Annexin-1 regulated by HAUSP is essential for UV-induced damage response

Mitigative Effects of l-Arginine and N-Acetyl Cysteine against Cisplatin-Induced Testicular Dysfunction and Toxicity through the Regulation of Antioxidant, Anti-inflammatory, and Antiapoptotic Markers: Role of miR-155 and miR-34c Expression

Testicular dysfunction is a common adverse effect of cisplatin (CIS) administration as a chemotherapeutic drug. The current study has outlined the role of micro-RNAs (miR-155 and 34c) in CIS-induced testicular dysfunction and evaluated the protective effect of N-acetyl cysteine (NAC) and/or l-arginine (LA). Seven groups of Albino rats were used for this study. The control (C) group received physiological saline; the CIS group was injected CIS (7 mg/kg IP, once) on day 21 of the experiment; the NAC group was administered NAC (150 mg/kg intragastric, for 28 days); and the LA group was injected LA (50 mg/kg IP, for 28 days). NAC+CIS, LA+CIS, and NAC+LA+CIS groups received the above regime. CIS significantly reduced serum testosterone, LH, and FSH concentrations with decline of testicular enzyme activities. CIS caused significant elevation in testicular oxidative-stress biomarkers, inflammation-associated cytokines, and apoptosis markers, along with overexpression of miR-155 and low miR-34c expression. Additionally, marked testicular degenerative changes were observed in the examined histological section; a significant decrease in the expression of PCNA with significant increase in expressions of F4/80 and BAX was confirmed. The administration of NAC or LA upregulated testicular functions and improved histopathological and immunohistochemical changes as well as miRNA expression compared with the CIS-administered group. Rats receiving both NAC and LA showed a more significant ameliorative effect compared with groups receiving NAC or LA alone. In conclusion, NAC or LA showed an ameliorative effect against CIS-induced testicular toxicity and dysfunction through the regulation of antioxidant, anti-inflammatory, and antiapoptotic markers and via modulating miR-155 and miR-34c expression.

Tau: More than a microtubule-binding protein in neurons

Tau protein was discovered as a microtubule-associated protein nearly 50 years ago, and our understanding of tau has revolved around that role. Even with tau's rise to stardom as a central player in neurodegenerative disease, therapeutic efforts have largely been targeted toward cytoskeletal changes. While some studies hinted toward non-cytoskeletal roles for tau, it is only fairly recently that these ideas have begun to receive considerable attention. Many new binding partners for tau have been identified, including DNA, RNA, RNA-binding proteins, some receptors, and other tau molecules. The diversity of tau binding partners coupled with the discovery of tau other than axonal compartments such as nucleus, dendrites, and synapses have led to the proposal of novel functions for tau in roles such as nuclear stability, cell signaling, transcriptional processing, and protein synthesis. Tau self-assembly in particular has made an impact, leading to the hypothesis that a prion-like function of hyperphosphorylated tau is central to tauopathies. With tau emerging as a multifaceted protein that operates in many parts of the cell and with many molecular partners, the field of tau biology is primed for discoveries that can provide new perspectives on both the unique biochemistry of tau and the nature of devastating neurological diseases.

Current and future directions of USP7 interactome in cancer study

The ubiquitin-proteasome system (UPS) is an essential protein quality controller for regulating protein homeostasis and autophagy. Ubiquitination is a protein modification process that involves the binding of one or more ubiquitins to substrates through a series of enzymatic processes. These include ubiquitin-activating enzymes (E1), ubiquitin-conjugating enzymes (E2), and ubiquitin ligases (E3). Conversely, deubiquitination is a reverse process that removes ubiquitin from substrates via deubiquitinating enzymes (DUBs). Dysregulation of ubiquitination-related enzymes can lead to various human diseases, including cancer, through the modulation of protein ubiquitination. The most structurally and functionally studied DUB is the ubiquitin-specific protease 7 (USP7). Both the TRAF and UBL domains of USP7 are known to bind to the [P/A/E]-X-X-S or K-X-X-X-K motif of substrates. USP7 has been shown to be involved in cancer pathogenesis by binding with numerous substrates. Recently, a novel substrate of USP7 was discovered through a systemic analysis of its binding motif. This review summarizes the currently discovered substrates and cellular functions of USP7 in cancer and suggests putative substrates of USP7 through a comprehensive systemic analysis.

