Analysis of the function, mechanism and clinical application prospect of TRPS1, a new marker for breast cancer.

It has been discovered that Trichorhinophalangeal Syndrome-1 (TRPS1), a novel member of the GATA transcription factor family, participates in both normal physiological processes and the development of numerous diseases. Recently, TRPS1 has been identified as a new biomarker to aid in cancer diagnosis and is very common in breast cancer (BC), especially in triple-negative breast cancer (TNBC). In this review, we discussed the structure and function of TRPS1 in various normal cells, focused on its role in tumorigenesis and tumor development, and summarize the research status of TRPS1 in the occurrence and development of BC. We also analyzed the potential use of TRPS1 in guiding clinically personalized precision treatment and the development of targeted drugs.

RNA splicing factor RBFOX2 is a key factor in the progression of cancer and cardiomyopathy.

BACKGROUND: Alternative splicing of pre-mRNA is a fundamental regulatory process in multicellular eukaryotes, significantly contributing to the diversification of the human proteome. RNA-binding fox-1 homologue 2 (RBFOX2), a member of the evolutionarily conserved RBFOX family, has emerged as a critical splicing regulator, playing a pivotal role in the alternative splicing of pre-mRNA. This review provides a comprehensive analysis of RBFOX2, elucidating its splicing activity through direct and indirect binding mechanisms. RBFOX2 exerts substantial influence over the alternative splicing of numerous transcripts, thereby shaping essential cellular processes such as differentiation and development. MAIN BODY OF THE ABSTRACT: Dysregulation of RBFOX2-mediated alternative splicing has been closely linked to a spectrum of cardiovascular diseases and malignant tumours, underscoring its potential as a therapeutic target. Despite significant progress, current research faces notable challenges. The complete structural characterisation of RBFOX2 remains elusive, limiting in-depth exploration beyond its RNA-recognition motif. Furthermore, the scarcity of studies focusing on RBFOX2-targeting drugs poses a hindrance to translating research findings into clinical applications. CONCLUSION: This review critically assesses the existing body of knowledge on RBFOX2, highlighting research gaps and limitations. By delineating these areas, this analysis not only serves as a foundational reference for future studies but also provides strategic insights for bridging these gaps. Addressing these challenges will be instrumental in unlocking the full therapeutic potential of RBFOX2, paving the way for innovative and effective treatments in various diseases.

P4HB regulates the TGFß/SMAD3 signaling pathway through PRMT1 to participate in high glucose-induced epithelial-mesenchymal transition and fibrosis of renal tubular epithelial cells.

BACKGROUND: Diabetic nephropathy (DN) is a common complication of diabetes mellitus, and Prolyl 4-Hydroxylase Subunit Beta (P4HB) expression is increased in high glucose (HG)-induced renal tubular epithelial cells (TECs). But it's role in HG-induced TECs remains to be elucidated. METHODS: The HK-2 cells were induced using HG and transfected with SiRNA-P4HB. DCFH-DA staining was utilized for the detection of cellular levels of ROS. WB and immunofluorescence were utilized to detect the expression of P4HB, epithelial-mesenchymal transition (EMT), fibrosis, and TGFß/SMAD3-related proteins in HK-2 cells. Online databases were utilized for predicting the interaction target of P4HB, and immunoprecipitation (IP) experiments were employed to validate the binding of P4HB with the target. SiRNA and overexpression vectors of target gene were used to verify the mechanism of action of P4HB. RESULTS: HG induced an increase in the expression of P4HB and TGFß, p-SMAD3, and ROS in HK-2 cells. Furthermore, HG downregulated the expression of E-cadherin and upregulated the expression of N-cadherin, Vimentin, α-SMA, Fibronectin, Collagen IV, SNAIL, and SLUG in HK-2 cells. Interfering with P4HB significantly reversed the expression of these proteins. Database predictions and IP experiments showed that P4HB interacts with PRMT1, and the expression of PRMT1 was increased in HG-induced HK-2 cells. Interfering with PRMT1 inhibited the changes in expression of EMT and fibrosis related proteins induced by HG. However, overexpression of PRMT1 weakened the regulatory effect of P4HB interference on the EMT, fibrosis, and TGFß/SMAD3-related proteins in HK-2 cells. CONCLUSION: P4HB regulated the TGFß/SMAD3 signaling pathway through PRMT1 and thus participates in HG-induced EMT and fibrosis in HK-2 cells.

