Phosphorylation Of GSK-3β Research Articles

Possible involvement of Interleukin-17A in the deterioration of prepulse inhibition on acoustic startle response in mice.

Proinflammatory cytokines such as interleukin-6 (IL-6) and IL-17A have been implicated in the pathophysiology of schizophrenia which often shows sensorimotor gating abnormalities. This study aimed to examine whether a proinflammatory cytokine, IL-17A, induces impairment in sensorimotor gating in mice. We also examined whether IL-17A administration affects GSK3α/β protein level or phosphorylation in the striatum. Recombinant mouse IL-17A (low-dose: 0.5 ng/mL and high-dose: 50 ng/mL with 10 μL/g mouse body weight, respectively) or vehicle was intraperitoneally administered into C57BL/6 male mice 10 times in 3 weeks (sub-chronic administration). Prepulse inhibition test using acoustic startle stimulus was conducted 4 weeks after the final IL-17A administration. We evaluated the effect of IL-17A administration on protein level or phosphorylation of GSK3α/β in the striatum by using Western blot analysis. Administration of IL-17A induced significant PPI deterioration. Low-dose of IL-17A administration significantly decreased both GSK3α (Ser21) and GSK3β (Ser9) phosphorylation in mouse striatum. There was no significant alteration of GSK3α/β protein levels except for GSK3α in low-dose IL-17A administration group. We demonstrated for the first time that sub-chronic IL-17A administration induced PPI disruption and that IL-17A administration resulted in decreased phosphorylation of GSKα/β at the striatum. These results suggest that IL-17A could be a target molecule in the prevention and treatment of sensorimotor gating abnormalities observed in schizophrenia.

6-Methylcoumarin Promotes Melanogenesis through the PKA/CREB, MAPK, AKT/PI3K, and GSK3β/β-Catenin Signaling Pathways.

We investigated the effects of four coumarin derivatives, namely, 6-methylcoumarin, 7-methylcoumarin, 4-hydroxy-6-methylcoumarin, and 4-hydroxy-7-methylcoumarin, which have similar structures on melanogenesis in a murine melanoma cell line from a C57BL/6J mouse called B16F10. Our results showed that only 6-methylcoumarin significantly increased the melanin synthesis in a concentration-dependent manner. In addition, the tyrosinase, TRP-1, TRP-2, and MITF protein levels were found to significantly increase in response to 6-methylcoumarin in a concentration-dependent manner. To elucidate the molecular mechanism whereby 6-methylcoumarin-induced melanogenesis influences the melanogenesis-related protein expression and melanogenesis-regulating protein activation, we further assessed the B16F10 cells. The inhibition of the ERK, Akt, and CREB phosphorylation, and conversely, the increased p38, JNK, and PKA phosphorylation activated the melanin synthesis via MITF upregulation, which ultimately led to increased melanin synthesis. Accordingly, 6-methylcoumarin increased the p38, JNK, and PKA phosphorylation in the B16F10 cells, whereas it decreased the phosphorylated ERK, Akt, and CREB expressions. In addition, the 6-methylcoumarin activated GSK3β and β-catenin phosphorylation and reduced the β-catenin protein level. These results suggest that 6-methylcoumarin stimulates melanogenesis through the GSK3β/β-catenin signal pathway, thereby affecting the pigmentation process. Finally, we tested the safety of 6-methylcoumarin for topical applications using a primary human skin irritation test on the normal skin of 31 healthy volunteers. We found that 6-methylcoumarin did not cause any adverse effects at concentrations of 125 and 250 μM. Our findings indicate that 6-methylcoumarin may be an effective pigmentation stimulator for use in cosmetics and the medical treatment of photoprotection and hypopigmentation disorders.

Aspartate β-hydroxylase (ASPH) Accelerates Intrahepatic Cholangiocarcinoma Metastasis via Upregulating SHH Signaling Pathway.

Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive malignancy with a poor prognosis. Aspartate β-hydroxylase (ASPH) is an α-ketoglutarate-dependent dioxygenase involved in the post-translational hydroxylation of target proteins. ASPH has been demonstrated to be upregulated in ICC, yet its role remains to be elucidated. This study aimed to investigate the potential function of ASPH in ICC metastasis. Survival curves for the overall survival of pan-cancer data from The Cancer Genome Atlas (TCGA) database was depicted using the Kaplan-Meier method and compared using the log-rank test. The expression of ASPH, glycogen synthase kinase (GSK)-3β, phosphorylation GSK-3β (p-GSK-3β), epithelial-mesenchymal transition (EMT) biomarkers, and sonic hedgehog (SHH) signaling elements in ICC cell lines was analyzed by western blot. Wound healing and transwell assays were conducted to examine the effects of ASPH knockdown and overexpression on cell migration and invasion. An immunofluorescence assay was conducted to evaluate the expression of glioma-associated oncogene 2 (GLI2), GSK-3β and ASPH. The effect of ASPH on tumor in vivo was analyzed using a nude mouse xenograft model. Pan-cancer data showed that expressed ASPH was significantly correlated with a poor prognosis in patients. ASPH knockdown inhibited the migration and invasion of human ICC cells lines QBC939 and RBE. ASPH overexpression contributed to an increase in the N-cadherin and Vimentin, resulting in the promotion of the EMT process. The p-GSK-3β levels decreased in the presence of ASPH overexpression. The overexpression of ASPH led to an upregulation of the expression of SHH signaling elements GLI2 and SUFU. The results of in vivo experiments with a lung metastasis model in nude mice with ICC cell line RBE are consistent with these results. ASPH accelerated metastasis of ICC cells by facilitating EMT via a GSK-3β/SHH/GLI2 axis-dependent manner, in which phosphorylation of GSK-3β was downregulated and the SHH signaling pathway was activated.