USP7 - a crucial regulator of cancer hallmarks

Over the course of three decades of study, the deubiquitinase Herpesvirus associated Ubiquitin-Specific Protease/Ubiquitin-Specific Protease 7 (HAUSP/USP7) has gradually come to be recognized as a crucially important molecule in cellular physiology. The fact that USP7 is overexpressed in a number of cancers, including breast, prostate, colorectal, and lung cancers, supports the idea that USP7 is also an important regulator of tumorigenesis. In this review, we discuss USP7's function in relation to the cancer hallmarks described by Hanahan and Weinberg. This post-translational modifier can support increased proliferation, block unfavorable growth signals, stop cell death, and support an unstable cellular genome by manipulating key players in the pertinent signalling circuit. It is interesting to note that USP7 also aids in the stabilization of molecules that support angiogenesis and metastasis. Targeting USP7 has now emerged as a crucial component of USP7 research because pharmacological inhibition of USP7 supports p53-mediated cell cycle arrest and apoptosis. Efficacious USP7 inhibition is currently being investigated in both synthetic and natural compounds, but issues with selectivity and a lack of co-crystal structure have hindered USP7 inhibition from being tested in clinical settings. Moreover, the development of new, more effective USP7 inhibitors and their encouraging implications by numerous groups give us a glimmer of hope for USP7-targeting medications as effective substitutes for hazardous cancer chemotherapeutics.

Cisplatin-induced azoospermia and testicular damage ameliorated by adipose-derived mesenchymal stem cells

BACKGROUND

The testes are highly susceptible to the adverse effects of chemotherapy and radiation at all stages of life. Exposure to these threats mainly occurs during cancer treatment and as an occupational hazard in radiation centers. The present study investigated the regenerative ability of adipose-derived mesenchymal stem cells (ADMSCs) against the adverse effects of cisplatin on the structure and function of the testes.

METHODS

New Zealand white rabbits (N = 15) were divided into three groups of five: a negative control group (no treatment), a cisplatin group (single dose of cisplatin into each testis followed three days later by a PBS injection), and a cisplatin + ADMSCs group (cisplatin injection followed three days later by an ADMSC injection). On day 45 post-treatment, serum testosterone levels were evaluated, and the testes and epididymis were collected for histology, oxidative stress examination, and epididymal sperm analysis.

RESULTS

Cisplatin caused damage to the testicular tissue and decreased serum testosterone levels, epididymal sperm counts, and oxidants. An antioxidant imbalance was detected due to increasing malondialdehyde (MDA) and reduced glutathione (GSH) levels in testicular tissue. The ADMSC-treated group displayed a moderate epididymal sperm count, adequate antioxidant protection, suitable hormone levels, and enhanced testicular tissue morphology.

CONCLUSIONS

ADMSCs treatment repaired damaged testicular tissue, enhanced biochemical parameters, and modified pathological changes caused by cisplatin.

USP7 regulates the ERK1/2 signaling pathway through deubiquitinating Raf-1 in lung adenocarcinoma

Ubiquitin-specific protease 7 (USP7) is one of the deubiquitinating enzymes (DUBs) in the ubiquitin-specific protease (USP) family. It is a key regulator of numerous cellular functions including immune response, cell cycle, DNA damage and repair, epigenetics, and several signaling pathways. USP7 acts by removing ubiquitin from the substrate proteins. USP7 also binds to a specific binding motif of substrate proteins having the [P/A/E]-X-X-S or K-X-X-X-K protein sequences. To date, numerous substrate proteins of USP7 have been identified, but no studies have been conducted using the binding motif that USP7 binds. In the current study, we analyzed putative substrate proteins of USP7 through the [P/A/E]-X-X-S and K-X-X-X-K binding motifs using bioinformatics tools, and confirmed that Raf-1 is one of the substrates for USP7. USP7 binds to the Pro-Val-Asp-Ser (PVDS) motif of the conserved region 2 (CR2) which contains phosphorylation sites of Raf-1 and decreased M1-, K6-, K11-, K27-, K33-, and K48-linked polyubiquitination of Raf-1. We further identified that the DUB activity of USP7 decreases the threonine phosphorylation level of Raf-1 and inhibits signaling transduction through Raf activation. This regulatory mechanism inhibits the activation of the ERK1/2 signaling pathway, thereby inhibiting the G2/M transition and the cell proliferation of lung adenocarcinoma cells. In summary, our results indicate that USP7 deubiquitinates Raf-1 and is a new regulator of the ERK1/2 signaling pathway in lung adenocarcinoma.

Protein phosphatase 2A regulated by USP7 is polyubiquitinated and polyneddylated

Ubiquitin‑specific protease 7 (USP7) participates in the ubiquitin‑proteasome system (UPS), and is considered an essential regulator of substrate stability in cancers. In a previous study, the substrates that bind to USP7 were separated through two‑dimensional electrophoresis (2‑DE), which resulted in the identification of protein phosphatase 2A (PP2A) through matrix‑assisted laser desorption‑ionization time‑of‑flight mass spectrometry (MALDI‑TOF/MS) analysis. In the present study, GST pull‑down assay was performed to determine whether USP7 and PP2A directly bind to each other. Immunocytochemistry assay confirmed that USP7 co‑localizes with PP2A in the cytoplasm and nucleus of HeLa cells. Moreover, western blotting and immunoprecipitation were performed to determine whether polyubiquitination and polyneddylation of PP2A were formed. The results of the present study demonstrated that USP7 was a deubiquitinating enzyme of PP2A, and regulated the ubiquitination and stability of PP2A through the K48‑linked polyubiquitin chains. Consequently, the knockdown of USP7 reduced the expression of PP2A. The data of the present study revealed the cellular association between USP7 and PP2A, a new substrate of USP7.

