TRIM22 can activate the noncanonical NF-κB pathway by affecting IKKα

The roles and targeting options of TRIM family proteins in tumor

Tripartite motif (TRIM) containing proteins are a class of E3 ubiquitin ligases, which are critically implicated in the occurrence and development of tumors. They can function through regulating various aspects of tumors, such as tumor proliferation, metastasis, apoptosis and the development of drug resistance during tumor therapy. Some members of TRIM family proteins can mediate protein ubiquitination and chromosome translocation via modulating several signaling pathways, like p53, NF-κB, AKT, MAPK, Wnt/β-catenin and other molecular regulatory mechanisms. The multi-domain nature/multi-functional biological role of TRIMs implies that blocking just one function or one domain might not be sufficient to obtain the desired therapeutic outcome, therefore, a detailed and systematic understanding of the biological functions of the individual domains of TRIMs is required. This review mainly described their roles and underlying mechanisms in tumorigenesis and progression, and it might shade light on a potential targeting strategy for TRIMs in tumor treatment, especially using PROTACs.

TRIMs: Generalists Regulating the NLRP3 Inflammasome Signaling Pathway

Inflammation is a double-edged sword. The moderate inflammatory response is a fundamental defense mechanism produced by the body's resistance to dangerous stimuli and a repair process of the body itself. Increasing studies have confirmed that the overactivation of the inflammasome is involved in the occurrence and development of inflammatory diseases. Strictly controlling the overactivation of the inflammasome and preventing excessive inflammatory response have always been the research focus on inflammatory diseases. However, the endogenous regulatory mechanism of inflammasome is not completely clear. The tripartite motif (TRIM) protein is one of the members of E3 ligases in the process of ubiquitination. The universality and importance of the functions of TRIM members are recognized, including the regulation of inflammatory response. This article will focus on research on the relationship between TRIMs and NLRP3 Inflammasome, which may help us make some references for future related research and the discovery of treatment methods.

Biochemical strategies of E3 ubiquitin ligases target viruses in critical diseases

Viruses are known to cause various diseases in human and also infect other species such as animal plants, fungi, and bacteria. Replication of viruses depends upon their interaction with hosts. Human cells are prone to such unwanted viral infections. Disintegration and reconstitution require host machinery and various macromolecules like DNA, RNA, and proteins are invaded by viral particles. E3 ubiquitin ligases are known for their specific function, that is, recognition of their respective substrates for intracellular degradation. Still, we do not understand how ubiquitin proteasome system-based enzymes E3 ubiquitin ligases do their functional interaction with different viruses. Whether E3 ubiquitin ligases help in the elimination of viral components or viruses utilize their molecular capabilities in their intracellular propagation is not clear. The first time our current article comprehends fundamental concepts and new insights on the different viruses and their interaction with various E3 Ubiquitin Ligases. In this review, we highlight the molecular pathomechanism of viruses linked with E3 Ubiquitin Ligases dependent mechanisms. An enhanced understanding of E3 Ubiquitin Ligase-mediated removal of viral proteins may open new therapeutic strategies against viral infections.

TRIM proteins in lung cancer: Mechanisms, biomarkers and therapeutic targets

The tripartite motif (TRIM) family is defined by the presence of a Really Interesting New Gene (RING) domain, one or two B-box motifs and a coiled-coil region. TRIM proteins play key roles in many biological processes, including innate immunity, tumorigenesis, cell differentiation and ontogenetic development. Alterations in TRIM gene and protein levels frequently emerge in a wide range of tumors and affect tumor progression. As canonical E3 ubiquitin ligases, TRIM proteins participate in ubiquitin-dependent proteolysis of prominent components of the p53, NF-κB and PI3K/AKT signaling pathways. The occurrence of ubiquitylation events induced by TRIM proteins sustains internal balance between tumor suppressive and tumor promoting genes. In this review, we summarized the diverse mechanism of TRIM proteins responsible for the most common malignancy, lung cancer. Furthermore, we also discussed recent progress in both the diagnosis and therapeutics of tumors contributed by TRIM proteins.