Peli3 ablation ameliorates acetaminophen-induced liver injury through inhibition of GSK3β phosphorylation and mitochondrial translocation

The signaling pathways governing acetaminophen (APAP)-induced liver injury have been extensively studied. However, little is known about the ubiquitin-modifying enzymes needed for the regulation of APAP-induced liver injury. Here, we examined whether the Pellino3 protein, which has E3 ligase activity, is needed for APAP-induced liver injury and subsequently explored its molecular mechanism. Whole-body Peli3−/− knockout (KO) and adenovirus-mediated Peli3 knockdown (KD) mice showed reduced levels of centrilobular cell death, infiltration of immune cells, and biomarkers of liver injury, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), upon APAP treatment compared to wild-type (WT) mice. Peli3 deficiency in primary hepatocytes decreased mitochondrial and lysosomal damage and reduced the mitochondrial reactive oxygen species (ROS) levels. In addition, the levels of phosphorylation at serine 9 in the cytoplasm and mitochondrial translocation of GSK3β were decreased in primary hepatocytes obtained from Peli3−/− KO mice, and these reductions were accompanied by decreases in JNK phosphorylation and mitochondrial translocation. Pellino3 bound more strongly to GSK3β compared with JNK1 and JNK2 and induced the lysine 63 (K63)-mediated polyubiquitination of GSK3β. In rescue experiments, the ectopic expression of wild-type Pellino3 in Peli3−/− KO hepatocytes restored the mitochondrial translocation of GSK3β, but this restoration was not obtained with expression of a catalytically inactive mutant of Pellino3. These findings are the first to suggest a mechanistic link between Pellino3 and APAP-induced liver injury through the modulation of GSK3β polyubiquitination.

Bisphenol S Reduces Pig Spermatozoa Motility through Different Intracellular Pathways and Mechanisms than Its Analog Bisphenol A.

Bisphenol A (BPA: 2,3-bis (4-hydroxyphenyl) propane) is an environmental chemical widely used in the manufacturing of epoxy polymers and many thermoplastic consumer products. Serious concerns about its safety led to the development of analogs, such as BPS (4-hydroxyphenyl sulfone). Very limited studies about BPS's impact on reproduction, specifically in spermatozoa, exist in comparison with BPA. Therefore, this work aims to study the in vitro impact of BPS in pig spermatozoa in comparison with BPA, focusing on sperm motility, intracellular signaling pathways and functional sperm parameters. We have used porcine spermatozoa as an optimal and validated in vitro cell model to investigate sperm toxicity. Pig spermatozoa were exposed to 1 and 100 μM BPS or BPA for 3 and 20 h. Both bisphenol S and A (100 μM) significantly reduce pig sperm motility in a time-dependent manner, although BPS exerts a lower and slower effect than BPA. Moreover, BPS (100 μM, 20 h) causes a significant increase in the mitochondrial reactive species, whereas it does not affect sperm viability, mitochondrial membrane potential, cell reactive oxygen species, GSK3α/β phosphorylation or phosphorylation of PKA substrates. However, BPA (100 μM, 20 h) leads to a decrease in sperm viability, mitochondrial membrane potential, GSK3β phosphorylation and PKA phosphorylation, also causing an increase in cell reactive oxygen species and mitochondrial reactive species. These intracellular effects and signaling pathways inhibited might contribute to explaining the BPA-triggered reduction in pig sperm motility. However, the intracellular pathways and mechanisms triggered by BPS are different, and the BPS-caused reduction in motility can be only partially attributed to an increase in mitochondrial oxidant species.

The 15-hydroxyprostaglandin dehydrogenase inhibitor SW033291 ameliorates abnormal hepatic glucose metabolism through PGE2–EP4 receptor–AKT signaling in a type 2 diabetes mellitus mouse model