Annexin-A1; the culprit or the solution?

Annexin‐A1 has a well‐defined anti‐inflammatory role in the innate immune system, but its function in adaptive immunity remains controversial. This glucocorticoid‐induced protein has been implicated in a range of inflammatory conditions and cancers, as well as being found to be overexpressed on the T cells of patients with autoimmune disease. Moreover, the formyl peptide family of receptors, through which annexin‐A1 primarily signals, has also been implicated in these diseases. In contrast, treatment with recombinant annexin‐A1 peptides resulted in suppression of inflammatory processes in murine models of inflammation. This review will focus on what is currently known about annexin‐A1 in health and disease and discuss the potential of this protein as a biomarker and therapeutic target.

Acute Myeloid Leukemia-Related Proteins Modified by Ubiquitin and Ubiquitin-like Proteins

Acute myeloid leukemia (AML), the most common form of an acute leukemia, is a malignant disorder of stem cell precursors of the myeloid lineage. Ubiquitination is one of the post-translational modifications (PTMs), and the ubiquitin-like proteins (Ubls; SUMO, NEDD8, and ISG15) play a critical role in various cellular processes, including autophagy, cell-cycle control, DNA repair, signal transduction, and transcription. Also, the importance of Ubls in AML is increasing, with the growing research defining the effect of Ubls in AML. Numerous studies have actively reported that AML-related mutated proteins are linked to Ub and Ubls. The current review discusses the roles of proteins associated with protein ubiquitination, modifications by Ubls in AML, and substrates that can be applied for therapeutic targets in AML.

Ubiquitin-Specific Peptidase 7: A Novel Deubiquitinase That Regulates Protein Homeostasis and Cancers

Ubiquitin-Specific Peptidase 7 (USP7), or herpes virus-associated protease (HAUSP), is the largest family of the deubiquitinating enzymes (DUBs). Recent studies have shown that USP7 plays a vital role in regulating various physiological and pathological processes. Dysregulation of these processes mediated by USP7 may contribute to many diseases, such as cancers. Moreover, USP7 with aberrant expression levels and abnormal activity are found in cancers. Therefore, given the association between USP7 and cancers, targeting USP7 could be considered as an attractive and potential therapeutic approach in cancer treatment. This review describes the functions of USP7 and the regulatory mechanisms of its expression and activity, aiming to emphasize the necessity of research on USP7, and provide a better understanding of USP7-related biological processes and cancer.

Regulation of Cancer Metabolism by Deubiquitinating Enzymes: The Warburg Effect

Cancer is a disorder of cell growth and proliferation, characterized by different metabolic pathways within normal cells. The Warburg effect is a major metabolic process in cancer cells that affects the cellular responses, such as proliferation and apoptosis. Various signaling factors down/upregulate factors of the glycolysis pathway in cancer cells, and these signaling factors are ubiquitinated/deubiquitinated via the ubiquitin-proteasome system (UPS). Depending on the target protein, DUBs act as both an oncoprotein and a tumor suppressor. Since the degradation of tumor suppressors and stabilization of oncoproteins by either negative regulation by E3 ligases or positive regulation of DUBs, respectively, promote tumorigenesis, it is necessary to suppress these DUBs by applying appropriate inhibitors or small molecules. Therefore, we propose that the DUBs and their inhibitors related to the Warburg effect are potential anticancer targets.

Protein Stability of Pyruvate Kinase Isozyme M2 Is Mediated by HAUSP

The ubiquitin–proteasome system (UPS) is responsible for proteasomal degradation, regulating the half-life of the protein. Deubiquitinating enzymes (DUBs) are components of the UPS and inhibit degradation by removing ubiquitins from protein substrates. Herpesvirus-associated ubiquitin-specific protease (HAUSP) is one such deubiquitinating enzyme and has been closely associated with tumor development. In a previous study, we isolated putative HAUSP binding substrates by two-dimensional electrophoresis (2-DE) and identified them by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF/MS) analysis. The analysis showed that pyruvate kinase isoenzyme M2 (PKM2) was likely to be one of the substrates for HAUSP. Further study revealed that PKM2 binds to HAUSP, confirming the interaction between these proteins, and that PKM2 possesses the putative HAUSP binding motif, E or P/AXXS. Therefore, we generated mutant forms of PKM2 S57A, S97A, and S346A, and found that S57A had less binding affinity. In a previous study, we demonstrated that PKM2 is regulated by the UPS, and that HAUSP- as a DUB-acted on PKM2, thus siRNA for HAUSP increases PKM2 ubiquitination. Our present study newly highlights the direct interaction between HAUSP and PKM2.

