TRIM32 Overexpression Research Articles

Expression profiling of TRIM protein family in THP1-derived macrophages following TLR stimulation

Activated macrophages play an important role in many inflammatory diseases including septic shock and atherosclerosis. However, the molecular mechanisms limiting macrophage activation are not completely understood. Members of the tripartite motif (TRIM) family have recently emerged as important players in innate immunity and antivirus. Here, we systematically analyzed mRNA expressions of representative TRIM molecules in human THP1-derived macrophages activated by different toll-like receptor (TLR) ligands. Twenty-nine TRIM members were highly induced (>3 fold) by one or more TLR ligands, among which 19 of them belong to TRIM C-IV subgroup. Besides TRIM21, TRIM22 and TRIM38 were shown to be upregulated by TLR3 and TLR4 ligands as previous reported, we identified a novel group of TRIM genes (TRIM14, 15, 31, 34, 43, 48, 49, 51 and 61) that were significantly up-regulated by TLR3 and TLR4 ligands. In contrast, the expression of TRIM59 was down-regulated by TLR3 and TLR4 ligands in both human and mouse macrophages. The alternations of the TRIM proteins were confirmed by Western blot. Finally, overexpression of TRIM59 significantly suppressed LPS-induced macrophage activation, whereas siRNA-mediated knockdown of TRIM59 enhanced LPS-induced macrophage activation. Taken together, the study provided an insight into the TLR ligands-induced expressions of TRIM family in macrophages.

Trim32 Deficiency Enhances Th2 Immunity and Predisposes to Features of Atopic Dermatitis

Altered innate immunity is a feature of certain skin inflammatory diseases such as psoriasis and atopic dermatitis (AD). In this study, we provide evidence that deficiency in Trim32 (a tripartite motif [TRIM] protein with innate antiviral activity) contributes to a T helper type 2 biased response and predisposes to features of AD in mice. On treatment with the toll-like receptor 7 agonist imquimod (IMQ), Trim32 knockout mice displayed compromised psoriasiform phenotypes and defective T helper type 17 response. Instead, IMQ treatment of Trim32 knockout mice induced AD-like phenotypes with enhanced skin infiltration of eosinophils and mast cells, elevation of T helper type 2 cytokines/chemokines expression, and reduced expression of filaggrin protein expression. Furthermore, although the induction of phosphorylated Stat3 and RelA was compromised after IMQ treatment in the knockout mice, phosphorylated Stat6 was elevated. CC chemokine ligand 20 induction by tumor necrosis factor-α and IL-17A was reduced in Trim32-deficient keratinocytes, whereas CC chemokine ligand 5 induction by tumor necrosis factor-α and IL-4 was enhanced. In addition, Trim32 protein levels were elevated in mice treated with IMQ. Unlike Trim32 overexpression in psoriasis, TRIM32 levels were low in patients with AD. Based on Trim32 induction by IMQ, the lower levels of TRIM32 in AD skin compared with healthy control and psoriatic skin suggest a defective TRIM32 pathway in AD pathogenesis.

TRIM59 is upregulated and promotes cell proliferation and migration in human osteosarcoma.

Osteosarcoma is a prevalent type of cancer and has a high metastatic ability, particularly for metastasis to the lungs. Effective treatment strategies have improved, however, the detailed molecular mechanism underlying the onset of this malignancy remains to be fully elucidated. The current study investigated the role of the tripartite motif (TRIM) family protein TRIM59 in osteosarcoma growth and metastasis. It was identified that TRIM59 was overexpressed in clinical osteosarcoma tissues and cultured osteosarcoma cell lines. In addition, the MTT assay demonstrated that in U2OS and MG63 cells, knockdown of TRIM59 by specific siRNA inhibited proliferation, whereas overexpression of TRIM59 promoted cell proliferation. Furthermore, overexpression of TRIM59 significantly increased the U2OS cell migrative and invasive abilities in a Transwell chamber assay. In addition, TRIM59 was able to negatively regulate the protein levels of P53 without significantly affecting the mRNA levels in U2OS and MG63cells. These data suggest the oncogenic abilities of TRIM59 in osteosarcoma, which promote osteosarcoma cell proliferation, migration and invasion.