NAC1 promotes stemness and regulates myeloid-derived cell status in triple-negative breast cancer.

Triple negative breast cancer (TNBC) is a particularly lethal breast cancer (BC) subtype driven by cancer stem cells (CSCs) and an immunosuppressive microenvironment. Our study reveals that nucleus accumbens associated protein 1 (NAC1), a member of the BTB/POZ gene family, plays a crucial role in TNBC by maintaining tumor stemness and influencing myeloid-derived suppressor cells (MDSCs). High NAC1 expression correlates with worse TNBC prognosis. NAC1 knockdown reduced CSC markers and tumor cell proliferation, migration, and invasion. Additionally, NAC1 affects oncogenic pathways such as the CD44-JAK1-STAT3 axis and immunosuppressive signals (TGFß, IL-6). Intriguingly, the impact of NAC1 on tumor growth varies with the host immune status, showing diminished tumorigenicity in natural killer (NK) cell-competent mice but increased tumorigenicity in NK cell-deficient ones. This highlights the important role of the host immune system in TNBC progression. In addition, high NAC1 level in MDSCs also supports TNBC stemness. Together, this study implies NAC1 as a promising therapeutic target able to simultaneously eradicate CSCs and mitigate immune evasion.

Transcriptional silencing in Saccharomyces cerevisiae: known unknowns.

Transcriptional silencing in Saccharomyces cerevisiae is a persistent and highly stable form of gene repression. It involves DNA silencers and repressor proteins that bind nucleosomes. The silenced state is influenced by numerous factors including the concentration of repressors, nature of activators, architecture of regulatory elements, modifying enzymes and the dynamics of chromatin.Silencers function to increase the residence time of repressor Sir proteins at silenced domains while clustering of silenced domains enables increased concentrations of repressors and helps facilitate long-range interactions. The presence of an accessible NDR at the regulatory regions of silenced genes, the cycling of chromatin configurations at regulatory sites, the mobility of Sir proteins, and the non-uniform distribution of the Sir proteins across the silenced domain, all result in silenced chromatin that only stably silences weak promoters and enhancers via changes in transcription burst duration and frequency.These data collectively suggest that silencing is probabilistic and the robustness of silencing is achieved through sub-optimization of many different nodes of action such that a stable expression state is generated and maintained even though individual constituents are in constant flux.

Calcium modulates the tethering of BCOR-PRC1.1 enzymatic core to KDM2B via liquid-liquid phase separation.

Recruitment of non-canonical BCOR-PRC1.1 to non-methylated CpG islands via KDM2B plays a fundamental role in transcription control during developmental processes and cancer progression. However, the mechanism is still largely unknown on how this recruitment is regulated. Here, we unveiled the importance of the Poly-D/E regions within the linker of BCOR for its binding to KDM2B. Interestingly, we also demonstrated that these negatively charged Poly-D/E regions on BCOR play autoinhibitory roles in liquid-liquid phase separation (LLPS) of BCORANK-linker-PUFD/PCGF1RAWUL. Through neutralizing negative charges of these Poly-D/E regions, Ca2+ not only weakens the interaction between BCOR/PCGF1 and KDM2B, but also promotes co-condensation of the enzymatic core of BCOR-PRC1.1 with KDM2B into liquid-like droplet. Accordingly, we propose that Ca2+ could modulate the compartmentation and recruitment of the enzymatic core of BCOR-PRC1.1 on KDM2B target loci. Thus, our finding advances the mechanistic understanding on how the tethering of BCOR-PRC1.1 enzymatic core to KDM2B is regulated.

Phosphorylation activates master growth regulator DELLA by promoting histone H2A binding at chromatin in Arabidopsis.

