Protein SUMOylation modification and its associations with disease

SENP3: Cancers and diseases

SUMOylation is a protein modification process that involves the covalent attachment of a small ubiquitin-like modifier (SUMO) to a specific lysine residue on the target protein. This modification can influence the function, localization, stability, and interactions of proteins, thereby regulating various cellular processes. Altering the SUMOylation of certain proteins is expected to be a potential approach for treating specific cancers and diseases. Among these, SENP3 can affect target proteins by regulating the deSUMOylation process, which in turn influences the transcriptional activity of downstream genes, playing a role in either promoting or inhibiting cancer. SENP3 regulates the SUMO status of proteins in numerous signaling pathways, modulating the activity of specific signaling molecules to impact cellular responses and tumor progression. Additionally, SENP3 promotes cell growth and division by deSUMOylating key cyclins. In the context of DNA repair, SENP3 regulates the activity of proteins associated with DNA repair by deSUMOylating repair factors, thereby enhancing DNA repair and maintaining genome stability. Furthermore, SENP3 has specific functions in various other diseases. The complex roles of SENP3 indicate its potential as both a therapeutic target and a biomarker.

Exploring the landscape of post-translational modification in drug discovery

Post-translational modifications (PTMs) play a crucial role in regulating protein function, and their dysregulation is frequently associated with various diseases. The emergence of epigenetic drugs targeting factors such as histone deacetylases (HDACs) and histone methyltransferase enhancers of zeste homolog 2 (EZH2) has led to a significant shift towards precision medicine, offering new possibilities to overcome the limitations of traditional therapeutics. In this review, we aim to systematically explore how small molecules modulate PTMs. We discuss the direct targeting of enzymes involved in PTM pathways, the modulation of substrate proteins, and the disruption of protein-enzyme interactions that govern PTM processes. Additionally, we delve into the emerging strategy of employing multifunctional molecules to precisely regulate the modification levels of proteins of interest (POIs). Furthermore, we examine the specific characteristics of these molecules, evaluating their therapeutic benefits and potential drawbacks. The goal of this review is to provide a comprehensive understanding of PTM-targeting strategies and their potential for personalized medicine, offering a forward-looking perspective on the evolution of precision therapeutics.

The therapeutic potential of RNA m(6)A in lung cancer

Lung cancer (LC) is a highly malignant and metastatic form of cancer. The global incidence of and mortality from LC is steadily increasing; the mean 5-year overall survival (OS) rate for LC is less than 20%. This frustrating situation may be attributed to the fact that the pathogenesis of LC remains poorly understood and there is still no cure for mid to advanced LC. Methylation at the N6-position of adenosine (N6mA) of RNA (m(6)A) is widely present in human tissues and organs, and has been found to be necessary for cell development and maintenance of homeostasis. However, numerous basic and clinical studies have demonstrated that RNA m(6)A is deregulated in many human malignancies including LC. This can drive LC malignant characteristics such as proliferation, stemness, invasion, epithelial-mesenchymal transition (EMT), metastasis, and therapeutic resistance. Intriguingly, an increasing number of studies have also shown that eliminating RNA m(6)A dysfunction can exert significant anti-cancer effects on LC such as suppression of cell proliferation and viability, induction of cell death, and reversal of treatment insensitivity. The current review comprehensively discusses the therapeutic potential of RNA m(6)A and its underlying molecular mechanisms in LC, providing useful information for the development of novel LC treatment strategies.

Recent pharmacological insights on abating toxic protein species burden in neurological disorders: Emphasis on 26S proteasome activation

Protein homeostasis (proteostasis) refers to the plethora of mechanisms that safeguard the proper folding of the newly synthesized proteins. It entails various intricately regulated cues that demolish the toxic protein species to prevent their aggregation. The ubiquitin-proteasome system (UPS) is recognized as a salient protein degradation system, with a substantial role in maintaining proteostasis. However, under certain circumstances the protein degradation capacity of the UPS is overwhelmed, leading to the accumulation of misfolded proteins. Several neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease, Huntington disease, and amyotrophic lateral sclerosis are characterized with the presence of protein aggregates and proteinopathy. Accordingly, enhancing the 26S proteasome degradation activity might delineate a pioneering approach in targeting various proteotoxic disorders. Regrettably, the exact molecular approaches that enhance the proteasomal activity are still not fully understood. Therefore, this review aimed to underscore several signaling cascades that might restore the degradation capacity of this molecular machine. In this review, we discuss the different molecular components of the UPS and how 26S proteasomes are deleteriously affected in many neurodegenerative diseases. Moreover, we summarize different signaling pathways that can be utilized to renovate the 26S proteasome functional capacity, alongside currently known druggable targets in this circuit and various classes of proteasome activators.

Exploring the contribution of Zfp521/ZNF521 on primary hematopoietic stem/progenitor cells and leukemia progression

Hematopoietic stem cells (HSCs) drive cellular turnover in the hematopoietic system by balancing self-renewal and differentiation. In the adult bone marrow (BM), these cells are regulated by a complex cellular microenvironment known as "niche," which involves dynamic interactions between diverse cellular and non-cellular elements. During blood cell maturation, lineage branching is guided by clusters of genes that interact or counteract each other, forming complex networks of lineage-specific transcription factors. Disruptions in these networks can lead to obstacles in differentiation, lineage reprogramming, and ultimately malignant transformation, including acute myeloid leukemia (AML). Zinc Finger Protein 521 (Znf521/Zfp521), a conserved transcription factor enriched in HSCs in both human and murine hematopoiesis, plays a pivotal role in regulating HSC self-renewal and differentiation. Its enforced expression preserves progenitor cell activity, while inhibition promotes differentiation toward the lymphoid and myeloid lineages. Transcriptomic analysis of human AML patient samples has revealed upregulation of ZNF521 in AMLs with the t(9;11) fusion gene MLL-AF9. In vitro studies have shown that ZNF521 collaborates with MLL-AF9 to enhance the growth of transformed leukemic cells, increase colony formation, and activate MLL target genes. Conversely, inhibition of ZNF521 using short-hairpin RNA (shRNA) results in decreased leukemia proliferation, reduced colony formation, and induction of cell cycle arrest in MLL-rearranged AML cell lines. In vivo experiments have demonstrated that mZFP521-deficient mice transduced with MLL-AF9 experience a delay in leukemia development. This review provides an overview of the regulatory network involving ZNF521, which plays a crucial role in controlling both HSC self-renewal and differentiation pathways. Furthermore, we examine the impact of ZNF521 on the leukemic phenotype and consider it a potential marker for MLL-AF9+ AML.

Disulfiram/copper complex improves the effectiveness of the WEE1 inhibitor Adavosertib in p53 deficient non-small cell lung cancer via ferroptosis

Cancer cells lacking functional p53 exhibit poor prognosis, necessitating effective treatment strategies. Inhibiting WEE1, the G2/M cell cycle checkpoint gatekeeper, represents a promising approach for treating p53-deficient NSCLC. Here, we investigate the connection between p53 and WEE1, as well as explore a synergistic therapeutic approach for managing p53-deficient NSCLC. Our study reveals that p53 deficiency upregulates both protein levels and kinase activity of WEE1 by inhibiting its SUMOylation process, thereby enhancing the susceptibility of p53-deficient NSCLC to WEE1 inhibitors. Furthermore, we demonstrate that the WEE1 inhibitor Adavosertib induces intracellular lipid peroxidation, specifically in p53-deficient NSCLC cells, suggesting potential synergy with pro-oxidant reagents. Repurposing Disulfiram (DSF), an alcoholism medication used in combination with copper (Cu), exhibits pro-oxidant properties against NSCLC. The levels of WEE1 protein in p53-deficient NSCLC cells treated with DSF-Cu exhibit a time-dependent increase. Subsequent evaluation of the combination therapy involving Adavosertib and DSF-Cu reveals reduced cell viability along with smaller tumor volumes and lighter tumor weights observed in both p53-deficient cells and xenograft models while correlating with solute carrier family 7-member 11 (SLC7A11)/glutathione-regulated ferroptosis pathway activation. In conclusion, our findings elucidate the molecular interplay between p53 and WEE1 and unveil a novel synergistic therapeutic strategy for treating p53-deficient NSCLC.

SUMO: A new perspective to decipher fibrosis

Fibrosis is characterized by excessive extracellular matrix (ECM) deposition resulting from dysregulated wound healing and connective tissue repair mechanisms. Excessive accumulation of ECM leads to fibrous tissue formation, impairing organ function and driving the progression of various fibrotic diseases. Recently, the role of small ubiquitin-like modifiers (SUMO) in fibrotic diseases has attracted significant attention. SUMO-mediated SUMOylation, a highly conserved posttranslational modification, participates in a variety of biological processes, including nuclear-cytosolic transport, cell cycle progression, DNA damage repair, and cellular metabolism. Conversely, SUMO-specific proteases cleave the isopeptide bond of SUMO conjugates, thereby regulating the deSUMOylation process. Mounting evidence indicates that SUMOylation and deSUMOylation regulate the functions of several proteins, such as Smad3, NF-κB, and promyelocytic leukemia protein, which are implicated in fibrotic diseases like liver fibrosis, myocardial fibrosis, and pulmonary fibrosis. This review summarizes the role of SUMO in fibrosis-related pathways and explores its pathological relevance in various fibrotic diseases. All evidence suggest that the SUMO pathway is important targets for the development of treatments for fibrotic diseases.

