Ubiquitin-Protein Ligases/metabolism* ; Proteolysis ; Biological Products ; Ligands

Ubiquitin, a critical small molecular protein, plays an important role in regulating multiple signaling pathways. Ubiquitination is a post-translational modification induced by ubiquitin through an ATP-dependent enzyme catalyzed reaction. A large number of proteins in the complicated signaling network participate in wound healing. This paper reviews the research progress in regulation of ubiquitin and ubiquitination for wound healing processes regarding the recent years.
Signal Transduction ; physiology ; Ubiquitin ; metabolism ; Ubiquitin-Protein Ligases ; physiology ; Ubiquitination ; Wound Healing ; physiology

Neurodegenerative diseases are a group of chronic progressive neuronal damage disorders. The cause is unclear, most of them share a same pathological hallmark with misfold proteins accumulating in neurons. Carboxyl-terminus of Hsc70 interacting protein (CHIP) is a dual functional molecule, which has a N terminal tetratrico peptide repeat (TPR) domain that interacts with Hsc/Hsp70 complex and Hsp90 enabling CHIP to modulate the aberrant protein folding; and a C terminal U-box ubiquitin ligase domain that binds to the 26S subunit of the proteasome involved in protein degradation via ubiqutin-proteasome system. CHIP protein mediates interactions between the chaperone system and the ubiquitin-proteasome system, and plays an important role in maintaining the protein homeostasis in cells. This article reviews the molecular characteristics and physiological functions of CHIP, and its role in cellular metabolism and discusses the relationship between CHIP dysfunction and neurodegenerative diseases.
Animals ; Humans ; Neurodegenerative Diseases ; genetics ; metabolism ; Protein Binding ; Protein Folding ; Proteolysis ; Ubiquitin-Protein Ligases ; genetics ; metabolism

Parkinson's disease (PD) is a common neurodegenerative disorder associated with aging. Great progresses have been made toward understanding the pathogenesis over the past decades. It seems that both genetic factors and environmental factors contribute to PD, while the precise pathogenesis still remains unknown. Recently, increasing evidence has suggested that autophagy dysregulation is closely related to PD. Dysregulation of the autophagic pathways has been observed in the brains of PD patients or in animal models of PD, and a number of PD-associated proteins, such as a-synuclein, Parkin and PINK1, were found to involve in autophagy, suggesting a link between autophagy and pathogenesis of PD. In this review, we summarized the role of PD-associated proteins in autophagy pathways. In addition, we described the efficacy of autophagy-modulating compounds in PD models and discussed promising strategies for PD therapy.
Animals ; Autophagy ; Humans ; Parkinson Disease ; physiopathology ; Protein Kinases ; metabolism ; Ubiquitin-Protein Ligases ; metabolism ; alpha-Synuclein ; metabolism

OBJECTIVE: To explore the interaction between BCL2-associated athanogene 5 (BAG5) and Parkin protein,and the regulatory mechanism of BAG5 protein on the level of Parkin protein. METHODS: We performed GST pull-down assay to identify which domain of PINK1 interacted with Parkin, and generated different deletions of BAG5 to identify the domains. Chase time experiment was done to determine the effect of co-regulation of BAG5 protein on the ubiquitination. We further examined the possible interaction between Parkin and PINK1 in 293A cells by co-immunoprecipitation method. RESULTS: BAG5 directly interacted with the Parkin, and all the 4 BAG domains interacted with the Parkin. BAG5 stabilized the Parkin by interfering its degradation via the ubiquitin-mediated proteasomal pathway. CONCLUSION BAG5 directly interacts with the Parkin, and BAG5 stabilizes the Parkin via the ubiquitin-mediated proteasomal pathway.
Adaptor Proteins, Signal Transducing ; metabolism ; Humans ; Parkinson Disease ; metabolism ; Protein Binding ; Ubiquitin-Protein Ligases ; metabolism ; Ubiquitination

This study investigated the mechanism of Danggui Shaoyao Powder(DSP) against mitophagy in rat model of Alzheimer's disease(AD) induced by streptozotocin(STZ) based on PTEN induced putative kinase 1(PINK1)-Parkin signaling pathway. The AD rat model was established by injecting STZ into the lateral ventricle, and the rats were divided into normal group, model group, DSP low-dose group(12 g·kg~(-1)·d~(-1)), DSP medium-dose group(24 g·kg~(-1)·d~(-1)), and DSP high-dose group(36 g·kg~(-1)·d~(-1)). Morris water maze test was used to detect the learning and memory function of the rats, and transmission electron microscopy and immunofluorescence were employed to detect mitophagy. The protein expression levels of PINK1, Parkin, LC3BⅠ/LC3BⅡ, and p62 were assayed by Western blot. Compared with the normal group, the model group showed a significant decrease in the learning and memory function(P<0.01), reduced protein expression of PINK1 and Parkin(P<0.05), increased protein expression of LC3BⅠ/LC3BⅡ and p62(P<0.05), and decreased occurrence of mitophagy(P<0.01). Compared with the model group, the DSP medium-and high-dose groups notably improved the learning and memory ability of AD rats, which mainly manifested as shortened escape latency, leng-thened time in target quadrants and elevated number of crossing the platform(P<0.05 or P<0.01), remarkably activated mitophagy(P<0.05), up-regulated the protein expression of PINK1 and Parkin, and down-regulated the protein expression of LC3BⅠ/LC3BⅡ and p62(P<0.05 or P<0.01). These results demonstrated that DSP might promote mitophagy mediated by PINK1-Parkin pathway to remove damaged mitochondria and improve mitochondrial function, thereby exerting a neuroprotective effect.
Rats ; Animals ; Mitophagy ; Alzheimer Disease/genetics* ; Powders ; Protein Kinases/metabolism* ; Ubiquitin-Protein Ligases/metabolism*

