Skeletal muscle gene expression in older adults with type 2 diabetes mellitus undergoing calorie-restricted diet and recreational sports training - a randomized clinical trial.

AIMS: This study aimed to evaluate the impact of a 12-week calorie-restricted diet and recreational sports training on gene expressions IL-15, ATROGIN-1 and MURF-1 in skeletal muscle of T2D patients. METHODS: Older adults with T2D (n = 39, 60 ± 6.0 years, BMI 33.5 ± 0.6 kg/m2) were randomly allocated to Diet+Soccer (DS), Diet+Running (DR) or Diet (D). The training sessions were moderate-to-high-intensity and performed 3 × 40 min/week for 12-weeks. Gene expression from vastus lateralis muscle obtained by qRT-PCR, dual-energy X-ray and fasting blood testing measurements were performed before and after 12-weeks. Statistical analysis adopted were two-way ANOVA and Paired t-test for gene expression, and RM-ANOVA test for the remainder variables. RESULTS: Total body weight was reduced in ~4 kg representing body fat mass in all groups after 12-weeks (P < 0.05). HbA1c values decreased in all groups post-intervention. Lipids profile improved in the training groups (P < 0.05) after 12-weeks. ATROGIN-1 and MURF-1 mRNA reduced in the DS (1.084 ± 0.14 vs. 0.754 ± 1.14 and 1.175 ± 0.34 vs. 0.693 ± 0.12, respectively; P < 0.05), while IL-15 mRNA increased in the DR (1.056 ± 0.12 vs. 1.308 ± 0.13; P < 0.05) after 12-weeks intervention. CONCLUSION: Recreational training with a moderate calorie-restricted diet can downregulates the expression of atrophy-associated myokines and increases the expression of anti-inflammatory gene IL-15.

E3 Ubiquitin Ligase Riplet Is Expressed in T Cells and Suppresses T Cell-Mediated Antitumor Immune Responses.

The E3 ubiquitin ligase Riplet mediates retinoic acid-inducible gene-I polyubiquitination and is essential for viral-induced expression of type I IFNs in dendritic cells and macrophages. The function of Riplet in innate immunity has been well demonstrated; however, its role in adaptive immunity during the antitumor immune response is unclear. In this study, we examined the role of Riplet in the T cell-mediated antitumor immune response. Riplet was expressed in T cells and upregulated in CD8+ T cells in response to TCR-mediated stimulation. Furthermore, PR domain containing 1, eomesodermin, and killer cell lectin-like receptor G1 expression was increased in effector CD8+ T cells by Riplet knockout in vitro, which suggests that Riplet is involved in the effector function of CD8+ T cells. Our results indicated that Riplet deficiency augmented the antitumor response of MO4 (OVA-expressing melanoma)-bearing mice treated with OVA peptide-pulsed dendritic cells. Moreover, both CD4+ and CD8+ T cells played important roles in Riplet-mediated augmentation of the antitumor immune response. In tumor-draining lymph nodes, the Th1 response was promoted, and the induction of OVA-specific CD8+ T cells and IFN-γ production were enhanced by Riplet deficiency. Furthermore, the IFN-γ response and OVA-specific cytotoxicity of CD8+ T cells in tumor tissue were augmented by Riplet deficiency. The expression of Cxcl9fluorescence-minus-one and Cxcl10 mRNA was also enhanced in the tumor microenvironment by Riplet knockout, consistent with the augmented recruitment of CTLs. Overall, we clarified a function of Riplet in T cells, which is to suppress the antitumor immune response through modulating Th1 and CTLs.

Proteasome inhibition-enhanced fracture repair is associated with increased mesenchymal progenitor cells in mice.

The ubiquitin/proteasome system controls the stability of Runx2 and JunB, proteins essential for differentiation of mesenchymal progenitor/stem cells (MPCs) to osteoblasts. Local administration of proteasome inhibitor enhances bone fracture healing by accelerating endochondral ossification. However, if a short-term administration of proteasome inhibitor enhances fracture repair and potential mechanisms involved have yet to be exploited. We hypothesize that injury activates the ubiquitin/proteasome system in callus, leading to elevated protein ubiquitination and degradation, decreased MPCs, and impaired fracture healing, which can be prevented by a short-term of proteasome inhibition. We used a tibial fracture model in Nestin-GFP reporter mice, in which a subgroup of MPCs are labeled by Nestin-GFP, to test our hypothesis. We found increased expression of ubiquitin E3 ligases and ubiquitinated proteins in callus tissues at the early phase of fracture repair. Proteasome inhibitor Bortezomib, given soon after fracture, enhanced fracture repair, which is accompanied by increased callus Nestin-GFP+ cells and their proliferation, and the expression of osteoblast-associated genes and Runx2 and JunB proteins. Thus, early treatment of fractures with Bortezomib could enhance the fracture repair by increasing the number and proliferation of MPCs.

