Recruitment of TRIM33 to cell-context specific PML nuclear bodies regulates nodal signaling in mESCs.

TRIM33 is a chromatin reader required for mammalian mesendoderm differentiation after activation of Nodal signaling, while its role in mESCs is still elusive. Here, we report that TRIM33 co-localizes with promyelocytic leukemia nuclear bodies (PML-NBs) specifically in mESCs, to mediate Nodal signaling-directed transcription of Lefty1/2. We show that TRIM33 puncta formation in mESCs depends on PML and on specific assembly of PML-NBs. Moreover, TRIM33 and PML co-regulate Lefty1/2 expression in mESCs, with both PML protein and formation of mESCs-specific PML-NBs being required for TRIM33 recruitment to these loci, and PML-NBs directly associating with the Lefty1/2 loci. Finally, a TurboID proximity-labeling experiment confirmed that TRIM33 is highly enriched only in mESCs-specific PML-NBs. Thus, our study supports a model in which TRIM33 condensates regulate Nodal signaling-directed transcription in mESCs and shows that PML-NBs can recruit distinct sets of client proteins in a cell-context-dependent manner.

Identification of RSK substrates using an analog-sensitive kinase approach.

The p90 ribosomal S6 kinases (RSK) family of serine/threonine kinases comprises four isoforms (RSK1-4) that lie downstream of the ERK1/2 mitogen-activated protein kinase pathway. RSKs are implicated in fine tuning of cellular processes such as translation, transcription, proliferation, and motility. Previous work showed that pathogens such as Cardioviruses could hijack any of the four RSK isoforms to inhibit PKR activation or to disrupt cellular nucleocytoplasmic trafficking. In contrast, some reports suggest nonredundant functions for distinct RSK isoforms, whereas Coffin-Lowry syndrome has only been associated with mutations in the gene encoding RSK2. In this work, we used the analog-sensitive kinase strategy to ask whether the cellular substrates of distinct RSK isoforms differ. We compared the substrates of two of the most distant RSK isoforms: RSK1 and RSK4. We identified a series of potential substrates for both RSKs in cells and validated RanBP3, PDCD4, IRS2, and ZC3H11A as substrates of both RSK1 and RSK4, and SORBS2 as an RSK1 substrate. In addition, using mutagenesis and inhibitors, we confirmed analog-sensitive kinase data showing that endogenous RSKs phosphorylate TRIM33 at S1119. Our data thus identify a series of potential RSK substrates and suggest that the substrates of RSK1 and RSK4 largely overlap and that the specificity of the various RSK isoforms likely depends on their cell- or tissue-specific expression pattern.

Trim33 conditions the lifespan of primitive macrophages and onset of definitive macrophage production.

Trim33 (Tif1γ) is a transcriptional regulator that is notably involved in several aspects of hematopoiesis. It is essential for the production of erythrocytes in zebrafish, and for the proper functioning and aging of hematopoietic stem and progenitor cells (HSPCs) in mice. Here, we have found that, in zebrafish development, Trim33 is essential cell-autonomously for the lifespan of the yolk sac-derived primitive macrophages, as well as for the initial production of definitive (HSPC-derived) macrophages in the first niche of definitive hematopoiesis, the caudal hematopoietic tissue. Moreover, Trim33 deficiency leads to an excess production of definitive neutrophils and thrombocytes. Our data indicate that Trim33 radically conditions the differentiation output of aorta-derived HSPCs in all four erythro-myeloid cell types, in a niche-specific manner.

Multi-omics integration highlights the role of ubiquitination in endometriosis fibrosis.