Identification of crucial genes and possible molecular pathways associated with active vitamin D intervention in diabetic kidney disease

Background

A significant cause of advanced renal failure is diabetic nephropathy (DKD), with few treatment options available. Calcitriol shows potential in addressing fibrosis related to DKD, though its molecular mechanisms remain poorly understood. This research seeks to pinpoint the crucial genes and pathways influenced by calcitriol within the scope of DKD-related fibrosis.

Methods

Single-cell gene expression profiling of calcitriol treated DKD rat kidney tissue and screening of fibrosis-associated cell subsets. Mendelian randomization and enrichment analyses (CIBERSORT, GSVA, GSEA, Motif Enrichment) were used to explore gene-immune cell interactions and signaling pathways. Key findings were validated using independent datasets and protein expression data from the Human Protein Atlas.

Results

Calcitriol treatment reduced proliferative cell populations and highlighted the FoxO signaling pathway's role in DKD. SUMO3 and CD74 were identified as key markers linked to immune infiltration and renal function. These genes were significantly associated with creatinine levels and eGFR, indicating their potential role in DKD progression.

Conclusion

Our results suggest that calcitriol modulates DKD fibrosis through the FoxO pathway, with SUMO3 and CD74 serving as potential biomarkers for kidney protection. These results provide fresh insights into strategies for treating DKD.

AMPK induces PIAS3 mediated SUMOylation of E3 ubiquitin ligase Smurf1 impairing osteogenic differentiation and traumatic heterotopic ossification

AMP-activated protein kinase (AMPK) is a typical sensor of intracellular energy metabolism. Our previous study revealed the role of activated AMPK in the suppression of osteogenic differentiation and traumatic heterotopic ossification, but the underlying mechanism remains poorly understood. The E3 ubiquitin ligase Smurf1 is a crucial regulator of osteogenic differentiation and bone formation. We report here that Smurf1 is primarily SUMOylated at a C-terminal lysine residue (K324), which enhances its activity, facilitating ALK2 proteolysis and subsequent bone morphogenetic protein (BMP) signaling pathway inhibition. Furthermore, SUMOylation of the SUMO E3 ligase PIAS3 and Smurf1 SUMOylation was suppressed during the osteogenic differentiation and traumatic heterotopic ossification. More importantly, we found that AMPK activation enhances the SUMOylation of Smurf1, which is mediated by PIAS3 and increases the association between PIAS3 and AMPK. Overall, our study revealed that Smurf1 can be SUMOylated by PIAS3, Furthermore, Smurf1 SUMOylation mediates osteogenic differentiation and traumatic heterotopic ossification through suppression of the BMP signaling pathway. This study revealed that promotion of Smurf1 SUMOylation by AMPK activation may be implicated in traumatic heterotopic ossification treatment.

Cbx4 SUMOylates BRD4 to regulate the expression of inflammatory cytokines in post-traumatic osteoarthritis

Brominated domain protein 4 (BRD4) is a chromatin reader known to exacerbate the inflammatory response in post-traumatic osteoarthritis (PTOA) by controlling the expression of inflammatory cytokines. However, the extent to which this regulatory effect is altered after BRD4 translation remains largely unknown. In this study, we showed that the E3 SUMO protein ligase CBX4 (Cbx4) is involved in the SUMO modification of BRD4 to affect its ability to control the expression of the proinflammatory genes IL-1β, TNF-α, and IL-6 in synovial fibroblasts. Specifically, Cbx4-mediated SUMOylation of K1111 lysine residues prevents the degradation of BRD4, thereby activating the transcriptional activities of the IL-1β, TNF-α and IL-6 genes, which depend on BRD4. SUMOylated BRD4 also recruits the multifunctional methyltransferase subunit TRM112-like protein (TRMT112) to further promote the processing of proinflammatory gene transcripts to eventually increase their expression. In vivo, treatment of PTOA with a Cbx4 inhibitor in rats was comparable to treatment with BRD4 inhibitors, indicating the importance of SUMOylation in controlling BRD4 to alleviate PTOA. Overall, this study is the first to identify Cbx4 as the enzyme responsible for the SUMO modification of BRD4 and highlights the central role of the Cbx4-BRD4 axis in exacerbating PTOA from the perspective of inflammation.

Sphingosine Kinase 1 Aggravates Liver Fibrosis by Mediating Macrophage Recruitment and Polarization

BACKGROUND & AIMS

Sphingosine kinase 1 (SphK1) has distinct roles in the activation of Kupffer cells and hepatic stellate cells in liver fibrosis. Here, we aim to investigate the roles of SphK1 on hepatic macrophage recruitment and polarization in liver fibrosis.

METHODS

Liver fibrosis was induced by carbon tetrachloride in wild-type and SphK1-/- mice to study the recruitment and polarization of macrophages. The effects of SphK1 originated from macrophages or other liver cell types on liver fibrosis were further strengthened by bone marrow transplantation. The direct effects of SphK1 on macrophage polarization were also investigated in vitro. Expression analysis of SphK1 and macrophage polarization index was conducted with human liver samples.

RESULTS

SphK1 deletion attenuated the recruitment of hepatic macrophages along with reduced M1 and M2 polarization in mice induced by carbon tetrachloride. SphK1 deficiency in endogenous liver cells attenuated macrophage recruitment via C-C motif chemokine ligand 2. Macrophage SphK1 activated the ASK1-JNK1/2-p38 signaling pathway to promote M1 polarization. Furthermore, macrophage SphK1 downregulated small ubiquitin-like modifier-specific peptidase1 to decrease de-SUMOylation of Kruppel-like factor 4 to promote M2 polarization. Finally, we confirmed that SphK1 expression was elevated and positively correlated with macrophage M1 and M2 polarization in human fibrosis livers.

CONCLUSIONS

Our findings demonstrated that SphK1 aggravated liver fibrosis by promoting macrophage recruitment and M1/M2 polarization. SphK1 in macrophages is a potential therapeutic target for the treatment of liver fibrosis.

Insight into the regulatory mechanism of β-arrestin2 and its emerging role in diseases

β-arrestin2, a member of the arrestin family, mediates the desensitization and internalization of most G protein-coupled receptors (GPCRs) and functions as a scaffold protein in signalling pathways. Previous studies have demonstrated that β-arrestin2 expression is dysregulated in malignant tumours, fibrotic diseases, cardiovascular diseases and metabolic diseases, suggesting its pathological roles. Transcription and post-transcriptional modifications can affect the expression of β-arrestin2. Furthermore, post-translational modifications, such as phosphorylation, ubiquitination, SUMOylation and S-nitrosylation affect the cellular localization of β-arrestin2 and its interaction with downstream signalling molecules, which further regulate the activity of β-arrestin2. This review summarizes the structure and function of β-arrestin2 and reveals the mechanisms involved in the regulation of β-arrestin2 at multiple levels. Additionally, recent studies on the role of β-arrestin2 in some major diseases and its therapeutic prospects have been discussed to provide a reference for the development of drugs targeting β-arrestin2.

SENP3 sensitizes macrophages to ferroptosis via de-SUMOylation of FSP1

Ferroptosis, driven by an imbalance in redox homeostasis, has recently been identified to regulate macrophage function and inflammatory responses. SENP3 is a redox-sensitive de-SUMOylation protease that plays an important role in macrophage function. However, doubt remains on whether SENP3 and SUMOylation regulate macrophage ferroptosis. For the first time, the results of our study suggest that SENP3 sensitizes macrophages to RSL3-induced ferroptosis. We showed that SENP3 promotes the ferroptosis of M2 macrophages to decrease M2 macrophage proportion in vivo. Mechanistically, we identified the ferroptosis repressor FSP1 as a substrate for SUMOylation and confirmed that SUMOylation takes place mainly at its K162 site. We found that SENP3 sensitizes macrophages to ferroptosis by interacting with and de-SUMOylating FSP1 at the K162 site. In summary, our study describes a novel type of posttranslational modification for FSP1 and advances our knowledge of the biological functions of SENP3 and SUMOylation in macrophage ferroptosis.

SENP6 restricts the IFN-I-induced signaling pathway and antiviral activity by deSUMOylating USP8

Type I interferon (IFN-I) exhibits broad-spectrum antiviral properties and is commonly employed in clinical for the treatment of viral infections. In this study, we unveil SENP6 as a potent regulator of IFN-I antiviral activity. SENP6 does not impact the production of IFN-I induced by viruses but rather modulates IFN-I-activated signaling. Mechanistically, SENP6 constitutively interacts with USP8 and inhibits the SUMOylation of USP8, consequently restricting the interaction between USP8 and IFNAR2. The dissociation of USP8 from IFNAR2 enhances IFNAR2 ubiquitination and degradation, thus attenuating IFN-I antiviral activity. Correspondingly, the downregulation of SENP6 promotes the interaction between USP8 and IFNAR2, leading to a reduction in IFNAR2 ubiquitination and, consequently, an enhancement in IFN-I-induced signaling. This study deciphers a critical deSUMOylation-deubiquitination crosstalk that finely regulates the IFN-I response to viral infection.