Genome-Wide Identification, Characterization and Expression Analysis of Soybean CHYR Gene Family.

The CHYR (CHY ZINC-FINGER AND RING FINGER PROTEIN) proteins have been functionally characterized in iron regulation and stress response in Arabidopsis, rice and Populus. However, their roles in soybean have not yet been systematically investigated. Here, in this study, 16 GmCHYR genes with conserved Zinc_ribbon, CHY zinc finger and Ring finger domains were obtained and divided into three groups. Moreover, additional 2-3 hemerythrin domains could be found in the N terminus of Group III. Phylogenetic and homology analysis of CHYRs in green plants indicated that three groups might originate from different ancestors. Expectedly, GmCHYR genes shared similar conserved domains/motifs distribution within the same group. Gene expression analysis uncovered their special expression patterns in different soybean tissues/organs and under various abiotic stresses. Group I and II members were mainly involved in salt and alkaline stresses. The expression of Group III members was induced/repressed by dehydration, salt and alkaline stresses, indicating their diverse roles in response to abiotic stress. In conclusion, our work will benefit for further revealing the biological roles of GmCHYRs.

Wilms' tumor 1-associating protein complex regulates alternative splicing and polyadenylation at potential G-quadruplex-forming splice site sequences.

Wilms' tumor 1-associating protein (WTAP) is a core component of the N6-methyladenosine (m6A)-methyltransferase complex, along with VIRMA, CBLL1, ZC3H13 (KIAA0853), RBM15/15B, and METTL3/14, which generate m6A, a key RNA modification that affects various processes of RNA metabolism. WTAP also interacts with splicing factors; however, despite strong evidence suggesting a role of Drosophila WTAP homolog fl(2)d in alternative splicing (AS), its role in splicing regulation in mammalian cells remains elusive. Here we demonstrate using RNAi coupled with RNA-seq that WTAP, VIRMA, CBLL1, and ZC3H13 modulate AS, promoting exon skipping and intron retention in AS events that involve short introns/exons with higher GC content and introns with weaker polypyrimidine-tract and branch points. Further analysis of GC-rich sequences involved in AS events regulated by WTAP, together with minigene assay analysis, revealed potential G-quadruplex formation at splice sites where WTAP has an inhibitory effect. We also found that several AS events occur in the last exon of one isoform of MSL1 and WTAP, leading to competition for polyadenylation. Proteomic analysis also suggested that WTAP/CBLL1 interaction promotes recruitment of the 3'-end processing complex. Taken together, our results indicate that the WTAP complex regulates AS and alternative polyadenylation via inhibitory mechanisms in GC-rich sequences.

Bone Marrow-Derived Mesenchymal Stem Cells Ameliorate Sepsis-Induced Acute Kidney Injury by Promoting Mitophagy of Renal Tubular Epithelial Cells via the SIRT1/Parkin Axis.

Sepsis is a common risk factor for acute kidney injury (AKI). Bone marrow-derived mesenchymal stem cells (BMSCs) bear multi-directional differentiation potential. This study explored the role of BMSCs in sepsis-induced AKI (SI-AKI). A rat model of SI-AKI was established through cecal ligation and perforation. The SI-AKI rats were injected with CM-DiL-labeled BMSCs, followed by evaluation of pathological injury of kidney tissues and kidney injury-related indicators and inflammatory factors. HK-2 cells were treated with lipopolysaccharide (LPS) to establish SI-SKI model in vitro. Levels of mitochondrial proteins, autophagy-related proteins, NLRP3 inflammasome-related protein, and expressions of Parkin and SIRT1 in renal tubular epithelial cells (RTECs) of kidney tissues and HK-2 cells were detected. The results showed that BMSCs could reach rat kidney tissues and alleviate pathological injury of SI-SKI rats. BMSCs inhibited inflammation and promoted mitophagy of RTECs and HK-2 cells in rats with SI-AKI. BMSCs upregulated expressions of Parkin and SIRT1 in HK-2 cells. Parkin silencing or SIRT1 inhibitor reversed the promoting effect of BMSCs on mitophagy. BMSCs inhibited apoptosis and pyroptosis of RTECs in kidney tissues by upregulating SIRT1/Parkin. In conclusion, BMSCs promoted mitophagy and inhibited apoptosis and pyroptosis of RTECs in kidney tissues by upregulating SIRT1/Parkin, thereby ameliorating SI-AKI.

