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Protein ubiquitination is an important means of post-translational modification which plays an essential role in the regulation of various aspects of leukocyte development and function. The specificity of ubiquitin tagging to a protein substrate is determined by E3 ubiquitin ligases via defined E3-substrate interactions. In this review, we will focus on two E3 ligases, VHL and Itch, to discuss the latest progress in understanding their roles in the differentiation and function of CD4 T helper cell subsets, the stability of regulatory T cells, effector function of CD8 T cells, as well as the development and maturation of innate lymphoid cells. The biological implications of these E3 ubiquitin ligases will be highlighted in the context of normal and dysregulated immune responses including the control of homeostasis, inflammation, auto-immune responses and anti-tumor immunity. Further elucidation of the ubiquitin system in immune cells will help in the design of new therapeutic interventions for human immunological diseases and cancer.
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Objective To investigate the effect of microRNA-1183 on proliferation and metastasis on gastric cancer cells and to explore the role of microRNA-1183 and CBL-B signaling pathways in this process. Methods MGC803 cells were transfected with a microRNA-1183 mimic. Real-time PCR detected the expression of microRNA-1183 in gastric cancer cell line MGC803. MTT detected the proliferative effect of microRNA-1183 on MGC803 gastric cancer cells. A Transwell assay detected the effect of microRNA-1183 on the metastasis of MGC803 gastric cancer cells. A dual luciferase reporter assay detected the binding ability between microRNA-1183 and CBL-B. The expression of the protein was tested by Western blotting. Results MTT assay results showed that microRNA-1183 promoted the proliferation of MGC803 cells. Transwell assay results revealed that microRNA-1183 promoted the metastasis of MGC803 cells. The results of BLAST contrast analysis show that CBL-B is one of the target genes of microRNA-1183. Western blotting analysis showed that the mimic microRNA-1183 inhibited the expression of CBL-B. A dual luciferase reporter assay showed that CBL-B was the target gene of microRNA-1183. A CBL-B knockdown promoted the proliferation and metastasis of MGC803 cells. microRNA-1183 promoted the proliferation and metastasis of MGC803 cells by inhibiting the expression of CBL-B. Conclusion microRNA-1183 can inhibit the proliferation and metastasis of gastric cancer cell lines by inhibiting the expression of CBL-B.
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Objective To analyze differentially expressed proteins in A375 melanoma cells before and after short hairpin RNA (shRNA)-mediated Cbl-b gene silencing.Methods The label-free quantitative proteomics approach was performed to identify differentially expressed proteins between A375 cells transfected with lentiviral vectors containing Cbl-b shRNA (Cbl-b shRNA group) and those with control lentiviral vectors (control group).Then,the properties of differentially expressed proteins were analyzed by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) enrichment analysis.Western blot analysis was conducted to determine the expression of differential proteins (EphA2 and GSK3β) and phosphorylated protein kinase (p-AKT) after shRNA-mediated Cbl-b gene silencing.Statistical analysis was carried out by t test of two independent-samples for comparison of protein expression abundance between the two groups with SPSS 23.0 software.Additionally,the results of GO and KEGG enrichment analysis were analyzed by Fisher's exact test.Results A total of 3 449 proteins were identified and quantified,and 74 of them were differentially expressed between the Cbl-b shRNA group and control group.Compared with the control group,52 proteins were up-regulated and 22 were down-regulated in the Cbl-b shRNA group.GO enrichment analysis of differential proteins revealed that the top five significantly enriched biological processes were integrin-mediated cell adhesion,single-organism metabolic process,regulation of integrin-mediated cell adhesion,regulation of protein-targeting mitochondria and nucleic acid metabolic process.The top five significantly enriched molecular functions included DNA binding,2-iron,2-sulfur cluster binding,signaling receptor activity,cadherin binding and cell adhesion molecule binding.The top five significantly enriched cell components included nucleosome,DNA packaging complex,photoreceptor connecting cilium,DNA-protein complex and extracellular region part.KEGG enrichment analysis demonstrated that the top five significantly enriched melanoma-related signaling pathways were folate biosynthesis,axon guidance,extracellular matrix-receptor interaction,adherens junction and Wnt signaling pathways.As Western blot analysis revealed,the Cbl-b shRNA group showed lower protein expression of EphA2 (0.369),but higher protein expression of GSK3β (3.524) compared with the control group (1),which were consistent with the results of proteomics analysis.Additionally,the protein expression of p-AKT was down-regulated in Cbl-b shRNA group (0.453) compared with the control group (1).Conclusion Cbl-b may be involved in the occurrence of melanoma through a variety of biological pathways,and the EphA2/PI3K/AKT signaling pathway may be one important pathway.