Regulations of m6A and other RNA modifications and their roles in cancer

RNA modification is an essential component of the epitranscriptome, regulating RNA metabolism and cellular functions. Several types of RNA modifications have been identified to date; they include N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N6,2'-O-dimethyladenosine (m6Am), N4-acetylcytidine (ac4C), etc. RNA modifications, mediated by regulators including writers, erasers, and readers, are associated with carcinogenesis, tumor microenvironment, metabolic reprogramming, immunosuppression, immunotherapy, chemotherapy, etc. A novel perspective indicates that regulatory subunits and post-translational modifications (PTMs) are involved in the regulation of writer, eraser, and reader functions in mediating RNA modifications, tumorigenesis, and anticancer therapy. In this review, we summarize the advances made in the knowledge of different RNA modifications (especially m6A) and focus on RNA modification regulators with functions modulated by a series of factors in cancer, including regulatory subunits (proteins, noncoding RNA or peptides encoded by long noncoding RNA) and PTMs (acetylation, SUMOylation, lactylation, phosphorylation, etc.). We also delineate the relationship between RNA modification regulator functions and carcinogenesis or cancer progression. Additionally, inhibitors that target RNA modification regulators for anticancer therapy and their synergistic effect combined with immunotherapy or chemotherapy are discussed.

A Novel Gene Signature Associated with Protein Post-translational Modification to Predict Clinical Outcomes and Therapeutic Responses of Colorectal Cancer

Accumulated evidence highlights the biological significance of diverse protein post-translational modifications (PTMs) in tumorigenicity and progression of colorectal cancer (CRC). In this study, ten PTM patterns (ubiquitination, methylation, phosphorylation, glycosylation, acetylation, SUMOylation, citrullination, neddylation, palmitoylation, and ADP-ribosylation) were analyzed for model construction. A post-translational modification index (PTMI) with a 14-gene signature was established. CRC patients with high PTMI had a worse prognosis after validating in nine independent datasets. By incorporating PTMI with clinical features, a nomogram with excellent predictive performance was constructed. Two molecular subtypes of CRC with obvious difference in survival time were identified by unsupervised clustering. Furthermore, PTMI was related to known immunoregulators and key tumor microenvironment components. Low-PTMI patients responded better to fluorouracil-based chemotherapy and immune checkpoint blockade therapy compared to high-PTMI patients, which was validated in multiple independent datasets. However, patients with high PTMI might be sensitive to bevacizumab. In short, we established a novel PTMI model by comprehensively analyzing diverse post-translational modification patterns, which can accurately predict clinical prognosis and treatment response of CRC patients.

Ubiquitination-Related Gene Signature, Nomogram and Immune Features for Prognostic Prediction in Patients with Head and Neck Squamous Cell Carcinoma

The objective of this research was to create a prognostic model focused on genes related to ubiquitination (UbRGs) for evaluating their clinical significance in head and neck squamous cell carcinoma (HNSCC) patients. The transcriptome expression data of UbRGs were obtained from The Cancer Genome Atlas (TCGA) database, and weighted gene co-expression network analysis (WGCNA) was used to identify specific UbRGs within survival-related hub modules. A multi-gene signature was formulated using LASSO Cox regression analysis. Furthermore, various analyses, including time-related receiver operating characteristics (ROCs), Kaplan-Meier, Cox regression, nomogram prediction, gene set enrichment, co-expression, immune, tumor mutation burden (TMB), and drug sensitivity, were conducted. Ultimately, a prognostic signature consisting of 11 gene pairs for HNSCC was established. The Kaplan-Meier curves indicated significantly improved overall survival (OS) in the low-risk group compared to the high-risk group (p < 0.001), suggesting its potential as an independent and dependable prognostic factor. Additionally, a nomogram with AUC values of 0.744, 0.852, and 0.861 at 1-, 3-, and 5-year intervals was developed. Infiltration of M2 macrophages was higher in the high-risk group, and the TMB was notably elevated compared to the low-risk group. Several chemotherapy drugs targeting UbRGs were recommended for low-risk and high-risk patients, respectively. The prognostic signature derived from UbRGs can effectively predict prognosis and provide new personalized therapeutic targets for HNSCC.

Topotecan and Ginkgolic Acid Inhibit the Expression and Transport Activity of Human Organic Anion Transporter 3 by Suppressing SUMOylation of the Transporter

Organic anion transporter 3 (OAT3), expressed at the basolateral membrane of kidney proximal tubule cells, facilitates the elimination of numerous metabolites, environmental toxins, and clinically important drugs. An earlier investigation from our laboratory revealed that OAT3 expression and transport activity can be upregulated by SUMOylation, a post-translational modification that covalently conjugates SUMO molecules to substrate proteins. Topotecan is a semi-synthetic derivative of the herbal extract camptothecin, approved by the FDA to treat several types of cancer. Ginkgolic acid (GA) is one of the major components in the extract of Ginkgo biloba leaves that has long been used in food supplements for preventing dementia, high blood pressure, and supporting stroke recovery. Both topotecan and GA have been shown to affect protein SUMOylation. In the current study, we tested our hypothesis that topotecan and GA may regulate OAT3 SUMOylation, expression, and transport function. Our data show that the treatment of OAT3-expressing cells with topotecan or GA significantly decreases the SUMOylation of OAT3 by 50% and 75%, respectively. The same treatment also led to substantial reductions in OAT3 expression and the OAT3-mediated transport of estrone sulfate, a prototypical substrate. Such reductions in cell surface expression of OAT3 correlated well with an increased rate of OAT3 degradation. Mechanistically, we discovered that topotecan enhanced the association between OAT3 and the SUMO-specific protease SENP2, a deSUMOylation enzyme, which contributed to the significant decrease in OAT3 SUMOylation. In conclusion, this study unveiled a novel role of topotecan and GA in inhibiting OAT3 expression and transport activity and accelerating OAT3 degradation by suppressing OAT3 SUMOylation. During comorbidity therapies, the use of topotecan or Ginkgo biloba extract could potentially decrease the transport activity of OAT3 in the kidneys, which will in turn affect the therapeutic efficacy and toxicity of many other drugs that are substrates for the transporter.

SUMOylation of annexin A6 retards cell migration and tumor growth by suppressing RHOU/AKT1-involved EMT in hepatocellular carcinoma

BACKGROUND

The protein annexin A6 (AnxA6) is involved in numerous membrane-related biological processes including cell migration and invasion by interacting with other proteins. The dysfunction of AnxA6, including protein expression abundance change and imbalance of post-translational modification, is tightly related to multiple cancers. Herein we focus on the biological function of AnxA6 SUMOylation in hepatocellular carcinoma (HCC) progression.

METHODS

The modification sites of AnxA6 SUMOylation were identified by LC-MS/MS and amino acid site mutation. AnxA6 expression was assessed by immunohistochemistry and immunofluorescence. HCC cells were induced into the epithelial-mesenchymal transition (EMT)-featured cells by 100 ng/mL 12-O-tetradecanoylphorbol-13-acetate exposure. The ability of cell migration was evaluated under AnxA6 overexpression by transwell assay. The SUMO1 modified AnxA6 proteins were enriched from total cellular proteins by immunoprecipitation with anti-SUMO1 antibody, then the SUMOylated AnxA6 was detected by Western blot using anti-AnxA6 antibody. The nude mouse xenograft and orthotopic hepatoma models were established to determine HCC growth and tumorigenicity in vivo. The HCC patient's overall survival versus AnxA6 expression level was evaluated by the Kaplan-Meier method.

RESULTS

Lys579 is a major SUMO1 modification site of AnxA6 in HCC cells, and SUMOylation protects AnxA6 from degradation via the ubiquitin-proteasome pathway. Compared to the wild-type AnxA6, its SUMO site mutant AnxA6K579R leads to disassociation of the binding of AnxA6 with RHOU, subsequently RHOU-mediated p-AKT1ser473 is upregulated to facilitate cell migration and EMT progression in HCC. Moreover, the SENP1 deSUMOylates AnxA6, and AnxA6 expression is negatively correlated with SENP1 protein expression level in HCC tissues, and a high gene expression ratio of ANXA6/SENP1 indicates a poor overall survival of patients.

CONCLUSIONS

AnxA6 deSUMOylation contributes to HCC progression and EMT phenotype, and the combination of AnxA6 and SENP1 is a better tumor biomarker for diagnosis of HCC grade malignancy and prognosis.

The SUMOylation pathway regulates the pathogenicity of Fusarium oxysporum f. sp. niveum in watermelon through stabilizing the pH regulator FonPalC via SUMOylation

SUMOylation is a key post-translational modification, where small ubiquitin-related modifier (SUMO) proteins regulate crucial biological processes, including pathogenesis, in phytopathogenic fungi. Here, we investigated the function and mechanism of the SUMOylation pathway in the pathogenicity of Fusarium oxysporum f. sp. niveum (Fon), the fungal pathogen that causes watermelon Fusarium wilt. Disruption of key SUMOylation pathway genes, FonSMT3, FonAOS1, FonUBC9, and FonMMS21, significantly reduced pathogenicity, impaired penetration ability, and attenuated invasive growth capacity of Fon. Transcription and proteomic analyses identified a diverse set of SUMOylation-regulated differentially expressed genes and putative FonSMT3-targeted proteins, which are predicted to be involved in infection, DNA damage repair, programmed cell death, reproduction, growth, and development. Among 155 putative FonSMT3-targeted proteins, FonPalC, a Pal/Rim-pH signaling regulator, was confirmed to be SUMOylated. The FonPalC protein accumulation was significantly decreased in SUMOylation-deficient mutant ∆Fonsmt3. Deletion of FonPalC resulted in impaired mycelial growth, decreased pathogenicity, enhanced osmosensitivity, and increased intracellular vacuolation in Fon. Importantly, mutations in conserved SUMOylation sites of FonPalC failed to restore the defects in ∆Fonpalc mutant, indicating the critical function of the SUMOylation in FonPalC stability and Fon pathogenicity. Identifying key SUMOylation-regulated pathogenicity-related proteins provides novel insights into the molecular mechanisms underlying Fon pathogenesis regulated by SUMOylation.