Abstract 1229: E3 ubiquitin ligase TRIM32 negatively regulates tumor suppressor p53 to promote tumorigenesis

Abstract Tumor suppressor p53 plays a key role in maintaining genomic stability and preventing tumorigenesis through its regulation of cellular stress responses, including apoptosis, cell cycle arrest and senescence. To ensure its proper levels and functions in cells, p53 is tightly regulated mainly through post-translational modifications. Ubiquitination is the most important post-translational modification for p53. TRIM32 is a protein of the tripartite motif (TRIM) family. The proteins of TRIM family have been reported to be involved in different biological processes, including cell growth, differentiation, development, muscular physiology, innate immune response and cancer. However, like the majority of TRIM family proteins, the biological function of TRIM32 is not well-understood. Here, we identified TRIM32 as a novel p53 target gene and E3 ubiquitin ligase for p53. In response to stress, including ionizing radiation (IR) and chemotherapeutic agents (e.g. etoposide and 5-fluorouracil), p53 protein binds to the p53 responsive element in the promoter of the TRIM32 gene and transcriptionally induces the expression of TRIM32 in cells. In turn, TRIM32 protein interacts with p53 protein and promotes p53 degradation through ubiquitination to negatively regulate p53-mediated apoptosis, cell cycle arrest and senescence in response to stress. Thus, p53 and TRIM32 form a novel negative feedback loop in cells to regulate p53 protein levels and function. TRIM32 is frequently overexpressed in different types of human tumors, including lung, colorectal and liver cancers. TRIM32 overexpression promotes the oncogenic transformation of primary mouse embryonic fibroblasts in a largely p53-dependent manner. Furthermore, TRIM32 overexpression promotes tumorigenesis in mice through the down-regulation of p53 function. Taken together, our results demonstrated that as a novel p53 target and a novel negative regulator for p53, TRIM32 plays an important role in regulation of p53 and p53-mediated cellular stress responses. Furthermore, our results revealed that impairing p53 function is a novel mechanism for TRIM32 in tumorigenesis. Citation Format: Cen Zhang, Juan Liu, Xiaolong Wang, Ken H. Young, Wenwei Hu, Zhaohui Feng. E3 ubiquitin ligase TRIM32 negatively regulates tumor suppressor p53 to promote tumorigenesis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1229. doi:10.1158/1538-7445.AM2015-1229

Abstract 473: TRIM59, a novel prognostic marker for gastric cancer, promotes tumorigenesis via ubiquitination and degradation of the p53 tumor suppressor

Abstract As a key tumor suppressor, p53 plays crucial roles in gastric cancer initiation and progression. However, the underlying mechanisms for the down-regulation of p53 in gastric cancer patients are not fully understood. Several tripartite motif (TRIM) family proteins are identified to be involved in the tumorigenesis of multiple cancer types, but the significance and biological function of a new TRIM family protein, TRIM59, in terms of whether and how it affects p53 signaling in gastric cancer are largely unknown. We analyzed multiple microarray datasets from the Oncomine database and tested the expression level of TRIM59 in gastric tumors vs. their matched normal tissues and in gastric carcinoma cell lines using quantitative-polymerase chain reactions (Q-PCR) and immunohistochemical staining. We found Expression of TRIM59 was significantly up-regulated in gastric cancer and strongly associated with poor prognosis. TRIM59 knockdown led to significantly attenuated gastric cancer cell proliferation, clone formation, migration, and in vivo xenograft tumorigenicity, whereas over-expression of TRIM59 showed the opposite effects. Mechanistically, TRIM59 interacted with p53 and enhanced ubiquitination and degradation of the p53 protein. In addition, elevated expression of TRIM59 correlated with down-regulation of p53 target genes in human gastric tumors. In summary, TRIM59 is a novel prognostic marker for gastric cancer and promotes tumorigenesis through facilitating p53 ubiquitination and degradation. Citation Format: Zhicheng Zhou, You Wang, Jian Li, Hui Cao, Helen He Zhu, Wei-Qiang Gao. TRIM59, a novel prognostic marker for gastric cancer, promotes tumorigenesis via ubiquitination and degradation of the p53 tumor suppressor. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 473. doi:10.1158/1538-7445.AM2014-473

E3 ubiquitin ligase TRIM32 negatively regulates tumor suppressor p53 to promote tumorigenesis.