BACKGROUND: Endometriosis, characterized by the presence of active endometrial-like tissues outside the uterus, causes symptoms like dysmenorrhea and infertility due to the fibrosis of endometrial cells, which involves excessive deposition of extracellular matrix (ECM) proteins. Ubiquitination, an important post-transcriptional modification, regulates various biological processes in human diseases. However, its role in the fibrosis process in endometriosis remains unclear. METHODS: We employed multi-omics approaches on two cohorts of endometriosis patients with 39 samples. GO terms and KEGG pathways enrichment analyses were used to investigate the functional changes involved in endometriosis. Pearson's correlation coefficient analysis was conducted to explore the relationship between global proteome and ubiquitylome in endometriosis. The protein expression levels of ubiquitin-, fibrosis-related proteins, and E3 ubiquitin-protein ligase TRIM33 were validated via Western blot. Transfecting human endometrial stroma cells (hESCs) with TRIM33 small interfering RNA (siRNA) in vitro to explore how TRIM33 affects fibrosis-related proteins. RESULTS: Integration of proteomics and transcriptomics showed genes with concurrent change of both mRNA and protein level which involved in ECM production in ectopic endometria. Ubiquitylomics distinguished 1647 and 1698 ubiquitinated lysine sites in the ectopic (EC) group compared to the normal (NC) and eutopic (EU) groups, respectively. Further multi-omics integration highlighted the essential role of ubiquitination in key fibrosis regulators in endometriosis. Correlation analysis between proteome and ubiquitylome showed correlation coefficients of 0.32 and 0.36 for ubiquitinated fibrosis proteins in EC/NC and EC/EU groups, respectively, indicating positive regulation of fibrosis-related protein expression by ubiquitination in ectopic lesions. We identified ubiquitination in 41 pivotal proteins within the fibrosis-related pathway of endometriosis. Finally, the elevated expression of TGFBR1/α-SMA/FAP/FN1/Collagen1 proteins in EC tissues were validated across independent samples. More importantly, we demonstrated that both the mRNA and protein levels of TRIM33 were reduced in endometriotic tissues. Knockdown of TRIM33 promoted TGFBR1/p-SMAD2/α-SMA/FN1 protein expressions in hESCs but did not significantly affect Collagen1/FAP levels, suggesting its inhibitory effect on fibrosis in vitro. CONCLUSIONS: This study, employing multi-omics approaches, provides novel insights into endometriosis ubiquitination profiles and reveals aberrant expression of the E3 ubiquitin ligase TRIM33 in endometriotic tissues, emphasizing their critical involvement in fibrosis pathogenesis and potential therapeutic targets.

TRIM33 drives prostate tumor growth by stabilizing androgen receptor from Skp2-mediated degradation.

Androgen receptor (AR) is a master transcription factor that drives prostate cancer (PCa) development and progression. Alterations in the expression or activity of AR coregulators significantly impact the outcome of the disease. Using a proteomics approach, we identified the tripartite motif-containing 33 (TRIM33) as a novel transcriptional coactivator of AR. We demonstrate that TRIM33 facilitates AR chromatin binding to directly regulate a transcription program that promotes PCa progression. TRIM33 further stabilizes AR by protecting it from Skp2-mediated ubiquitination and proteasomal degradation. We also show that TRIM33 is essential for PCa tumor growth by avoiding cell-cycle arrest and apoptosis, and TRIM33 knockdown sensitizes PCa cells to AR antagonists. In clinical analyses, we find TRIM33 upregulated in multiple PCa patient cohorts. Finally, we uncover an AR-TRIM33-coactivated gene signature highly expressed in PCa tumors and predict disease recurrence. Overall, our results reveal that TRIM33 is an oncogenic AR coactivator in PCa and a potential therapeutic target for PCa treatment.

Exploiting ELIOT for Scaffold-Repurposing Opportunities: TRIM33 a Possible Novel E3 Ligase to Expand the Toolbox for PROTAC Design.

The field of targeted protein degradation, through the control of the ubiquitin-proteasome system (UPS), is progressing considerably; to exploit this new therapeutic modality, the proteolysis targeting chimera (PROTAC) technology was born. The opportunity to use PROTACs engaging of new E3 ligases that can hijack and control the UPS system could greatly extend the applicability of degrading molecules. To this end, here we show a potential application of the ELIOT (E3 LIgase pocketOme navigaTor) platform, previously published by this group, for a scaffold-repurposing strategy to identify new ligands for a novel E3 ligase, such as TRIM33. Starting from ELIOT, a case study of the cross-relationship using GRID Molecular Interaction Field (MIF) similarities between TRIM24 and TRIM33 binding sites was selected. Based on the assumption that similar pockets could bind similar ligands and considering that TRIM24 has 12 known co-crystalised ligands, we applied a scaffold-repurposing strategy for the identification of TRIM33 ligands exploiting the scaffold of TRIM24 ligands. We performed a deeper computational analysis to identify pocket similarities and differences, followed by docking and water analysis; selected ligands were synthesised and subsequently tested against TRIM33 via HTRF binding assay, and we obtained the first-ever X-ray crystallographic complexes of TRIM33α with three of the selected compounds.