TRIM22 activates NF-κB signaling in glioblastoma by accelerating the degradation of IκBα

NF-κB signaling plays a critical role in tumor growth and treatment resistance in GBM as in many other cancers. However, the molecular mechanisms underlying high, constitutive NF-κB activity in GBM remains to be elucidated. Here, we screened a panel of tripartite motif (TRIM) family proteins and identified TRIM22 as a potential activator of NF-κB using an NF-κB driven luciferase reporter construct in GBM cell lines. Knockout of TRIM22 using Cas9-sgRNAs led to reduced GBM cell proliferation, while TRIM22 overexpression enhanced proliferation of cell populations, in vitro and in an orthotopic xenograft model. However, two TRIM22 mutants, one with a critical RING-finger domain deletion and the other with amino acid changes at two active sites of RING E3 ligase (C15/18A), were both unable to promote GBM cell proliferation over controls, thus implicating E3 ligase activity in the growth-promoting properties of TRIM22. Co-immunoprecipitations demonstrated that TRIM22 bound a negative regulator of NF-κB, NF-κB inhibitor alpha (IκBα), and accelerated its degradation by inducing K48-linked ubiquitination. TRIM22 also formed a complex with the NF-κB upstream regulator IKKγ and promoted K63-linked ubiquitination, which led to the phosphorylation of both IKKα/β and IκBα. Expression of a non-phosphorylation mutant, srIκBα, inhibited the growth-promoting properties of TRIM22 in GBM cell lines. Finally, TRIM22 was increased in a cohort of primary GBM samples on a tissue microarray, and high expression of TRIM22 correlated with other clinical parameters associated with progressive gliomas, such as wild-type IDH1 status. In summary, our study revealed that TRIM22 activated NF-κB signaling through posttranslational modification of two critical regulators of NF-κB signaling in GBM cells.

TRIM62 knockout protects against cerebral ischemic injury in mice by suppressing NLRP3-regulated neuroinflammation

Cerebral stroke is a leading global cause for mortality and disability. However, its pathogenesis is still unclear. Most tripartite motif (TRIM) family proteins, including TRIM62, have E3 ubiquitin ligase activities, and have multiple functions in regulating cellular processes. Nevertheless, the effects of TRIM62 on cerebral stroke still remain vague. Here, we reported that TRIM62 expression was markedly up-regulated in oxygen and glucose deprivation (OGD)-treated microglial cells. After cerebral ischemia, significantly elevated expression of TRIM62 was detected in peri-infarct area of wild type (WT) mice. The TRIM62 knockout (KO) mice exhibited alleviated apoptosis and neuroinflammation in the ischemic brain, eventually attenuating the stroke outcomes. Both in vitro and in vivo studies showed that nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome was dramatically activated in cerebral ischemia/reperfusion (I/R) conditions, while being ameliorated in TRIM62-KO mice, contributing to the suppression of neuroinflammatory response. Importantly, the in vitro experiments showed that OGD could induce the K63-ubiquitination of TRIM62 and the interaction between TRIM62 and NLRP3. In addition, adenovirus-regulated TRIM62 over-expression promoted the NLRP3 and nuclear factor κB (NF-κB) signaling, along with elevated interleukin-1β (IL-1β) and IL-18 transcriptional activities. Together, our results demonstrated that TRIM62 suppression was strongly protective in ischemic stroke through inhibiting NLRP3-regulated neuroinflammation.

Knockdown of TRIM22 Relieves Oxygen-Glucose Deprivation/Reoxygenation-Induced Apoptosis and Inflammation Through Inhibition of NF-κB/NLRP3 Axis

Tripartite motif-containing 22 (TRIM22) has been documented to participate in numerous cellular activities during human diseases. However, whether TRIM22 is involved in the regulation of neuronal survival during the progression of cerebral ischemia/reperfusion (I/R) injury remains unknown. In the present study, treatment of HCN-2 cells with oxygen-glucose deprivation/reoxygenation (OGD/R) markedly upregulated TRIM22 expression. A significant increase in TRIM22 expression was observed in the ischemic cortex tissues from middle cerebral artery occlusion/reperfusion mice. OGD/R inhibited the viability and induced the apoptosis of HCN-2 cells, which was accompanied by an increase in caspase-3 activity and an increase in LDH release. Furthermore, OGD/R increased the levels of tumor necrosis factor-alpha, interleukin (IL)-1 beta, IL-6, and monocyte chemoattractant protein-1 and induced NLRP3 inflammasome activation, as evidenced by increases in NACHT, LRR and PYD domains-containing protein 3, apoptosis-associated speck-like protein containing a caspase recruitment domain and cleaved caspase-1 expression and caspase-1 activity. However, these changes induced by OGD/R were blocked by silencing of TRIM22. In addition, TRIM22 regulated NF-κB activity in HCN-2 cells undergoing OGD/R stimulation. Furthermore, inhibition of NF-κB by pyrrolidine dithiocarbamate inhibited OGD/R-induced NLRP3 inflammasome activation in HCN-2 cells. Taken together, silencing of TRIM22 protects neurons against OGD/R-induced apoptosis and inflammation. The anti-inflammatory effect of TRIM22 knockdown was the consequence of inhibition of NF-κB/NLRP3 axis. TRIM22 may be a potential target for treating cerebral I/R injury.