Tumor suppressor p53 has a key role in maintaining genomic stability and preventing tumorigenesis through its regulation of cellular stress responses, including apoptosis, cell cycle arrest and senescence. To ensure its proper levels and functions in cells, p53 is tightly regulated mainly through post-translational modifications, such as ubiquitination. Here, we identified E3 ubiquitin ligase TRIM32 as a novel p53 target gene and negative regulator to regulate p53-mediated stress responses. In response to stress, such as DNA damage, p53 binds to the p53 responsive element in the promoter of the TRIM32 gene and transcriptionally induces the expression of TRIM32 in cells. In turn, TRIM32 interacts with p53 and promotes p53 degradation through ubiquitination. Thus, TRIM32 negatively regulates p53-mediated apoptosis, cell cycle arrest and senescence in response to stress. TRIM32 is frequently overexpressed in different types of human tumors. TRIM32 overexpression promotes cell oncogenic transformation and tumorigenesis in mice in a largely p53-dependent manner. Taken together, our results demonstrated that as a novel p53 target and a novel negative regulator for p53, TRIM32 has an important role in regulation of p53 and p53-mediated cellular stress responses. Furthermore, our results also revealed that impairing p53 function is a novel mechanism for TRIM32 in tumorigenesis.

A novel accessory molecule Trim59 involved in cytotoxicity of BCG-activated macrophages.

BCG-activated macrophages (BAM) could kill the tumor cells through cell-cell contact. In this process membrane proteins play an important role. However, up to date, few membrane proteins were revealed. In this study, we selected a surface molecule named Trim59, which was specifically expressed on BAM membrane (compared with the negative control). We cloned and prokaryoticly expressed the extracellular domain of Trim59, purified the recombinant protein and generated polyclonal antibodies. Immunohistochemistry showed that Trim59 abundantly expressed in spleen, stomach and ovary; intermediately expressed in brain, lung, kidney, muscle and intestine; but not in thymus, liver, heart, uterus. Using the antibodies to block Trim59 on BAM significantly reduced BAM cytotoxicity against MCA207 cells. This demonstrated that Trim59 serves as an indispensable molecule in maintaining BAM activity. Overexpression of Trim59 in Raw264.7 cell line failed to lyse target MCA207 cells, which potentiated Trim59 per se could not enhance macrophage cytotoxicity; on another hand, overexpression of Trim59 enhance the pinocytosis and Phagocytosis activity of Raw-264.7, which imply Trim59 might mediate the cell-molecule interaction. Our results indicate Trim59 might be an essential accessory molecule in mediating BAM tumoricidal functions; and Trim59 is a phagocytosis-correlated molecule.

TRIM59 interacts with ECSIT and negatively regulates NF-κB and IRF-3/7-mediated signal pathways

Innate immune responses are triggered by pathogen-associated molecular patterns (PAMPs) through pattern recognition receptors (PRRs) and then activate intracellular signaling pathways including NF-κB and interferon regulatory factors. Recently, it has been reported that tripartite motif (TRIM) proteins function as crucial regulators via ubiquitin-mediated modifications for these signaling pathways. In this study, we showed that one of the TRIM family ubiquitin ligases, TRIM59, interacts with ECSIT as an adaptor protein required for the TLR-mediated transduction pathway. Luciferase reporter assays using reporter plasmids including NF-κB responsive element, interferon β (IFN-β) promoter and interferon-sensitive response element (ISRE) showed that overexpression of TRIM59 repressed their transcriptional activities, whereas knockdown of TRIM59 enhanced their transcriptional activities. Furthermore, TRIM59 inhibited phosphorylation and dimerization of IRF3 and IRF7, suggesting that TRIM59 negatively regulates upstream kinases for IRFs. These findings indicate that TRIM59 may serve as a multifunctional regulator for innate immune signaling pathways.

