Stepwise activation of a metabotropic glutamate receptor.

Metabotropic glutamate receptors belong to a family of G protein-coupled receptors that are obligate dimers and possess a large extracellular ligand-binding domain that is linked via a cysteine-rich domain to their 7-transmembrane domain1. Upon activation, these receptors undergo a large conformational change to transmit the ligand binding signal from the extracellular ligand-binding domain to the G protein-coupling 7-transmembrane domain2. In this manuscript, we propose a model for a sequential, multistep activation mechanism of metabotropic glutamate receptor subtype 5. We present a series of structures in lipid nanodiscs, from inactive to fully active, including agonist-bound intermediate states. Further, using bulk and single-molecule fluorescence imaging, we reveal distinct receptor conformations upon allosteric modulator and G protein binding.

Urinary phenols and parabens exposure in relation to urinary incontinence in the US population.

BACKGROUND: Our study aimed to investigate the impact of urinary concentrations of personal care products (PCPs)-related phenols (PNs) and parabens (PBs), including Triclosan (TCS), Bisphenol A (BPA), Benzophenone-3 (BP-3), Butylparaben (BPB), Ethylparaben (EPB), Methylparaben (MPB), and Propylparaben (PPB), on urinary incontinence (UI) occurrence. METHOD: We conducted a cross-sectional analysis using data from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2007 to 2016. Regression analysis was employed to investigate the relationship between exposure to PCPs-related substances, various levels of exposure, and UI within both the general population and the female demographic. Additionally, the Bayesian Kernel Machine Regression (BKMR) model was used to assess the effects of mixtures on UI. RESULTS: Our analysis comprised 7,690 participants who self-reported their diagnosis. Among them, 12.80% experienced stress urinary incontinence (SUI), 11.80% reported urge urinary incontinence (UUI), and 10.22% exhibited mixed urinary incontinence (MUI). In our fully adjusted multivariable models, BP-3 exposure exhibited a positive association with SUI (OR 1.07, 95% CI 1.02-1.14, p = 0.045). BPA exposure correlated with an increased risk of UUI (OR 1.21, 95% CI 1.01-1.44, p = 0.046) and MUI (OR 1.26, 95% CI 1.02-1.54, p = 0.029). TCS exposure displayed a negative correlation with the incidence of MUI (OR 0.87, 95% CI 0.79-0.97, p = 0.009). No significant links were observed between parabens and urinary incontinence. Notably, among the female population, our investigation revealed that BPA exposure heightened the risk of MUI (OR 1.28, 95% CI 1.01-1.63, p = 0.043). Participants in the highest tertile of BP-3 exposure demonstrated elevated likelihoods of SUI and MUI compared to those in the lowest tertile. In the BKMR analysis, negative trends were observed between the mixture and the risks of UUI and MUI when the mixture ranged from the 25th to the 40th and 35th to the 40th percentiles or above, respectively. Additionally, a positive trend was identified between the mixture and MUI when it was in the 40th to 55th percentile. CONCLUSION: In conclusion, our findings suggest that exposure to BPA, TCS, and BP-3 may contribute to the development of urinary incontinence.

Dynamic carboxymethyl chitosan prodrug hydrogel precisely mediates robust therapy on wound infection.

Dynamic antibacterial polysaccharide prodrug hydrogels are in great demand for treatment of wound infection owing to their unique advantages such as excellent biocompatibility, superior antimicrobial property as well as favorable wound healing capacity. Herein, this work highlights the successful development of a dynamic carboxymethyl chitosan (CMC) prodrug hydrogel, which is facilely constructed through Schiffer base reaction between antibacterial components (amikacin and CMC) and crosslinker (dialdehyde PEG). Moderate dynamic imine linkages endow the hydrogel with excellent injectable and self-healing capability as well as targeted on-demand drug release in slightly alkaline condition at infected wound. All ingredients and their strong intermolecular interactions endow the hydrogel with favorable swelling and moisture retention capability. Moreover, the covalent and non-covalent interactions also endow the hydrogel with superior adhesion and mechanical property. These attractive characteristics enable hydrogel to effectively kill pathogens, promote wound healing and reduce side effects of amikacin. Thereby, such a dynamic CMC prodrug hydrogel may open a new avenue for a robust therapy on wound infection, greatly advancing their use in clinics.