Nuclear localization signal in TRIM22 is essential for inhibition of type 2 porcine reproductive and respiratory syndrome virus replication in MARC-145 cells

Porcine reproductive and respiratory syndrome virus (PRRSV) infection causes one of the most economically important swine diseases worldwide. Tripartite motif-containing 22 (TRIM22), a TRIM family protein, has been identified as a crucial restriction factor that inhibits a group of human viruses. Currently, the role of cellular TRIM22 in PRRSV infection remains unclear. In the present study, we analyzed the effect of TRIM22 on PRRSV replication in vitro and explored the underlying mechanism. Ectopic expression of TRIM22 impaired the viral replication, while TRIM22-RNAi favored the replication of PRRSV in MARC-145 cells. Additionally, we observed that TRIM22 deletion SPRY domain or Nuclear localization signal (NLS) losses the ability to inhibit PRRSV replication. Finally, Co-IP analysis identified that TRIM22 interacts with PRRSV nucleocapsid (N) protein through the SPRY domain, while the NLS2 motif of N protein is involved in interaction with TRIM22. Although the concentration of PRRSV N protein was not altered in the presence of TRIM22, the abundance of N proteins from simian hemorrhagic fever virus (SHFV), equine arteritis virus (EAV), and murine lactate dehydrogenase-elevating virus (LDV) diminished considerably with increasing TRIM22 expression. Together, our findings uncover a previously unrecognized role for TRIM22 and extend the antiviral effects of TRIM22 to arteriviruses.

TRIM22 regulates macrophage autophagy and enhances Mycobacterium tuberculosis clearance by targeting the nuclear factor-multiplicity κB/beclin 1 pathway

Autophagy is a crucial host-defense mechanism against Mycobacterium tuberculosis (Mtb) infection by spanning innate and adaptive immune functions. TRIM22 is a member of tripartite motif family protein which involved in innate immunity and autophagy process. However, its role in the modulation of bacterial infection has not been investigated. Here, we demonstrated that TRIM22 is upregulated in a dose-dependent and time-dependent manner during Mtb infection of THP-1 cells. Downregulation of TRIM22 significantly decreased light chain 3 (LC3)-II protein level and the formation of LC3 puncta, while it markedly increased SQSTM1, a marker of autophagic degradation, in Mtb-infected THP-1 cells. What is more, enhanced bacterial survival was observed in TRIM22 knockdown THP-1 cells, while rapamycin abrogated this effect. In the presence of vector containing TRIM22 in THP-1 cells prior to infection, the survival of Mtb was decreased, while BafA restored this effect. Further study demonstrated that TRIM22 expression was regulated by MicroRNA-20b, and that TRIM22 regulates Mtb-infected THP-1 autophagy via the nuclear factor-κB/beclin 1 pathway. Using a nuclear factor-κB inhibitor BAY 11-7082, we found that TRIM22-induced high expression of LC3-II and the formation of LC3 was substantially attenuated, while the TRIM22-induced low expression of SQSTM1 was markedly increased in BAY 11-7082-treatment cells. In addition, the bacterial survival reduced by TRIM22 was significantly reversed by BAY 11-7082. Overall, these results suggest that TRIM22-augmented autophagy prevents intracellular Mtb to evade autophagic clearance, thereby inhibiting the persistence of Mtb infections.

Viral gene products actively promote latent infection by epigenetic silencing mechanisms

Many viruses undergo an acute infection in the host organism and then are cleared by the ensuing host immune response, but other viruses establish a persistent infection involving a latent infection or a chronic infection. Latent infection by the herpesviruses or human immunodeficiency virus involves epigenetic silencing of the DNA genome or proviral genome, respectively. Latent infection was previously thought to be a default pathway resulting from infection of a nonpermissive cell, but recent studies have shown that viral gene products can promote epigenetic silencing and latent infection. This review will summarize the viral gene products that have been shown to promote epigenetic silencing of the genomes and their potential for therapeutics to target these viral gene products and disrupt or lock in latent infection.