Type 2 diabetes mellitus (T2DM) is associated with high rates of morbidity and mortality worldwide. Prostaglandin E2 (PGE2) is a lipid signaling molecule that can ameliorate the symptoms of some metabolic diseases, including T2DM, and improve tissue repair and regeneration. Although SW033291 can increase PGE2 levels through its action as a small molecule inhibitor of the PGE2-degrading enzyme 15-hydroxyprostaglandin dehydrogenase, its effects on T2DM remain unclear. In the present study, we evaluated whether SW033291 treatment exerts a protective effect against T2DM and explored the underlying mechanisms. A T2DM mouse model was established using a high-fat diet combined with streptozotocin treatment. Palmitic acid-treated LO2 cells were used as an insulin-resistant cell model. SW033291 treatment reduced body weight and fasting blood glucose levels as well as serum triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels in vivo. In addition to ameliorating glucose and insulin tolerance, SW033291 treatment reversed the T2DM-induced decrease in glycogen synthesis and increase in gluconeogenesis in the liver. Furthermore, SW033291 administration increased hepatic glycogen synthase kinase 3 beta (GSK3β) phosphorylation levels to promote glycogen synthesis. SW033291 treatment also inhibited gluconeogenesis by upregulating AKT serine/threonine kinase (AKT) and forkhead box O1 (FOXO1) phosphorylation and reducing glucose-6-phosphatase and phosphoenolpyruvate carboxykinase 1 expression in the livers of T2DM model mice. Additionally, SW033291 treatment improved abnormal hepatic glucose metabolism through the PGE2–EP4 receptor–AKT–GSK3β/FOXO1 signaling pathway in vitro. These results suggest a novel role of SW033291 in improving T2DM and support its potential as a novel therapeutic agent.

Effects of Allium hookeri Extracts on Hair-Inductive and Anti-Oxidative Properties in Human Dermal Papilla Cells.

Oxidative stress and cellular senescence in dermal papilla cells (DPCs) are major etiological factors causing hair loss. In this study, the effect of the Allium hookeri extract (AHE) on hair-inductive and anti-oxidative properties was investigated in human DPCs. As a result, it was found that a non-cytotoxic concentration of the extracts increased the viability and size of the human DPC spheroid, which was associated with the increased expression of hair-growth-related genes in cells. To determine whether or not these effects could be attributed to intracellular anti-oxidative effects, liquid chromatography-mass spectrometry alongside various biochemical analyses are conducted herein. An ingredient called alliin was identified as one of the main components. Furthermore, AHE treatment induced a significant decrease in H2O2-mediated cytotoxicities, cell death, and cellular senescence in human DPCs. Upon analyzing these results with a molecular mechanism approach, it was shown that AHE treatment increased β-Catenin and NRF2 translocation into the nucleus while inhibiting the translocation of NF-κB (p50) through p38 and PKA-mediated phosphorylations of GSK3β, an upstream regulator of those proteins. These results overall indicate the possibility that AHE can regulate GSK3β-mediated β-Catenin, NRF2, and NF-κB signaling to enhance hair-inductive properties and ultimately protect against oxidative stress-induced cellular damage in human DPCs.

High doses of rosuvastatin induce impaired branched-chain amino acid catabolism and lead to insulin resistance.

What is the central question of this study? Is there a risk of developing diabetes associated with statin treatment? What is the underlying mechanism of the increased incidence rate of new-onset diabetes in patients treated with rosuvastatin? What is the main finding and its importance? Rosuvastatin therapy reduced intraperitoneal glucose tolerance and changed the catabolism of branched-chain amino acid (BCAAs) in white adipose tissue and skeletal muscle. Protein phosphatase 2Cm knockdown completely abolished the effects of insulin and rosuvastatin on glucose absorption. This study provides mechanistic support for recent clinical data on rosuvastatin-related new-onset diabetes and underscores the logic for intervening in BCAA catabolism to prevent the harmful effects of rosuvastatin. Accumulating evidence indicates that patients treated with rosuvastatin have an increased risk of developing new-onset diabetes. However, the underlying mechanism remains unclear. In this study, we administered rosuvastatin (10mg/kg body weight) to male C57BL/6J mice for 12weeks and found that oral rosuvastatin dramatically reduced intraperitoneal glucose tolerance. Rosuvastatin-treated mice showed considerably higher serum levels of branched-chain amino acids (BCAAs) than control mice. They also showed dramatically altered expression of BCAA catabolism-related enzymes in white adipose tissue and skeletal muscle, including downregulated mRNA expression of BCAT2 and protein phosphatase 2Cm (PP2Cm) and upregulated mRNA expression of branched-chain ketoacid dehydrogenase kinase (BCKDK). The levels of BCKD in the skeletal muscle were reduced in rosuvastatin-treated mice, which was associated with lower PP2Cm protein levels and increased BCKDK levels. We also investigated the effects of rosuvastatin and insulin administration on glucose metabolism and BCAA catabolism in C2C12 myoblasts. We observed that incubation with insulin enhanced glucose uptake and facilitated BCAA catabolism in C2C12 cells, which was accompanied by elevated Akt and glycogen synthase kinase 3 β (GSK3β) phosphorylation. These effects of insulin were prevented by co-incubation of the cells with 25μM rosuvastatin. Moreover, the effects of insulin and rosuvastatin administration on glucose uptake and Akt and GSK3β signaling in C2C12 cells were abolished when PP2Cm was knocked down. Although the relevance of these data, obtained with high doses of rosuvastatin in mice, to therapeutic doses in humans remains to be elucidated, this study highlights a potential mechanism for the diabetogenic effects of rosuvastatin, and suggests that BCAA catabolism could be a pharmacological target for preventing the adverse effects of rosuvastatin.

