Dynamic ubiquitination in eukaryotes either enters proteins into the 26S proteasome degradation pathway or functions in signal transduction, and therefore regulates protein stability, localization and activity, thus participates in transcription, cell cycle, inflammation, tumor, immunity and other functions. Ubiquitination modification is a reversible process, which is regulated by ubiquitin ligases (E3s) and deubiquitylases (DUBs). DUBs mediate the deubiquitination of substrate proteins, regulate protein functions, and participate in various cellular processes. The protein abundance, localization and catalytic activity of deubiquitylases are strictly regulated. During the occurrence and development of tumors, many important tumor-related proteins are regulated by deubiquitylases, and dysfunction of deubiquitylases also affect DNA damage repair, apoptosis, autophagy, molecular signaling pathways and chromatin remodeling, which modulate the process of cell growth, invasion and metastasis in tumors. Therefore, DUB is an important protein family involved in tumorigenesis, and is potential drug targets. Many small molecule inhibitors have been used in the research of anti-tumor treatments. This article mainly summarizes the regulation mechanism of ubiquitin molecules, ubiquitin chain specificity, and deubiquitinating enzyme system in tumors, and provides basis for the design of clinical drug targets and diagnostic indicators.
The lineage transition between epithelium and mesenchyme is a process known as epithelial-mesenchymal transition (EMT), by which polarized epithelial cells lose their adhesion property and obtain mesenchymal cell phenotypes. EMT is commonly found in embryonic development, wound healing, organ fibrosis and tumor metastasis. EMT and mesenchymal-epithelial transition (MET) are involved in the early and late development of embryo, such as implantation, gastrulation, heart development and so on. EMT and MET are involved in the regulation of stem cell phenotype changes and cell migration, which are important mechanisms of cell differentiation and three-dimensional tissue construction. The expression of cell adhesion molecules is transformed from E-cadherin to N-cadherin, which is an important sign of EMT. By interacting with β-catenin, p120-catenin and α-catenin, E-cadherin can affect the activation of Wnt, small GTPase superfamily and other signaling pathways and regulate cytoskeleton movement. TGF, Notch, Wnt, BMP, FGF, and other signaling pathways, Snail, Twist, Zeb and other transcription factors, together with epigenetic modifying enzymes, participate in the initiation and regulation of EMT in a coordinated way. In vitro models showed that E-cadherin was involved in self-renewal of stem cells. Somatic cell reprogramming could be regarded as MET, and the expression of E-cadherin can be obtained in somatic cells after transfection of reprogramming factors. In vitro studies have found that EMT and its related molecules (such as E-cadherin, Snail, Twist, Zeb, etc.) were involved in the early triploblast differentiation and the formation of specific cell types in the late stage. The study on the mechanism of EMT will help to improve the differentiation efficiency of stem cells in vitro and promote the induction of organoids.
Dickkopf-3 (DKK3), as a critical inhibitor of the Wnt/β-catenin signaling pathway, may be involved in melanogenesis. In the current study, we investigated the effects of DKK3 on melanogenesis in melanocytes of alpaca. Overexpression of DKK3 in alpaca melanocytes, the expression of Wnt1, Lef1, Myc and the major target genes termed microphthalmia-associated transcription factor (MITF) and its downstream genes, including tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1) and tyrosinase-related protein 2 (TYRP2) were significantly decreased at both mRNA and protein levels (P<0.05); total alkali melanin, pheomelanin and eumelanin were decreased by 80.30%, 72.17% and 64.60% (P<0.05), respectively. In contrast, in the melanocytes transfected with siRNA-DKK3 (a small interference RNA targeting DKK3), the expression of Wnt1, Lef1, Myc, MITF, TYR, TYRP1 and TYRP2 were significantly increased at both mRNA and protein levels (P<0.05); total alkali melanin, pheomelanin and eumelanin were significantly increased by 1.65 folds, 1.25 folds and 1.21 folds (P<0.05), respectively. These results indicate that DKK3 regulates melanogenesis in alpaca melanocytes via the Wnt/β-catenin signaling pathway and down-regulates MITF.