Cytoprotective Effect of Ascorbic Acid and Rutin against Oxidative Changes in the Proteome of Skin Fibroblasts Cultured in a Three-Dimensional System

The combination of ascorbic acid and rutin, commonly used in oral preparations for their antioxidant and anti-inflammatory properties, can also be used to protect skin cells from the effects of UV radiation in sunlight. Here, we tested the potential protective effect of ascorbic acid and rutin used together in UVB-irradiated human skin fibroblasts, and assessed the proteomic profile of these cells, grown in a three-dimensional (3D) system. Proteomic findings revealed a combined effect of ascorbic acid and rutin in UV-irradiated fibroblasts against overexpression of pro-inflammatory signaling proteins and DNA reorganization/expression. These effects were not observed when cells were treated with either compounds alone. The antioxidant effects of ascorbic acid and rutin also prevented protein modifications by lipid peroxidation products. Further, ascorbic acid stimulated rutin-protein adduct formation, which supports intra/extracellular signaling and the Nrf2/ARE antioxidant pathway, contributing to the protective effects against UV-induced oxidative stress. The combined effect of ascorbic acid and rutin suggests that this combination of compounds is potentially effective against skin damage caused by UV radiation.

HAUSP promoted the growth of glioma cells in vitro and in vivo via stabilizing NANOG

OBJECTIVE

To investigate the role and mechanisms of HAUSP (Herpesvirus Associated Ubiquitin Specific Protease) and NANOG in pathogenesis of malignant human gliomas progression.

METHODS

Lentivirus-mediated HAUSP over-expression and RNAiHAUSP mediated HAUSP down-regulation were established in the glioma cells (U87 and U251 cell lines). Firstly, Real-time qPCR, western-blot (WB) and immunofluorescence staining were performed to detect mRNA levels, protein expressions and deposition of HAUSP and NANOG in the glioma cells, respectively. Then cell proliferation, invasion, apoptosis and xenograft tumor growth in nude mice were assessed by using cell counting kit-8 (CCK-8) assay, transwell assay, flow cytometry (FCM) and Hematoxylin-Eosin (HE) staining.

RESULTS

We first demonstrated HAUSP was significantly increased in lentivirus- mediated HAUSP over-expression cells compared to the Control group. HAUSP over-expression could upregulate genes involved in proliferation and invasion such as NANOG. However, the mRNA of NANOG had no significant changes. Similarly, in RNAiHAUSP mediated HAUSP down-regulation group, HAUSP were significantly decreased compared to the Control group. Simultaneously, NANOG protein were decreased significantly, which decreased the proliferation and invasion, increased the apoptosis rate of glioma cells. Finally, low expression of HAUSP could suppress xenograft tumors growth in nude mice in different periods.

CONCLUSION

This study revealed that HAUSP-NANOG pathway is a key target to inhibit glioma cells proliferation, and NANOG play important role in the formation and evolution of glioma cells. The regulation of HAUSP could change the biological activity of glioma cells through regulate NANOG expression.

Nuclear Tau, p53 and Pin1 Regulate PARN-Mediated Deadenylation and Gene Expression

While nuclear tau plays a role in DNA damage response (DDR) and chromosome relaxation, the mechanisms behind these functions are not fully understood. Here, we show that tau forms complex(es) with factors involved in nuclear mRNA processing such as tumor suppressor p53 and poly(A)-specific ribonuclease (PARN) deadenylase. Tau induces PARN activity in different cellular models during DDR, and this activation is further increased by p53 and inhibited by tau phosphorylation at residues implicated in neurological disorders. Tau's binding factor Pin1, a mitotic regulator overexpressed in cancer and depleted in Alzheimer's disease (AD), also plays a role in the activation of nuclear deadenylation. Tau, Pin1 and PARN target the expression of mRNAs deregulated in AD and/or cancer. Our findings identify novel biological roles of tau and toxic effects of hyperphosphorylated-tau. We propose a model in which factors involved in cancer and AD regulate gene expression by interactions with the mRNA processing machinery, affecting the transcriptome and suggesting insights into alternative mechanisms for the initiation and/or developments of these diseases.

Integrative genomic analysis identifies associations of molecular alterations to APOBEC and BRCA1/2 mutational signatures in breast cancer

BACKGROUND

The observed mutations in cancer are the result of ~30 mutational processes, which stamp particular mutational signatures (MS). Nevertheless, it is still not clear which genomic alterations correlate to several MS. Here, a method to analyze associations of genomic data with MS is presented and applied to The Cancer Genome Atlas breast cancer data revealing promising associations.