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Objective To construct a recombinant lentiviral vector carrying the casitas B-lineage lymphoma (Cbl)-b short hairpin RNA (shRNA),and to evaluate its effect on the biological behavior of A375 melanoma cells in vitro.Methods Three specific shRNAs targeting Cbl-b gene and a negative control shRNA were designed and synthesized,and recombinant lentiviral vectors were constructed.A375 cells were divided into 5 groups to be transfected with 3 kinds of lentiviral vector expressing Cbl-b genespecific shRNAs (CBLB-shRNA-1 group,CBLB-shRNA-2 group and CBLB-shRNA-3 group),a lentiviral vector containing negative control shRNA (negative control group),and an empty vector (blank control group).Real-time fluorescence-based quantitative PCR and Western blot analysis were performed to determine the silencing efficiency at 72 hours after transfection.Cell counting kit-8 (CCK-8)assay was conducted to evaluate cellular proliferative activity at 24,48,72 and 96 hours after transfection,flow cytometry to detect cell apoptosis and cell cycle at 72 hours after transfection,and Transwell invasion assay to assess cellular invasive activity at 72 hours after transfection.Results Three recombinant lentiviral vectors containing Cbl-b shRNA were constructed successfully.As Western blot analysis revealed,the CBLB-shRNA-3 showed the highest silencing efficiency.CCK-8 assay indicated that the proliferative activity of A375 cells was significantly lower in the CBLB-shRNA-3 group than in the negative control group and blank control group at 72 and 96 hours after transfection(all P ＜ 0.01).Flow cytometry showed that the apoptosis rate of A375 cells was significantly higher in the CBLB-shRNA-3 group (22.73％ ± 6.58％) than in the negative control group (6.08％ ± 1.35％,P ＜ 0.01) and blank control group (6.34％ ± 1.07％,P ＜ 0.01).The CBLB-shRNA-3 group showed a significantly higher proportion of A375 cells at G1 phase,but a significantly lower proportion of A375 cells at S phase compared with the negative control group and blank control group(all P ＜ 0.01).Transwell assay showed that there were significant differences in the number of A375 cells crossing the artificial basement membrane (matrigel) at 72 hours after transfection among the negative control group,blank control group and CBLB-shRNA-3 group (76.60 ± 1.82,73.20 ± 3.83,19.60 ± 1.14,respectively;F =794.50,P ＜ 0.01).Conclusions A recombinant CBLB-shRNA-3-expressing lentiviral vector which can efficiently silence Cbl-b gene has been successfully constructed.It can inhibit the proliferation,cell cycle progression and invasive activity of A375 cells,but promote the apoptosis of A375 cells.
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Objective To observe the expression of microRNA-150 (miR-150) in conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma, so as to investigate its mechanism in proliferation, migration and invasion of conjunctival MALT lymphoma. Methods The expressions of ;m'P-150 and Cbl-b, a possible downstream molecule of miR-150, were measured by qPCR in MALT lymphoma tissues and precancerous tissues collected from 3 patients with conjunctival MALT lymphoma in Changzheng Hospital of Second Military Medical University. Then, we transfected miR-150 inhibitor and negative control into human multiple myeloma cell lines RPM1 8226 by cell transfection. CCK-8 assay and flow cytometry (FCM) method were used to investigate the role of miR-150 in the proliferation and apoptosis of RPM1 8226 cells. Transwell assay was used to analyze the effect of miR-150 on the migration and invasion of RPMI 8226 cells. Western blotting analysis was used to examine the regulation of miR150 on Cbl-b expression in RPMI 8226 cells. Results The expression of miR-150 was significantly increased in the conjunctival MALT lymphoma tissues compared with precancerous tissues (P< 0. 05,P< 0. 01). Compared with negative control group, the proliferation of RPMI 8226 cells was significantly repressed (P< 0. 01), the apoptosis was significantly increased (P< 0. 01), and the migration and invasion were significantly decreased (P< 0. 05,P< 0. 01) after transfection of miR-150 inhibitor. The expression of Cbl-b was significantly up-regulated in MALT lymphoma tissues, and was significantly increased after inhibiting miR-150 expression. Conclusion Up-regulated miR-150 can promote the proliferation, migration and invasion of lymphoma cells and is involved in the generation of conjunctival MALT lymphoma, which may be mediated by inhibiting its downstream target gene Cbl-b.
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Objective To evaluate in vitro effects of specific small interfering RNA (siRNA)-silencing of the casitas B-lineage lymphoma b (Cbl-b)gene on immunocompetence of primary murine lymphocytes. Methods Spleens were resected from C57BL/6 mice, and splenic lymphocytes were sterily isolated and cultured in vitro. These lymphocytes were divided into 3 groups: silence group transfected with a Cbl-b-specific siRNA using the EntransterTM-R 4000 reagent, negative control group transfected with a negative control siRNA using the EntransterTM-R4000 reagent, blank control group receiving no treatment. After additional culture for 72 hours, ELISA was performed to measure levels of interferon γ(IFN-γ)and tumor necrosis factor α (TNF-α)in culture supernatants of lymphocytes. In addition, the Cbl-b gene-silenced lymphocytes were co-cultured with B16F10 melanoma cells to evaluate their immunocytotoxic effects on melanoma cells. Results Splenic lymphocytes were successfully isolated from C57BL/6 mice and cultured in vitro, and the Cbl-b-specific siRNA was also successfully transfected into the primary murine lymphocytes and effectively down-regulated the expression of Cbl-b gene in them. Compared with the negative control group and blank control group, the silence group showed significantly increased supernatant levels of IFN-γ and TNF-α(all P < 0.05). The immunocytotoxic effect of lymphocytes on melanoma cells was significantly stronger in the silence group than in the negative control group. Conclusion Cbl-b gene silencing can promote secretion of IFN-γ and TNF-α by murine lymphocytes, and enhance their immunocytotoxic effects on B16F10 melanoma cells in vitro.