Inhibition of GSK3B phosphorylation improves glucose and lipid metabolism disorder

Hepatic glycolipid metabolism disorder is considered as one of the key pathogenic factors for many chronic diseases. Revealing the molecular mechanism of metabolic disorder and exploring drug targets are crucial for the treatment of glucose and lipid metabolic diseases. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been reported to be associated with the pathogenesis of various metabolic diseases. Herein, GAPDH-knockdown ZFL cells and GAPDH-downregulation zebrafish exhibited significant lipid deposition increase and glycogen reduction, thus inducing glucose and lipid metabolism disorders. Using high-sensitivity mass spectrometry-based proteomic and phosphoproteomic analysis, we identified 6838 proteins and 3738 phosphorylated proteins in GAPDH-knockdown ZFL cells. The protein-protein interaction network and DEPPs analyses showed that gsk3baY216 were involved in lipid and glucose metabolism, which was verified by In vitro study. The enzyme activity analysis and cell staining results showed that HepG2 and NCTC-1469 cells transfected with GSK3BY216F plasmid had significantly lower glucose and insulin levels, the decreased lipid deposition, and the increased glycogen synthesis than those transfected with GSK3BY216E plasmid, suggesting that inhibition of GSK3B phosphorylation could significantly improve GSK3B hyperphosphorylation-induced glucose tolerance impairment and insulin sensitivity reduction. To our knowledge, this is the first multi-omic study of GAPDH-knockdown ZFL cells. This study provides insights into the molecular mechanism of glucose and lipid metabolic disorder, and provides potential targets (kinases) for the treatments of human glucose and lipid metabolic diseases.

Eurycomanone stimulates bone mineralization in zebrafish larvae and promotes osteogenic differentiation of mesenchymal stem cells by upregulating AKT/GSK-3β/β-catenin signaling

Eurycomanone (EN) is a diterpenoid compound isolated from the roots of Eurycoma longifolia (E. longifolia). Previous studies have confirmed that E. longifolia can enhance bone regeneration and bone strength. We previously isolated and identified ten quassinoids from E. longifolia, and the result displayed that five aqueous extracts have the effects on promotion of bone formation, among whom EN showed the strongest activity. However, the molecular mechanism of EN on bone formation was unknown, and we further investigated in this study. After the verification of purity of extracted EN, following experiments were conducted. Firstly, the pharmacologic action of EN on normal bone mineralization and the therapeutic effect of EN on Dex-induced bone loss using zebrafish larvae. The mineralization area and integral optical density (IOD) were evaluated using alizarin red staining. Then the vital signaling pathways of EN relevant to OP was identified through network pharmacology analysis. Eventually in vitro, the effect of EN on cell viability, osteogenesis activities were investigated in human bone marrow mesenchymal stem cells (hMSCs) and C3H10 cells, and the molecular mechanisms by which applying AKT inhibitor A-443654 in hMSCs. In zebrafish larvae, the administration in medium of EN (0.2, 1, and 5 μM) dramatically enhanced the skull mineralization area and integral optical density (IOD), and increased mRNA expressions of osteoblast formation genes (ALP, RUNX2a, SP7, OCN). Meanwhile, exposure of EN remarkably alleviated the inhibition of bone formation induced by dexamethasone (Dex), prominently improved the mineralization, up-regulated osteoblast-specific genes and down-regulated osteoclast-related genes (CTSK, RANKL, NFATc1, TRAF6) in Dex-treated bone loss zebrafish larvae. Network pharmacology outcomes showed the MAPK and PI3K-AKT signaling pathways are closely associated with 10 hub genes (especially AKT1), and AKT/GSK-3β/β-catenin was selected as the candidate analysis pathway. In hMSCs and C3H10 cells, results showed that EN at appropriate concentrations of 0.008–5 μM effectively increased the cell proliferation. In addition, EN (0.04, 0.2, and 1 μM) significantly stimulated osteogenic differentiation and mineralization as well as significantly increased the protein phosphorylation of AKT and GSK-3β, and expression of β-catenin, evidencing by the results of ALP and ARS staining, qPCR and western blotting. Whereas opposite results were presented in hMSCs when treated with AKT inhibitor A-443654, which effectively inhibited the pro-osteogenesis effect induced by EN, suggesting EN represent powerful potential in promoting osteogenesis of hMSCs, which may be closely related to the AKT/GSK-3β/β-catenin signaling pathway. Altogether, our findings indicate that EN possesses remarkable effect on bone formation via activating AKT/GSK-3β/β-catenin signaling pathway in most tested concentrations. This study demonstrates EN is a new effective monomer in promoting bone formation, which may be a promising anabolic agent for osteoporosis (OP) treatment.