Oncocytic intraductal carcinoma of salivary glands: a distinct variant with TRIM33-RET fusions and BRAF V600E mutations.

AIMS: Salivary gland intraductal carcinoma (IDC) is a complex ductal neoplasm surrounded by a layer of myoepithelial cells. Recent insights have shown that there are three different types: intercalated duct-like, with frequent NCOA4-RET fusions; apocrine, with salivary duct carcinoma-like mutations; and mixed intercalated duct-like/apocrine, with RET fusions, including TRIM27-RET. In addition, an oncocytic IDC has been described, but it remains unclear whether it represents a fourth variant or simply oncocytic metaplasia of another IDC type. Our aim was to more completely characterize oncocytic IDC. METHODS AND RESULTS: Six IDCs with oncocytic changes were retrieved from the authors' archives, from three men and three women ranging in age from 45 to 75 years (mean, 63 years). Five arose in the parotid gland, with one in an accessory parotid gland. Four patients with follow-up were free of disease after 1-23 months. Several immunostains (S100, mammaglobin, androgen receptor, and p63/p40) and molecular tools (RNA sequencing, RET fluorescence in-situ hybridisation, BRAF V600E VE1 immunohistochemistry, and Sanger sequencing) were applied. Histologically, the tumours were variably cystic with solid intracystic nodules often difficult to recognise as intraductal. In all, tumour ducts were positive for S100 and mammaglobin, negative for androgen receptor, and completely surrounded by myoepithelial cells positive for p63/p40. Molecular analysis revealed TRIM33-RET in two of six cases, NCOA4-RET in one of six cases, and BRAF V600E in two of six cases. One case had no identifiable alterations. CONCLUSIONS: Oncocytic IDC shares similarities with intercalated duct-like IDC. Although additional verification is needed, the oncocytic variant appears to be sufficiently unique to be now regarded as the fourth distinct subtype of IDC. Because of its indolent nature, oncocytic IDC should be distinguished from histological mimics.

Regulation of ß-catenin by IGFBP2 and its cytoplasmic actions in glioma.

PURPOSE: IGFBP2 is one of the highly expressed genes in glioblastoma (GBM). It has both IGF dependent and independent activities. IGF independent actions are mediated by the activation of integrin signalling through its RGD motif present at C-terminal domain. One of the actions of IGFBP2 is to regulate ß-catenin by the inactivation of GSK3ß, which preferentially accumulates in the cytoplasm. The mechanism of nuclear ß-catenin regulation by IGFBP2 and role of cytoplasmic ß-catenin is not clear. We aimed to understand the mechanism in GBM cell lines. METHODS: The gene expression studies were performed by RT-PCR, western blot analysis; the knockdown of genes was performed by shRNA transfection; RNAIP and luciferase reporter assays were utilized to study the cytoplasmic regulation of genes by ß-catenin; neurosphere assays were performed to study the stemness of cells. RESULTS: IGFBP2 overexpression or treatment in GBM cells regulates ß-catenin, TRIM33 (E3 ubiquitin ligase) and Oct4 genes. TRIM33 was induced by IGFBP2. ß-catenin was found to accumulate predominantly in the cytoplasm and nuclear ß-catenin was depleted by IGFBP2 induced TRIM33. IGFBP2 regulated cytoplasmic ß-catenin binds to 3' UTR of Oct4 RNA. IGFBP2 was also able to induce stemness of glioma cells. CONCLUSIONS: IGFBP2 induces TRIM33 which regulates the nuclear ß-catenin protein. In addition, IGFBP2 stabilizes the cytoplasmic ß-catenin which is involved in the regulation of Oct4 transcript and consequently induction of stemness of glioma cells.

Trim33 is essential for macrophage and neutrophil mobilization to developmental or inflammatory cues.

