SENP2-NDR2-p21 axis modulates lung cancer cell growth

Sentrin/small ubiquitin-like modifier (SUMO)-specific proteases (SENPs) perform pivotal roles in SUMO maturation and recycling, which modulate the balance of SUMOylation/de-SUMOylation and spatiotemporal functions of SUMOylation targets. The malfunction of SENPs often results in cellular dysfunction and various diseases. However, studies rarely investigated the correlation between SENP2 and lung cancer. This study revealed that SENP2 is a required contributor to lung cancer-cell growth and targets nuclear Dbf2-related 2 (NDR2, also known as serine/threonine kinase 38L or STK38L) for de-SUMOylation, which improves NDR2 kinase activity. This condition leads to the instability of downstream target p21 in accelerating the G1/S cell cycle transition and suggests SENP2 as a promising therapeutic target for lung cancer in the future. Specifically, astragaloside IV, an active ingredient of Jinfukang Oral Liquid (JOL, a clinical combination antilung cancer drug approved by the National Food and Drug Administration (FDA) of China), can repress lung cancer-cell growth via the SENP2-NDR2-p21 axis, which provides new insights into the molecular mechanism of JOL for lung cancer treatment.

SENP3-regulated Nodal signaling plays a potential role in cardiac left-right asymmetry development

Congenital heart disease (CHD) is a type of major defect that occurs during embryonic development. Although significant advances have been made in the treatment of CHD, its etiology and molecular mechanism remain unclear. To identify the critical role of SUMOylation in cardiac development, we generated SENP3 knockout mice and showed that SENP3 knockout mice die on embryonic day 8.5 with an open neural tube and reversed left-right cardiac asymmetry. Moreover, SENP3 knockout promoted apoptosis and senescence of H9C2 cells. Further studies showed that Nodal, a critical gene that forms left-right asymmetry, is regulated by SENP3 and that SENP3 regulates cell apoptosis and senescence in a Nodal-dependent manner. Furthermore, Nodal was hyper-SUMOylated after SENP3 knockout, and SUMOylation of Nodal inhibited its ubiquitination and ubiquitin-proteasome degradation pathway. Nodal overexpression enhanced cell apoptosis and senescence; however, the mutation at the SUMOylation site of Nodal reversed its effect on the apoptosis and senescence of H9C2 cells. More importantly, the SENP3-Nodal axis regulates cell senescence by inducing cell autophagy. These results suggest that the SENP3-Nodal signaling axis regulates cardiac senescence-autophagy homeostasis, which in turn affects cardiac development and results in the occurrence of CHD.

Etoposide-induced SENP8 confers a feed-back drug resistance on acute lymphoblastic leukemia cells

Chemotherapy is the most common treatment for acute lymphoblastic leukemia (ALL). However, many ALL patients eventually develop relapse and treating relapsed ALL has always been challenging. Therefore, exploring the resistance mechanism of chemotherapeutic drugs and proposing feasible intervention strategies are of great significance for ALL treatment. Here, we show that SENP8, whose coding protein is an important deNEDDylase targeting the substrate for deNEDDylation, is highly expressed in relapsed ALL specimens. Interestingly, overexpressing SENP8 specifically reduces the chemosensitivity of ALL cells to etoposide (VP-16) and significantly alleviates the proapoptotic effect of VP-16 on ALL cells. By contrast, NEDDylation inhibition reduces the chemosensitivity of ALL cells to VP-16. Furthermore, VP-16 induces SENP8 accumulation and the instability of MDM2 as well as the stabilization of p53 in ALL cells, and SENP8 knockdown can sensitize ALL cells to VP-16. Our study reveals a novel function of SENP8 in ALL and that VP-16-induced SENP8 confers a feed-back drug resistance on ALL cells, suggesting a possibility of overcoming the chemotherapeutic resistance to VP-16 via targeting SENP8.