Abstract A37: PDZD2 is essential for steady-state hematopoiesis and its 37-kDa secreted product, sPDZD2, functions as a soluble tumor suppressor in AML

Abstract PDZ domain-containing protein 2 (PDZD2) is almost universally silenced through hypermethylation in myeloid malignancies. PDZD2 encodes for a 300kDa protein that it is cleaved into a 37kDa protein that is secreted to the tissue microenvironment (sPDZD2). Given that sPDZD2 has been reported to function as a tumor suppressor in solid tumors and its almost universal loss in AML, we hypothesized that PDZD2 is required for normal hematopoiesis and that sPDZD2 functions as a soluble tumor suppressor in the hematopoietic system. To determine if sPDZD2 is secreted to the bone marrow (BM) microenvironment we analyzed sPDZD2 levels in BM plasma isolated from primary AMLs and healthy donors using ELISA. We confirmed sPDZD2 secretion by normal CD34+ HSPC and detected lower levels in AMLs. In addition, treatment of a panel of AML cell lines (n=9) and primary human AML cells (n=4) with recombinant sPDZD2 (r-sPDZD2; dose: 100nM-300nM/day) led to growth inhibition, upregulation of differentiation markers (CD15/CD11b) and cell cycle arrest in G0/G1. To identify signaling pathways downstream of sPDZD2, we treated MV4-11 cells with 100nM r-sPDZD2 and performed phospho-kinase protein array followed by immunoblot. In vitro treatment with r-sPDZD2 led to inhibition of CREB(S133) phosphorylation, as well as increased GSK3b(S9), RSK1/2(S221/S227) and p53(S46) phosphorylation. In order to determine whether PDZD2 plays a role in normal hematopoiesis we performed in vitro differentiation in CRISPR-edited human HSPCs. We used a Cy3-labeled recombinant Cas9 protein and specific single guide RNAs (gRNAs) targeted against PDZD2. Cy3-positive cells were then used for in vitro myeloid or erythroid differentiation, and cell surface markers were evaluated by flow-cytometry analysis over a period of 11 days. While PDZD2-edited cells (PDZD2 KO) displayed a minor defect on myeloid differentiation due to insufficient upregulation of CD15, erythropoiesis appears to be more compromised, with a significant failure to adequately upregulate both CD235a and CD7. To determine the role of Pdzd2 in vivo, we took advantage of a Pdzd2Gt/Gt gene-trap knock-out mouse model and performed peripheral blood (PB) and BM analysis. PB counts at 8-weeks of age showed anemia, with a significant decrease in both red blood cell counts and hemoglobin levels, an observation compatible with the impaired erythropoiesis seen in vitro after PDZD2 KO in human HSPCs. In addition, we observed a trend to decreased MEPs and short-term HSCs, in the BM of 12-week-old mice (n=3), though the small size of the cohort prevented robust statistical analysis. In summary, our findings are the first to shed light on a previously unrecognized role for PDZD2 in hematopoiesis. Loss of PDZD2 in HSPC resulted in impaired erythroid differentiation both in vitro and in vivo. Moreover, our findings validate a soluble tumor suppressor role for sPDZD2 in AML, similar to that seen in solid tumors. Importantly, we further demonstrate a potential role for recombinant sPDZD2 as a novel therapeutic approach for AML. Citation Format: Marlise L Guerrero Schimpf, Courtney C Sparger, Hsuan-Ting Huang, Dean Wade, Maria E. Figueroa. PDZD2 is essential for steady-state hematopoiesis and its 37-kDa secreted product, sPDZD2, functions as a soluble tumor suppressor in AML [abstract]. In: Proceedings of the AACR Special Conference: Acute Myeloid Leukemia and Myelodysplastic Syndrome; 2023 Jan 23-25; Austin, TX. Philadelphia (PA): AACR; Blood Cancer Discov 2023;4(3_Suppl):Abstract nr A37.

PP1γ regulates neuronal insulin signaling and aggravates insulin resistance leading to AD-like phenotypes

BackgroundPP1γ is one of the isoforms of catalytic subunit of a Ser/Thr phosphatase PP1. The role of PP1γ in cellular regulation is largely unknown. The present study investigated the role of PP1γ in regulating neuronal insulin signaling and insulin resistance in neuronal cells. PP1 was inhibited in mouse neuroblastoma cells (N2a) and human neuroblastoma cells (SH-SY5Y). The expression of PP1α and PP1γ was determined in insulin resistant N2a, SH-SY5Y cells and in high-fat-diet-fed-diabetic mice whole-brain-lysates. PP1α and PP1γ were silenced by siRNA in N2a and SH-SY5Y cells and effect was tested on AKT isoforms, AS160 and GSK3 isoforms using western immunoblot, GLUT4 translocation by confocal microscopy and glucose uptake by fluorescence-based assay.ResultsResults showed that, in one hand PP1γ, and not PP1α, regulates neuronal insulin signaling and insulin resistance by regulating phosphorylation of AKT2 via AKT2-AS160-GLUT4 axis. On the other hand, PP1γ regulates phosphorylation of GSK3β via AKT2 while phosphorylation of GSK3α via MLK3. Imbalance in this regulation results into AD-like phenotype.ConclusionPP1γ acts as a linker, regulating two pathophysiological conditions, neuronal insulin resistance and AD.9kZE1HTKkUH8PMrXCf3pWdVideo

AQP8 may affect glioma proliferation and growth by regulating GSK‐3β phosphorylation and nuclear transport of β‐catenin