METHODS

The MS were discretized into clusters whose extremes were statistically associated with mutations, copy number, and gene expression data.

RESULTS

Known associations for apolipoprotein B editing complex (APOBEC) and for BRCA1 and BRCA2 support the proposal. For BRCA1/2, mutations in ARAP3, three focal deletions, and one amplification were detected. Around 50 mutated genes for the two APOBEC signatures were identified including three kinesins (KIF13A, KIF1B, KIF4A), three ubiquitins (USP45, UBR4, UBR1), and two demethylases (KDM5B, KDM5C) among other genes also connected to DNA damage pathways. The results suggest novel roles for other genes currently not involved in DNA repair. The altered expression program was very high for the BRCA1/2 signature, high for APOBEC signature 13 clearly associated to immune response, and low for APOBEC signature 2. The remaining signatures show scarce associations.

CONCLUSION

Specific genetic alterations can be associated with particular MS.

USP7: Novel Drug Target in Cancer Therapy

Ubiquitin specific protease 7 (USP7) is one of the deubiquitinating enzymes (DUB) that erases ubiquitin and protects substrate protein from degradation. Full activity of USP7 requires the C-terminal Ub-like domains fold back onto the catalytic domain, allowing the remodeling of the active site to a catalytically competent state by the C-terminal peptide. Until now, numerous proteins have been identified as substrates of USP7, which play a key role in cell cycle, DNA repair, chromatin remodeling, and epigenetic regulation. Aberrant activation or overexpression of USP7 may promote oncogenesis and viral disease, making it a target for therapeutic intervention. Currently, several synthetic small molecules have been identified as inhibitors of USP7, and applied in the treatment of diverse diseases. Hence, USP7 may be a promising therapeutic target for the treatment of cancer.

Single-cell transcriptomes of the regenerating intestine reveal a revival stem cell

The turnover of the intestinal epithelium is driven by multipotent LGR5⁺ crypt-base columnar cells (CBCs) located at the bottom of crypt zones¹. However, CBCs are lost following injury, such as irradiation², but the intestinal epithelium is nevertheless able to recover³. Thus, a second population of quiescent '+4' cells, or reserve stem cells (RSCs), has previously been proposed to regenerate the damaged intestine^4-7. Although CBCs and RSCs were thought to be mutually exclusive^4,8, subsequent studies have found that LGR5⁺ CBCs express RSC markers⁹ and that RSCs were dispensable-whereas LGR5⁺ cells were essential-for repair of the damaged intestine³. In addition, progenitors of absorptive enterocytes¹⁰, secretory cells^11-15 and slow cycling LGR5⁺ cells¹⁶ have been shown to contribute to regeneration whereas the transcriptional regulator YAP1, which is important for intestinal regeneration, was suggested to induce a pro-survival phenotype in LGR5⁺ cells¹⁷. Thus, whether cellular plasticity or distinct cell populations are critical for intestinal regeneration remains unknown. Here we applied single-cell RNA sequencing to profile the regenerating mouse intestine and identified a distinct, damage-induced quiescent cell type that we term the revival stem cell (revSC). revSCs are marked by high clusterin expression and are extremely rare under homoeostatic conditions, yet give rise-in a temporal hierarchy-to all the major cell types of the intestine, including LGR5⁺ CBCs. After intestinal damage by irradiation, targeted ablation of LGR5⁺ CBCs, or treatment with dextran sodium sulfate, revSCs undergo a YAP1-dependent transient expansion, reconstitute the LGR5⁺ CBC compartment and are required to regenerate a functional intestine. These studies thus define a unique stem cell that is mobilized by damage to revive the homoeostatic stem cell compartment and regenerate the intestinal epithelium.

Targeting the overexpressed USP7 inhibits esophageal squamous cell carcinoma cell growth by inducing NOXA-mediated apoptosis

Increasing evidence suggests that deubiquitinase USP7 participates in tumor progression by various mechanisms and serves as a potential therapeutic target. However, its expression and role in esophageal cancer remains elusive; the anti-cancer effect by targeting USP7 still needs to be investigated. Here, we reported that USP7 was overexpressed in esophageal squamous cell carcinoma (ESCC) tissues compared with adjacent tissues, implying that USP7 was an attractive anticancer target of ESCC. Pharmaceutical or genetic inactivation of USP7 inhibited esophageal cancer cells growth in vitro and in vivo and induced apoptosis. Mechanistically, inhibition of USP7 accumulated poly-ubiquitinated proteins, activated endoplasmic reticulum stress, and increased expression of ATF4, which transcriptionally upregulated expression of NOXA and induced NOXA-mediated apoptosis. These results provide an evidence for clinical investigation of USP7 inhibitors for the treatment of ESCC.