Parkinson’s disease (PD) is the second major neurodegenerative disease. The pathogenesis of PD is still unclear. It is generally believed that neural damage, mitochondrial dysfunction, inflammation, oxidative stress and autophagy dysfunction caused by the transmission and aggregation of α-synuclein play an important role in the occurrence and development of PD. More and more research show that metabolic disorder is one of the pathogenesis of PD. We examined whether overexpression of α-synuclein could induce metabolic disorder in mice and the possible mechanisms. Mice were divided into two groups: Thy1-αSYN transgenic mice (TG) and the control wild-type (WT) group. The rotarod test was used to analyze motor function in mice. We detected the body weight, plasma insulin content, glucose tolerance and insulin tolerance in the two group mice. The morphology of islets in the two groups were observed by hematoxylin eosin (HE) staining, and the islets were isolated to detect the glucose-stimulated insulin secretion (GSIS). The results showed that compared with the WT group, exercise tolerance of 12-month-old TG group decreased by 23.1% (P < 0.05), body weight increased by 7% (P< 0.01), glucose tolerance decreased (P < 0.05), insulin tolerance decreased (P < 0.05), and insulin contents in the peripheral blood decreased by 20% (P < 0.05). Compared with the WT group, the levels of α-syn proteins in the pancreas of the TG group increased by 1.32 times (P < 0.05), the area of islets in the TG group decreased (P < 0.05), the number of islets decreased (P < 0.01), and the insulin secretion function decreased (P< 0.01). This study showed that the role of α-synuclein in PD is not limited to the damage of dopaminergic neurons, it also can affect metabolism and the morphology and function of peripheral organs, which provides a new theoretical basis for the pathogenesis of PD.
Dual-specificity phosphatase 8 (DUSP8) is a member of the dual-specificity phosphatase family, which has been reported to participate in the development of many diseases. However, it is unclear whether DUSP8 plays an important role in the inflammatory response of macrophages and related immune cells. This study aims to detect the expression of DUSP8 in lipopolysaccharide (LPS)-induced macrophage inflammatory responses and to observe the effect of DUSP8 overexpression on macrophage inflammatory responses. 100 ng/ml LPS was used to treat bone marrow-derived macrophages (BMDMs) from wild-type C57BL/6 mice at different time points. Real-time PCR and Western blotting results showed that the expression of DUSP8 was significantly reduced in BMDMs (P<0.05) and reached the peak at 12 hours. Next, DUSP8 overexpression vectors (DUSP-EGFP) and control vectors (EGFP) were transfected into BMDM. Data showed that DUSP-EGFP transfection could significantly enhance the expression of DUSP8 in BMDMs (P<0.05). Moreover, FCM data showed that the expressions of CD80 and CD86 markedly decreased in BMDMs with DUSP8 overexpression (P<0.05). Meanwhile, the neutral red uptake assay data showed that the uptake in DUSP8 overexpression group was lower than that in the control group. Furthermore, ELISA results showed DUSP8 overexpression could significantly reduce the production of IL-1β and IL-6 (P<0.05). Besides, Western blotting results showed that the phosphorylation levels of p38 MAPK and JNK decreased in BMDMs after DUSP8 overexpression (P<0.05). All together, DUSP8 overexpression could significantly ameliorate LPS-induced macrophage inflammation, which was mainly related to the reduced expression of phosphorylated p38 MAPK and JNK.
Long non-coding RNAs (LncRNAs), as regulators of a class of gene expression, play a key role in the development of various types of tumor. We analyzed the TCGA database and found that the expression of LncRNA AC009686.2 in breast cancer tissues was significantly higher than that in normal tissues, and was positively correlated with the poor prognosis of breast cancer patients. qRT-PCR analysis showed that the expression of LncRNA AC009686.2 in breast cancer cells was significantly up-regulated, and the expression level of LncRNA AC009686.2 in MCF7, T47D, ZR7530, BT549, HCC1937, MDA-MB-231 and SKBR3 cells was 6.58, 5.66, 7.29, 9.06, 6.89, 11.17 and 5.38 folds of that in MCF10 A cells, respectively.LncRNA AC009686.2 knockdown in MDA-MB-231 and BT549 cells which expressed relatively high LncRNA AC009686.2 significantly inhibited cell proliferation, colony formation and invasion, and induced cell G1 /S phase arrest. The clone inhibition rates of MDA-MB-231 and BT549 cells with LncRNA AC009686.2 knockdown were 0.496%, 0.438% and 0.495%, 0.353% of the control group, respectively.LncRNA AC009686.2 knockdown also down.regulated protein levels of cyclinD2 and ZEB1. However, overexpression of ZEB1 could significantly reverse the decrease of cell invasion ability caused by LncRNA AC009686.2 knockdown. We further analysed in the software JASPAR database and found that LncRNA AC009686.2 promoter had ZEB1 binding site, and overexpression of ZEB1 could down-regulate the expression level of LncRNA AC009686.2 in breast cancer cells. In conclusion, LncRNA AC009686.2 which highly expressed in breast cancer, promotes cell proliferation and invasion by up-regulating cyclinD2 and ZEB1 expression, while ZEB1 positively regulates LncRNA AC009686.2 expression. This study will provide a theoretical basis for elucidating the role of LncRNA AC009686.2 in breast cancer and related molecular mechanisms.