DELLA proteins are conserved master growth regulators that play a central role in controlling plant development in response to internal and environmental cues. DELLAs function as transcription regulators, which are recruited to target promoters by binding to transcription factors (TFs) and histone H2A via their GRAS domain. Recent studies showed that DELLA stability is regulated post-translationally via two mechanisms, phytohormone gibberellin-induced polyubiquitination for its rapid degradation, and Small Ubiquitin-like Modifier (SUMO)-conjugation to increase its accumulation. Moreover, DELLA activity is dynamically modulated by two distinct glycosylations: DELLA-TF interactions are enhanced by O-fucosylation, but inhibited by O-linked N-acetylglucosamine (O-GlcNAc) modification. However, the role of DELLA phosphorylation remains unclear as previous studies showing conflicting results ranging from findings that suggest phosphorylation promotes or reduces DELLA degradation to others indicating it has no effect on its stability. Here, we identify phosphorylation sites in REPRESSOR OF ga1-3 (RGA, an AtDELLA) purified from Arabidopsis by mass spectrometry analysis, and show that phosphorylation of two RGA peptides in the PolyS and PolyS/T regions enhances RGA activity by promoting H2A binding and RGA association with target promoters. Notably, phosphorylation does not affect RGA-TF interactions or RGA stability. Our study has uncovered a molecular mechanism of phosphorylation-induced DELLA activity.

ATXN3: a multifunctional protein involved in the polyglutamine disease spinocerebellar ataxia type 3.

ATXN3 is a ubiquitin hydrolase (or deubiquitinase, DUB), product of the ATXN3 gene, ubiquitously expressed in various cell types including peripheral and neuronal tissues and involved in several cellular pathways. Importantly, the expansion of the CAG trinucleotides within the ATXN3 gene leads to an expanded polyglutamine domain in the encoded protein, which has been associated with the onset of the spinocerebellar ataxia type 3, also known as Machado-Joseph disease, the most common dominantly inherited ataxia worldwide. ATXN3 has therefore been under intensive investigation for decades. In this review, we summarize the main functions of ATXN3 in proteostasis, DNA repair and transcriptional regulation, as well as the emerging role in regulating chromatin structure. The mentioned molecular functions of ATXN3 are also reviewed in the context of the pathological expanded form of ATXN3.

miR-96-5p expression is sufficient to induce and maintain the senescent cell fate in the absence of stress.

Senescence is a cell fate driven by different types of stress that results in exit from the cell cycle and expression of an inflammatory senescence-associated secretory phenotype (SASP). Here, we demonstrate that stable overexpression of miR-96-5p was sufficient to induce cellular senescence in the absence of genotoxic stress, inducing expression of certain markers of early senescence including SASP factors while repressing markers of deep senescence including LINE-1 and type 1 interferons. Stable miR-96-5p overexpression led to genome-wide changes in heterochromatin followed by epigenetic activation of p16Ink4a, p21Cip1, and SASP expression, induction of a marker of DNA damage, and induction of a transcriptional signature similar to other senescent lung and endothelial cell types. Expression of miR-96-5p significantly increased following senescence induction in culture cells and with aging in tissues from naturally aged and Ercc1-/Δ progeroid mice. Mechanistically, miR-96-5p directly suppressed expression of SIN3B and SIN3 corepressor complex constituents KDM5A and MORF4L2, and siRNA-mediated knockdown of these transcriptional regulators recapitulated the senescent phenotype. In addition, pharmacologic inhibition of the SIN3 complex suppressed senescence and SASP markers. These results clearly demonstrate that a single microRNA is sufficient to drive early senescence in the absence of genotoxic stress through targeting epigenetic and transcriptional regulators, identifying novel targets for the development of senotherapeutics.

PRMT1 inhibition perturbs RNA metabolism and induces DNA damage in clear cell renal cell carcinoma.

In addition to the ubiquitous loss of the VHL gene in clear cell renal cell carcinoma (ccRCC), co-deletions of chromatin-regulating genes are common drivers of tumorigenesis, suggesting potential vulnerability to epigenetic manipulation. A library of chemical probes targeting a spectrum of epigenetic regulators is screened using a panel of ccRCC models. MS023, a type I protein arginine methyltransferase (PRMT) inhibitor, is identified as an antitumorigenic agent. Individual knockdowns indicate PRMT1 as the specific critical dependency for cancer growth. Further analyses demonstrate impairments to cell cycle and DNA damage repair pathways upon MS023 treatment or PRMT1 knockdown. PRMT1-specific proteomics reveals an interactome rich in RNA binding proteins and further investigation indicates significant widespread disruptions in mRNA metabolism with both MS023 treatment and PRMT1 knockdown, resulting in R-loop accumulation and DNA damage over time. Our data supports PRMT1 as a target in ccRCC and informs a mechanism-based strategy for translational development.