Targeting ubiquitin specific protease 7 in cancer: A deubiquitinase with great prospects

Deubiquitinase (DUB)-mediated cleavage of ubiquitin chain balances ubiquitination and deubiquitination for determining protein fate. USP7 is one of the best characterized DUBs and functionally important. Numerous proteins have been identified as potential substrates and binding partners of USP7; those play crucial roles in diverse array of cellular and biological processes including tumour suppression, cell cycle, DNA repair, chromatin remodelling, and epigenetic regulation. This review aims at summarizing the current knowledge of this wide association of USP7 with many cellular processes that enlightens the possibility of abnormal USP7 activity in promoting oncogenesis and the importance of identification of specific inhibitors.

Ubiquitin-specific peptidase 5 and ovarian tumor deubiquitinase 6A are differentially expressed in p53+/+ and p53-/- HCT116 cells

Most proteins undergo ubiquitination, a process by which ubiquitin proteins bind to their substrate proteins; by contrast, deubiquitination is a process that reverses ubiquitination. Deubiquitinating enzymes (DUBs) function to remove ubiquitin proteins from the protein targets and serve an essential role in regulating DNA repair, protein degradation, apoptosis and immune responses. Abnormal regulation of DUBs may affect a number of cellular processes and may lead to a variety of human diseases, including cancer. Therefore, it is important to identify abnormally expressed DUBs to identify DUB-related diseases and biological mechanisms. The present study aimed to develop a multiplex polymerase chain reaction screening platform comprising primers for various DUB genes. This assay was used to identify p53-related DUBs in HCT116 p53+/+ and p53-/- cells. The results demonstrated that ubiquitin-specific peptidase 5 (USP5) and ovarian tumor deubiquitinase 6A (OTUD6A) were differentially expressed in p53+/+ and p53-/- HCT116 cells. Based on the data obtained through DUB screening, the protein expression levels of USP5 and OTUD6A were examined by western blotting, which confirmed that both of these DUBs were also expressed differentially in p53+/+ and p53-/- HCT116 cells. In conclusion, results from the DUB screening performed by the present study revealed that the expression of USP5 and OTUD6A may be affected by p53, and this method may be useful for the rapid and cost-effective identification of possible biomarkers.

Ubiquitin specific protease 19 involved in transcriptional repression of retinoic acid receptor by stabilizing CORO2A

Deubiquitination via deubiquitinating enzymes (DUBs) has been emerged as one of the important post-translational modifications, resulting in the regulation of numerous target proteins. In this study, we screened new protein biomarkers for adipogenesis, and related studies showed that ubiquitin specific protease 19 (USP19) as a DUB is gradually decreased during adipogenesis and it regulates coronin 2A (CORO2A) as one of the components for the nuclear receptor co-repressor (NCoR) complex in some studies. The regulation of CORO2A through the deubiquitinating activity of USP19 affected the transcriptional repression activity of the retinoic acid receptor (RAR), suggesting that USP19 may be involved in the regulation of RAR-mediated adipogenesis.

Evaluation of miRNA-196a2 and apoptosis-related target genes: ANXA1, DFFA and PDCD4 expression in gastrointestinal cancer patients: A pilot study

Previous reports have suggested the significant association of miRNAs aberrant expression with tumor initiation, progression and metastasis in cancer, including gastrointestinal (GI) cancers. The current preliminary study aimed to evaluate the relative expression levels of miR-196a2 and three of its selected apoptosis-related targets; ANXA1, DFFA and PDCD4 in a sample of GI cancer patients. Quantitative real-time PCR for miR-196a2 and its selected mRNA targets, as well as immunohistochemical assay for annexin A1 protein expression were detected in 58 tissues with different GI cancer samples. In addition, correlation with the clinicopathological features and in silico network analysis of the selected molecular markers were analyzed. Stratified analyses by cancer site revealed elevated levels of miR-196a2 and low expression of the selected target genes. Annexin protein expression was positively correlated with its gene expression profile. In colorectal cancer, miR-196a over-expression was negatively correlated with annexin A1 protein expression (r = -0.738, p < 0.001), and both were indicators of unfavorable prognosis in terms of poor differentiation, larger tumor size, and advanced clinical stage. Taken together, aberrant expression of miR-196a2 and the selected apoptosis-related biomarkers might be involved in GI cancer development and progression and could have potential diagnostic and prognostic roles in these types of cancer; particularly colorectal cancer, provided the results experimentally validated and confirmed in larger multi-center studies.