TRIM32 promotes retinoic acid receptor α-mediated differentiation in human promyelogenous leukemic cell line HL60

Ubiquitination, one of the posttranslational modifications, appears to be involved in the transcriptional activity of nuclear receptors including retinoic acid receptor α (RARα). We previously reported that an E3 ubiquitin ligase, TRIM32, interacts with several important proteins including RARα and enhances transcriptional activity of RARα in mouse neuroblastoma cells and embryonal carcinoma cells. Retinoic acid (RA), which acts as a ligand to nuclear receptors including RARα, plays crucial roles in development, differentiation, cell cycles and apoptosis. In this study, we found that TRIM32 enhances RARα-mediated transcriptional activity even in the absence of RA and stabilizes RARα in the human promyelogenous leukemic cell line HL60. Moreover, we found that overexpression of TRIM32 in HL60 cells suppresses cellular proliferation and induces granulocytic differentiation even in the absence of RA. These findings suggest that TRIM32 functions as one of the coactivators for RARα-mediated transcription in acute promyelogenous leukemia (APL) cells, and thus TRIM32 may become a potentially therapeutic target for APL.

TRIM32 promotes neural differentiation through retinoic acid receptor-mediated transcription

Retinoic acid (RA), a metabolite of vitamin A, plays versatile roles in development, differentiation, cell cycles and regulation of apoptosis by regulating gene transcription through nuclear receptor activation. Ubiquitinylation, which is one of the post-translational modifications, appears to be involved in the transcriptional activity of intranuclear receptors including retinoic acid receptor α (RARα). Mutations in the tripartite motif-containing protein 32 gene (TRIM32; also known as E3 ubiquitin-protein ligase) have been reported to be responsible for limb-girdle muscular dystrophy type 2H in humans, and its encoded protein has been shown to interact with several other important proteins. In this study, we found that TRIM32 interacts with RARα and enhances its transcriptional activity in the presence of RA. We also found that overexpression of TRIM32 in mouse neuroblastoma cells and embryonal carcinoma cells promoted stability of RARα, resulting in enhancement of neural differentiation. These findings suggest that TRIM32 functions as one of the co-activators for RARα-mediated transcription, and thereby TRIM32 is a potential therapeutic target for developmental disorders and RA-dependent leukemias.

TRIM32 Protein Sensitizes Cells to Tumor Necrosis Factor (TNFα)-induced Apoptosis via Its RING Domain-dependent E3 Ligase Activity against X-linked Inhibitor of Apoptosis (XIAP)

TRIM32, which belongs to the tripartite motif (TRIM) protein family, has the RING finger, B-box, and coiled-coil domain structures common to this protein family, along with an additional NHL domain at the C terminus. TRIM32 reportedly functions as an E3 ligase for actin, a protein inhibitor of activated STAT y (PIASy), dysbindin, and c-Myc, and it has been associated with diseases such as muscular dystrophy and epithelial carcinogenesis. Here, we identify a new substrate of TRIM32 and propose a mechanism through which TRIM32 might regulate apoptosis. Our overexpression and knockdown experiments demonstrate that TRIM32 sensitizes cells to TNFα-induced apoptosis. The RING domain is necessary for this pro-apoptotic function of TRM32 as well as being responsible for its E3 ligase activity. TRIM32 colocalizes and directly interacts with X-linked inhibitor of apoptosis (XIAP), a well known cancer therapeutic target, through its coiled-coil and NHL domains. TRIM32 overexpression enhances XIAP ubiquitination and subsequent proteasome-mediated degradation, whereas TRIM32 knockdown has the opposite effect, indicating that XIAP is a substrate of TRIM32. In vitro reconstitution assay reveals that XIAP is directly ubiquitinated by TRIM32. Our novel results collectively suggest that TRIM32 sensitizes TNFα-induced apoptosis by antagonizing XIAP, an anti-apoptotic downstream effector of TNFα signaling. This function may be associated with TRIM32-mediated tumor suppressive mechanism.