Emerging roles of mitochondrial functions and epigenetic changes in the modulation of stem cell fate.

Mitochondria serve as essential organelles that play a key role in regulating stem cell fate. Mitochondrial dysfunction and stem cell exhaustion are two of the nine distinct hallmarks of aging. Emerging research suggests that epigenetic modification of mitochondria-encoded genes and the regulation of epigenetics by mitochondrial metabolites have an impact on stem cell aging or differentiation. Here, we review how key mitochondrial metabolites and behaviors regulate stem cell fate through an epigenetic approach. Gaining insight into how mitochondria regulate stem cell fate will help us manufacture and preserve clinical-grade stem cells under strict quality control standards, contributing to the development of aging-associated organ dysfunction and disease.

Analysis of the effect of Ivor-Lewis esophagectomy and McKeown esophagectomy on perioperative anxiety and depression in patients with esophageal cancer.

To compare the effects of Ivor-Lewis esophagectomy and McKeown esophagectomy on perioperative anxiety and depression in patients with esophageal cancer. Sixty-three patients with stage I-III middle and lower esophageal carcinoma from June 2021 to December 2022 were randomly divided into observation group (n = 32) treated with laparoscopic Ivor-Lewis esophagectomy and control group (n = 31) treated with laparoscopic McKeown esophagectomy. Self-Rating Depression Scale (SDS) and Self-Rating Anxiety Scale (SAS) were measured on the second day of admission and the fifth day after surgery to assess the presence of depression and anxiety. The preoperative and postoperative clinical data of both groups were compared, and multivariate analysis was used to identify risk factors associated with depression and anxiety in patients with esophageal cancer. There was no significant difference in SDS and SAS standard scores between the observation group and the control group (P > 0.05). The postoperative SDS and SAS scores in the control group were significantly higher than those before and after operation in the observation group (P < 0.01). According to univariate analysis, patients with TNM stage III, tumor diameter greater than 3 cm, postoperative complications, radical McKeown esophagectomy, and C-reactive protein levels above 10 mg/L had a higher incidence of depression and anxiety (P < 0.05). Multivariate logistic analysis showed that TNM stage III (depression: OR 1.683, 95 CI 1.429-1.861; Anxiety: OR 1.739, 95 CI 1.516-1.902), postoperative complications (depression: OR 2.345, 95 CI 1.435-3.891; Anxiety: OR 1.872, 95 CI 1.372-3.471), surgical approach (depression: OR 1.609, 95 CI 1.502-3.193; Anxiety: OR 1.658, 95 CI 1.469-2.059), and C-reactive protein (depression: OR 2.260, 95 CI 1.157-4.059; Anxiety: OR 0.373, 95 CI 0.253-0.976) were all independent factors for depression and anxiety in patients after esophageal cancer surgery (P < 0.05). The Ivor-Lewis esophagectomy has the advantages of fewer complications and low inflammatory response, which can help alleviate anxiety and depression and improve patients' quality of life and prognosis.

A mitochondrial EglN1-AMPKα axis drives breast cancer progression by enhancing metabolic adaptation to hypoxic stress.

Mitochondria play essential roles in cancer cell adaptation to hypoxia, but the underlying mechanisms remain elusive. Through mitochondrial proteomic profiling, we here find that the prolyl hydroxylase EglN1 (PHD2) accumulates on mitochondria under hypoxia. EglN1 substrate-binding region in the ß2ß3 loop is responsible for its mitochondrial translocation and contributes to breast tumor growth. Furthermore, we identify AMP-activated protein kinase alpha (AMPKα) as an EglN1 substrate on mitochondria. The EglN1-AMPKα interaction is essential for their mutual mitochondrial translocation. After EglN1 prolyl-hydroxylates AMPKα under normoxia, they rapidly dissociate following prolyl-hydroxylation, leading to their immediate release from mitochondria. In contrast, hypoxia results in constant EglN1-AMPKα interaction and their accumulation on mitochondria, leading to the formation of a Ca2+ /calmodulin-dependent protein kinase 2 (CaMKK2)-EglN1-AMPKα complex to activate AMPKα phosphorylation, ensuring metabolic homeostasis and breast tumor growth. Our findings identify EglN1 as an oxygen-sensitive metabolic checkpoint signaling hypoxic stress to mitochondria through its ß2ß3 loop region, suggesting a potential therapeutic target for breast cancer.