Ubiquitination, SUMOylation, and NEDDylation related genes serve as prognostic and therapeutic biomarkers for oral squamous cell carcinoma

BACKGROUND

Ubiquitination, small ubiquitin-related modifiers, and NEDDylation are now found to function in cancer biology; however, its role in the oral cancer patients remains unclear.

METHODS

A set of bioinformatic tools was integrated to analyze the expression and prognostic significance of ubiquitin and ubiquitin-like (UB/UBL) genes. A UB/UBL-related risk score was developed via correlation analyses, univariate Cox regression, and multivariate Cox regression. Nomogram analysis evaluates the model's prediction performance. The drug sensitivity analysis, immune profiles of UB/UBL-classified oral squamous cell carcinoma (OSCC) patients, and their related function pathway were investigated, and the role of UB/UBL-related genes in drug therapy was analyzed.

RESULTS

A total of six prognostic UB/UBL-related genes were obtained. PSMD3, PCGF2, and H2BC10 were significantly downregulated in OSCC tissue and associated with longer survival time. OSCC patients in the high-risk group showed a significantly lower overall survival and enriched in cancer-related pathways. The prognostic potential of genes associated with UB/UBL was discovered, and patients with high-risk scores showed an increase of protumor immune infiltrates and a high expression of immune checkpoints. Moreover, the area under the curve of the annual survival rate was 0.616, 0.671, and 0.673, respectively. Besides, patients in the high-risk group are more sensitive to docetaxel, doxorubicin, and methotrexate therapy.

CONCLUSIONS

We construct a prognosis model for OSCC patients with UB/UBL-related genes and try to find a new approach to treating oral cancer patients. The UB/UBL-related signature is helpful in developing new tumor markers, prognostic prediction, and in guiding treatment for OSCC patients.

Natural Product Baohuoside I Impairs the Stability and Membrane Location of MRP2 Reciprocally Regulated by SUMOylation and Ubiquitination in Hepatocytes

Epimedii Folium (EF) is a botanical dietary supplement to benefit immunity. Baohuoside I (BI), a prenylated flavonoid derived from EF, has exhibited the cholestatic risk before. Here, the mechanism of BI on the stability and membrane localization of liver MRP2, a bile acid exporter in the canalicular membrane of hepatocytes, was investigated. The fluorescent substrate of MRP2, CMFDA was accumulated in sandwich-cultured primary mouse hepatocytes (SCH) under BI stimulation, followed by reduced membrane MRP2 expression. BI triggered MRP2 endocytosis associated with oxidative stress via inhibition of the NRF2 signaling pathway. Meanwhile, BI promoted the degradation of MRP2 by reducing its SUMOylation and enhancing its ubiquitination level. Co-IP and fluorescence colocalization experiments all proved that MRP2 was a substrate protein for SUMOylation for SUMO proteins. CHX assays showed that SUMO1 prolonged the half-life of MRP2 and further increased its membrane expression, which could be reversed by UBC9 knockdown. Correspondingly, MRP2 accumulated in the cytoplasm by GP78 knockdown or under MG132 treatment. Additionally, the SUMOylation sites of MRP2 were predicted by the algorithm, and a conversion of lysines to arginines at positions 940 and 953 of human MRP2 caused its decreased stability and membrane location. K940 was further identified as the essential ubiquitination site for MRP2 by an in vitro ubiquitination assay. Moreover, the decreased ubiquitination of MRP2 enhanced the SUMOylation MRP2 and vice versa, and the crosstalk of these two modifiers could be disrupted by BI. Collectively, our findings indicated the process of MRP2 turnover from the membrane to cytoplasm at the post-translational level and further elucidated the novel toxicological mechanism of BI.

Myeloid SENP3 deficiency protects mice from diet and age-induced obesity via regulation of YAP1 SUMOylation

Obesity is characterized by chronic low-grade inflammation, which is driven by macrophage infiltration in adipose tissue and leads to elevated cytokines such as interleukin-1β (IL-1β) in the circulation and tissues. Previous studies demonstrate that SENP3, a redox-sensitive SUMO2/3-specific protease, is strongly implicated in the development and progression of cancer and cardiovascular diseases. However, the role of SENP3 in obesity-associated inflammation remains largely unknown. To better understand the effects of SENP3 on adipose tissue macrophage (ATM) activation and function within the context of obesity, we generated mice with myeloid-specific deletion of SENP3 (Senp3flox/flox;Lyz2-Cre mice). We found that the expression of SENP3 is dramatically increased in ATMs during high-fat diet (HFD)-induced obesity in mice. Senp3flox/flox;Lyz2-Cre mice show lower body weight gain and reduced adiposity and adipocyte size after challenged with HFD and during aging. Myeloid-specific SENP3 deletion attenuates macrophage infiltration in adipose tissue and reduces serum levels of inflammatory factors during diet and age-induced obesity. Furthermore, we found that SENP3 knockout markedly inhibits cytokine release from macrophage after lipopolysaccharide and palmitic acid treatment in vitro. Mechanistically, in cultured peritoneal macrophages, SENP3 protein level is enhanced by IL-1β, in parallel with the upregulation of Yes-associated protein 1 (YAP1). Moreover, we demonstrated that SENP3 modulates de-SUMO modification of YAP1 and SENP3 deletion abolishes the upregulation of YAP1 induced by IL-1β. Most importantly, SENP3 deficiency reduces YAP1 protein level in adipose tissue during obesity. Our results highlight the important role of SENP3 in ATM inflammation and diet and age-induced obesity.

Profile analysis of N4-acetylcytidine (ac4C) on mRNA of human lung adenocarcinoma and paired adjacent non-tumor tissues

BACKGROUND

RNA modification, a major component of post-transcriptional modification, plays an essential role in tumor initiation and progression. N4-acetylcytidine (ac4C) present in different species as a highly conserved RNA modification. ac4C on mRNA increases the stability of mRNA and the efficiency of protein translation. However, the mRNA profiling of ac4C in lung adenocarcinoma (LUAD) is unknown.

METHODS

NAT10 expression was tested using immunohistochemistry in tissue microarray (TMA). The ac4C peaks on mRNA were identified through acetylated RNA immunoprecipitation sequencing in both human LUAD tissues and adjacent non-tumor tissues, and differences of acetylation and mRNA between the two groups were analyzed. Furthermore, the function of AC4C-specific acetylated transcripts was analyzed bioinformatically. And a ac-RIP-PCR was used to verify the ac4C acetylation sites of TFAP2A.

RESULTS

The expression of acetylated key enzyme NAT10 was obviously increased in LUAD group. Then we found noticeable differences in ac4C mRNA modification between LUAD and adjacent non-tumor tissues. In addition, bioinformatics analysis showed that the distinctive distribution pattern of mRNA ac4C in LUAD affects a variety of cellular functions, such as protein sumoylation and transmembrane transporter activity. Importantly, we verified the ac4C level of TFAP2A was up-regulated in LUAD.

CONCLUSIONS

Our study revealed that the degree of ac4C in mRNA in LUAD was significantly higher than in adjacent tissues and was concentrated mainly in the coding sequences with a implications in a wide range of cellular functions. The ac4C may become a new molecular marker and treatment target for lung cancer.

Exome sequencing links the SUMO protease SENP7 with fatal arthrogryposis multiplex congenita, early respiratory failure and neutropenia

BACKGROUND

SUMOylation involves the attachment of small ubiquitin-like modifier (SUMO) proteins to specific lysine residues on thousands of substrates with target-specific effects on protein function. Sentrin-specific proteases (SENPs) are proteins involved in the maturation and deconjugation of SUMO. Specifically, SENP7 is responsible for processing polySUMO chains on targeted substrates including the heterochromatin protein 1α (HP1α).

METHODS

We performed exome sequencing and segregation studies in a family with several infants presenting with an unidentified syndrome. RNA and protein expression studies were performed in fibroblasts available from one subject.

RESULTS

We identified a kindred with four affected subjects presenting with a spectrum of findings including congenital arthrogryposis, no achievement of developmental milestones, early respiratory failure, neutropenia and recurrent infections. All died within four months after birth. Exome sequencing identified a homozygous stop gain variant in SENP7 c.1474C>T; p.(Gln492*) as the probable aetiology. The proband's fibroblasts demonstrated decreased mRNA expression. Protein expression studies showed significant protein dysregulation in total cell lysates and in the chromatin fraction. We found that HP1α levels as well as different histones and H3K9me3 were reduced in patient fibroblasts. These results support previous studies showing interaction between SENP7 and HP1α, and suggest loss of SENP7 leads to reduced heterochromatin condensation and subsequent aberrant gene expression.

CONCLUSION

Our results suggest a critical role for SENP7 in nervous system development, haematopoiesis and immune function in humans.