A review of nuclear Dbf2-related kinase 1 (NDR1) protein interaction as promising new target for cancer therapy

Nuclear Dbf2-related kinase 1 (NDR1) is a nuclear Dbf2-related (NDR) protein kinase family member, which regulates cell functions and participates in cell proliferation and differentiation through kinase activity. NDR1 regulates physiological functions by interacting with different proteins. Protein-protein interactions (PPIs) are crucial for regulating biological processes and controlling cell fate, and as a result, it is beneficial to study the actions of PPIs to elucidate the pathological mechanism of diseases. The previous studies also show that the expression of NDR1 is deregulated in numerous human cancer samples and it needs the context-specific targeting strategies for NDR1. Thus, a comprehensive understanding of the direct interaction between NDR1 and varieties of proteins may provide new insights into cancer therapies. In this review, we summarize recent studies of NDR1 in solid tumors, such as prostate cancer and breast cancer, and explore the mechanism of action of PPIs of NDR1 in tumors.

ACLY-β-catenin axis modulates hepatoblastoma cell proliferation

HB (hepatoblastoma) is most common in children with liver cancer and few options for treating HB. Thus, it is of great significance to investigate the regulatory mechanism of HB and/or identify new therapeutic targets for clinical treatment of HB. Here, we showed that ACLY (ATP citrate lyase), an important lipometabolic enzyme for de novo biosynthesis of fatty acids and steroids, has a higher expression in HB tissues than noncancerous tissues, and is required for HB cell proliferation. Moreover, knocking down ACLY in HB cells caused severe S-phase arrest and apoptosis. Mechanistically, ACLY knockdown significantly silenced the Wnt signaling pathway and reduced β-catenin expression in HB cells. Conversely, the apoptotic alleviation of HB cells by overexpressing ACLY was blocked by silencing β-catenin, suggesting the modulation of HB cells by ACLY-β-catenin axis. Our results uncovered the role of ACLY in HB cells and presented a theoretical approach for HB targeted therapy in the future.

Chiral Hydrogel Accelerates Re-Epithelization in Chronic Wounds via Mechanoregulation

Chronic wounds, such as diabetic foot ulcers (DFU), are a serious clinical problem. It is a challenge for the conventional wound dressings to achieve the desirable therapeutic efficacy due to the lack of biomimetic structural environment for rapid re-epithelization. Inspired by the naturally existing chiral structures in skin, a novel amino acid-based chiral hydrogel dressing is developed, consisting of left-handed or right-handed helical fibers self-assembled by l/d-phenylalanine derivatives. Compared to the levorotatory chiral hydrogel (LH), the dextral chiral hydrogel (DH) shows the ability to enhance cell adhesion, proliferation, and migration, and strongly promotes diabetic wound healing and re-epithelialization with a drug-free mode. Interestingly, the dextral chiral hydrogel is able to actively increase adsorption of type I collagen and promote proliferation and migration of keratinocyte in an integrin and YAP-mediated manner. This study not only provides a novel strategy for treatment of chronic wounds by utilizing dextral chiral hydrogel dressings, but also unveils the molecular mechanism for effect of dextral chiral structures on the promoted proliferation of keratinocyte.

