PELI1 overexpression contributes to pancreatic cancer progression through upregulating ubiquitination-mediated INPP5J degradation.

Inositol Polyphosphate-5-Phosphatase J (INPP5J), a 5-phosphatase, has been identified as a tumor suppressor in several types of cancer. However, its role in pancreatic cancer (PC) is unknown. We found that the INPP5J expression was markedly lower in PC tissues (n = 50) compared to paired adjacent non-tumor tissues, and the lower INPP5J expression was relevant to a worse prognosis of PC patients. We thus proposed that INPP5J might inhibit PC progression and conducted gain-of- and loss-of-function experiments to test our hypothesis. Our results showed that overexpression of INPP5J inhibited cell proliferation, invasion, migration, and xenografted tumor of PC cells. INPP5J silencing showed the opposite effect. Pellino E3 Ubiquitin Protein Ligase 1 (PELI1) is one of the ubiquitin ligases known to promote ubiquitination of its downstream targets. We found that PELI1 could interact with INPP5J and promote the ubiquitination and degradation of INPP5J. PELI1 overexpression enhanced malignant behaviors of PC cells. However, INPP5J overexpression restored the alterations caused by PELI1 overexpression. In conclusion, the results suggest that the decreased INPP5J expression, caused by PELI1 through ubiquitination, may promote PC progression. The PELI1-INPP5J axis represents a potential therapeutic targetable node for PC.

PELI1: key players in the oncogenic characteristics of pancreatic Cancer.

BACKGROUND: Pancreatic cancer (PC) is a highly malignant gastrointestinal tumor, which is characterized by difficulties in early diagnosis, early metastasis, limited therapeutic response and a grim prognosis. Therefore, it is imperative to explore potential therapeutic targets for PC. Currently, although the involvement of the Pellino E3 Ubiquitin Protein Ligase 1 (PELI1) in the human growth of some malignant tumors has been demonstrated, its association with PC remains uncertain. METHODS: Bioinformatics, qRT-PCR, Western blot and IHC were used to detect the expression of PELI1 in pancreas or PC tissues and cells at mRNA and protein levels. The effects of PELI1 on the proliferation and metastatic ability of pancreatic cancer in vitro and in vivo were investigated using CCK8, cloning formation, EdU, flow cytometry, IHC, Transwell assay, wound healing, nude mice subcutaneous tumorigenesis and intrasplenic injection to construct a liver metastasis model. The interactions of PELI1 with proteins as well as the main functions and pathways were investigated by protein profiling, Co-IP, GST-pull down, Immunofluorescence techniques, immunohistochemical co-localization and enrichment analysis. The rescue experiment verified the above experimental results. RESULTS: The mRNA and protein expression levels of PELI1 in PC tissues were upregulated and were associated with poor prognosis of patients, in vitro and in vivo experiments confirmed that PELI1 can affect the proliferation and metastatic ability of PC cells. Co-IP, GST-pull down, and other experiments found that PELI1 interacted with Ribosomal Protein S3 (RPS3) through the FHA structural domain and promoted the polyubiquitination of RPS3 in the K48 chain, thereby activates the PI3K/Akt/GSK3ß signaling pathway. Moreover, ubiquitinated degradation of RPS3 further reduces Tumor Protein P53 (p53) protein stability and increases p53 degradation by MDM2 Proto-Oncogene (MDM2). CONCLUSION: PELI1 is overexpressed in PC, which increased ubiquitination of RPS3 proteins and activates the PI3K/Akt/GSK3ß signaling pathway, as well as reduces the protective effect of RPS3 on p53 and promotes the degradation of the p53 protein, which facilitates the progression of PC and leads to a poor prognosis for patients. Therefore, PELI1 is a potential target for the treatment of PC.

TonEBP: A Key Transcription Factor in Microglia Following Intracerebral Hemorrhage Induced-Neuroinflammation.