SUMOylation of Smad2 mediates TGF-β-regulated endothelial-mesenchymal transition

Endothelial-mesenchymal transition (EndoMT) is a complex biological process in which endothelial cells are transformed into mesenchymal cells, and dysregulated EndoMT causes a variety of pathological processes. Transforming growth factor beta (TGF-β) signaling effectively induces the EndoMT process in endothelial cells, and Smad2 is the critical protein of the TGF-β signaling pathway. However, whether small ubiquitin-like modifier modification (SUMOylation) is involved in EndoMT remains unclear. Here, we show that Smad2 is predominantly modified by SUMO1 at two major SUMOylation sites with PIAS2α as the primary E3 ligase, whereas SENP1 (sentrin/SUMO-specific protease 1) mediates the deSUMOylation of Smad2. In addition, we identified that SUMOylation significantly enhances the transcriptional activity and protein stability of Smad2, regulating the expression of downstream target genes. SUMOylation increases the phosphorylation of Smad2 and the formation of the Smad2-Smad4 complex, thus promoting the nuclear translocation of Smad2. Ultimately, the wildtype, but not SUMOylation site mutant Smad2 facilitated the EndoMT process. More importantly, TGF-β enhances the nuclear translocation of Smad2 by enhancing its SUMOylation and promoting the EndoMT process. These results demonstrate that SUMOylation of Smad2 plays a critical role in the TGF-β-mediated EndoMT process, providing a new theoretical basis for the treatment and potential drug targets of EndoMT-related clinical diseases.

SUMO-Activating Enzyme Subunit 1 Is Associated with Poor Prognosis, Tumor Progression, and Radio-Resistance in Colorectal Cancer

Concurrent chemoradiotherapy is an effective treatment option for patients with low-grade colorectal cancer (CRC) in the local disease stage. At present, the principle of the Taiwan Medical Center is to treat CRC patients with combination radiotherapy and chemotherapy (high-dose 5-FU) for a period of about five weeks prior to surgery. Radical resection of the tumor is performed at least six to eight weeks after concurrent chemoradiotherapy (CCRT). However, this approach fails to produce the desired therapeutic effect in approximately 20% to 30% of patients, and such patients are unnecessarily exposed to the risks of radiation and drug toxicity posed by this therapy. Therefore, it is crucial to explore new biomarkers to predict the prognosis of CRC. SUMO-activating enzyme subunit 1 (SAE1) plays an important role in SUMOylation, a post-translational modification involved in cellular functions, such as cell proliferation, cell cycle, and apoptosis. In our study, to explore the clinical-pathological role of SAE1 protein in CRC, we evaluated the clinical data and paraffin sections from CRC patients. The expression of SAE1 was evaluated using immunohistochemical analysis, and clinical parameters were analyzed using chi-square and Kaplan-Meier survival tests. The results of in vitro proliferation and radiosensitive assays were compared between control groups and SAE1 siRNA groups. Western blotting was also used to detect the expressions of the SAE1, PARP, cyclin D1, p-NF-κB, and NF-κB proteins. Flow cytometry and colony formation assays were used to detect the effect of SAE-1 on radiosensitivity. In vivo, we detected the growth curve in a mouse xenograft model. The results showed that SAE-1 was revealed to be an independent prognostic biomarker of CRC. SAE1 knockdown inhibited CRC proliferation in vitro and in vivo, and led to the cleavage of PARP, downregulation of cyclin D1 protein expression, and downregulation of p-NF-κB/NF-κB. Additionally, SAE1 knockdown promoted radiosensitivity in CRC cells. Therefore, it was inferred that SAE1 may be used as a potential therapeutic target in CRC treatment.

SifA SUMOylation governs Salmonella Typhimurium intracellular survival via modulation of lysosomal function

One of the mechanisms shaping the pathophysiology during the infection of enteric pathogen Salmonella Typhimurium is host PTM machinery utilization by the pathogen encoded effectors. Salmonella Typhimurium (S. Tm) during infection in host cells thrives in a vacuolated compartment, Salmonella containing vacuole (SCV), which sequentially acquires host endosomal and lysosomal markers. Long tubular structures, called as Salmonella induced filaments (SIFs), are further generated by S. Tm, which are known to be required for SCV's nutrient acquisition, membrane maintenance and stability. A tightly coordinated interaction involving prominent effector SifA and various host adapters PLEKHM1, PLEKHM2 and Rab GTPases govern SCV integrity and SIF formation. Here, we report for the first time that the functional regulation of SifA is modulated by PTM SUMOylation at its 11th lysine. S. Tm expressing SUMOylation deficient lysine 11 mutants of SifA (SifAK11R) is defective in intracellular proliferation due to compromised SIF formation and enhanced lysosomal acidification. Furthermore, murine competitive index experiments reveal defective in vivo proliferation and weakened virulence of SifAK11R mutant. Concisely, our data reveal that SifAK11R mutant nearly behaves like a SifA knockout strain which impacts Rab9-MPR mediated lysosomal acidification pathway, the outcome of which culminates in reduced bacterial load in in vitro and in vivo infection model systems. Our results bring forth a novel pathogen-host crosstalk mechanism where the SUMOylation of effector SifA regulated S. Tm intracellular survival.

The regulation of human organic anion transporter 4 by insulin-like growth factor 1 and protein kinase B signaling

Human organic anion transporter 4 (hOAT4), mainly expressed in the kidney and placenta, is essential for the disposition of numerous drugs, toxins, and endogenous substances. Insulin-like growth factor 1 (IGF-1) is a hormone generated in the liver and plays important roles in systemic growth, development, and metabolism. In the current study, we explored the regulatory effects of IGF-1 and downstream signaling on the transport activity, protein expression, and SUMOylation of hOAT4. We showed that IGF-1 significantly increased the transport activity, expression, and maximal transport velocity Vmax of hOAT4 in kidney-derived cells. This stimulatory effect of IGF-1 on hOAT4 activity was also confirmed in cells derived from the human placenta. The increased activity and expression were correlated well with the reduced degradation rate of hOAT4 at the cell surface. Furthermore, IGF-1 significantly increased hOAT4 SUMOylation, and protein kinase B (PKB)-specific inhibitors blocked the IGF-1-induced regulations on hOAT4. In conclusion, our study demonstrates that the hepatic hormone IGF-1 regulates hOAT4 expressed in the kidney and placenta through the PKB signaling pathway. Our results support the remote sensing and signaling theory, where OATs play a central role in the remote communications among distal tissues.

Regulation and clinical potential of telomerase reverse transcriptase (TERT/hTERT) in breast cancer

Telomerase reverse transcriptase (TERT/hTERT) serves as the pivotal catalytic subunit of telomerase, a crucial enzyme responsible for telomere maintenance and human genome stability. The high activation of hTERT, observed in over 90% of tumors, plays a significant role in tumor initiation and progression. An in-depth exploration of hTERT activation mechanisms in cancer holds promise for advancing our understanding of the disease and developing more effective treatment strategies. In breast cancer, the expression of hTERT is regulated by epigenetic, transcriptional, post-translational modification mechanisms and DNA variation. Besides its canonical function in telomere maintenance, hTERT exerts non-canonical roles that contribute to disease progression through telomerase-independent mechanisms. This comprehensive review summarizes the regulatory mechanisms governing hTERT in breast cancer and elucidates the functional implications of its activation. Given the overexpression of hTERT in most breast cancer cells, the detection of hTERT and its associated molecules are potential for enhancing early screening and prognostic evaluation of breast cancer. Although still in its early stages, therapeutic approaches targeting hTERT and its regulatory molecules show promise as viable strategies for breast cancer treatment. These methods are also discussed in this paper. Video Abstract.

SUMO1 and Defective Spermatozoa Correlate with Endogenous Hydrogen Peroxide and Live Birth Outcome in Intrauterine Insemination Cycles for Unexplained Infertility

This study aimed to investigate the correlation between hydrogen peroxide (H2O2), small ubiquitin-like modifier molecules (SUMO), and pregnancy outcomes in couples with unexplained infertility (UI) undergoing intrauterine insemination (IUI) treatment. We prospectively collected semen samples from 56 couples with UI and divided the spermatozoa into motile and immotile fractions by density gradient centrifugation (DSC). Immunofluorescence staining was used to examine the immunostaining and localization of nuclear pore complex (NPC), SUMO1, and SUMO2/3 in spermatozoa. We detected H2O2 levels by chemiluminescence methods. We found that H2O2 levels correlated with NPC (neck) (r = 0.400) and NPC (tail) (r = 0.473) in motile sperm fractions. In immotile fractions, H2O2 positively correlated with NPC (tail) (r = 0.431) and SUMO1 (neck) (r = 0.282). Furthermore, the positive NPC (tail) group had a significantly lower live birth rate than the negative NPC group (17.9% = 5/28 vs. 42.9% = 12/28). In conclusion, H2O2 positively correlated with SUMO1 (neck) and NPC (tail) in human spermatozoa. The DSC may partially eliminate defective spermatozoa (positive NPC staining); however, if defective spermatozoa remain in the motile fraction, this scenario is associated with a low live birth rate following IUI treatment.