Macrophages infiltrate and establish in developing organs from an early stage, often before these have become vascularized. Similarly, leukocytes, in general, can quickly migrate through tissues to any site of wounding. This unique capacity is rooted in their characteristic amoeboid motility, the genetic basis of which is poorly understood. Trim33 (also known as Tif1-γ), a nuclear protein that associates with specific DNA-binding transcription factors to modulate gene expression, has been found to be mainly involved in hematopoiesis and gene regulation mediated by TGF-ß. Here, we have discovered that in Trim33-deficient zebrafish embryos, primitive macrophages are unable to colonize the central nervous system to become microglia. Moreover, both macrophages and neutrophils of Trim33-deficient embryos display a reduced basal mobility within interstitial tissues, and a profound lack of a response to inflammatory recruitment signals, including local bacterial infections. Correlatively, Trim33-deficient mouse bone marrow-derived macrophages display a strongly reduced three-dimensional amoeboid mobility in fibrous collagen gels. The transcriptional regulator Trim33 is thus revealed as being essential for the navigation of macrophages and neutrophils towards developmental or inflammatory cues within vertebrate tissues.

Loss of TRIM33 causes resistance to BET bromodomain inhibitors through MYC- and TGF-ß-dependent mechanisms.

Bromodomain and extraterminal domain protein inhibitors (BETi) hold great promise as a novel class of cancer therapeutics. Because acquired resistance typically limits durable responses to targeted therapies, it is important to understand mechanisms by which tumor cells adapt to BETi. Here, through pooled shRNA screening of colorectal cancer cells, we identified tripartite motif-containing protein 33 (TRIM33) as a factor promoting sensitivity to BETi. We demonstrate that loss of TRIM33 reprograms cancer cells to a more resistant state through at least two mechanisms. TRIM33 silencing attenuates down-regulation of MYC in response to BETi. Moreover, loss of TRIM33 enhances TGF-ß receptor expression and signaling, and blocking TGF-ß receptor activity potentiates the antiproliferative effect of BETi. These results describe a mechanism for BETi resistance and suggest that combining inhibition of TGF-ß signaling with BET bromodomain inhibition may offer new therapeutic benefits.

A Novel Role of Chromodomain Protein CBX8 in DNA Damage Response.

Induction of DNA damage induces a dynamic repair process involving DNA repair factors and epigenetic regulators. Chromatin alterations must occur for DNA repair factors to gain access to DNA lesions and restore original chromatin configuration to preserve the gene expression profile. We characterize the novel role of CBX8, a chromodomain-containing protein with established roles in epigenetic regulation in DNA damage response. CBX8 protein rapidly accumulates at the sites of DNA damage within 30 s and progresses to accumulate until 4 min before gradually dispersing back to its predamage distribution by 15 min. CBX8 recruitment to the sites of DNA damage is dependent upon PARP1 activation and not dependent on ATM activation. CBX8 biochemically interacts with TRIM33, and its recruitment to DNA damage is also dependent on the presence of TRIM33. Knockdown of CBX8 using siRNA significantly reduces the efficiency of both homologous and the other non-homologous recombination, as well as increases sensitivity of cells to ionizing radiation. These findings demonstrate that CBX8 functions in the PARP-dependent DNA damage response partly through interaction with TRIM33 and is required for efficient DNA repair.

TRIM33 is essential for osteoblast proliferation and differentiation via BMP pathway.

Tripartite motif containing 33 (TRIM33) functions both as a positive and negative regulator of the TGF-ß/BMP pathway in tumors; however, its effect and mechanism during osteoblast proliferation and differentiation, which involves the TGF-ß/BMP pathway is not defined. In this study, we used mouse C3H10T1/2 mesenchymal stem cell line and MC3T3-E1 preosteoblasts to investigate the role of TRIM33 during this process. The results demonstrated that the expression of TRIM33 increased during the differentiation. Moreover, the overexpression or knockdown of TRIM33 resulted in both an augmentation or decrease in osteoblast differentiation, which were measured by the expression of alkaline phosphatase (ALP) at the mRNA level, both Runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) at the protein level, and the formation of mineral modules. To further demonstrate the mechanism of TRIM33 in this process, we found that TRIM33 could positively mediate the BMP pathway by forming TRIM33-Smad1/5 complex. This interaction between TRIM33 and Smad1/5 triggered the phosphorylation of Smad1/5. In addition, the essential role of TRIM33 in osteoblast proliferation was determined in this study by CellCounting Kit (CCK) -8 and cell cycle assays. In summary, we establish the function of TRIM33 as a positive regulator of osteoblast differentiation in BMP pathway, which mediates its effect through its interaction with and activation of Smad1/5. In addition, the results clearly demonstrate that TRIM33 is necessary for osteoblast proliferation by regulating cell cycle. These results suggest that TRIM33 can be a positive target of osteoblast proliferation and differentiation through BMP pathway.