Transcription factors within microglia contribute to the inflammatory response following intracerebral hemorrhage (ICH). Therefore, we employed bioinformatics screening to identify the potential transcription factor tonicity-responsive enhancer-binding protein (TonEBP) within microglia. Inflammatory stimuli can provoke an elevated expression of TonEBP in microglia. Nevertheless, the expression and function of microglial TonEBP in ICH-induced neuroinflammation remain ambiguous. In our recent research, we discovered that ICH instigated an increased TonEBP in microglia in both human and mouse peri-hematoma brain tissues. Furthermore, our results indicated that TonEBP knockdown mitigates lipopolysaccharide (LPS)-induced inflammation and the activation of NF-κB signaling in microglia. In order to more deeply comprehend the underlying molecular mechanisms of how TonEBP modulates the inflammatory response, we sequenced the transcriptomes of TonEBP-deficient cells and sought potential downstream target genes of TonEBP, such as Pellino-1 (PELI1). PELI has been previously reported to mediate nuclear factor-κB (NF-κB) signaling. Through the utilization of CUT & RUN, a dual-luciferase reporter, and qPCR, we confirmed that TonEBP is the transcription factor of Peli1, binding to the Peli1 promoter. In summary, TonEBP may enhance the LPS-induced inflammation and activation of NF-κB signaling via PELI1.

Aberrant expression of PELI1 caused by Jagged1 accelerates the malignant phenotype of pancreatic cancer.

Pancreatic cancer is one of the most aggressive cancers. PELI1 has been reported to promote cell survival and proliferation in multiple cancers. As of now, the role of PELI1 in pancreatic cancer is largely unknown. Here, we found that the PELI1 mRNA was higher expressed in pancreatic tumor tissues than in adjacent normal tissues, and the high PELI1 level in pancreatic cancer patients had a short survival time compared with the low level. Moreover, the results showed that PELI1 promoted cell proliferation, migration, and invasion, and inhibited apoptosis in vitro. Xenograft tumor experiments were used to determine the biological function of PELI1, and the results showed that PELI1 promoted tumor growth in vivo. Additionally, we found that Jagged1 activated PELI1 transcription in pancreatic cancer cells. To sum up, our results show that PELI1 affects the malignant phenotype of pancreatic cancer.

Polyguluronic acid alleviates doxorubicin-induced cardiotoxicity by suppressing Peli1-NLRP3 inflammasome-mediated pyroptosis.

Polyguluronic acid (PG), a polysaccharide from alginate, possesses excellent bioactivities. We prepared high-purity PG with 10.41 kDa molecular weight (Mw) and a 59 average degree of polymerization (DP) by acid hydrolysis, three pH grades, Q-Sepharose column elution, and Sephadex G-25 column desalination. Then, we evaluated the PG protective effects on doxorubicin-induced cardiotoxicity (DIC) in vitro and in vivo. The nontoxic PG enhanced cellular viability, reduced cell pyroptosis morphology, diminished the LDH and IL-1ß release, and downregulated expressions of ASC oligomerization, NLRP3, cl-CASP1, and GSDMD, by which PG protected the cardiomyocytes from NLRP3 inflammasome-mediated pyroptosis in doxorubicin-stimulated HL-1 cells and C57BL/6J mice. The probable underlying mechanism may be that PG downregulated doxorubicin -induced Peli1, the deficiency of which could inhibit doxorubicin-induced NLRP3 inflammasome-mediated pyroptosis. These results suggested that polysaccharide PG from alginate could prevent DIC and may be a potential therapeutic agent or bioactive material for preventing DIC.

Role of Pellino-1 in Inflammation and Cardioprotection following Severe Sepsis: A Novel Mechanism in a Murine Severe Sepsis Model †.