Relationship between p16/ki67 immunoscores and PAX1/ZNF582 methylation status in precancerous and cancerous cervical lesions in high-risk HPV-positive women.

BACKGROUND: The risk of cervical cancer progression in high-risk human papillomavirus (HR-HPV)-positive women is associated with cervical lesion severity and molecular heterogeneity. Classification systems based on p16 and Ki67 expression cumulative scores (0-3 each)-p16/Ki67 collectively known as an immunoscore [IS]-are an accurate and reproducible method for grading cervical intraepithelial neoplasia (CIN) lesions. Meanwhile, DNA methylation is an early event in the development of cervical cancer. Hence, this study evaluated the relationship among CIN, p16/Ki-67 IS, and PAX1/ZNF582 methylation. METHODS: In this study, 414 HPV-positive paraffin-embedded specimens were collected, and PAX1/ZNF582 methylation and the p16/ki67 IS were determined. A total of 43 invalid samples were excluded and 371 were included in the statistical analyses. There were 103 cervicitis, 95 CIN1, 71 CIN2, 89 CIN3, and 13 squamous cell carcinoma (SCC) cases. The association between PAX1/ZNF582 methylation and p16/Ki6 immunohistochemical staining scores was analyzed. RESULTS: The ΔCp of PAX1m (PAX1 methylation) and ZNF582m (ZNF582 methylation) decreased with cervical lesion severity (Cuzick trend test, all P < 0.001). The severity of the cervical lesions and p16, Ki67, and p16/Ki67 IS showed an increasing trend (Multinomial Cochran-Armitage trend test, all P < 0.001). The prevalence of PAX1m/ZNF582m increased with an increase in the IS of p16, Ki67, and p16/Ki67 (Cochran-Armitage trend test, all P < 0.001). In cervical SCC, the IS was 5-6, and the PAX1m/ZNF582m was positive. Meanwhile, heterogeneity was observed in CIN lesions: 10 cases had an IS of 3-4 and were PAX1m/ZNF582m-positive in ≤ CIN1; 1 case had an IS of 0-2 and was PAX1m/ZNF582m-positive in CIN2/3. CONCLUSIONS: Significant heterogeneity was observed in CIN lesions for p16 and Ki67 immunohistochemical staining scores and PAX1/ZNF582 methylation. This may help clinicians personalize the management of CIN based on the predicted short-term risk of cancer progression, minimizing the rate of missed CIN1 diagnoses and incorrect treatment of CIN2/3.

Functional Analysis of RE1 Silencing Transcription Factor as a Putative Tumor Suppressor in Human Endometrial Cancer.

Uterine cancer is the most common gynecologic malignancy in the United States, with endometrioid endometrial adenocarcinoma (EC) being the most common histologic sub-type. Considering the molecular classifications of EC, efforts have been made to identify additional biomarkers that can assist in diagnosis, prognosis, and individualized therapy. We sought to explore the relationship of Repressor Element 1 (RE1) silencing transcription factor (REST), which downregulates neuronal genes in non-neuronal tissue, along with matrix metalloproteinase-24 (MMP24) and EC. We analyzed the expression of REST and MMP24 in 31 cases of endometrial cancer and 16 controls. We then explored the baseline expression of REST and MMP24 in two EC cell lines (Ishikawa and HEC-1-A) compared to a benign cell line (t-HESC) and subsequently evaluated proliferation, migration, and invasion in the setting of loss of REST gene expression. REST and MMP24 expression were significantly lower in human EC samples compared to control samples. REST was highly expressed in EC cell lines, but decreasing REST gene expression increased proliferation (FC: 1.13X, p < 0.0001), migration (1.72X, p < 0.0001), and invasion (FC: 7.77X, p < 0.05) in Ishikawa cells, which are hallmarks of cancer progression and metastasis. These findings elicit a potential role for REST as a putative tumor suppressor in EC.