Genome-wide analysis of RING-type E3 ligase family identifies potential candidates regulating high amylose starch biosynthesis in wheat (Triticum aestivum L.).

In ubiquitin-mediated post-translational modifications, RING finger families are emerged as important E3 ligases in regulating biological processes. Amylose and amylopectin are two major constituents of starch in wheat seed endosperm. Studies have been found the beneficial effects of high amylose or resistant starch on health. The ubiquitin-mediated post-translational regulation of key enzymes for amylose/amylopectin biosynthesis (GBSSI and SBEII) is still unknown. In this study, the genome-wide analysis identified 1272 RING domains in 1255 proteins in wheat, which is not reported earlier. The identified RING domains classified into four groups-RING-H2, RING-HC, RING-v, RING-G, based on the amino acid residues (Cys, His) at metal ligand positions and the number of residues between them with the predominance of RING-H2 type. A total of 1238 RING protein genes were found to be distributed across all 21 wheat chromosomes. Among them, 1080 RING protein genes were identified to show whole genome/segmental duplication within the hexaploid wheat genome. In silico expression analysis using transcriptome data revealed 698 RING protein genes, having a possible role in seed development. Based on differential gene expression and correlation analysis of 36 RING protein genes in diverse (high and low) amylose mutants and parent, 10 potential RING protein genes found to be involved in high amylose biosynthesis and significantly associated with two starch biosynthesis genes; GBSSI and SBEIIa. Characterization of mutant lines using next-generation sequencing method identified unique mutations in 698 RING protein genes. This study signifies the putative role of RING-type E3 ligases in amylose biosynthesis and this information will be helpful for further functional validation and its role in other biological processes in wheat.

ZNRF2 attenuates focal cerebral ischemia/reperfusion injury in rats by inhibiting mTORC1-mediated autophagy.

Zinc and ring finger 2 (ZNRF2), an E3 ubiquitin ligase, plays a crucial role in many diseases. However, its role in cerebral ischemia/reperfusion injury (CIRI) still remains unknown. In this study, the function and molecular mechanism of ZNRF2 in CIRI in vivo and vitro was studied. ZNRF2 was found to be dramatically downregulated in CIRI. Overexpression of ZNRF2 could significantly reduce the neurological deficit, brain infarct volume and histopathological damage of cortex in middle cerebral artery occlusion/reperfusion. Concomitantly, overexpression of ZNRF2 increased the primary neuronal viability and decreased the neuronal apoptosis induced by oxygen-glucose deprivation and reoxygenation (OGD/R). Mechanistically, overexpression of ZNRF2 inhibited the over-induction of autophagy induced by OGD/R which was abolished by mTORC1 inhibitor rapamycin. It can be concluded that ZNRF2 plays a protective effect in CIRI and the underlying mechanism may be related to the inhibition of mTORC1-mediated autophagy.

Circ_0114428 Regulates Sepsis-Induced Kidney Injury by Targeting the miR-495-3p/CRBN Axis.