The purpose of this work is to examine the impact of AQP8 on the proliferation and development of human glioma cell lines A172 and U251 and to determine if aquaporin 8 (AQP8) is associated with GSK-3β phosphorylation and nuclear transport of β-catenin in the Wnt signaling pathway. AQP8 knockdown cell lines were constructed using a CRISPR/Cas9 double vector lentivirus infection. SAM/dCas9 was used to construct AQP8 overexpression cell lines and the CV084 lentivirus vector was used to construct AQP8 rescue cell lines. AQP8 and its mRNA, and phosphorylated GSK-3β, β-catenin, and other related proteins, were detected using western blot and qRT-PCR. Glioma cell apoptosis was detected using Hoechst 33342 dye. The migration of glioma cells was discovered using a wound healing assay. β-catenin localization in cells was detected using immunofluorescence staining. The proliferative and migratory capacities of A172 and U251 cells were significantly enhanced after AQP8 overexpression. The Wnt signaling pathways appeared to have higher levels of phosphorylated GSK-3β and β-catenin, and a rise in the fluorescence intensity ratio of β-catenin in the nucleus and cytoplasm, which suggests that β-catenin translocated into the nucleus, while AQP8 knockdown produced the opposite effect. Further, overexpression of AQP8 in AQP8 knockdown cell lines rescued the reduction of related protein levels caused by AQP8 knockdown. High AQP8 expression promotes proliferation and growth of glioma cells, a process associated with phosphorylation of GSK-3β and nuclear translocation of β-catenin.

Visfatin-induced upregulation of lipogenesis via EGFR/AKT/GSK3β pathway promotes breast cancer cell growth

Breast cancer (BC) incidence and associated mortality have increased in tandem with the growth in obesity among the females worldwide. An adipokine, visfatin, has been shown to potentially impact glucose, lipid, and protein metabolism, and promote cancer growth however, the mechanism underlying the effect of visfatin on lipid metabolism dysregulation contributing to BC cell survival, proliferation, and metastasis has not been elucidated. Herein, we have investigated the role of visfatin on the induction of Sterol regulatory element binding protein (SREBP-1) and its upstream and downstream mediators in MCF-7 breast cancer cells. The survival and proliferation was investigated using MTT and Trypan blue assays, cytosolic lipid accumulation was observed using Nile red staining, mRNA and protein expressions were examined using RT-qPCR and western blotting, respectively, and cell cycle analysis was performed using fluorescence-activated cell sorting. Our results indicate that visfatin increased the survival and proliferation of MCF-7 cells in a time- and dose-dependent manner and augmented lipid buildup via activation of SREBP-1 and its associated downstream lipid synthesizing enzymes, at both mRNA and protein levels in MCF-7 cells. Inhibiting SREBP-1 using fatostatin or silencing with siRNA abrogated excessive lipid deposition by suppressing the expression of genes related to lipid synthesis pathway. Further, in-silico study showed high affinity binding of visfatin with epidermal growth factor receptor (EGFR), which was confirmed in an in-vitro study where visfatin increased the phosphorylation of EGFR at tyrosine residue and activated its downstream proteins via phosphorylation of AKT and GSK3β in MCF-7 cells. Inhibition of GSK3β by phosphorylation led to increased activity of SREBP-1 and associated downstream proteins. In summary, SREBP-1 may be a critical player in visfatin-induced lipid synthesis and accumulation in BC cells via activation of EGFR/AKT/GSK3β pathway leading to increased cell survival and proliferation of BC cells.

Reply.

We thank the authors of Hu et al. for their comments on our study.1 We understand the complexity of signaling pathways that can make the current study complicated for some to understand but are confident of its relevance and reproducibility. With regards to concern 1, relationship between hepatic mechanistic target of rapamycin complex 1 (mTORC1) and β‐catenin was shown in four ways. First, we identified compensatory activation of mTORC1 and its downstream effectors in β‐cateninΔHC mice after hepatectomy. Second, we showed demise of RaptorΔHC‐β‐cateninΔHC mice by 12 h and of RaptorΔHC mice by 48 h posthepatectomy. Third, RaptorΔHC mice without any challenge died at 40 days and showed early proliferative β‐catenin activation. RaptorΔHC‐β‐cateninΔHC mice showed demise by 30 days. Lastly, pharmacological inhibition of mechanistic target of rapamycin led to impaired liver regeneration (LR) and demise of β‐cateninΔHC by 14 days postsurgery. Collectively, our data demonstrate compensatory interplay between mTORC1 and β‐catenin signaling. For point 2, AAV8‐TBG–mediated gene deletion in our model should not disrupt pancreatic mTORC1 signaling.2 Decreased serum glucose level in Raptor knockouts has been reported due to compensatory AKT activation.3 Deleting Akt2 in the Raptor knockouts reversed changes in serum glucose and may be mediated by AKT‐driven glycogen synthase kinase 3 beta (GSK3β) phosphorylation and inactivation.3 We also observed increased AKT activation and GSK3β inactivation in RaptorΔHC mice. Thorough understanding of the intricacies of LR is important to appreciate the sequence of experimentation in our study. Also, because of the numbers of mice and time points, it is impossible to show every piece of data, but appropriate statistics were always included. Analysis of known mitogenic and developmental pathways during LR in β‐cateninΔHC mice was inconsequential. We identified insulin‐mTORC1 signaling as one possible mechanism driving LR in these mice. We did not address the role of Wnt‐dependent stabilization of proteins signaling, which may be agnostically contributing to cell division in LR.4 It is unlikely that Wnt/mTORC1 pathway signaling is playing a role in LR in β‐cateninΔHC mice because we did not see any difference in LDL related protein 6 phosphorylation.5 Eventually, we agree that, as a responsible researcher, it is pertinent to be cautious in interpreting every scientific study because there often are multiple explanations underlying an observation.