Developmental regulation of dermal adipose tissue by BCL11b.

The distinct anatomic environment in which adipose tissues arise during organogenesis is a principle determinant of their adult expansion capacity. Metabolic disease results from a deficiency in hyperplastic adipose expansion within the dermal/subcutaneous depot; thus, understanding the embryonic origins of dermal adipose is imperative. Using single-cell transcriptomics throughout murine embryogenesis, we characterized cell populations, including Bcl11b + cells, that regulate the development of dermal white adipose tissue (dWAT). We discovered that BCL11b expression modulates the Wnt signaling microenvironment to enable adipogenic differentiation in the dermal compartment. Subcutaneous and visceral adipose arises from a distinct population of Nefl + cells during embryonic organogenesis, whereas Pi16 + /Dpp4 + fibroadipogenic progenitors support obesity-stimulated hypertrophic expansion in the adult. Together, these results highlight the unique regulatory pathways used by anatomically distinct adipose depots, with important implications for human metabolic disease.

Discovery of a Highly Potent and Selective Inhibitor Targeting Protein Lysine Methyltransferase NSD2.

The histone lysine methyltransferase NSD2 has been recognized as an attractive target for cancer treatment, due to the functional implication of its dysregulation in the initiation and progression of many cancers. Although considerable efforts have been made to develop NSD2 small-molecule inhibitors, highly potent and selective ones are still rarely available till now. Here, we report the discovery of a series of novel NSD2 inhibitors via an extensive SAR exploration of the privileged quinazoline scaffold within compound 8. The most promising compound 42 showed excellent NSD2 enzymatic inhibitory activity and good antiproliferative activity in cells. In addition, it demonstrated favorable pharmacokinetic properties and significantly inhibited the tumor growth in a RS411 tumor xenograft model with good safety. Taken together, compound 42 could be a promising NSD2 inhibitor and deserves further investigation.

The ICF2 gene Zbtb24 specifically regulates the differentiation of B1 cells via promoting heme synthesis.

BACKGROUND: Loss-of-function mutations of ZBTB24 cause immunodeficiency, centromeric instability, and facial anomalies syndrome 2 (ICF2). ICF2 is a rare autosomal recessive disorder with immunological defects in serum antibodies and circulating memory B cells, resulting in recurrent and sometimes fatal respiratory and gastrointestinal infections. The genotype-phenotype correlation in patients with ICF2 indicates an essential role of ZBTB24 in the terminal differentiation of B cells. METHODS: We used the clustered regularly interspaced short palindromic repeats (CRISPER)/Cas9 technology to generate B cell specific Zbtb24-deficient mice and verified the deletion specificity and efficiency by quantitative polymerase chain reaction (Q-PCR) and western blotting analyses in fluorescence-activated cell sorting (FACS)-sorted cells. The development, phenotype of B cells and in vivo responses to T cell dependent or independent antigens post immunization were analyzed by flow cytometry and enzyme-linked immunosorbent assay (ELISA). Adoptive transfer experiment in combination with in vitro cultures of FACS-purified B cells and RNA-Seq analysis were utilized to specifically determine the impact of Zbtb24 on B cell biology as well as the underlying mechanisms. RESULTS: Zbtb24 is dispensable for B cell development and maintenance in naive mice. Surprisingly, B cell specific deletion of Zbtb24 does not evidently compromise germinal center reactions and the resulting primary and secondary antibody responses induced by T cell dependent antigens (TD-Ags), but significantly inhibits T cell independent antigen-elicited antibody productions in vivo. At the cellular level, Zbtb24-deficiency specifically impedes the plasma cell differentiation of B1 cells without impairing their survival, activation and proliferation in vitro. Mechanistically, Zbtb24-ablation attenuates heme biosynthesis partially through mTORC1 in B1 cells, and addition of exogenous hemin abrogates the differentiation defects of Zbtb24-null B1 cells. CONCLUSIONS: Zbtb24 seems to regulate antibody responses against TD-Ags B cell extrinsically, but it specifically promotes the plasma cell differentiation of B1 cells via heme synthesis in mice. Our study also suggests that defected B1 functions contribute to recurrent infections in patients with ICF2.