Ubiquitination detection techniques

Ubiquitination is an intricately regulated post-translational modification that involves the covalent attachment of ubiquitin to a substrate protein. The complex dynamic nature of the ubiquitination process regulates diverse cellular functions including targeting proteins for degradation, cell cycle, deoxyribonucleic acid (DNA) damage repair, and numerous cell signaling pathways. Ubiquitination also serves as a crucial mechanism in protein quality control. Dysregulation in ubiquitination could result in lethal disease conditions such as cancers and neurodegenerative diseases. Therefore, the ubiquitination cascade has become an attractive target for therapeutic interventions. Enormous efforts have been made to detect ubiquitination involving different detection techniques to better grasp the underlying molecular mechanisms of ubiquitination. This review discusses a wide range of techniques stretching from the simplest assays to real-time assays. This includes western blotting/immunoblotting, fluorescence assays, chemiluminescence assays, spectrophotometric assays, and nanopore sensing assays. This review compares these applications, and the inherent advantages and limitations.

SUMOylation of AnxA6 facilitates EGFR-PKCα complex formation to suppress epithelial cancer growth

BACKGROUND

The Annexin A6 (AnxA6) protein is known to inhibit the epidermal growth factor receptor (EGFR)-extracellular signal regulated kinase (ERK)1/2 signaling upon EGF stimulation. While the biochemical mechanism of AnxA6 inactivating phosphorylation of EGFR and ERK1/2 is not completely explored in cancer cells.

METHODS

Cells were transiently co-transfected with pFlag-AnxA6, pHA-UBC9 and pHis-SUMO1 plasmids to enrich the SUMOylated AnxA6 by immunoprecipitation, and the modification level of AnxA6 by SUMO1 was detected by Western blot against SUMO1 antibody. The SUMOylation level of AnxA6 was compared in response to chemical SUMOylation inhibitor treatment. AnxA6 SUMOylation sites were further identified by LC-MS/MS and amino acid site mutation validation. AnxA6 gene was silenced through AnxA6 targeting shRNA-containing pLKO.1 lentiviral transfection in HeLa cells, while AnxA6 gene was over-expressed within the Lenti-Vector carrying AnxA6 or mutant AnxA6^K299R plasmid in A431 cells using lentiviral infections. Moreover, the mutant plasmid pGFP-EGFR^T790M/L858R was constructed to test AnxA6 regulation on EGFR mutation-induced signal transduction. Moreover, cell proliferation, migration, and gefitinib chemotherapy sensitivity were evaluated in HeLa and A431 cells under AnxA6 konckdown or AnxA6 overexpression by CCK8, colony form and wound healing assays. And tumorigenicity in vivo was measured in epithelial cancer cells-xenografted nude mouse model.

RESULTS

AnxA6 was obviously modified by SUMO1 conjugation within Lys (K) residues, and the K299 was one key SUMOylation site of AnxA6 in epithelial cancer cells. Compared to the wild type AnxA6, AnxA6 knockdown and its SUMO site mutant AnxA6^K299R showed less suppression of dephosphorylation of EGFR-ERK1/2 under EGF stimulation. The SUMOylated AnxA6 was prone to bind EGFR in response to EGF inducement, which facilitated EGFR-PKCα complex formation to decrease the EGF-induced phosphorylation of EGFR-ERK1/2 and cyclin D1 expression. Similarly, AnxA6 SUMOylation inhibited dephosphorylation of the mutant EGFR, thereby impeding EGFR mutation-involved signal transduction. Moreover, AnxA6 knockdown or the K299 mutant AnxA6^K299R conferred AnxA6 inability to suppress tumor progression, resulting in drug resistance to gefitinib in epithelial cancer cells. And in epithelial cancer cells-xenografted nude mouse model, both the weight and size of tumors derived from AnxA6 knockdown or AnxA6^K299R mutation-expressing cells were much greater than that of AnxA6-expressing cells.

CONCLUSIONS

Besides EGFR gene mutation, protein SUMOylation modification of EGFR-binding protein AnxA6 also functions pivotal roles in mediating epithelial cancer cell growth and gefitinib drug effect. Video Abstract.

ERα promotes SUMO1 transcription by binding with the ERE and enhances SUMO1-mediated protein SUMOylation in breast cancer

Background

Estrogen plays a crucial role in the tumorigenesis of breast cancer (BC), and epigenetic modification by SUMOylation is essential for cancer development. However, the mechanism underlying estrogen's actions on protein SUMOylation and its effect on BC development are still incompletely understood.

Methods

SUMO1 in BC cell lines was verified via real-time quantitative PCR (RT-qPCR) and western blot. Cell proliferation and colony formation assays was also performed to evaluate SUMOylation as mediated by SUMO1. Luciferase activity to examine whether E2 promoted the transcription of SUMO1, and chromatin immunoprecipitation (ChIP) assay to determine the binding of estrogen receptor alpha (ERα) to SUMO1 were conduction, and an animal model was used to evaluate the effects of E2-ERα-enhanced SUMO1 transcription.

Results

E2 promoted SUMO1 mRNA and protein expression levels in a dose- and time-dependent manner in ER-positive BC cells; it exerted no influence on SUMO2/3 expression; in E2-induced SUMO1 transcription, ERα, but not ERβ, was essential to the process. In addition, E2-ERα upregulated the transcription of SUMO1 by binding with an estrogen-response element half-site (1/2ERE, in the -134 to -123 bp region) of the SUMO1 promoter, and E2-ERα induced SUMO1 transcription-enhanced cellular viability in ER-positive BC cells. To further determine SUMOylation as mediated by SUMO1 in ER-positive BC, we evaluated novel SUMO1 target proteins such as Ras and demonstrated that E2 increased Ras SUMOylation and cellular proliferation by affecting downstream signaling-pathway transduction. Finally, our data revealed that E2-ERα enhanced SUMO1 transcription to promote tumor growth in a BC orthotopic tumor model.

Conclusions

Collectively, our results showed that E2 promoted the transcription and protein expression of SUMO1 via ERα binding to a 1/2ERE in the SUMO1 promoter, and that E2-ERα also augmented SUMO1-mediated Ras SUMOylation and mediated cellular responses in ER-positive BC. We therefore achieved significant insights into the mechanism involved in ER-positive BC development and provided a novel target for its treatment.

Understanding the role of cGAS-STING signaling in ischemic stroke: a new avenue for drug discovery

INTRODUCTION

Ischemic stroke is a significant global health challenge with limited treatment options. Neuroinflammation, driven by microglial activation, plays a critical role in stroke pathophysiology. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway has emerged as a key player in microglial activation, sterile neuroinflammation, and cell death following stroke. Understanding the interplay between this pathway and stroke pathophysiology is crucial for exploring newer therapeutics for stroke patients.

AREAS COVERED

This review discusses the pivotal role of the cGAS-STING pathway in ischemic stroke. It explores the interplay between cGAS-STING activation, neuroinflammation, microglia activation, M2 polarization, neutrophil infiltration, and cytokine release. Additionally, the authors examine its contributions to various cell death programs (pyroptosis, apoptosis, necroptosis, lysosomal cell death, autophagy, and ferroptosis). The review summarizes recent studies on targeting cGAS-STING signaling in stroke, highlighting the therapeutic potential of small molecule inhibitors and RNA-based approaches in mitigating neuroinflammation, preventing cell death, and improving patient outcomes.

EXPERT OPINION

Understanding cGAS-STING signaling in ischemic stroke offers an exciting avenue for drug discovery. Targeting this pathway holds promise for developing novel therapeutics that effectively mitigate neuroinflammation, prevent cell death, and enhance patient outcomes. Further research and development of therapeutic strategies are warranted to fully exploit the potential of this pathway as a therapeutic target for stroke.

SENP3-mediated deSUMOylation of c-Jun facilitates microglia-induced neuroinflammation after cerebral ischemia and reperfusion injury

Recent evidences have implicated that SENP3 is a deSUMOylase which possesses neuronal damage effects in cerebral ischemia. However, its role in microglia remains poorly understood. Here, we found that SENP3 was upregulated in the peri-infarct areas of mice following ischemic stroke. Furthermore, knockdown of SENP3 significantly inhibits the expression of proinflammatory cytokines and chemokines in microglial cells. Mechanistically, SENP3 can bind and then mediated the deSUMOylation of c-Jun, which activated its transcriptional activity, ultimately followed by the activation of MAPK/AP-1 signaling pathway. In addition, microglia-specific SENP3 knockdown alleviated ischemia-induced neuronal damage, and markedly diminished infract volume, ameliorated sensorimotor and cognitive function in animals subjected to ischemic stroke. These results indicated SENP3 functions as a novel regulator of microglia-induced neuroinflammation by activating the MAPK/AP-1 signaling pathway via mediating the deSUMOylation of c-Jun. Interventions of SENP3 expression or its interaction with c-Jun would be a new and promising therapeutic strategy for ischemic stroke.