OBJECTIVES: Intra-abdominal sepsis is commonly diagnosed in the surgical population and remains the second most common cause of sepsis overall. Sepsis-related mortality remains a significant burden in the intensive care unit despite advances in critical care. Nearly a quarter of the deaths in people with heart failure are caused by sepsis. We have observed that overexpression of mammalian Pellino-1 (Peli1), an E3 ubiquitin ligase, causes inhibition of apoptosis, oxidative stress, and preservation of cardiac function in a myocardial infarction model. Given these manifold applications, we investigated the role of Peli1 in sepsis using transgenic and knockout mouse models specific to this protein. Therefore, we aimed to explore further the myocardial dysfunction seen in sepsis through its relation to the Peli 1 protein by using the loss of function and gain-of-function strategy. METHODS: A series of genetic animals were created to understand the role of Peli1 in sepsis and the preservation of heart function. Wild-type, global Peli1 knock out (Peli1-/-), cardiomyocyte-specific Peli1 deletion (CP1KO), and cardiomyocyte-specific Peli1 overexpressing (alpha MHC (αMHC) Peli1; AMPEL1Tg/+) animals were divided into sham and cecal ligation and puncture (CLP) surgical procedure groups. Cardiac function was determined by two-dimensional echocardiography pre-surgery and at 6- and 24-h post-surgery. Serum IL-6 and TNF-alpha levels (ELISA) (6 h), cardiac apoptosis (TUNEL assay), and Bax expression (24 h) post-surgery were measured. Results are expressed as mean ± S.E.M. RESULTS: AMPEL1Tg/+ prevents sepsis-induced cardiac dysfunction assessed by echocardiographic analysis, whereas global and cardiomyocyte-specific deletion of Peli1 shows significant deterioration of cardiac functions. Cardiac function was similar across the sham groups in all three genetically modified mice. ELISA assay displayed how Peli 1 overexpression decreased cardo-suppressive circulating inflammatory cytokines (TNF-alpha, IL-6) compared to both the knockout groups. The proportion of TUNEL-positive cells varied according to Peli1 expression, with overexpression (AMPEL1Tg/+) leading to a significant reduction and Peli1 gene knockout (Peli1-/- and CP1KO) leading to a significant increase in their presence. A similar trend was also observed with Bax protein expression. The improved cellular survival associated with Peli1 overexpression was again shown with the reduction of oxidative stress marker 4-Hydroxy-2-Nonenal (4-HNE). CONCLUSION: Our results indicate that overexpression of Peli1 is a novel approach that not only preserved cardiac function but reduced inflammatory markers and apoptosis following severe sepsis in a murine genetic model.

Regulatory T Cells Overexpressing Peli1 Show Better Efficacy in Repairing Ovarian Endocrine Function in Autoimmune Premature Ovarian Insufficiency.

Regulatory T (Treg) cell dysfunction is involved in the pathogenesis of autoimmune premature ovarian insufficiency (POI). Adoptive transfer of Treg cells has been shown to be effective in the treatment of autoimmune POI in mice. However, the therapeutic effect of Treg cell therapy is limited because the phenotype and function of Treg cells is not properly maintained when they are reinfused in an inflammatory environment. Therefore, enhancing the function of Treg cells using genetic engineering is of great significance for improving the efficacy of Treg cells in the treatment of immune diseases. In this study, we investigated the role of the E3 ubiquitinated ligase Pellino 1 (Peli1) in the proliferation and immunosuppressive function of Treg cells and the therapeutic effect of Treg cells overexpressing Peli1 on autoimmune POI. The results showed that the overexpression of Peli1 promoted cell proliferation and enhanced the immunosuppressive function of Treg cells in vitro. After the adoptive transfer of Treg cells overexpressing Peli1 in autoimmune POI mice, the apoptosis rate of ovarian granulosa cells declined. The levels of the inflammatory inhibitors interleukin 10 and transforming growth factor-ß as well as the ovarian hormone estradiol were elevated. The number of primordial, primary, secondary, and mature follicles was restored to a certain extent compared with those in control subjects. These results revealed that the adoptive transfer of Treg cells overexpressing Peli1 promoted its efficacy against zona pellucida protein 3 peptide-induced POI, which provides new insights into the treatment of autoimmune POI.

Role of the Peli1-RIPK1 Signaling Axis in Methamphetamine-Induced Neuroinflammation.

Severe neurological inflammation is one of the main symptoms of methamphetamine (meth)-induced brain injury. Studies have demonstrated that meth exposure facilitates neuroinflammation via Pellino E3 ubiquitin protein ligase 1 (Peli1)-mediated signaling. However, the involved mechanisms remain incompletely understood. Herein, we used Peli1-/- mice and Peli1-knockdown microglial BV2 cells to decipher the roles of Peli1 and downstream signaling in meth-induced neuroinflammation. After meth administration for seven consecutive days, Peli1-/- mice exhibited better learning and memory behavior and dramatically lower interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, and IL-6 levels than wild-type mice. Moreover, in vitro experiments revealed that Peli1 knockdown significantly attenuated the meth-induced upregulation of cytokines. Besides, meth markedly activated and increased the levels of receptor-interacting protein kinase 1 (RIPK1), and Peli1 knockout or knockdown prevented these effects, indicating that RIPK1 participated in meth-induced Peli1-mediated inflammation. Specifically, treating the cells with necrostatin-1(Nec-1), an antagonist of RIPK1, remarkably inhibited the meth-induced increase in IL-1ß, TNF-α, and IL-6 expression, confirming the involvement of RIPK1 in Peli1-mediated neuroinflammation. Finally, meth induced a dramatic transfer of the mixed lineage kinase domain-like protein, a downstream effector of RIRK1, to the cell membrane, disrupting membrane integrity and causing cytokine excretion. Therefore, targeting the Peli1-RIPK1 signaling axis is a potentially valid therapeutic approach against meth-induced neuroinflammation.