APC and ZBTB2 May Mediate M2 Macrophage Infiltration to Promote the Development of Renal Fibrosis: A Bioinformatics Analysis.

Background and Purpose: The continuous accumulation of M2 macrophages may potentially contribute to the development of kidney fibrosis in chronic kidney disease (CKD). The purpose of this study was to analyze the infiltration of M2 macrophages in uremic patients and to seek new strategies to slow down the progression of renal fibrosis. Methods: We conducted a comprehensive search for expression data pertaining to uremic samples within the Gene Expression Omnibus (GEO) database, encompassing the time frame from 2010 to 2022. Control and uremic differentially expressed genes (DEGs) were identified. Immune cell infiltration was investigated by CIBERSORT and modules associated with M2 macrophage infiltration were identified by weighted gene coexpression network analysis (WGCNA). Consistent genes were identified using the least absolute shrinkage and selection operator (LASSO) and selection and visualization of the most relevant features (SVM-RFE) methods to search for overlapping genes. Receiver operating characteristic (ROC) curves were examined for the diagnostic value of candidate genes. Quantitative real-time PCR (qPCR) examined the expression levels of candidate genes obtained from uremic patients in M2 macrophage. Results: A total of 1298 DEGs were identified within the GSE37171 dataset. Significant enrichment of DEGs was observed in 20 biological processes (BP), 19 cellular components (CC), 6 molecular functions (MF), and 70 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. CIBERSORT analysis observed a significant increase in B-cell memory, dendritic cell activation, M0, M1, M2, and plasma cell numbers in uremic samples. We identified the 10 most interrelated genes. In particular, adenomatous polyposis coli (APC) and zinc finger and BTB structural domain 2 (ZBTB2) were adversely associated with the infiltration of M2 macrophages. Importantly, the expression levels of APC and ZBTB2 were far lower in M2 macrophages from uremic patients than those in healthy individuals. Conclusion: The development of renal fibrosis may be the result of M2 macrophage infiltration promoted by APC and ZBTB2.

ANKRD1 aggravates renal ischaemia‒reperfusion injury via promoting TRIM25-mediated ubiquitination of ACSL3.

BACKGROUND: Renal ischaemia‒reperfusion injury (IRI) is the primary cause of acute kidney injury (AKI). To date, effective therapies for delaying renal IRI and postponing patient survival remain absent. Ankyrin repeat domain 1 (ANKRD1) has been implicated in some pathophysiologic processes, but its role in renal IRI has not been explored. METHODS: The mouse model of IRI-AKI and in vitro model were utilised to investigate the role of ANKRD1. Immunoprecipitation-mass spectrometry was performed to identify potential ANKRD1-interacting proteins. Protein‒protein interactions and protein ubiquitination were examined using immunoprecipitation and proximity ligation assay and immunoblotting, respectively. Cell viability, damage and lipid peroxidation were evaluated using biochemical and cellular techniques. RESULTS: First, we unveiled that ANKRD1 were significantly elevated in renal IRI models. Global knockdown of ANKRD1 in all cell types of mouse kidney by recombinant adeno-associated virus (rAAV9)-mitigated ischaemia/reperfusion-induced renal damage and failure. Silencing ANKRD1 enhanced cell viability and alleviated cell damage in human renal proximal tubule cells exposed to hypoxia reoxygenation or hydrogen peroxide, while ANKRD1 overexpression had the opposite effect. Second, we discovered that ANKRD1's detrimental function during renal IRI involves promoting lipid peroxidation and ferroptosis by directly binding to and decreasing levels of acyl-coenzyme A synthetase long-chain family member 3 (ACSL3), a key protein in lipid metabolism. Furthermore, attenuating ACSL3 in vivo through pharmaceutical approach and in vitro via RNA interference mitigated the anti-ferroptotic effect of ANKRD1 knockdown. Finally, we showed ANKRD1 facilitated post-translational degradation of ACSL3 by modulating E3 ligase tripartite motif containing 25 (TRIM25) to catalyse K63-linked ubiquitination of ACSL3, thereby amplifying lipid peroxidation and ferroptosis, exacerbating renal injury. CONCLUSIONS: Our study revealed a previously unknown function of ANKRD1 in renal IRI. By driving ACSL3 ubiquitination and degradation, ANKRD1 aggravates ferroptosis and ultimately exacerbates IRI-AKI, underlining ANKRD1's potential as a therapeutic target for kidney IRI. KEY POINTS/HIGHLIGHTS: Ankyrin repeat domain 1 (ANKRD1) is rapidly activated in renal ischaemia‒reperfusion injury (IRI) models in vivo and in vitro. ANKRD1 knockdown mitigates kidney damage and preserves renal function. Ferroptosis contributes to the deteriorating function of ANKRD1 in renal IRI. ANKRD1 promotes acyl-coenzyme A synthetase long-chain family member 3 (ACSL3) degradation via the ubiquitin‒proteasome pathway. The E3 ligase tripartite motif containing 25 (TRIM25) is responsible for ANKRD1-mediated ubiquitination of ACSL3.