Septic acute kidney injury (AKI) is considered as a severe and common complication of sepsis, with complex pathogenesis. Recently, Circular RNA (circRNA) is considered to be implicated in this disease. This study was intended to elucidate the role of circ_0114428 and the potential mechanism of action in sepsis-induced kidney injury. Sepsis-induced kidney injury cell model was established in human kidney 2 (HK2) cells by the treatment of lipopolysaccharide (LPS). The expression of circ_0114428, CRBN mRNA, and miR-495-3p was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability was assessed by cell counting kit-8 (CCK-8) assay. The inflammatory response was monitored according to the release of proinflammatory factors by enzyme-linked immunosorbent assay (ELISA). Cell apoptosis was evaluated by flow cytometry assay. The activities of oxidative indicators were examined using the corresponding kits. Endoplasmic reticulum (ER) stress-related proteins and CRBN protein were quantified by western blot. RNA immunoprecipitation (RIP) assay was performed to ensure whether circ_0114428 could interact with Argonaute 2 (Ago2) protein. The potential miRNAs targeted by circ_0114428 were predicted by the bioinformatics tool and screened by RNA pull-down assay. The interaction between miR-495-3p and circ_0114428 or CRBN was validated by dual-luciferase reporter assay. The results showed that circ_0114428 and CRBN were upregulated in septic AKI serum specimens and LPS-induced HK2 cells. Circ_0114428 knockdown attenuated LPS-induced apoptosis, inflammation, oxidative stress, and ER stress, which were rescued by CRBN overexpression. Further analysis revealed that miR-495-3p was targeted by circ_0114428 and directly bound to CRBN, and circ_0114428 regulated CRBN expression by sponging miR-495-3p. Besides, miR-495-3p inhibition also reversed the effects of circ_0114428 knockdown. In conclusion, circ_00114428 knockdown attenuated LPS-induced HK2 cell injury by regulating CRBN expression via targeting miR-495-3p.

E3 ubiquitin ligase PJA1 regulates lung adenocarcinoma apoptosis and invasion through promoting FOXR2 degradation.

Among all lung cancer cases, lung adenocarcinoma (LAC) represents nearly 40% and remains the leading cause of cancer deaths worldwide. Although the combination therapy of surgical treatment with radiotherapy, chemotherapy, and immunotherapy, has been used to treat LAC, unfortunately, high recurrence rates and poor survival remain. Therefore, novel prognostic markers and new targets for molecular targeted therapy in LAC is urgently needed. Fork-head box R2 (FOXR2) plays a key role in a wide range of cellular processes, including cellular proliferation, invasion, differentiation, and apoptosis, and it has been reported to be implicated in progression of LAC, thus inhibition of FOXR2 may be a novel targeting therapy for lung cancer. This current study found that E3 ligase PJA1 regulates ubiquitin-mediated degradation of FOXR2 and predicts good outcome of patients with LAC. In addition, it was showed force expression of PJA1 significantly inhibited LAC cells invasion and induced apoptosis in vitro through inactivating Wnt/ß-catenin signaling pathway. In short, our findings reveal that PJA1 could be a potential diagnostic and prognostic biomarkers and the PJA1- FOXR2 axis could be served as a promising target for LAC therapy.

E3 ubiquitin ligase Grail promotes hepatic steatosis through Sirt1 inhibition.

In obese adults, nonalcoholic fatty liver disease (NAFLD) is accompanied by multiple metabolic dysfunctions. Although upregulated hepatic fatty acid synthesis has been identified as a crucial mediator of NAFLD development, the underlying mechanisms are yet to be elucidated. In this study, we reported upregulated expression of gene related to anergy in lymphocytes (GRAIL) in the livers of humans and mice with hepatic steatosis. Grail ablation markedly alleviated the high-fat diet-induced hepatic fat accumulation and expression of genes related to the lipid metabolism, in vitro and in vivo. Conversely, overexpression of GRAIL exacerbated lipid accumulation and enhanced the expression of lipid metabolic genes in mice and liver cells. Our results demonstrated that Grail regulated the lipid accumulation in hepatic steatosis via interaction with sirtuin 1. Thus, Grail poses as a significant molecular regulator in the development of NAFLD.

Knockdown of TRIM32 inhibits tumor growth and increases the therapeutic sensitivity to temozolomide in glioma in a p53-dependent and -independent manner.

Tripartite motif protein 32 (TRIM32), an E3 ubiquitin ligase, has been reported to participate in many human cancers. However, the underlying role of TRIM32 in glioma remains largely unknown. Here, we aimed to explore the function of TRIM32 in glioma cells and the clinical implications and found that TRIM32 was upregulated in glioma tissues. Consistently, overexpression of TRIM32 promoted glioma U87 and U251 cell proliferation and conferred cell resistance to temozolomide (TMZ). Conversely, knockdown of TRIM32 inhibited glioma cells proliferation in vitro and in vivo and sensitized glioma cells to the treatment of TMZ in a p53-dependent and -independent manner. Mechanistically, knockdown of TRIM32 induced apoptosis of U87 an U251 cells. In addition, TRIM32 interacted with the antiapoptotic proteins BCL-xL and BCL-w, which antagonized the inhibitory effect of TRIM32 knockdown in U87 cells. Together, our study uncovered the role of TRIM32 in glioma and TRIM32 may be a potential therapeutic target for gliomas.

