Cell-Permeable PROTAC Degraders against KEAP1 Efficiently Suppress Hepatic Stellate Cell Activation through the Antioxidant and Anti-Inflammatory Pathway

Abstract

Accumulating evidence indicates that oxidative stress and inflammation are involved in the physiopathology of liver fibrogenesis. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor, which regulates the expression of redox regulators to establish cellular redox homeostasis. The Nrf2 modulator can serve as a primary cellular defense against the cytotoxic effects of oxidative stress. We designed a chimeric Keap1–Keap1 peptide (KKP1) based on the proteolysis-targeting chimera technology. The KKP1 peptide not only can efficiently penetrate into the rat hepatic stellate cell line (HSC-T6) cells but also can induce Keap1 protein degradation by the ubiquitination–proteasome degradation pathway, which releases Nrf2 and promotes the transcriptional activity of the Nrf2/antioxidant response element pathway. It then activates the protein expression of the downstream antioxidant factors, the glutamate-cysteine ligase catalytic subunit and heme oxygenase-1 (HO-1). Finally, Keap1 protein degradation inhibits the nuclear factor-kappaB inflammatory signal pathway, the downstream inflammatory factor tumor necrosis factor alpha, and the interleukin-1beta protein expression and further inhibits the expression of the fibrosis biomarker gene. The current research suggests that our designed KKP1 may provide a new avenue for the future treatment of liver fibrosis.

A Novel Gain-of-Signal Assay to Detect Targeted Protein Degradation

“…Furthermore, constructs validated through transient transfection strategies will likely rely on gene therapy methods for clinical translation, which have made advances in recent years but are still in need of additional development efforts; thus, delivery of bioPROTACs remains a bottleneck for therapeutic use . Alternative delivery methods, such as cell-penetrating peptides, may also be feasible for some protein-based degrader constructs; − however, it is unclear whether comparable concentrations of degraders can accumulate in a cell using this technique or if their activity could persist long enough to see the same effect. bioPROTACs will need to overcome these delivery limitations for clinical use, but if successful, bioPROTACs could be impactful therapies against targets for which small-molecule PROTACs are not well suited.…”

Emerging Landscape of Cell-Penetrating Peptide-Mediated Organelle Restoration and Replacement

“…CPPs are a diverse group of long peptides of 4–30 amino acids capable of delivering bioactive cargos of proteins, − peptides, , nucleic acids, − nanoparticles, and pharmacologic agents into the cellular cytoplasm through different internalization mechanisms mainly including energy-dependent endocytosis and energy-independent direct penetration. ,− Since the discovery of the first qualitative CPP-TAT, − increasing research activities and preclinical evaluations of CPP-derived therapies have provided us with promising results in various disease models. , Thus, these breakthroughs bring new prospects for the development of CPP-derived therapeutics to treat human diseases related to intracellular organelles.…”

Emerging Landscape of Osteogenesis Imperfecta Pathogenesis and Therapeutic Approaches

“…The most prevalent genes linked to OI are COL1A1 and COL1A2, responsible for encoding the two chains of type I collagen. 4 Mutations in COL1A1 and COL1A2 account for most OI cases. Nevertheless, with the advancement of our understanding of the genetic basis of OI, mutations in additional genes have also been identified (summarized in Figure 1).…”

“…OI can arise from genetic mutations in at least 20 distinct genes that are associated with the synthesis, processing, or regulation of collagen. The most prevalent genes linked to OI are COL1A1 and COL1A2 , responsible for encoding the two chains of type I collagen . Mutations in COL1A1 and COL1A2 account for most OI cases.…”