely linked to other biological behaviors. Meanwhile, we think studies on disruption of epithelial barrier, epithelial cell death and altered basal stem cell populations and stemness in fibrosis are not appreciated. We believe that therapies targeted epithelial cells can prevent the progress of fibrosis, but not reverse it. The epithelial cell targeting therapies will provide a wonderful preventive and delaying action.

Engineered extracellular vesicle-encapsulated CHIP as novel nanotherapeutics for treatment of renal fibrosis

Renal interstitial fibrosis (RIF) is a fundamental pathological feature of chronic kidney disease (CKD). However, toxicity and poor renal enrichment of fibrosis inhibitors limit their further applications. In this study, a platform for CKD therapy is developed using superparamagnetic iron oxide nanoparticles (SPION) decorated mesenchymal stem cells derived extracellular vesicles with carboxyl terminus of Hsc70-interacting protein (CHIP) high expression (SPION-EVs) to achieve higher renal-targeting antifibrotic therapeutic effect. SPION-EVs selectively accumulate at the injury renal sites under an external magnetic field. Moreover, SPION-EVs deliver CHIP to induce Smad2/3 degradation in renal tubular cells which alleviates Smad2/3 activation-mediated fibrosis-like changes and collagen deposition. The extracellular vesicle engineering technology provides a potential nanoplatform for RIF therapy through CHIP-mediated Smad2/3 degradation.