Circular RNA circRNA_101996 promoted cervical cancer development by regulating miR-1236-3p/TRIM37 axis.

Circular RNAs (circRNAs) appear to be significant modulators in various physiological processes. Recently, it is found that circRNA_101996 exerts important roles in various cancers. Our previous studies showed that circRNA_101996 promoted cervical cancer growth and metastasis by regulating miR-8075/TPX2. However, the potential regulatory role of circRNA_101996 in cervical cancer still needs further investigation. Our results in this study suggested that circRNA_101996 was over-expressed in cervical cancer patients. circRNA_101996 up-regulation remarkably assisted cell proliferation, cell cycle progression, and cell migration in cervical cancer, while circRNA_101996 knockdown exerted the inverse effects. The molecular investigations indicated that circRNA_101996 could increase the expression level of miR-1236-3p, tripartite motif-containing 37 (TRIM37), through binding to miR-1236-3p and reducing its expression. Moreover, in vivo results demonstrated that circRNA_101996 shRNA can function as a tumor suppressor through down-regulating TRIM37 in cervical cancer. In conclusion, our data indicated that circRNA_101996/miR-1236-3p/TRIM37 axis accelerated cervical cancer development, providing novel insights into cervical cancer diagnosis and treatment.

Overexpression of the TRIM24 E3 Ubiquitin Ligase is Linked to Genetic Instability and Predicts Unfavorable Prognosis in Prostate Cancer.

Tripartite motif containing 24 (TRIM24) is a multifunctional protein involved in p53 degradation, chromatin binding, and transcriptional modulation of nuclear receptors. Emerging research has revealed that upregulation of TRIM24 in numerous tumor types is linked to poor prognosis, attributing an important role to TRIM24 in tumor biology. In order to better understand the role of TRIM24 in prostate cancer, we analyzed its immunohistochemical expression on a tissue microarray containing >17,000 prostate cancer specimens. TRIM24 immunostaining was detectable in 61% of 15,321 interpretable cancers, including low expression in 46% and high expression in 15% of cases. TRIM24 upregulation was associated with high Gleason grade, advanced pathologic tumor stage, lymph node metastasis, higher preoperative prostate-specific antigen level, increased cell proliferation as well as increased genomic instability, and predicted prognosis independent of clinicopathologic parameters available at the time of the initial biopsy (all P<0.0001). TRIM24 upregulation provides additional prognostic information in prostate cancer, particularly in patients with low Gleason grade tumors who may be eligible for active surveillance strategies, suggesting promising potential for TRIM24 in the routine diagnostic work-up of these patients.

Circular RNA ITCH suppresses metastasis of gastric cancer via regulating miR-199a-5p/Klotho axis.

Circular RNAs (circRNAs) are considered as a new regulatory factor in growth, metastasis and therapeutic resistance of human cancers. But the clinical significance and underlying mechanism of circular RNA ITCH (circ-ITCH) in gastric cancer (GC) remain unknown. In the present study, we found that circ-ITCH was down-regulated in GC cell lines, GC tissues and their serum-derived exosomes. The level of circ-ITCH was related to invasion depth. Functional assays showed that circ-ITCH overexpression inhibited the proliferation, migration, invasion and epithelial mesenchymal transition (EMT) of GC cells, whereas circ-ITCH knockdown appeared an opposite effect. Bioinformatic analysis and luciferase reporter assay confirmed that circ-ITCH acted as miR-199a-5p sponge and increased the level of Klotho. The expression level of miR-199-5p was up-regulated in GC tissues and negatively correlated with that of circ-ITCH. MiR-199a-5p mimics reversed the effects on inhibiting metastasis induced by circ-ITCH overexpression and decreased the level of Klotho in GC cells. Our findings indicate that circ-ITCH suppresses metastasis of GC by acting as the sponge of miR-199a-5p and increasing Klotho expression, which serves as a potential biomarker and targets for the diagnosis and therapy of GC.Abbreviations: CircRNAs: circular RNAs; GC: gastric cancer; circ-ITCH: circular RNA Itchy E3 ubiquitin protein ligase; ceRNA: competitive endogenous RNA; EMT: Epithelial-mesenchymal transition; siRNA: Small interfering RNA; TEM: transmission electron microscope; NTA: nanoparticle tracking analysis.