SUMOylation targeting mitophagy in cardiovascular diseases

Small ubiquitin-like modifier (SUMO) plays a key regulatory role in cardiovascular diseases, such as cardiac hypertrophy, hypertension, atherosclerosis, and cardiac ischemia-reperfusion injury. As a multifunctional posttranslational modification molecule in eukaryotic cells, SUMOylation is essentially associated with the regulation of mitochondrial dynamics, especially mitophagy, which is involved in the progression and development of cardiovascular diseases. SUMOylation targeting mitochondrial-associated proteins is admittedly considered to regulate mitophagy activation and mitochondrial functions and dynamics, including mitochondrial fusion and fission. SUMOylation triggers mitochondrial fusion to promote mitochondrial dysfunction by modifying Fis1, OPA1, MFN1/2, and DRP1. The interaction between SUMO and DRP1 induces SUMOylation and inhibits lysosomal degradation of DRP1, which is further involved in the regulation of mitochondrial fission. Both SUMOylation and deSUMOylation contribute to the initiation and activation of mitophagy by regulating the conjugation of MFN1/2 SERCA2a, HIF1α, and PINK1. SUMOylation mediated by the SUMO molecule has attracted much attention due to its dual roles in the development of cardiovascular diseases. In this review, we systemically summarize the current understanding underlying the expression, regulation, and structure of SUMO molecules; explore the biochemical functions of SUMOylation in the initiation and activation of mitophagy; discuss the biological roles and mechanisms of SUMOylation in cardiovascular diseases; and further provide a wider explanation of SUMOylation and deSUMOylation research to provide a possible therapeutic strategy for cardiovascular diseases. Considering the precise functions and exact mechanisms of SUMOylation in mitochondrial dysfunction and mitophagy will provide evidence for future experimental research and may serve as an effective approach in the development of novel therapeutic strategies for cardiovascular diseases. Regulation and effect of SUMOylation in cardiovascular diseases via mitophagy. SUMOylation is involved in multiple cardiovascular diseases, including cardiac hypertrophy, hypertension, atherosclerosis, and cardiac ischemia-reperfusion injury. Since it is expressed in multiple cells associated with cardiovascular disease, SUMOylation can be regulated by numerous ligases, including the SENP family proteins PIAS1, PIASy/4, UBC9, and MAPL. SUMOylation regulates the activation and degradation of PINK1, SERCA2a, PPARγ, ERK5, and DRP1 to mediate mitochondrial dynamics, especially mitophagy activation. Mitophagy activation regulated by SUMOylation further promotes or inhibits ventricular diastolic dysfunction, perfusion injury, ventricular remodelling and ventricular noncompaction, which contribute to the development of cardiovascular diseases.

Identification of Natural Products as SENP2 Inhibitors for Targeted Therapy in Heart Failure

Aims: Sentrin-specific protease -2 (SENP2) is involved in deSUMOylation. Increased deSUMOylation in murine hearts by SENP2 upregulation resulted in cardiac dysfunction and congenital heart defects. Natural compounds via regulating cell proliferation and survival, induce cell cycle cessation, cell death, apoptosis, and producing reactive oxygen species and various enzyme systems cause disease prevention. Then, natural compounds can be suitable inhibitors and since SENP2 is a protein involved in heart disease, so our aim was inhibition of SENP2 by natural products for heart disease treatment. Material and methods: Molecular docking and molecular dynamics simulation of natural products i.e. Gallic acid (GA), Caffeic acid (CA), Thymoquinone (TQ), Betanin, Betanidin, Fisetin, and Ebselen were done to evaluate the SENP2 inhibitory effect of these natural products. The toxicity of compounds was also predicted. Results: The results showed that Betanin constituted a stable complex with SENP2 active site as it revealed low RMSD, high binding energy, and hydrogen bonds. Further, as compared to Ebselen, Betanin demonstrated low toxicity, formed a stable complex with SENP2 via four to seven hydrogen bonds, and constituted more stable MD plots. Therefore, depending upon the outcomes presented herein, Betanin significantly inhibited SENP2 and hence may be considered as a suitable natural compound for the treatment of heart failure. Further clinical trials must be conducted to validate its use as a potential SENP2 inhibitor.

SUMOylation involves in β-arrestin-2-dependent metabolic regulation in breast cancer cell

β-arrestin-2, a multifunctional adaptor protein, was originally identified as a negative regulator of G protein-mediated signaling. We previously revealed that SUMOylation as a novel mechanism modulates β-arrestin-2-mediated IL-1R/TRAF6 signaling. However, the potential role of β-arrestin-2 SUMOylation in tumor cells was incompletely explored. In this study, we showed that SUMOylation deficiency of β-arrestin-2 resulted in slower migration of breast cancer cells, but little effect on the cell proliferation. Importantly, our data indicated that SUMOylation involves in β-arrestin-2-dependent metabolic regulation, suggesting a potent regulatory pattern for β-arrestin-2-mediated biological functions of tumor cells.