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Aim To explore the mechanism of insulin in combination with selenium preventing myocardial apoptosis in diabetic cardiomyopathy rats .Methods SD rats ( n =50 ) were randomly divided into five groups: control , diabetic cardiomyopathy ( DCM ) , DCM with insulin treatment , DCM with selenium treat-ment, and DCM with insulin and selenium combination treatment .The cell apoptosis was observed by TUNEL . The levels of Bcl-2, caspase-3, PARP, Cbl-b and p38 MAPK were examined by Western blot .The inter-actions of Cbl-b-p38 MAPK and Ku70-Bax were detec-ted by immunoprecipitation .Results Insulin in com-bination with selenium synergistically inhibited apopto-sis, up-regulated Cbl-b, down-regulated p38MAPK ex-pressions and increased the interactions of Cbl-b-p38MAPK and Ku70-Bax.Conclusion Insulin and selenium synergistically inhibit myocardial apoptosis by regulating Cbl-b-inhibited p38 MAPK and preventing Bax translocation .
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Objective To construct a eukaryotic expression plasmid vector encoding Cbl-b gene-specific short hairpin RNAs (shRNAs),and to evaluate its interference effect,so as to lay a foundation for further study on the role of Cbl-b in the immunotherapy of malignant melanoma.Methods According to the sequence of Cbl-b cDNA,4 pairs of shRNAs targeting the Cbl-b gene were designed and synthesized,and then inserted into the plasmid PGPU6/GFP/Neo to construct recombinant plasmids.After identification by DNA sequencing,the 4 shRNA expression vectors were cotransfected into 293T cells with the Cbl-b gene eukarytic expresson plasmid,respectively.The knockdown efficiency of these shRNA expression plasmids on Cbl-b expression was evaluated by real-time (RT) fluorescence-based quantitative PCR and Western blot at 48 hours aftert transfection.Results Sequencing analysis revealed that all the 4 pairs of shRNAs were successfully inserted into the eukarytic expression vector PGPU6/GFP/Neo.As RT-PCR and Western blot showed,all the 4 shRNA-expressing vectors could downregulate Cbl-b expession,and the NO.1 shRNA-expressing vector displayed the strongest interference effect(P ＜ 0.05).Conclusions A eukaryotic expression plasmid vector was successfully constructed for Cbl-b gene-specific shRNAs,and the most effective shRNA was selected in this study.
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Arsenic trioxide (ATO) is a strong inducer of apoptosis in malignant hematological cells. Inducible phosphatidyl inositol 3 kinase (PI3K)-Akt activation promotes resistance to ATO. In the present study, we evaluated whether E3 ubiquitin ligase Cbl-b, a negative regulator of PI3K activation, is involved in the action of ATO. The effect of ATO on cell viability was measured by the Trypan blue exclusion assay or by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was determined by flow cytometry and protein expression was assayed by Western blotting. ATO decreased the viability of HL60 cells and induced cellular apoptosis, which was accompanied by transient activation of Akt. The PI3K/Akt inhibitor, LY294002, significantly increased ATO-induced apoptosis (P < 0.05). In addition, ATO up-regulated the expression of Cbl-b proteins. Furthermore, ATO inhibited cell viability with an IC50 of 18.54 μM at 24 h in rat basophilic leukemia-2H3 cells. ATO induced cellular apoptosis with transient activation of Akt and Cbl-b was also up-regulated. Rat basophilic leukemia-2H3 cells transfected with a dominant negative (DN) Cbl-b mutation showed overexpression of Cbl-b (DN) and enhanced Akt activation. Compared with cells transfected with vector, ATO-induced apoptosis was decreased and G2/M phase cells were increased at the same concentration (P < 0.05). The PI3K/Akt inhibitor, LY294002, re-sensitized Cbl-b (DN) overexpressing cells to ATO and reversed G2/M arrest (P < 0.05). Taken together, these results suggest that Cbl-b potentiates the apoptotic action of ATO by inhibition of the PI3K/Akt pathway.
Subject(s)
Animals , Humans , Rats , Apoptosis/drug effects , Arsenicals/pharmacology , Oxides/pharmacology , /antagonists & inhibitors , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Proto-Oncogene Proteins c-cbl/pharmacology , Ubiquitin-Protein Ligases/pharmacology , Blotting, Western , Flow Cytometry , Signal Transduction/drug effects , Up-Regulation/drug effectsABSTRACT
Cbl-b (Casitas B cell lymphoma-b ) gene is a member of the cbl family,and the Cbl-b pro-tein plays an important role in regulating anti-tumor immunity by interacting with the signal transduetion pro-tein. Silencing Cbl-b expression in peripheral blood T cells by gene interference technology can regulate body's anti-tumor immunity.It is expected to achieve a major breakthrough in cancer therapy.