Autonomous Synthesis of Functional, Permanently Phosphorylated Proteins for Defining the Interactome of Monomeric 14-3-3ζ.

14-3-3 proteins are dimeric hubs that bind hundreds of phosphorylated "clients" to regulate their function. Installing stable, functional mimics of phosphorylated amino acids into proteins offers a powerful strategy to study 14-3-3 function in cellular-like environments, but a previous genetic code expansion (GCE) system to translationally install nonhydrolyzable phosphoserine (nhpSer), with the γ-oxygen replaced with CH2, site-specifically into proteins has seen limited usage. Here, we achieve a 40-fold improvement in this system by engineering into Escherichia coli a six-step biosynthetic pathway that produces nhpSer from phosphoenolpyruvate. Using this autonomous "PermaPhos" expression system, we produce three biologically relevant proteins with nhpSer and confirm that nhpSer mimics the effects of phosphoserine for activating GSK3β phosphorylation of the SARS-CoV-2 nucleocapsid protein, promoting 14-3-3/client complexation, and monomerizing 14-3-3 dimers. Then, to understand the biological function of these phosphorylated 14-3-3ζ monomers (containing nhpSer at Ser58), we isolate its interactome from HEK293T lysates and compare it with that of wild-type 14-3-3ζ. These data identify two new subsets of 14-3-3 client proteins: (i) those that selectively bind dimeric 14-3-3ζ and (ii) those that selectively bind monomeric 14-3-3ζ. We discover that monomeric-but not dimeric-14-3-3ζ interacts with cereblon, an E3 ubiquitin-ligase adaptor protein of pharmacological interest.

Abstract 2573: A novel regulation of the Wnt/β-catenin pathway involving NLRP12 during colorectal tumorigenesis

Abstract NLRP12, a member of the NOD-like receptor family, has been characterized as a negative regulator of NF-κB and MAPK pathways in immune cells. We previously demonstrated that Nlrp12-deficient mice are highly susceptible to azoxymethane plus dextran sodium sulfate induced colorectal tumorigenesis in mice. However, the precise mechanism of NLRP12-mediated protection against colorectal cancer (CRC) was poorly understood. RNA-seq analysis revealed that tumors of Nlrp12-deficient mice express higher levels of protooncogenes (cMyc, Ccnd1), Wnt target genes (Ctnnb1, Axin2, Yap1, Tcf3, Lgr5), matrix metalloproteinases, and epithelial to mesenchymal transition markers (Vim, Fn1, Foxc2, Zeb2, Ezh2) compared to wild-type tumor. Interestingly, higher expression of these genes in Nlrp12-deficient tumors was not linked to any inflammatory signaling pathways as there was no difference in the activation of NF-kB, ERK, JNK, AKT, and STAT3 signaling pathways between Nlrp12-/- and wild-type tumors. However, we observed higher activation of β-catenin in Nlrp12-deficient tumors. Using intestinal epithelial cell specific Nlrp12-conditional knockout mice we showed that Nlrp12 deficiency in intestinal epithelial cells leads to increased tumorigenesis, metastasis, and β-catenin activation. To further understand the role of NLRP12 in the regulation of the Wnt/β-catenin, we overexpressed NLRP12 in HEK293T cells and HCT116 cells followed by stimulation with Wnt ligand Wnt3A. NLRP12 overexpressed cells showed significantly reduced activation of β-catenin and expression of Wnt target genes. Consistently, knocking down of NLRP12 in HEK293T and HCT116 cells caused higher activation of the Wnt/β-catenin pathway. Further biochemical analysis revealed that NLRP12-mediated suppression of β-catenin activation is associated with reduced phosphorylation of GSK3β. Interestingly, human and mouse colorectal tumors showed reduced expression of NLRP12 along with increased activation of β-catenin and GSK3β phosphorylation. Altogether, these data suggest that NLRP12 is a potent negative regulator of the Wnt/β-catenin pathway in colorectal tumor cells, and the NLRP12-GSK3β axis could be a novel target for CRC treatment. Citation Format: Shahanshah Khan, Lan Peng, Cheryl M. Lewis, Yunpeng Gao, Ram S. Mani, Hasan Zaki. A novel regulation of the Wnt/β-catenin pathway involving NLRP12 during colorectal tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2573.