Identification of two phosphorylation sites essential for annexin A1 in blood-brain barrier protection after experimental intracerebral hemorrhage in rats

Annexin A1 has been reported to exert a blood-brain barrier protection. This study was designed to examine the role of annexin A1 in intracerebral hemorrhage-induced blood-brain barrier dysfunction. A collagenase intracerebral hemorrhage model was performed in adult male Sprague Dawley rats. First, a possible relationship between annexin A1 and intracerebral hemorrhage pathology was confirmed by a loss of annexin A1 in the cerebrovascular endothelium and serum of intracerebral hemorrhage rats, and the rescue effects of i.v. administration of human recombinant annexin A1 in vivo and annexin A1 overexpression in vitro on the barrier function of brain microvascular endothelial cells exposed to intracerebral hemorrhage stimulus. Second, we found that intracerebral hemorrhage significantly increased the phosphorylation ratio of annexin A1 at the serine/threonine residues. Finally, based on site-specific mutagenesis, we identified two phosphorylation sites (a) annexin A1 phosphorylation at threonine 24 is required for its interaction with actin cytoskeleton, and (b) phosphorylation at serine27 is essential for annexin A1 secretion, both of which were essential for maintaining cytoskeleton integrity and paracellular permeability. In conclusion, annexin A1 prevents intracerebral hemorrhage-induced blood-brain barrier dysfunction in threonine 24 and serine27 phosphorylation-dependent manners. Annexin A1 phosphorylation may be a self-help strategy in brain microvascular endothelial cells after intracerebral hemorrhage; however, that was almost completely abolished by the intracerebral hemorrhage-induced loss of annexin A1.

Deubiquitinating enzyme USP37 regulating oncogenic function of 14-3-3γ

14-3-3 is a family of highly conserved protein that is involved in a number of cellular processes. In this study, we identified that the high expression of 14-3-3γ in various cancer cell lines correlates with the invasiveness of the cancer cells. Overexpression of 14-3-3γ causes changes to the morphologic characteristics of cell transformation, and promotes cell migration and invasion. The cells overexpressed with 14-3-3γ have been shown to stimulate foci and tumor formation in SCID-NOD mice in concert with signaling components as reported with the 14-3-3β. In our previous study, we demonstrated that 14-3-3γ inhibits apoptotic cell death and mediates the promotion of cell proliferation in immune cell lines. Earlier, binding partners for 14-3-3γ were defined by screening. We found that USP37, one of deubiquitinating enzymes (DUBs), belongs to this binding partner group. Therefore, we investigated whether 14-3-3γ mediates proliferation in cancer cells, and 14-3-3γ by USP37 is responsible for promoting cell proliferation. Importantly, we found that USP37 regulates the stability of ubiquitin-conjugated 14-3-3γ through its catalytic activity. This result implies that the interactive behavior between USP37 and 14-3-3γ could be involved in the regulation of 14-3-3γ degradation. When all these findings are considered together, USP37 is shown to be a specific DUB that prevents 14-3-3γ degradation, which may contribute to malignant transformation via MAPK signaling pathway, possibly providing a new target for therapeutic objectives of cancer.

The Antiapoptosis Effect of Glycyrrhizate on HepG2 Cells Induced by Hydrogen Peroxide

This study demonstrated that glycyrrhizate (GAS) could protect HEPG2 cells against damage and apoptosis induced by H₂O₂ (1600 μM, 4 h). Cell viability assay revealed that GAS was noncytotoxity at concentration 125 µg/mL, and GAS (5 μg/mL, 25 μg/mL, and 125 μg/mL) protected HepG2 cells against H₂O₂-induced cytotoxicity. H₂O₂ induced the HepG2 cells apoptosis, obvious morphologic changes were observed after Hochest 33258 staining, and more apoptotic cells were counted in flow cytometry assay compared to that of the natural group. Pretreatment GAS (5 μg/mL, 25 μg/mL, and 125 μg/mL) prior to H₂O₂ reverses the morphologic changes and reduced the apoptotic cells in HepG2 cells. GAS reduced the release of MDA, increased the activities of superoxide dismutase, and diminished the release of ALT and AST during oxidative stress in HepG2 cells. After Elisa kit detecting, GAS inhibited the caspase activity induced by H₂O₂, GAS decreased the level of caspase-3 and caspase-9 from mitochondria in dose-dependent manner. Western blot results showed that pretreatment GAS upregulated the expression of Bcl-2 and decreased the expression of Bax. These results reveal that GAS has the cytoprotection in HepG2 cells during ROS exposure by inhibiting the caspase activity in the mitochondria and influencing apoptogenic factors of the expression of Bax and Bcl-2.