Step-wise activation of a Family C GPCR.

Metabotropic glutamate receptors belong to a family of G protein-coupled receptors that are obligate dimers and possess a large extracellular ligand-binding domain (ECD) that is linked via a cysteine-rich domain (CRDs) to their 7-transmembrane (TM) domain. Upon activation, these receptors undergo a large conformational change to transmit the ligand binding signal from the ECD to the G protein-coupling TM. In this manuscript, we propose a model for a sequential, multistep activation mechanism of metabotropic glutamate receptor subtype 5. We present a series of structures in lipid nanodiscs, from inactive to fully active, including agonist-bound intermediate states. Further, using bulk and single-molecule fluorescence imaging we reveal distinct receptor conformations upon allosteric modulator and G protein binding.

Low glucose metabolite 3-phosphoglycerate switches PHGDH from serine synthesis to p53 activation to control cell fate.

Glycolytic intermediary metabolites such as fructose-1,6-bisphosphate can serve as signals, controlling metabolic states beyond energy metabolism. However, whether glycolytic metabolites also play a role in controlling cell fate remains unexplored. Here, we find that low levels of glycolytic metabolite 3-phosphoglycerate (3-PGA) can switch phosphoglycerate dehydrogenase (PHGDH) from cataplerosis serine synthesis to pro-apoptotic activation of p53. PHGDH is a p53-binding protein, and when unoccupied by 3-PGA interacts with the scaffold protein AXIN in complex with the kinase HIPK2, both of which are also p53-binding proteins. This leads to the formation of a multivalent p53-binding complex that allows HIPK2 to specifically phosphorylate p53-Ser46 and thereby promote apoptosis. Furthermore, we show that PHGDH mutants (R135W and V261M) that are constitutively bound to 3-PGA abolish p53 activation even under low glucose conditions, while the mutants (T57A and T78A) unable to bind 3-PGA cause constitutive p53 activation and apoptosis in hepatocellular carcinoma (HCC) cells, even in the presence of high glucose. In vivo, PHGDH-T57A induces apoptosis and inhibits the growth of diethylnitrosamine-induced mouse HCC, whereas PHGDH-R135W prevents apoptosis and promotes HCC growth, and knockout of Trp53 abolishes these effects above. Importantly, caloric restriction that lowers whole-body glucose levels can impede HCC growth dependent on PHGDH. Together, these results unveil a mechanism by which glucose availability autonomously controls p53 activity, providing a new paradigm of cell fate control by metabolic substrate availability.

A cleaved METTL3 potentiates the METTL3-WTAP interaction and breast cancer progression.

N6-methyladenosine (m6A) methylation of RNA by the methyltransferase complex (MTC), with core components including METTL3-METTL14 heterodimers and Wilms' tumor 1-associated protein (WTAP), contributes to breast tumorigenesis, but the underlying regulatory mechanisms remain elusive. Here, we identify a novel cleaved form METTL3a (residues 239-580 of METTL3). We find that METTL3a is required for the METTL3-WTAP interaction, RNA m6A deposition, as well as cancer cell proliferation. Mechanistically, we find that METTL3a is essential for the METTL3-METTL3 interaction, which is a prerequisite step for recruitment of WTAP in MTC. Analysis of m6A sequencing data shows that depletion of METTL3a globally disrupts m6A deposition, and METTL3a mediates mammalian target of rapamycin (mTOR) activation via m6A-mediated suppression of TMEM127 expression. Moreover, we find that METTL3 cleavage is mediated by proteasome in an mTOR-dependent manner, revealing positive regulatory feedback between METTL3a and mTOR signaling. Our findings reveal METTL3a as an important component of MTC, and suggest the METTL3a-mTOR axis as a potential therapeutic target for breast cancer.