Deciphering the role of cytoplasmic domain of Channelrhodopsin in modulating the interactome and SUMOylome of Chlamydomonas reinhardtii

Translocation of channelrhodopsins (ChRs) is mediated by the intraflagellar transport (IFT) machinery. However, the functional role of the network involving photoreceptors, IFT and other proteins in controlling algal ciliary motility is still not fully delineated. In the current study, we have identified two important motifs at the C-terminus of ChR1, VXPX and LKNE. VXPX is a known ciliary targeting sequence in animals, and LKNE is a well-known SUMOylation motif. To the best of our knowledge, this study gives prima facie insight into the role of SUMOylation in Chlamydomonas. We prove that VMPS of ChR1 is important for interaction with GTPase CrARL11. We show that SUMO motifs are present in the C-terminus of putative ChR1s from green algae. Performing experiments with n-Ethylmaleimide (NEM) and Ubiquitin-like protease 1 (ULP-1) we show that SUMOylation may modulate ChR1 protein in Chlamydomonas. Experiments with 2D08, a known sumoylation blocker, increased the concentration of ChR1 protein. Finally, we show the endogenous SUMOylated proteins (SUMOylome) of C. reinhardtii, identified by using immunoprecipitation followed by nano-LC-MS/MS detection. This report establishes a link between evolutionarily conserved SUMOylation, and ciliary machinery for the maintenance and functioning of cilia across the eukaryotes. Our enriched SUMOylome of C. reinhardtii comprehends the proteins related to ciliary development and, photo-signaling, along with orthologue(s) associated to human ciliopathies as SUMO targets.

Targeting protein modifications in metabolic diseases: molecular mechanisms and targeted therapies

The ever-increasing prevalence of noncommunicable diseases (NCDs) represents a major public health burden worldwide. The most common form of NCD is metabolic diseases, which affect people of all ages and usually manifest their pathobiology through life-threatening cardiovascular complications. A comprehensive understanding of the pathobiology of metabolic diseases will generate novel targets for improved therapies across the common metabolic spectrum. Protein posttranslational modification (PTM) is an important term that refers to biochemical modification of specific amino acid residues in target proteins, which immensely increases the functional diversity of the proteome. The range of PTMs includes phosphorylation, acetylation, methylation, ubiquitination, SUMOylation, neddylation, glycosylation, palmitoylation, myristoylation, prenylation, cholesterylation, glutathionylation, S-nitrosylation, sulfhydration, citrullination, ADP ribosylation, and several novel PTMs. Here, we offer a comprehensive review of PTMs and their roles in common metabolic diseases and pathological consequences, including diabetes, obesity, fatty liver diseases, hyperlipidemia, and atherosclerosis. Building upon this framework, we afford a through description of proteins and pathways involved in metabolic diseases by focusing on PTM-based protein modifications, showcase the pharmaceutical intervention of PTMs in preclinical studies and clinical trials, and offer future perspectives. Fundamental research defining the mechanisms whereby PTMs of proteins regulate metabolic diseases will open new avenues for therapeutic intervention.

Fundamental concepts of protein therapeutics and spacing in oncology: an updated comprehensive review

Current treatment regimens in cancer cases cause significant side effects and cannot effectively eradicate the advanced disease. Hence, much effort has been expended over the past years to understand how cancer grows and responds to therapies. Meanwhile, proteins as a type of biopolymers have been under commercial development for over three decades and have been proven to improve the healthcare system as effective medicines for treating many types of progressive disease, such as cancer. Following approving the first recombinant protein therapeutics by FDA (Humulin), there have been a revolution for drawing attention toward protein-based therapeutics (PTs). Since then, the ability to tailor proteins with ideal pharmacokinetics has provided the pharmaceutical industry with an important noble path to discuss the clinical potential of proteins in oncology research. Unlike traditional chemotherapy molecules, PTs actively target cancerous cells by binding to their surface receptors and the other biomarkers particularly associated with tumorous or healthy tissue. This review analyzes the potential and limitations of protein therapeutics (PTs) in the treatment of cancer as well as highlighting the evolving strategies by addressing all possible factors, including pharmacology profile and targeted therapy approaches. This review provides a comprehensive overview of the current state of PTs in oncology, including their pharmacology profile, targeted therapy approaches, and prospects. The reviewed data show that several current and future challenges remain to make PTs a promising and effective anticancer drug, such as safety, immunogenicity, protein stability/degradation, and protein-adjuvant interactions.

SUMOylation regulates low-temperature survival and oxidative DNA damage tolerance in Botrytis cinerea

SUMOylation as one of the protein post-translational modifications plays crucial roles in multiple biological processes of eukaryotic organisms. Botrytis cinerea is a devastating fungal pathogen and capable of infecting plant hosts at low temperature. However, the molecular mechanisms of low-temperature adaptation are largely unknown in fungi. Combining with biochemical methods and biological analyses, we report that SUMOylation regulates pathogen survival at low temperature and oxidative DNA damage response during infection in B. cinerea. The heat shock protein (Hsp70) BcSsb and E3 ubiquitin ligase BcRad18 were identified as substrates of SUMOylation; moreover, their SUMOylation both requires a single unique SUMO-interacting motif (SIM). SUMOylated BcSsb regulates β-tubulin accumulation, thereby affecting the stability of microtubules and consequently mycelial growth at low temperature. On the contrary, SUMOylated BcRad18 modulates mono-ubiquitination of the sliding clamp protein proliferating cell nuclear antigen (PCNA), which is involved in response to oxidative DNA damage during infection. Our study uncovers the molecular mechanisms of SUMOylation-mediated low-temperature survival and oxidative DNA damage tolerance during infection in a devastating fungal pathogen, which provides novel insights into low-temperature adaptation and pathogenesis for postharvest pathogens as well as new targets for inhibitor invention in disease control.

Mitochondrial Dysfunction in Down Syndrome: From Pathology to Therapy

Mitochondrial dysfunctions have been described in Down syndrome (DS) caused by either partial or full trisomy of chromosome 21 (HSA21). Mitochondria play a crucial role in various vital functions in eukaryotic cells, especially in energy production, calcium homeostasis and programmed cell death. The function of mitochondria is primarily regulated by genes encoded in the mitochondrion and nucleus. Many genes on HSA21 are involved in oxidative phosphorylation (OXPHOS) and regulation of mitochondrial functions. This review highlights the HSA21 dosage-sensitive nuclear-encoded mitochondrial genes associated with overexpression-related phenotypes seen in DS. This includes impaired mitochondrial dynamics, structural defects and dysregulated bioenergetic profiles such as OXPHOS deficiency and reduced ATP production. Various therapeutic approaches for modulating energy deficits in DS, effects and molecular mechanism of gene therapy and drugs that exert protective effects through modulation of mitochondrial function and attenuation of oxidative stress in DS cells were discussed. It is prudent that improving DS pathophysiological conditions or quality of life may be feasible by targeting something as simple as cellular mitochondrial biogenesis and function.

Current understanding of the cGAS-STING signaling pathway: Structure, regulatory mechanisms, and related diseases

The innate immune system protects the host from external pathogens and internal damage in various ways. The cGAS-STING signaling pathway, comprised of cyclic GMP-AMP synthase (cGAS), stimulator of interferon genes (STING), and downstream signaling adaptors, plays an essential role in protective immune defense against microbial DNA and internal damaged-associated DNA and is responsible for various immune-related diseases. After binding with DNA, cytosolic cGAS undergoes conformational change and DNA-linked liquid-liquid phase separation to produce 2'3'-cGAMP for the activation of endoplasmic reticulum (ER)-localized STING. However, further studies revealed that cGAS is predominantly expressed in the nucleus and strictly tethered to chromatin to prevent binding with nuclear DNA, and functions differently from cytosolic-localized cGAS. Detailed delineation of this pathway, including its structure, signaling, and regulatory mechanisms, is of great significance to fully understand the diversity of cGAS-STING activation and signaling and will be of benefit for the treatment of inflammatory diseases and cancer. Here, we review recent progress on the above-mentioned perspectives of the cGAS-STING signaling pathway and discuss new avenues for further study.

Pancreatic Hormone Insulin Modulates Organic Anion Transporter 1 in the Kidney: Regulation via Remote Sensing and Signaling Network

Organic anion transporter 1 (OAT1) expressed in the kidney plays an important role in the elimination of numerous anionic drugs used in the clinic. We report here that insulin, a pancreas-secreted hormone, regulated the expression and activity of kidney-specific OAT1 both in cultured cells and in rats. We showed that treatment of OAT1-expressing cells with insulin led to an increase in OAT1 expression, transport activity, and SUMOylation. Such insulin-induced increase was blocked by afuresertib, a specific inhibitor for protein kinase B (PKB), suggesting insulin regulates OAT1 through PKB signaling pathway. Furthermore, insulin stimulated transport activity and SUMOylation of endogenously expressed OAT1 in rat kidneys. In conclusion, our data support a remote sensing and signaling model, in which OAT1 plays an essential role in intercellular and inter-organ communication and in maintaining local and whole-body homeostasis. Such complex and dedicated communication is carried out by insulin, and PKB signaling and membrane sorting.