Abstract 4047: TRIM32 facilitates cell growth, migration and anti-apoptosis

Abstract Introduction: Tripartite motif (TRIM) proteins are characterized by the presence of a RING finger, one or two zinc-binding motifs named B-boxes and an associated coiled-coil region. Most TRIM proteins have been reported to have a role in the ubiquitination process. Furthermore, several TRIM family members are involved in various cellular processes such as transcriptional regulation, cell growth, apoptosis, development and oncogenesis. TRIM32 also has a RING-finger domain and functions as an E3-ubiquitin ligase. In the previous study, it has been reported that TRIM32 protein expression is elevated in a mouse skin carcinogenesis model and in human skin squamous cell carcinoma and TRIM32 mRNA expression is elevated in human head and neck squamous cell carcinoma. However, the involvement of TRIM32 in carcinogenesis has not been fully elucidated. In this study, we studied the function of TRIM32 in the progression of carcinogenesis. Methods: We established the cell lines overexpressed TRIM32 wild type and the deletion mutant of the RING-finger domain by the infection of retrovirus vectors. Using these cell lines, we analyzed the effect of TRIM32 on cell growth, transforming activity, cell motility and apoptosis induced by cisplatin. Additionally, we investigated whether siRNA for TRIM32 effects on these functions. Furthermore, we examined the expression level of TRIM32 protein in oral carcinoma samples using immunohistochemical method and analyzed the relationship between TRIM32 and clinical presentation. Results: Overexpression of TRIM32 promoted cell growth, transforming activity and cell motility, whereas a dominant negative mutant of TRIM32 lacking the RING-finger domain inhibited these effects. In addition, we found that TRIM32 suppressed apoptosis induced by cisplatin in HEp2 cell lines, originating from human laryngeal squamous cell carcinoma. In contrast, siRNA for TRIM32 suppressed cell proliferation, cell motility and anti-apoptosis. In clinical research, a high-expression group of TRIM32 presented more advanced stage (clinical stage, T stage and neck lymph node metastasis) than a low-expression group. Conclusions: In this study, our experimental results in vitro were supported by clinical research. These findings suggest that TRIM32 is a novel oncogene that promotes tumor growth, metastasis and resistance to anti-cancer drugs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4047. doi:10.1158/1538-7445.AM2011-4047

The TRIM-NHL Protein TRIM32 Activates MicroRNAs and Prevents Self-Renewal in Mouse Neural Progenitors

In the mouse neocortex, neural progenitor cells generate both differentiating neurons and daughter cells that maintain progenitor fate. Here, we show that the TRIM-NHL protein TRIM32 regulates protein degradation and microRNA activity to control the balance between those two daughter cell types. In both horizontally and vertically dividing progenitors, TRIM32 becomes polarized in mitosis and is concentrated in one of the two daughter cells. TRIM32 overexpression induces neuronal differentiation while inhibition of TRIM32 causes both daughter cells to retain progenitor cell fate. TRIM32 ubiquitinates and degrades the transcription factor c-Myc but also binds Argonaute-1 and thereby increases the activity of specific microRNAs. We show that Let-7 is one of the TRIM32 targets and is required and sufficient for neuronal differentiation. TRIM32 is the mouse ortholog of Drosophila Brat and Mei-P26 and might be part of a protein family that regulates the balance between differentiation and proliferation in stem cell lineages.

Tripartite Motif Protein 32 Facilitates Cell Growth and Migration via Degradation of Abl-Interactor 2

Tripartite motif protein 32 (TRIM32) mRNA has been reported to be highly expressed in human head and neck squamous cell carcinoma, but the involvement of TRIM32 in carcinogenesis has not been fully elucidated. In this study, we found by using yeast two-hybrid screening that TRIM32 binds to Abl-interactor 2 (Abi2), which is known as a tumor suppressor and a cell migration inhibitor, and we showed that TRIM32 mediates the ubiquitination of Abi2. Overexpression of TRIM32 promoted degradation of Abi2, resulting in enhancement of cell growth, transforming activity, and cell motility, whereas a dominant-negative mutant of TRIM32 lacking the RING domain inhibited the degradation of Abi2. In addition, we found that TRIM32 suppresses apoptosis induced by cis-diamminedichloroplatinum (II) in HEp2 cell lines. These findings suggest that TRIM32 is a novel oncogene that promotes tumor growth, metastasis, and resistance to anticancer drugs.