Fluorinated carboxymethyl chitosan-based nano-prodrugs for precisely synergistic chemotherapy.

The clinical transformation of polysaccharide-based nano-prodrugs remains a long way off, due to the shackles on easy metabolic clearance, dilemma of dose-dependent toxicity and immunogenicity, and poor tumor selectivity. To address these challenges, the fluorinated dual-crosslinked carboxymethyl chitosan (CMCS)-based nano-prodrugs with precise structure were facilely developed through the reaction of CMCS with water-soluble stimuli-responsive synergistic small molecule prodrug (Pt(IV)-1), glutaraldehyde and heptafluorobutyric anhydride successively. The fluorination enabled the nano-prodrugs to display metabolic stability and improve tumoral cellular uptake. The pH/glutathione (GSH)-sensitive dual-crosslinked structure enabled the nano-prodrugs to show physicochemical stability at physiological pH, selective drug release and synergistic cytotoxicity at tumoral intracellular pH/GSH, and circumventing the dilemma of dose-dependent toxicity and immunogenicity induced by that crosslinked or grafted via a single drug. These superior performances promoted stability in long-term storage and circulation, normal blood routine and aminotransferase, fantastic hemocompatibility, selective tumor accumulation and precisely synergistic chemotherapy, therefore achieving significant tumor growth inhibition while minimizing side effects. Thus, the precise fluorinated dual-crosslinked CMCS-based nano-prodrugs have great potential for selective clinical cancer treatment.

AMPK directly phosphorylates TBK1 to integrate glucose sensing into innate immunity.

Nutrient sensing and damage sensing are two fundamental processes in living organisms. While hyperglycemia is frequently linked to diabetes-related vulnerability to microbial infection, how body glucose levels affect innate immune responses to microbial invasion is not fully understood. Here, we surprisingly found that viral infection led to a rapid and dramatic decrease in blood glucose levels in rodents, leading to robust AMPK activation. AMPK, once activated, directly phosphorylates TBK1 at S511, which triggers IRF3 recruitment and the assembly of MAVS or STING signalosomes. Consistently, ablation or inhibition of AMPK, knockin of TBK1-S511A, or increased glucose levels compromised nucleic acid sensing, while boosting AMPK-TBK1 cascade by AICAR or TBK1-S511E knockin improves antiviral immunity substantially in various animal models. Thus, we identify TBK1 as an AMPK substrate, reveal the molecular mechanism coupling a dual sensing of glucose and nuclei acids, and report its physiological necessity in antiviral defense.

The aldolase inhibitor aldometanib mimics glucose starvation to activate lysosomal AMPK.

The activity of 5'-adenosine monophosphate-activated protein kinase (AMPK) is inversely correlated with the cellular availability of glucose. When glucose levels are low, the glycolytic enzyme aldolase is not bound to fructose-1,6-bisphosphate (FBP) and, instead, signals to activate lysosomal AMPK. Here, we show that blocking FBP binding to aldolase with the small molecule aldometanib selectively activates the lysosomal pool of AMPK and has beneficial metabolic effects in rodents. We identify aldometanib in a screen for aldolase inhibitors and show that it prevents FBP from binding to v-ATPase-associated aldolase and activates lysosomal AMPK, thereby mimicking a cellular state of glucose starvation. In male mice, aldometanib elicits an insulin-independent glucose-lowering effect, without causing hypoglycaemia. Aldometanib also alleviates fatty liver and nonalcoholic steatohepatitis in obese male rodents. Moreover, aldometanib extends lifespan and healthspan in both Caenorhabditis elegans and mice. Taken together, aldometanib mimics and adopts the lysosomal AMPK activation pathway associated with glucose starvation to exert physiological roles, and might have potential as a therapeutic for metabolic disorders in humans.