Inflammatory bowel disease refers to chronic inflammatory disorders that affect the gastrointestinal tract. Ubiquitination is an important protein post-translational modification. In recent years, the research of ubiquitination-deubiquitination system in the development of inflammatory bowel disease has become a hot spot. Up to now, the E3 ubiquitin ligases such as ring finger protein 183 (RNF183), RNF20, Itch and A20 were well studied in inflammatory bowel disease. RNF183 promotes the activation of the NF-κB pathway by increasing the ubiquitination and degradation of IκBα; RNF20 drives histone H2B monoubiquitylation, downregulates a panel of inflammation-associated genes; Itch inhibits IL-17-mediated colon inflammation by retinoid acid related orphan receptor γt ubiquitination; A20 has ubiquitinating-deubiquitinating activity to regulates colon inflammation. This article reviews the role and regulatory mechanism of RNF183, RNF20, Itch and A20 in the pathogenesis of inflammatory bowel disease.
Histones ; metabolism ; Humans ; Inflammatory Bowel Diseases ; physiopathology ; NF-kappa B ; metabolism ; Ubiquitin-Protein Ligases ; metabolism ; Ubiquitination

Proteolysis targeting chimera (PROTAC) refers to heterobifunctional small molecules that can simultaneously bind an E3 ubiquitin ligase and a target protein, enabling specific degradation of the target protein with the aid of the ubiquitin proteasome system. At present, most PROTAC drugs are in the clinical trial stage, and the ligands are mainly non-covalent compounds. PROTAC drugs have the advantage of overcoming drug resistance and degrading "undruggable" target proteins, but non-covalent ligands could lead to the hook effect that undermines drug efficacy. With its own advantages, covalent ligands can avoid the occurrence of this phenomenon, which is of great help to the development of PROTAC. This review summarizes the progress in preclinical and clinical research and application of PROTAC molecules targeting three different classes of protein targets, including intranuclear, transmembrane, and cytosolic proteins. We also offer perspective discussions to provide research ideas and references for the future development of PROTAC.
Proteolysis ; Proteolysis Targeting Chimera ; Proteasome Endopeptidase Complex/metabolism* ; Ubiquitin-Protein Ligases/metabolism* ; Proteins/metabolism* ; Ligands

The ubiquitin-proteasome system plays an important role in protein degradation. The process of ubiquitination requires ubiquitin activating enzyme E1, ubiquitin-conjugating enzyme E2, and ubiquitin ligase E3 to complete the coordination. Our previous studies have shown that HUWE1 (HECT, UBA and WWE domain containing 1), as an E3 ubiquitin ligase, can degrade epidermal growth factor receptor (EGFR) to inhibit renal tubulointerstitial fibrosis. However, E2 ubiquitin-conjugating enzymes binding to HUWE1 are still unclear. The aim of the present study was to identify E2 ubiquitin-conjugating enzymes of HUWE1. Real-time PCR was used to identify E2 ubiquitin-conjugating enzyme that may interact with HUWE1. The expression of E2 ubiquitin-conjugating enzyme was detected in kidney of unilateral ureteral obstruction (UUO) mice and HK-2 cells treated with transforming growth factor-β (TGF-β). The results showed that the expressions of E2 ubiquitin-conjugating enzyme UBE2Q2 were significantly down-regulated at both RNA and protein levels in UUO kidneys. The expression of UBE2Q2 was also down-regulated in HK-2 cells stimulated with TGF-β, which was consistent with the change in the expression of HUWE1. These findings indicated that UBE2Q2 expression was synergistic with HUWE1 in the injured kidney. Co-immunoprecipitation (Co-IP) experiments showed that HUWE1 interacted with UBE2Q2 in HK-2 cells. The co-localization of UBE2Q2 and HUWE1 was confirmed by cell immunofluorescence staining. After knocking down UBE2Q2 by siRNA, ubiquitin binding to HUWE1 and EGFR was decreased. In sum, our results demonstrated that UBE2Q2, ubiquitin-conjugating enzyme, works with HUWE1 to mediate ubiquitination and degradation of target protein in kidney.
Animals ; Cell Line ; Fibrosis ; Humans ; Kidney Diseases ; Mice ; Ubiquitin-Conjugating Enzymes/metabolism* ; Ubiquitin-Protein Ligases/metabolism* ; Ubiquitination

To explore the regulation of eIF4E, we screened the protein interacting with eIF4E from human cDNA library by using yeast two-hybrid system. Several clones interacting with eIF4E were identified. One of them was homologous with HUWE1 (HECT, UBA and WWE domain containing 1, also named as ARF-BP1, HECTH9 or HUWE1). Cell co-immunoprecipitation showed that eIF4E could bind to HUWE1 in mammalian cells. We also found that HUWE1 bearing the HECT domain is necessary for its association with eIF4E.
Animals ; Eukaryotic Initiation Factor-4E ; metabolism ; Humans ; Ubiquitin-Protein Ligases ; metabolism