Metformin Pre-Treatment as a Means of Mitigating Disuse-Induced Rat Soleus Muscle Wasting

Currently, no ideal treatment exists to combat skeletal muscle disuse-induced atrophy and loss of strength. Because the activity of AMP-activated protein kinase (AMPK) in rat soleus muscle is suppressed at the early stages of disuse, we hypothesized that pre-treatment of rats with metformin (an AMPK activator) would exert beneficial effects on skeletal muscle during disuse. Muscle disuse was performed via hindlimb suspension (HS). Wistar rats were divided into four groups: (1) control (C), (2) control + metformin for 10 days (C+Met), (3) HS for 7 days (HS), (4) metformin treatment for 7 days before HS and during the first 3 days of 1-week HS (HS+Met). Anabolic and catabolic markers were assessed using WB and RT-PCR. Treatment with metformin partly prevented an HS-induced decrease in rat soleus weight and size of slow-twitch fibers. Metformin prevented HS-related slow-to-fast fiber transformation. Absolute soleus muscle force in the HS+Met group was increased vs. the HS group. GSK-3β (Ser9) phosphorylation was significantly increased in the HS+Met group vs. the HS group. Metformin pre-treatment partly prevented HS-induced decrease in 18S+28S rRNA content and attenuated upregulation of calpain-1 and ubiquitin. Thus, pre-treatment of rats with metformin can ameliorate disuse-induced reductions in soleus muscle weight, the diameter of slow-type fibers, and absolute muscle strength.

Abstract 4614: Investigating lymphatic vessel remodeling and anti-tumor immunity in pancreatic cancer using tumor-on-chip and mouse models

Abstract Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest tumors in humans. PDAC has an immunosuppressive tumor microenvironment, constituting for poor immunotherapy outcomes. Lymphatic vessels (LVs) transport leukocytes and antigens from tumor peripheries to draining lymph nodes (dLNs) for activation of anti-tumor immune responses. It is believed that impairment of the lymphatic function may result in delayed and ineffective immune activation against tumors. In this study, we created a three-dimensional (3D) tumor-on-chip model to examine phenotypical and functional changes in 3D engineered LVs, composed of human primary lymphatic endothelial cells (LECs) in co-culture with PDAC cells. Our in vitro studies revealed that PDAC cells induce lymphangiogenesis and tighten cell-cell junctions in LECs, forming “zipper-like” LEC junctions, compared to control LECs with “button-like” junctions. We introduced 70kDa dextran into the LV lumens and showed PDAC-induced zippering of junctions decreased vessel permeability. These results led us to hypothesize that altered LEC junctions may affect fluid drainage into the LVs in vivo. We inoculated PDAC cells into the mouse ear pinnae and performed whole-mount immunostaining and lymphatic drainage experiment by injecting Evans blue into the ears and measured the remained Evans blue in the ears. In the ear experiments, inoculated PDAC cells affected host LVs with originally button-like junctions to become zipper-like and impede lymphatic drainage. To identify a potential signaling pathway that may be responsible for LEC junction zippering, we used phospho-kinase arrays and discovered that PDAC cells induced LECs to increase phosphorylation of GSK3-β, JNK kinases, and enhanced the total protein level of β-catenin, implying that PDAC cells turned on the WNT signaling in LECs. In preliminary screening, we treated LECs co-cultured with PDAC cells with WNT-C59, an WNT inhibitor that blocks secretion of all WNT ligands, which resulted in decreased number of LV sprouting and less contractile actin-cytoskeleton in LECs. It is critical to know which molecules were secreted by PDAC cells and influenced the WNT signaling in LECs. With that in mind, we plan to perform mass spectrometry with PDAC-conditioned media to identify PDAC-specific secretome; and run RNA-seq with LECs isolated from mouse ears with or without PDAC to investigate molecular basis of the WNT activation in LECs and LV remodeling. Finally, we plan to examine the egress of leukocytes from primary PDAC tumor site, T cell activation in tumor-dLNs, and PDAC tumor growth with or without WNT inhibition in Kaeda mice. The identity and function of PDAC-egressed immune cells, and those which stayed within the primary tumor will enhance our understanding of the roles of LVs in orchestrating anti-tumor immunity in PDAC. Citation Format: Anna Maria Kolarzyk, Conor Loy, Renhao Lu, Iwijn De Vlaminck, Deborah Fowell, Esak Lee. Investigating lymphatic vessel remodeling and anti-tumor immunity in pancreatic cancer using tumor-on-chip and mouse models. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4614.

Penazaphilones J-L, Three New Hydrophilic Azaphilone Pigments from Penicillium sclerotiorum cib-411 and Their Anti-Inflammatory Activity.

Penazaphilones J-L (1-3), three new hydrophilic azaphilone pigments, as well as six known compounds, were discovered from the filamentous fungus Penicillium sclerotiorum cib-411. Compounds 1-3 were structurally elucidated by the detailed interpretation of their 1D and 2D NMR spectroscopic data. Compound 1 is an unprecedented hybrid of an azaphilone and a glycerophosphate choline. Compounds 2 and 3 each contain an intact amino acid moiety. The bioassay showed that compound 3 exhibited significant anti-inflammatory activity. Concretely, compound 3 significantly suppressed the NO production, the expression levels of COX-2, IL-6, IL-1β, and iNOS mRNA in LPS-stimulated RAW264.7 cells. Moreover, treatment of compound 3 prevented the translocation of NF-κB through inhibiting the phosphorylation of PI3K, PDK1, Akt, and GSK-3β. Thus, the inhibition of compound 3 against LPS-induced inflammation should rely on its inactivation on NF-κB.