Identification of serum metabolites enhancing inflammatory responses in COVID-19.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is characterized by a strong production of inflammatory cytokines such as TNF and IL-6, which underlie the severity of the disease. However, the molecular mechanisms responsible for such a strong immune response remains unclear. Here, utilizing targeted tandem mass spectrometry to analyze serum metabolome and lipidome in COVID-19 patients at different temporal stages, we identified that 611 metabolites (of 1,039) were significantly altered in COVID-19 patients. Among them, two metabolites, agmatine and putrescine, were prominently elevated in the serum of patients; and 2-quinolinecarboxylate was changed in a biphasic manner, elevated during early COVID-19 infection but levelled off. When tested in mouse embryonic fibroblasts (MEFs) and macrophages, these 3 metabolites were found to activate the NF-κB pathway that plays a pivotal role in governing cytokine production. Importantly, these metabolites were each able to cause strong increase of TNF and IL-6 levels when administered to wildtype mice, but not in the mice lacking NF-κB. Intriguingly, these metabolites have little effects on the activation of interferon regulatory factors (IRFs) for the production of type I interferons (IFNs) for antiviral defenses. These data suggest that circulating metabolites resulting from COVID-19 infection may act as effectors to elicit the peculiar systemic inflammatory responses, exhibiting severely strong proinflammatory cytokine production with limited induction of the interferons. Our study may provide a rationale for development of drugs to alleviate inflammation in COVID-19 patients.

Midkine noncanonically suppresses AMPK activation through disrupting the LKB1-STRAD-Mo25 complex.

Midkine (MDK), a secreted growth factor, regulates signal transduction and cancer progression by interacting with receptors, and it can be internalized into the cytoplasm by endocytosis. However, its intracellular function and signaling regulation remain unclear. Here, we show that intracellular MDK interacts with LKB1 and STRAD to disrupt the LKB1-STRAD-Mo25 complex. Consequently, MDK decreases the activity of LKB1 to dampen both the basal and stress-induced activation of AMPK by glucose starvation or treatment of 2-DG. We also found that MDK accelerates cancer cell proliferation by inhibiting the activation of the LKB1-AMPK axis. In human cancers, compared to other well-known growth factors, MDK expression is most significantly upregulated in cancers, especially in liver, kidney and breast cancers, correlating with clinical outcomes and inversely correlating with phosphorylated AMPK levels. Our study elucidates an inhibitory mechanism for AMPK activation, which is mediated by the intracellular MDK through disrupting the LKB1-STRAD-Mo25 complex.

Filamentous GLS1 promotes ROS-induced apoptosis upon glutamine deprivation via insufficient asparagine synthesis.

GLS1 orchestrates glutaminolysis and promotes cell proliferation when glutamine is abundant by regenerating TCA cycle intermediates and supporting redox homeostasis. CB-839, an inhibitor of GLS1, is currently under clinical investigation for a variety of cancer types. Here, we show that GLS1 facilitates apoptosis when glutamine is deprived. Mechanistically, the absence of exogenous glutamine sufficiently reduces glutamate levels to convert dimeric GLS1 to a self-assembled, extremely low-Km filamentous polymer. GLS1 filaments possess an enhanced catalytic activity, which further depletes intracellular glutamine. Functionally, filamentous GLS1-dependent glutamine scarcity leads to inadequate synthesis of asparagine and mitogenome-encoded proteins, resulting in ROS-induced apoptosis that can be rescued by asparagine supplementation. Physiologically, we observed GLS1 filaments in solid tumors and validated the tumor-suppressive role of constitutively active, filamentous GLS1 mutants K320A and S482C in xenograft models. Our results change our understanding of GLS1 in cancer metabolism and suggest the therapeutic potential of promoting GLS1 filament formation.

Metabolic reprogramming in astrocytes results in neuronal dysfunction in intellectual disability.