Tak1, Smad4 and Trim33 redundantly mediate TGF-ß3 signaling during palate development.

Transforming growth factor-beta3 (TGF-ß3) plays a critical role in palatal epithelial cells by inducing palatal epithelial fusion, failure of which results in cleft palate, one of the most common birth defects in humans. Recent studies have shown that Smad-dependent and Smad-independent pathways work redundantly to transduce TGF-ß3 signaling in palatal epithelial cells. However, detailed mechanisms by which this signaling is mediated still remain to be elucidated. Here we show that TGF-ß activated kinase-1 (Tak1) and Smad4 interact genetically in palatal epithelial fusion. While simultaneous abrogation of both Tak1 and Smad4 in palatal epithelial cells resulted in characteristic defects in the anterior and posterior secondary palate, these phenotypes were less severe than those seen in the corresponding Tgfb3 mutants. Moreover, our results demonstrate that Trim33, a novel chromatin reader and regulator of TGF-ß signaling, cooperates with Smad4 during palatogenesis. Unlike the epithelium-specific Smad4 mutants, epithelium-specific Tak1:Smad4- and Trim33:Smad4-double mutants display reduced expression of Mmp13 in palatal medial edge epithelial cells, suggesting that both of these redundant mechanisms are required for appropriate TGF-ß signal transduction. Moreover, we show that inactivation of Tak1 in Trim33:Smad4 double conditional knockouts leads to the palatal phenotypes which are identical to those seen in epithelium-specific Tgfb3 mutants. To conclude, our data reveal added complexity in TGF-ß signaling during palatogenesis and demonstrate that functionally redundant pathways involving Smad4, Tak1 and Trim33 regulate palatal epithelial fusion.

TIF1γ requires sumoylation to exert its repressive activity on TGFß signaling.

TIF1γ, a new regulator of TGFß signaling, inhibits the Smad4-mediated TGFß response by interaction with Smad2/3 or ubiquitylation of Smad4. We have shown that TIF1γ participates in TGFß signaling as a negative regulator of Smad4 during the TGFß-induced epithelial-to-mesenchymal transition (EMT) in mammary epithelial cells, and during terminal differentiation of mammary alveolar epithelial cells and lactation. We demonstrate here that TIF1γ is sumoylated and interacts with Ubc9, the only known SUMO-conjugating enzyme. Four functional sumoylation sites lie within the middle domain of TIF1γ, the Smad interaction domain. We show that a sumoylation-defective TIF1γ mutant significantly reduces TIF1γ inhibition of Smad complexes and that of the Smad-mediated TGFß transcriptional response. Moreover, chromatin immunoprecipitation experiments indicate that TIF1γ sumoylation is required to limit Smad4 binding on the PAI-1 TGFß target gene promoter. Ectopic expression of TIF1γ in mammary epithelial cells inhibits TGFß-induced EMT, an effect relieved by expression of non-sumoylated TIF1γ. Taken together, our results identify a new TGFß regulatory layer, whereby sumoylation strengthens the TIF1γ repressive action on canonical TGFß signaling.

Smad4 and Trim33/Tif1γ redundantly regulate neural stem cells in the developing cortex.