SCF-Slimb is critical for Glycogen synthase kinase-3ß-mediated suppression of TAF15-induced neurotoxicity in Drosophila.

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disorder characterized pathologically by motor neuron degeneration and associated with aggregation of RNA-binding proteins. TATA-binding protein-associated factor 15 (TAF15) accumulates as cytoplasmic aggregates in neuronal cells, and clearance of these aggregates is considered a potential therapeutic strategy for ALS. However, the exact pathogenic mechanism of TAF15-induced neurotoxicity remains to be elucidated. Glycogen synthase kinase-3 (GSK-3) plays a critical role in the protection of ALS pathology. In the present study, we use a transgenic fly model over-expressing human TAF15 to study the protective effects of Shaggy/GSK3ß on TAF15-induced neuronal toxicity in Drosophila brain. Transgenic flies were examined for locomotor activity and lithium treatment. The expression level and solubility of TAF15 were assessed with western blotting, whereas immunohistochemistry was used to assess TAF15 aggregation in Drosophila brain. We have revealed that Shaggy/GSK3ß was abnormally activated in neurons of TAF15-expressing flies and its inhibition can suppress the defective phenotypes, thereby preventing retinal degeneration and locomotive activity caused by TAF15. We have also found that Shaggy/GSK3ß inhibition in neuronal cells leads to a reduction in TAF15 levels. Indeed, the F-box proteins Slimb and archipelago genetically interact with TAF15 and control TAF15 protein level in Drosophila. Importantly, SCFslimb is a critical regulator for Shaggy/GSK3ß-mediated suppression of TAF15-induced toxicity in Drosophila. The present study has provided an in vivo evidence supporting the molecular mechanism of GSK3ß inhibition for protection against TAF15-linked proteinopathies.

CHIP-mediated CIB1 ubiquitination regulated epithelial-mesenchymal transition and tumor metastasis in lung adenocarcinoma.

CIB1 is a homolog of calmodulin that regulates cell adhesion, migration, and differentiation. It has been considered as an oncogene in many tumor cells; however, its role in lung adenocarcinoma (LAC) has not been studied. In this study, the expression levels of CIB1 in LAC tissues and adjacent normal tissues were examined by immunohistochemistry, and the relationship between CIB1 expression and patient clinicopathological characteristics was analyzed. The effects of CIB1 on epithelial-mesenchymal transition (EMT), migration, and metastasis of LAC cells were determined in vitro and vivo. Proteins interacting with CIB1 were identified using electrospray mass spectrometry (LS-MS), and CHIP was selected in the following assays. Carboxyl-terminus of Hsp70-interacting protein (CHIP) is a ubiquitin E3 ligase. We show that CHIP can degrade CIB1 via promoting polyubiquitination of CIB1 and its subsequent proteasomal degradation. Besides, lysine residue 10 and 65 of CIB1 is the ubiquitinated site of CIB1. Furthermore, CHIP-mediated CIB1 downregulation is critical for the suppression of metastasis and migration of LAC. These results indicated that CHIP-mediated CIB1 ubiquitination could regulate epithelial-mesenchymal and tumor metastasis in LAC.

MicroRNA-221 Promotes Cell Proliferation and Inhibits Apoptosis in Osteosarcoma Cells by Directly Targeting FBXW11 and Regulating Wnt Signaling.