Astrocyte aerobic glycolysis provides vital trophic support for central nervous system neurons. However, whether and how astrocytic metabolic dysregulation contributes to neuronal dysfunction in intellectual disability (ID) remain unclear. Here, we demonstrate a causal role for an ID-associated SNX27 mutation (R198W) in cognitive deficits involving reshaping astrocytic metabolism. We generated SNX27R196W (equivalent to human R198W) knock-in mice and found that they displayed deficits in synaptic function and learning behaviors. SNX27R196W resulted in attenuated astrocytic glucose uptake via GLUT1, leading to reduced lactate production and a switch from homeostatic to reactive astrocytes. Importantly, lactate supplementation or a ketogenic diet restored neuronal oxidative phosphorylation and reversed cognitive deficits in SNX27R196W mice. In summary, we illustrate a key role for astrocytic SNX27 in maintaining glucose supply and glycolysis and reveal that altered astrocytic metabolism disrupts the astrocyte-neuron interaction, which contributes to ID. Our work also suggests a feasible strategy for treating ID by restoring astrocytic metabolic function.

ω-3 and ω-6 Polyunsaturated Fatty Acids Regulate the Proliferation, Invasion and Angiogenesis of Gastric Cancer Through COX/PGE Signaling Pathway.

BACKGROUND: This study aims to investigate the effects of ω-3, ω-6 polyunsaturated fatty acids (PUFAs), and their middle metabolites prostaglandin (PGE)2 and PGE3 on proliferation, invasion, and angiogenesis formation of gastric cancer cells and to explore associated mechanism. METHODS: RT-PCR and ELISA were used to detect the expression of cyclooxygenase (COX)-1 and COX-2 in gastric cancer cell lines. The effect of ω-3, ω-6, PGE2, and PGE3 on the proliferation, invasion, and angiogenesis of gastric cancer cells were measured by cell proliferation, invasion, and angiogenesis assay in vitro. COX-2 small interfering RNA (siRNA) was transfected into gastric cancer cells, and the expression of COX-2 protein was detected by Western blot. COX-2 gene silencing influencing proliferation, invasion, and angiogenesis potential of gastric cancer cells was detected by WST-1, transwell chamber, and angiogenesis assay, respectively. RESULTS: COX-2 was only expressed in MKN74 and MKN45 cells. In gastric cancer cell lines with positive COX-2 expression, ω-6 and PGE2 could significantly enhance the proliferation, invasion, and angiogenesis of gastric cancer cells, and after transfection with COX-2 siRNA, the effects of ω-6 and PGE2 on enhancing the proliferation, invasion, and angiogenesis of gastric cancer cells were significantly attenuated; ω-3 and PEG3 could inhibit the proliferation, invasion, and angiogenesis of gastric cancer cells. In gastric cancer cell lines with negative COX-2 expression, ω-6 and PGE2 had no significant effect on the proliferation, invasion, and angiogenesis of gastric cancer; ω-3 and PGE3 could significantly inhibit the proliferation, invasion, and angiogenesis of gastric cancer. CONCLUSION: ω-6 PUFAs reinforce the metastatic potential of gastric cancer cells via COX-2/PGE2; ω-3 PUFAs inhibit the metastatic potential of gastric cancer via COX-1/PGE3 signaling axis.

Low-dose metformin targets the lysosomal AMPK pathway through PEN2.

Metformin, the most prescribed antidiabetic medicine, has shown other benefits such as anti-ageing and anticancer effects1-4. For clinical doses of metformin, AMP-activated protein kinase (AMPK) has a major role in its mechanism of action4,5; however, the direct molecular target of metformin remains unknown. Here we show that clinically relevant concentrations of metformin inhibit the lysosomal proton pump v-ATPase, which is a central node for AMPK activation following glucose starvation6. We synthesize a photoactive metformin probe and identify PEN2, a subunit of γ-secretase7, as a binding partner of metformin with a dissociation constant at micromolar levels. Metformin-bound PEN2 forms a complex with ATP6AP1, a subunit of the v-ATPase8, which leads to the inhibition of v-ATPase and the activation of AMPK without effects on cellular AMP levels. Knockout of PEN2 or re-introduction of a PEN2 mutant that does not bind ATP6AP1 blunts AMPK activation. In vivo, liver-specific knockout of Pen2 abolishes metformin-mediated reduction of hepatic fat content, whereas intestine-specific knockout of Pen2 impairs its glucose-lowering effects. Furthermore, knockdown of pen-2 in Caenorhabditis elegans abrogates metformin-induced extension of lifespan. Together, these findings reveal that metformin binds PEN2 and initiates a signalling route that intersects, through ATP6AP1, the lysosomal glucose-sensing pathway for AMPK activation. This ensures that metformin exerts its therapeutic benefits in patients without substantial adverse effects.