MTA2 knockdown suppresses human osteosarcoma metastasis by inhibiting uPA expression.

The relationship between metastasis-associated protein 2 (MTA2) overexpression and tumor growth and metastasis has been extensively studied in a variety of tumor cells but not in human osteosarcoma cells. This study aims to elucidate the clinical significance, underlying molecular mechanisms, and biological functions of MTA2 in human osteosarcoma in vitro and in vivo. Our results show that MTA2 was elevated in osteosarcoma cell lines and osteosarcoma tissues and was associated with tumor stage and overall survival of osteosarcoma patients. Knockdown of MTA2 inhibited osteosarcoma cell migration and invasion by reducing the expression of urokinase-type plasminogen activator (uPA). Bioinformatic analysis demonstrated that high levels of uPA in human osteosarcoma tissues correlated positively with MTA2 expression. Furthermore, treatment with recombinant human uPA (Rh-uPA) caused significant restoration of OS cell migration and invasion in MTA2 knockdown osteosarcoma cells. We found that ERK1/2 depletion increased the expression of uPA, facilitating osteosarcoma cell migration and invasion. Finally, MTA2 depletion significantly reduced tumor metastasis and the formation of lung nodules in vivo. Overall, our study suggests that MTA2 knockdown suppresses osteosarcoma cell metastasis by decreasing uPA expression via ERK signaling. This finding provides new insight into potential treatment strategies against osteosarcoma metastasis by targeting MTA2.

WTAP-mediated m6A modification of TRIM22 promotes diabetic nephropathy by inducing mitochondrial dysfunction via ubiquitination of OPA1.

OBJECTIVES: Diabetic nephropathy (DN) is one of the most serious microvascular complications of diabetes and is the most common cause of end-stage renal disease. Tripartite motif-containing (TRIM) proteins are a large family of E3 ubiquitin ligases that contribute to protein quality control by regulating the ubiquitin - proteasome system. However, the detailed mechanisms through which various TRIM proteins regulate downstream events have not yet been fully elucidated. The current research aimed to determine the function and mechanism of TRIM22 in DN. METHODS: DN models were established by inducing HK-2 cells using high glucose (HG) and diabetic mice (db/db mice). Cell viability, apoptosis, mitochondrial reactive oxygen species, and mitochondrial membrane potential were detected by Cell Counting Kit-8 and flow cytometry, respectively. Pathological changes were evaluated using hematoxylin and eosin, periodic acid schiff and Masson staining. The binding between TRIM22 and optic atrophy 1 (OPA1) was analyzed using co-immunoprecipitation. The m6A level of TRIM22 5'UTR was detected using RNA immunoprecipitation. RESULTS: TRIM22 was highly expressed in patients with DN. TRIM22 silencing inhibited HG-induced apoptosis and mitochondrial dysfunction in HK-2 cells. Promoting mitochondrial fusion alleviated TRIM22 overexpression-induced cell apoptosis, mitochondrial dysfunction in HK-2 cells, and kidney damage in mice. Mechanistically, TRIM22 interacted with OPA1 and induced its ubiquitination. Wilms tumor 1-associating protein (WTAP) promoted m6A modification of TRIM22 through the m6A reader insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1). DISCUSSION: TRIM22 silencing inhibited the progression of DN by interacting with OPA1 and inducing its ubiquitination. Furthermore, WTAP promoted m6A modification of TRIM22 via IGF2BP1.