Differential Expression of Seven De-sumoylation Enzymes (SENPs) in Major Ocular Tissues of Mouse Eye

PURPOSE

Protein Sumoylation is one of the most important and prevalent posttranscriptional modification. Increasing evidence have shown that the SENPs (sentrin/SUMOspecific proteases) are critical for steady-state levels of SUMO modification of target proteins, and protein de-sumoylation modulates a great diversity of biological processes including transcription, development, differentiation, neuroprotection, as well as pathogenesis. In the vertebrate eye, we and others have previously shown that sumoylation participated in the differentiation of major ocular tissues including retina and lens. However, the biological significance of seven SENP enzymes: SENP1 to 3 and SENP5 to 8 have not be fully investigated in the ocular tissues.

METHODS

The 5 major ocular cell lines were cultured in Dulbecco's modified Eagle's medium (DMEM) containing fetal bovine serum (FBS) or rabbit serum (RBS) and 1% Penicillin- Streptomycin. The mRNA levels were analysed with qRT-PCR. The protein levels were determined with western blot analysis and quantitated with Image J.

RESULTS

At the mRNA level, all SENPs were highly expressed in retina, and much reduced expression patterns in cornea, lens epithelium and lens fiber. At the protein level, SENP1 to -3, and SENP6 were highly abundant in cornea, while SENP5, SENP7 and SENP8 were enriched in retina, and these SENPs were relatively less abundant in lens tissues.

CONCLUSION

Our results for the first time established the differentiation expression patterns of the 7 de-sumoylation enzymes (SENPs), which provides a basis for further investigation of protein desumoylation functions in vertebrate eye.

DIAPH3 promotes the tumorigenesis of lung adenocarcinoma

Aberrant activation of MEKK-MEK-ERK signaling is frequently observed in lung cancer. Several inhibitors, which target this pathway, have shown clinical potential for the lung cancer treatment. Better understanding the regulation of this pathway would help the development of treatment strategies. In this study, we have identified the DIAPH3 as an up-regulated gene in lung adenocarcinoma. DIAPH3 promoted the growth of lung cancer cells both in the liquid culture and in the soft agar, and knockdown DIAPH3 inhibited the tumorigenesis both in the nude mice and in the de novo mouse model. In the molecular mechanism study, DIAPH3 was identified as the binding protein of STK38, impaired the interaction between STK38 and MEKK, and activated ERK signaling. Taken together, this study demonstrated the oncogenic roles of DIAPH3 in the tumorigenesis of lung cancer by interacting with STK38.

SUMOylation is required for PIPK1γ-driven keratinocyte migration and growth

PIPKIγ, a key member of the type I phosphatidylinositol 4-phosphate kinase (PIPKI) family that regulates the spatial-temporal generation of PIP2, has been implicated in diverse biological processes including cell survival, cell polarity, and cell migration. An essential role of PIPKIγ in tumor cells and nerve cells has been established in previous studies. However, the function and regulatory mechanism of PIPKIγ remains incompletely understood. Here, we showed that PIPKIγ can specifically associate with the SUMO-conjugating (E2) enzyme UBC9 and can be SUMOylated both in vivo and in vitro. We further identified that Lys-591 is the critical SUMO-acceptor site of PIPKIγ and that SUMO conjugation at this site is required for PIPKIγ-driven keratinocyte migration and growth. Mechanistically, SUMOylation deficiency significantly disrupts PIPKIγ-mediated generation of intracellular PIP2, rather than the subcellular translocation and protein stability of PIPKIγ. Our findings reveal that PIPKIγ is a novel SUMOylation target and highlight the essential role of PIPKIγ SUMOylation in human keratinocyte function, providing an important orientation for in-depth study of wound repair.