Nuclear UHRF1 is a gate-keeper of cellular AMPK activity and function.

The AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis. Although much has been learned on how low energy status and glucose starvation activate AMPK, how AMPK activity is properly controlled in vivo is still poorly understood. Here we report that UHRF1, an epigenetic regulator highly expressed in proliferating and cancer cells, interacts with AMPK and serves to suppress AMPK activity under both basal and stressed conditions. As a nuclear protein, UHRF1 promotes AMPK nuclear retention and strongly suppresses nuclear AMPK activity toward substrates H2B and EZH2. Importantly, we demonstrate that UHRF1 also robustly inhibits AMPK activity in the cytoplasm compartment, most likely as a consequence of AMPK nucleocytoplasmic shuttling. Mechanistically, we found that UHRF1 has no obvious effect on AMPK activation by upstream kinases LKB1 and CAMKK2 but inhibits AMPK activity by acting as a bridging factor targeting phosphatase PP2A to dephosphorylate AMPK. Hepatic overexpression of UHRF1 showed profound effects on glucose and lipid metabolism in wild-type mice but not in those with the liver-specific knockout of AMPKα1/α2, whereas knockdown of UHRF1 in adipose tissue led to AMPK activation and reduced sizes of adipocytes and lipogenic activity, highlighting the physiological significance of this regulation in glucose and lipid metabolism. Thus, our study identifies UHRF1 as a novel AMPK gate-keeper with critical roles in cellular metabolism.

Interleukin-1 receptor antagonist inhibits matastatic potential by down-regulating CXCL12/CXCR4 signaling axis in colorectal cancer.

BACKGROUND: The aim of this study was to investigate the co-operative role of CXCR4/CXCL12 axis and IL-1Ra in metastatic processes mechanism by interactions between colorectal cancer cells and stromal cells in their microenvironment. METHODS: Expression of IL-1α, interleukin-1 receptor type I (IL-1 RI), CXCL12 and CXCR4 mRNA and proteins were determined by RT-PCR and Western blot. The effect of secreted level of CXCL12 by IL-1Ra on fibroblasts was measured by ELISA. CXCL12 regulate metastatic potential of colorectal cancer was evaluated by proliferation, invasion and angiogenesis assays, respectively, in which invasion and angiogenesis assays used an in vitro system consisting of co-cultured colorectal cells and stromal cells. RESULTS: IL-1α was expressed in high liver metastatic colorectal cancer cell lines (HT-29 and WiDr). The colorectal cancer cell-derived IL-1α and rIL-1α significantly promoted CXCL12 expression by fibroblasts, and this enhancing effect can be significantly inhibited by IL-1Ra (P < 0.01). CXCL12 not only enhanced the migration and proliferation of human umbilical vein endothelial cells, but also significantly enhanced angiogenesis (P < 0.01). Furthermore, the high liver-metastatic colorectal cancer cell line (HT-29), which secretes IL-1α, significantly enhanced angiogenesis compared to the low liver-metastatic cell line (CaCo-2), which does not produce IL-1α (P < 0.01). On the contrary, IL-1Ra can significantly inhibit migration, proliferation and angiogenesis (P < 0.01). CONCLUSION: Autocrine IL-1α and paracrine CXCL12 co-enhances the metastatic potential of colorectal cancer cells; IL-1Ra can inhibit the metastatic potential of colorectal cancer cells via decrease IL-1α/CXCR4/CXCL12 signaling pathways. Video Abstract.