During central nervous system (CNS) development, proliferation and differentiation of neural stem cells (NSCs) have to be regulated in a spatio-temporal fashion. Here, we report different branches of the transforming growth factor ß (TGFß) signaling pathway to be required for the brain area-specific control of NSCs. In the midbrain, canonical TGFß signaling via Smad4 regulates the balance between proliferation and differentiation of NSCs. Accordingly, Smad4 deletion resulted in horizontal expansion of NSCs due to increased proliferation, decreased differentiation, and decreased cell cycle exit. In the developing cortex, however, ablation of Smad4 alone did not have any effect on proliferation and differentiation of NSCs. In contrast, concomitant mutation of both Smad4 and Trim33 led to an increase in proliferative cells in the ventricular zone due to decreased cell cycle exit, revealing a functional redundancy of Smad4 and Trim33. Furthermore, in Smad4-Trim33 double mutant embryos, cortical NSCs generated an excess of deep layer neurons concurrent with a delayed and reduced production of upper layer neurons and, in addition, failed to undergo the neurogenic to gliogenic switch at the right developmental stage. Thus, our data disclose that in different regions of the developing CNS different aspects of the TGFß signaling pathway are required to ensure proper development.

Tripartite Motif-containing 33 (TRIM33) protein functions in the poly(ADP-ribose) polymerase (PARP)-dependent DNA damage response through interaction with Amplified in Liver Cancer 1 (ALC1) protein.

Activation of poly(ADP-ribose) polymerase (PARP) near sites of DNA breaks facilitates recruitment of DNA repair proteins and promotes chromatin relaxation in part through the action of chromatin-remodeling enzyme Amplified in Liver Cancer 1 (ALC1). Through proteomic analysis we find that ALC1 interacts after DNA damage with Tripartite Motif-containing 33 (TRIM33), a multifunctional protein implicated in transcriptional regulation, TGF-ß signaling, and tumorigenesis. We demonstrate that TRIM33 is dynamically recruited to DNA damage sites in a PARP1- and ALC1-dependent manner. TRIM33-deficient cells show enhanced sensitivity to DNA damage and prolonged retention of ALC1 at sites of DNA breaks. Conversely, overexpression of TRIM33 alleviates the DNA repair defects conferred by ALC1 overexpression. Thus, TRIM33 plays a role in PARP-dependent DNA damage response and regulates ALC1 activity by promoting its timely removal from sites of DNA damage.

TRIM33 enhances the ubiquitination of TFRC to enhance the susceptibility of liver cancer cells to ferroptosis.

BACKGROUND: Hepatocellular carcinoma (HCC) is a common malignancy, and ferroptosis is a novel form of cell death driven by excessive lipid peroxidation. In recent years, ferroptosis has been widely utilized in cancer treatment, and the ubiquitination modification system has been recognized to play a crucial role in tumorigenesis and metastasis. Increasing evidence suggests that ubiquitin regulates ferroptosis-related substrates involved in this process. However, the precise mechanism of utilizing ubiquitination modification to regulate ferroptosis for HCC treatment remains unclear. METHODS: In this study, we detected the expression of TRIM33 in HCC using immunohistochemistry and western blotting techniques. The functional role of TRIM33 was verified through both in vitro and in vivo experiments. To evaluate the level of ferroptosis, mitochondrial superoxide levels, MDA levels, Fe2+ levels, and cell viability were assessed. Downstream substrates of TRIM33 were screened and confirmed via immunoprecipitation, immunofluorescence staining, and ubiquitination modification experiments. RESULTS: Our findings demonstrate that TRIM33 inhibits the growth and metastasis of HCC cells both in vitro and in vivo while promoting their susceptibility to ferroptosis. Mechanistically speaking, TRIM33 induces cellular ferroptosis through E3 ligase-dependent degradation of TFRC-a known inhibitor of this process-thus elucidating the specific type and site at which TFRC undergoes modification by TRIM33. CONCLUSION: In summary, our study reveals an important role for TRIM33 in HCC treatment while providing mechanistic support for its function. Additionally highlighted is the significance of ubiquitination modification leading to TFRC degradation-an insight that may prove valuable for future targeted therapies.

TRIM33 plays a critical role in regulating dendritic cell differentiation and homeostasis by modulating Irf8 and Bcl2l11 transcription.