BACKGROUND AND OBJECTIVES: MicroRNAs play a crucial role in the progression of various cancers, and microRNA-221 (miR-221) has been observed to be significantly overexpressed in osteosarcoma (OS) cells. FBXW11, a vital F-box protein of the ubiquitin-proteasome system, mediates the proliferation and survival of cancer cells by targeting multiple substrates for degradation. FBXW11 inhibits OS growth and metastasis by antagonizing the ß-catenin/Wnt signaling pathway. Therefore, we hypothesized that miR-221 targets FBXW11 to mediate Wnt signaling and promote OS proliferation. METHODS: In this study, we demonstrated the increased expression of miR-221 and FBXW11 in OS tissues and cell lines by real-time polymerase chain reaction (RT-PCR). Moreover, to elucidate the regulatory mechanism(s) of miR-221 and FBXW11 in progression, cell viability and apoptosis were analyzed by the MTT assay and flow cytometry, respectively. RESULTS: The results showed that the overexpression of miR-221 in OS cells dramatically promoted cell growth and cell cycle progression, and inhibited apoptosis, whereas miR-221 inhibitors conversely inhibited proliferation and promoted apoptosis in OS cells. The data also showed that FBXW11 directly targeted miR-221 and miR-221 regulated OS cell proliferation and apoptosis by binding to FBXW11. We further confirmed that miR-221 targeted FBXW11 to promote proliferation and inhibit apoptosis in OS cell lines by inhibiting Wnt signaling. INTERPRETATION AND CONCLUSIONS: Overall, our study revealed a functional mechanism for miR-221 in OS. Further studies will elucidate its role in the progression of OS and inhibiting miR-221 may represent a useful treatment strategy.

Epigenetic modification and a role for the E3 ligase RNF40 in cancer development and metastasis.

RNF40 (OMIM: 607700) is a really interesting new gene (RING) finger E3 ubiquitin ligase containing multiple coiled-coil domains and a C-terminal RING finger motif, which engage in protein-DNA and protein-protein interactions. RNF40 encodes a polypeptide of 1001 amino acids with a predicted molecular mass of 113,678 Da. RNF40 and its paralog RNF20 form a stable heterodimer complex that can monoubiquitylate histone H2B at lysine 120 as well as other nonhistone proteins. Cancer is a major public health problem and the second leading cause of death. Through its protein ubiquitylation activity, RNF40 acts as a tumor suppressor or oncogene to play major epigenetic roles in cancer development, progression, and metastasis, highlighting the essential function of RNF40 and the importance of studying it. In this review, we summarize current knowledge about RNF40 gene structure and the role of RNF40 in histone H2B monoubiquitylation, DNA damage repair, apoptosis, cancer development, and metastasis. We also underscore challenges in applying this information to cancer prognosis and prevention and highlight the urgent need for additional investigations of RNF40 as a potential target for cancer therapeutics.

Parkin overexpression alleviates cardiac aging through facilitating K63-polyubiquitination of TBK1 to facilitate mitophagy.

Cumulative clinical and experimental evidence has revealed a cardinal role for mitochondrial integrity in cardiac aging. Parkin-mediated mitophagy is essential to ensure mitochondrial quality control in myocardium. This study was designed to examine the impact of Parkin overexpression on aging-induced myocardial anomalies and the underlying mechanisms with a focus on Parkin-regulated mitophagy. Cardiac function, myocardial apoptosis, mitochondrial ultrastructure and mitophagy were examined in young (3 mo) and old (24-26 mo) wild-type (WT) and Parkin transgenic mice. Our data revealed compromised myocardial function and mitochondrial morphology along with overtly apoptosis with advanced aging, the effects of which were attenuated by Parkin overexpression. Advanced aging dampened mitophagy as evidenced by decreased levels of Parkin, LC3II, phosphorylation of p62 and TBK1 in isolated mitochondria as well as reduced mitochondria autophagosomes, the effects of which were mitigated by restoration of mitophagy via Parkin overexpression. Using the low-dose doxorubicin (DOX) in vitro model of cell senescence, we noted that Parkin-offered beneficial effect against senescence was abolished by the TBK1 kinase inhibitor BX795. With TBK1 overexpression in cardiomyocytes, we uncovered the interaction of Parkin with TBK1 using a Co-immunoprecipitation (Co-IP) assay. The interaction of Parkin with TBK1 contributed to K63-linked polyubiquitination of TBK1. Our study also noted that DOX disturbed K63-linked polyubiquitination of TBK1 with downregulation of Parkin. Parkin overexpression promoted K63-linked polyubiquitination of TBK1 through Lys30 and Lys401 residues to foster TBK1 phosphorylation to facilitate efficient mitophagy. In summary, these findings suggested that Parkin effectively rescued cardiac aging through promoting K63-linked polyubiquitination of TBK1 to facilitate mitophagy.