The SUMOylation Pathway Components Are Required for Vegetative Growth, Asexual Development, Cytotoxic Responses, and Programmed Cell Death Events in Fusarium oxysporum f. sp. niveum

SUMOylation is an essential protein modification process that regulates numerous crucial cellular and biochemical processes in phytopathogenic fungi, and thus plays important roles in multiple biological functions. The present study characterizes the SUMOylation pathway components, including SMT3 (SUMO), AOS1 (an E1 enzyme), UBC9 (an E2 enzyme), and MMS21 (an E3 ligase), in Fusarium oxysporum f. sp. niveum (Fon), the causative agent of watermelon Fusarium wilt, in terms of the phylogenetic relationship, gene/protein structures, and basic biological functions. The SUMOylation components FonSMT3, FonAOS1, FonUBC9, and FonMMS21 are predominantly located in the nucleus. FonSMT3, FonAOS1, FonUBC9, and FonMMS21 are highly expressed in the germinating macroconidia, but their expression is downregulated gradually in infected watermelon roots with the disease progression. The disruption of FonUBA2 and FonSIZ1 seems to be lethal in Fon. The deletion mutant strains for FonSMT3, FonAOS1, FonUBC9, and FonMMS21 are viable, but exhibit significant defects in vegetative growth, asexual reproduction, conidial morphology, spore germination, responses to metal ions and DNA-damaging agents, and apoptosis. The disruption of FonSMT3, FonAOS1, FonUBC9, and FonMMS21 enhances sensitivity to cell wall-perturbing agents, but confers tolerance to digestion by cell wall-degrading enzymes. Furthermore, the disruption of FonSMT3, FonAOS1, and FonUBC9 negatively regulates autophagy in Fon. Overall, these results demonstrate that the SUMOylation pathway plays vital roles in regulating multiple basic biological processes in Fon, and, thus, can serve as a potential target for developing a disease management approach to control Fusarium wilt in watermelon.

Increased Small Ubiquitin-like Modifier-Activating Enzyme SAE1 Promotes Hepatocellular Carcinoma by Enhancing mTOR SUMOylation

SUMOylation, one of the most important posttranslational modifications of proteins, plays an essential role in various biological processes; however, enzymes that control SUMOylation in hepatocellular carcinoma (HCC) are still unclear. Comprehensive exploration of the expression and clinical significance of SUMO enzymes in HCC would be of great value. Here, we obtained the gene expression profile of each small ubiquitin-like modifier (SUMO) protein and the corresponding clinical information from The Cancer Genome Atlas. We found that all SUMO enzymes were significantly increased in HCC tissues compared with that in adjacent nontumorous tissues. We identified a 6-gene prognostic signature, including SAE1, PIAS2, PIAS3, SENP3, SENP5, and UBC9, that could effectively predict the overall survival in patients with HCC. Specifically, SAE1 was the most valuable prognostic indicator. In 282 clinical samples, we found that SAE1 was closely related to the clinicopathologic parameters and prognosis of patients with HCC. In vitro and in vivo studies showed that SAE1 knockdown inhibits the proliferation, migration, and invasion of HCC cells. Mechanistically, we confirmed that SAE1 plays a role in driving HCC progression, which is largely dependent on the SUMOylation of mTOR signaling. In conclusion, our study revealed that the expression of SUMO enzymes, especially SAE1, is highly associated with HCC development and acts as a promising prognostic predictor.

The role of SUMOylation in the neurovascular dysfunction after acquired brain injury

Acquired brain injury (ABI) is the most common disease of the nervous system, involving complex pathological processes, which often leads to a series of nervous system disorders. The structural destruction and dysfunction of the Neurovascular Unit (NVU) are prominent features of ABI. Therefore, understanding the molecular mechanism underlying NVU destruction and its reconstruction is the key to the treatment of ABI. SUMOylation is a protein post-translational modification (PTM), which can degrade and stabilize the substrate dynamically, thus playing an important role in regulating protein expression and biological signal transduction. Understanding the regulatory mechanism of SUMOylation can clarify the molecular mechanism of the occurrence and development of neurovascular dysfunction after ABI and is expected to provide a theoretical basis for the development of potential treatment strategies. This article reviews the role of SUMOylation in vascular events related to ABI, including NVU dysfunction and vascular remodeling, and puts forward therapeutic prospects.

SUMO-specific protease 1 inhibitors-A literature and patent overview

INTRODUCTION

Cancer is currently one of the biggest killers threatening human health. More and more studies have confirmed that SUMO-specific protease 1 (SENP1) is over-expressed in various cancer tissues. Therefore, targeting SENP1 expression may become a new strategy for tumor therapy.

AREAS COVERED

This review reports the latest advances in literature and patents on SENP1 inhibitor development over the past 10 years. With SENP1 as the keyword, articles and patents from PubMed, Google scholar and ScienceDirect databases were covered.

EXPERT OPINION

The available complex crystal structures of SENP1-SUMO1, afforded structure-based drug design opportunities, which led to the development of various isoform-selective small molecule inhibitors belonging to diverse classes (derivatives of benzamides, naphthalenesulfonic acids, pyridones, and the like). Preclinical studies have initially shown the potential advantages of these compounds, which have certain significance for the development of anticancer drugs.

Identification of NRAS Diagnostic Biomarkers and Drug Targets for Endometrial Cancer-An Integrated in Silico Approach

The diagnosis of endometrial cancer involves sequential, invasive tests to assess the thickness of the endometrium by a transvaginal ultrasound scan. In 6−33% of cases, endometrial biopsy results in inadequate tissue for a conclusive pathological diagnosis and 6% of postmenopausal women with non-diagnostic specimens are later discovered to have severe endometrial lesions. Thus, identifying diagnostic biomarkers could offer a non-invasive diagnosis for community or home-based triage of symptomatic or asymptomatic women. Herein, this study identified high-risk pathogenic nsSNPs in the NRAS gene. The nsSNPs of NRAS were retrieved from the NCBI database. PROVEAN, SIFT, PolyPhen-2, SNPs&GO, PhD-SNP and PANTHER were used to predict the pathogenicity of the nsSNPs. Eleven nsSNPs were identified as “damaging”, and further stability analysis using I-Mutant 2.0 and MutPred 2 indicated eight nsSNPs to cause decreased stability (DDG scores < −0.5). Post-translational modification and protein−protein interactions (PPI) analysis showed putative phosphorylation sites. The PPI network indicated a GFR-MAPK signalling pathway with higher node degrees that were further evaluated for drug targets. The P34L, G12C and Y64D showed significantly lower binding affinity towards GTP than wild-type. Furthermore, the Kaplan−Meier bioinformatics analyses indicated that the NRAS gene deregulation affected the overall survival rate of patients with endometrial cancer, leading to prognostic significance. Findings from this could be considered novel diagnostic and therapeutic markers.

SUMOylation targeting mitophagy in cardiovascular diseases

Small ubiquitin-like modifier (SUMO) plays a key regulatory role in cardiovascular diseases, such as cardiac hypertrophy, hypertension, atherosclerosis, and cardiac ischemia-reperfusion injury. As a multifunctional posttranslational modification molecule in eukaryotic cells, SUMOylation is essentially associated with the regulation of mitochondrial dynamics, especially mitophagy, which is involved in the progression and development of cardiovascular diseases. SUMOylation targeting mitochondrial-associated proteins is admittedly considered to regulate mitophagy activation and mitochondrial functions and dynamics, including mitochondrial fusion and fission. SUMOylation triggers mitochondrial fusion to promote mitochondrial dysfunction by modifying Fis1, OPA1, MFN1/2, and DRP1. The interaction between SUMO and DRP1 induces SUMOylation and inhibits lysosomal degradation of DRP1, which is further involved in the regulation of mitochondrial fission. Both SUMOylation and deSUMOylation contribute to the initiation and activation of mitophagy by regulating the conjugation of MFN1/2 SERCA2a, HIF1α, and PINK1. SUMOylation mediated by the SUMO molecule has attracted much attention due to its dual roles in the development of cardiovascular diseases. In this review, we systemically summarize the current understanding underlying the expression, regulation, and structure of SUMO molecules; explore the biochemical functions of SUMOylation in the initiation and activation of mitophagy; discuss the biological roles and mechanisms of SUMOylation in cardiovascular diseases; and further provide a wider explanation of SUMOylation and deSUMOylation research to provide a possible therapeutic strategy for cardiovascular diseases. Considering the precise functions and exact mechanisms of SUMOylation in mitochondrial dysfunction and mitophagy will provide evidence for future experimental research and may serve as an effective approach in the development of novel therapeutic strategies for cardiovascular diseases. Regulation and effect of SUMOylation in cardiovascular diseases via mitophagy. SUMOylation is involved in multiple cardiovascular diseases, including cardiac hypertrophy, hypertension, atherosclerosis, and cardiac ischemia-reperfusion injury. Since it is expressed in multiple cells associated with cardiovascular disease, SUMOylation can be regulated by numerous ligases, including the SENP family proteins PIAS1, PIASy/4, UBC9, and MAPL. SUMOylation regulates the activation and degradation of PINK1, SERCA2a, PPARγ, ERK5, and DRP1 to mediate mitochondrial dynamics, especially mitophagy activation. Mitophagy activation regulated by SUMOylation further promotes or inhibits ventricular diastolic dysfunction, perfusion injury, ventricular remodelling and ventricular noncompaction, which contribute to the development of cardiovascular diseases.

Role of SUMOylation in Neurodegenerative Diseases

Neurodegenerative diseases (NDDs) are irreversible, progressive diseases with no effective treatment. The hallmark of NDDs is the aggregation of misfolded, modified proteins, which impair neuronal vulnerability and cause brain damage. The loss of synaptic connection and the progressive loss of neurons result in cognitive defects. Several dysregulated proteins and overlapping molecular mechanisms contribute to the pathophysiology of NDDs. Post-translational modifications (PTMs) are essential regulators of protein function, trafficking, and maintaining neuronal hemostasis. The conjugation of a small ubiquitin-like modifier (SUMO) is a reversible, dynamic PTM required for synaptic and cognitive function. The onset and progression of neurodegenerative diseases are associated with aberrant SUMOylation. In this review, we have summarized the role of SUMOylation in regulating critical proteins involved in the onset and progression of several NDDs.