Peli1 deletion in macrophages attenuates myocardial ischemia/reperfusion injury by suppressing M1 polarization.

The polarization of macrophages to the M1 or M2 phenotype has a pivotal role in inflammatory response following myocardial ischemia/reperfusion injury. Peli1, an E3 ubiquitin ligase, is closely associated with inflammation and autoimmunity as an important regulatory protein in the Toll-like receptor signaling pathway. We aimed to explore the function of Peli1 in macrophage polarization under myocardial ischemia/reperfusion injury and elucidate the possible mechanisms. We show here that Peli1 is upregulated in peripheral blood mononuclear cells from patients with myocardial ischemia/reperfusion, which is correlated with myocardial injury and cardiac dysfunction. We also found that the proportion of M1 macrophages was reduced and myocardial infarct size was decreased, paralleling improvement of cardiac function in mice with Peli1 deletion in hematopoietic cells or macrophages. Macrophage Peli1 deletion lessened M1 polarization and reduced the migratory ability in vitro. Mechanistically, Peli1 contributed to M1 polarization by promoting K63-linked ubiquitination and nuclear translocation of IRF5. Moreover, Peli1 deficiency in macrophages reduced the apoptosis of cardiomyocytes in vivo and in vitro. Together, our study demonstrates that Peli1 deficiency in macrophages suppresses macrophage M1 polarization and alleviates myocardial ischemia/reperfusion injury by inhibiting the nuclear translocation of IRF5, which may serve as a potential intervention target for myocardial ischemia/reperfusion injury.

Decreased Peli1 expression attenuates osteoarthritis by protecting chondrocytes and inhibiting M1-polarization of macrophages.

AIMS: Pellino1 (Peli1) has been reported to regulate various inflammatory diseases. This study aims to explore the role of Peli1 in the occurrence and development of osteoarthritis (OA), so as to find new targets for the treatment of OA. METHODS: After inhibiting Peli1 expression in chondrocytes with small interfering RNA (siRNA), interleukin (IL)-1ß was used to simulate inflammation, and OA-related indicators such as synthesis, decomposition, inflammation, and apoptosis were detected. Toll-like receptor (TLR) and nuclear factor-kappa B (NF-κB) signalling pathway were detected. After inhibiting the expression of Peli1 in macrophages Raw 264.7 with siRNA and intervening with lipopolysaccharide (LPS), the polarization index of macrophages was detected, and the supernatant of macrophage medium was extracted as conditioned medium to act on chondrocytes and detect the apoptosis index. The OA model of mice was established by destabilized medial meniscus (DMM) surgery, and adenovirus was injected into the knee cavity to reduce the expression of Peli1. The degree of cartilage destruction and synovitis were evaluated by haematoxylin and eosin (H&E) staining, Safranin O/Fast Green staining, and immunohistochemistry. RESULTS: In chondrocytes, knockdown of Peli1 produced anti-inflammatory and anti-apoptotic effects by targeting the TLR and NF-κB signalling pathways. We found that in macrophages, knockdown of Peli1 can inhibit M1-type polarization of macrophages. In addition, the corresponding conditioned culture medium of macrophages applied to chondrocytes can also produce an anti-apoptotic effect. During in vivo experiments, the results have also shown that knockdown Peli1 reduces cartilage destruction and synovial inflammation. CONCLUSION: Knockdown of Peli1 has a therapeutic effect on OA, which therefore makes it a potential therapeutic target for OA.Cite this article: Bone Joint Res 2023;12(2):121-132.