Nuclear translocation of annexin 1 following oxygen-glucose deprivation-reperfusion induces apoptosis by regulating Bid expression via p53 binding

Previous data have suggested that the nuclear translocation of annexin 1 (ANXA1) is involved in neuronal apoptosis after ischemic stroke. As the mechanism and function of ANXA1 nuclear migration remain unclear, it is important to clarify how ANXA1 performs its role as an apoptosis 'regulator' in the nucleus. Here we report that importazole (IPZ), an importin β (Impβ)-specific inhibitor, decreased ANXA1 nuclear accumulation and reduced the rate of neuronal death induced by nuclear ANXA1 migration after oxygen-glucose deprivation-reoxygenation (OGD/R). Notably, ANXA1 interacted with the Bid (BH3-interacting-domain death agonist) promoter directly; however; this interaction could be partially blocked by the p53 inhibitor pifithrin-α (PFT-α). Accordingly, ANXA1 was shown to interact with p53 in the nucleus and this interaction was enhanced following OGD/R. A luciferase reporter assay revealed that ANXA1 was involved in the regulation of p53-mediated transcriptional activation after OGD/R. Consistent with this finding, the nuclear translocation of ANXA1 after OGD/R upregulated the expression of Bid, which was impeded by IPZ, ANXA1 shRNA, or PFT-α. Finally, cell-survival testing demonstrated that silencing ANXA1 could improve the rate of cell survival and decrease the expression of both cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase. These data suggested that Impβ-dependent nuclear ANXA1 migration participates in the OGD/R-dependent induction of neuronal apoptosis. ANXA1 interacts with p53 and promotes p53 transcriptional activity, which in turn regulates Bid expression. Silencing ANXA1 decreases the expression of Bid and suppresses caspase-3 pathway activation, thus improving cell survival after OGD/R. This study provides a novel mechanism whereby ANXA1 regulates apoptosis, suggesting the potential for a previously unidentified treatment strategy in minimizing apoptosis after OGD/R.

Mixed Lineage Leukemia 5 (MLL5) Protein Stability Is Cooperatively Regulated by O-GlcNac Transferase (OGT) and Ubiquitin Specific Protease 7 (USP7)

Mixed lineage leukemia 5 (MLL5) protein is a trithorax family histone 3 lysine 4 (H3K4) methyltransferase that regulates diverse biological processes, including cell cycle progression, hematopoiesis and cancer. The mechanisms by which MLL5 protein stability is regulated have remained unclear to date. Here, we showed that MLL5 protein stability is cooperatively regulated by O-GlcNAc transferase (OGT) and ubiquitin-specific protease 7 (USP7). Depletion of OGT in cells led to a decrease in the MLL5 protein level through ubiquitin/proteasome-dependent proteolytic degradation, whereas ectopic expression of OGT protein suppressed MLL5 ubiquitylation. We further identified deubiquitinase USP7 as a novel MLL5-associated protein using mass spectrometry. USP7 stabilized the MLL5 protein through direct binding and deubiquitylation. Loss of USP7 induced degradation of MLL5 protein. Conversely, overexpression of USP7, but not a catalytically inactive USP7 mutant, led to decreased ubiquitylation and increased MLL5 stability. Co-immunoprecipitation and co-immunostaining assays revealed that MLL5, OGT and USP7 interact with each other to form a stable ternary complex that is predominantly located in the nucleus. In addition, upregulation of MLL5 expression was correlated with increased expression of OGT and USP7 in human primary cervical adenocarcinomas. Our results collectively reveal a novel molecular mechanism underlying regulation of MLL5 protein stability and provide new insights into the functional interplay among O-GlcNAc transferase, deubiquitinase and histone methyltransferase.

HAUSP-nucleolin interaction is regulated by p53-Mdm2 complex in response to DNA damage response

HAUSP (herpes virus-associated ubiquitin specific protease, known as ubiquitin specific protease 7), one of DUBs, regulates the dynamics of the p53 and Mdm2 network in response to DNA damage by deubiquitinating both p53 and its E3 ubiquitin ligase, Mdm2. Its concerted action increases the level of functional p53 by preventing proteasome-dependent degradation of p53. However, the protein substrates that are targeted by HAUSP to mediate DNA damage responses in the context of the HAUSP-p53-Mdm2 complex are not fully identified. Here, we identified nucleolin as a new substrate for HAUSP by proteomic analysis. Nucleolin has two HAUSP binding sites in its N- and C-terminal regions, and the mutation of HAUSP interacting peptides on nucleolin disrupts their interaction and it leads to the increased level of nucleolin ubiquitination. In addition, HAUSP regulates the stability of nucleolin by removing ubiquitin from nucleolin. Nucleolin exists as a component of the HAUSP-p53-Mdm2 complex, and both Mdm2 and p53 are required for the interaction between HAUSP and nucleolin. Importantly, the irradiation increases the HAUSP-nucleolin interaction, leading to nucleolin stabilization significantly. Taken together, this study reveals a new component of the HAUSP-p53-Mdm2 complex that governs dynamic cellular responses to DNA damage.