The development of distinct dendritic cell (DC) subsets, namely, plasmacytoid DCs (pDCs) and conventional DC subsets (cDC1s and cDC2s), is controlled by specific transcription factors. IRF8 is essential for the fate specification of cDC1s. However, how the expression of Irf8 is regulated is not fully understood. In this study, we identified TRIM33 as a critical regulator of DC differentiation and maintenance. TRIM33 deletion in Trim33fl/fl Cre-ERT2 mice significantly impaired DC differentiation from hematopoietic progenitors at different developmental stages. TRIM33 deficiency downregulated the expression of multiple genes associated with DC differentiation in these progenitors. TRIM33 promoted the transcription of Irf8 to facilitate the differentiation of cDC1s by maintaining adequate CDK9 and Ser2 phosphorylated RNA polymerase II (S2 Pol II) levels at Irf8 gene sites. Moreover, TRIM33 prevented the apoptosis of DCs and progenitors by directly suppressing the PU.1-mediated transcription of Bcl2l11, thereby maintaining DC homeostasis. Taken together, our findings identified TRIM33 as a novel and crucial regulator of DC differentiation and maintenance through the modulation of Irf8 and Bcl2l11 expression. The finding that TRIM33 functions as a critical regulator of both DC differentiation and survival provides potential benefits for devising DC-based immune interventions and therapies.

Sequence Alignment between TRIM33 Gene and Human Noncoding RNAs: A Potential Explanation for Paraneoplastic Dermatomyositis.

BACKGROUND: This computational analysis investigated sequence complementarities between the TRIM33 gene and human noncoding (nc)RNAs and characterized their interactions in the context of paraneoplastic dermatomyositis. METHODS: TRIM33 FASTA sequence (NCBI Reference Sequence: NC_000001.11) was used for BLASTN analysis against Human GRCh38 in the Ensembl.org database. Retrieved ncRNAs showing hits to TRIM33 were searched in the GeneCards.org database and further analyzed through RNAInter, QmRLFS-finder, Spliceator, and NcPath enrichment analysis. RESULTS: A total of 100 hits were found, involving the lncRNAs NNT-AS1, MKLN1-AS, LINC01206, and PAXBP1-AS1, whose dysregulation has been reported in either cancer or dermatomyositis. Additionally, the lncRNAs NNT-AS1 and PAXBP1-AS1 may interact with microRNA-142-3p, reducing its expression and increasing that of TRIM33. Sequence complementarity affected only TRIM33 intron 1, possibly resulting in alternatively spliced isoforms of TIF1γ with increased immunogenicity. The results also revealed nucleotide alignment between TRIM33 and the gene regulatory elements of 28 ncRNA genes involved in immune pathways. CONCLUSIONS: This pivotal study demonstrates sequence complementarity between TRIM33 and human ncRNAs dysregulated in cancer and dermatomyositis. This scenario may lead to the overproduction of more immunogenic TIF1γ variants in tumors and the stimulation of autoimmunity. Further experimental analyses using targeted methods such as Western blot or Chip-Seq are required to confirm these data.

TRIM33 loss in multiple myeloma is associated with genomic instability and sensitivity to PARP inhibitors.

Deletions of chromosome 1p (del(1p)) are a recurrent genomic aberration associated with poor outcome in Multiple myeloma (MM.) TRIM33, an E3 ligase and transcriptional co-repressor, is located within a commonly deleted region at 1p13.2. TRIM33 is reported to play a role in the regulation of mitosis and PARP-dependent DNA damage response (DDR), both of which are important for maintenance of genome stability. Here, we demonstrate that MM patients with loss of TRIM33 exhibit increased chromosomal instability and poor outcome. Through knockdown studies, we show that TRIM33 loss induces a DDR defect, leading to accumulation of DNA double strand breaks (DSBs) and slower DNA repair kinetics, along with reduced efficiency of non-homologous end joining (NHEJ). Furthermore, TRIM33 loss results in dysregulated ubiquitination of ALC1, an important regulator of response to PARP inhibition. We show that TRIM33 knockdown sensitizes MM cells to the PARP inhibitor Olaparib, and this is synergistic with the standard of care therapy bortezomib, even in co-culture with bone marrow stromal cells (BMSCs). These findings suggest that TRIM33 loss contributes to the pathogenesis of high-risk MM and that this may be therapeutically exploited through the use of PARP inhibitors.