Endoclip combined with colonic transendoscopic enteral tubing: a new approach for managing iatrogenic colonoscopy perforation.

BACKGROUND: Iatrogenic colonoscopy perforation (ICP) is a rare but most serious complication during colonoscopy investigation. However, endoscopic closure plays an important role in the dealing with ICP with the development of endoscopic techniques presently, there are still some portion of patients transferred to surgery. METHODS: Once a perforation was detected, endoclips were used to closed the defect of the colon. Then a colonic TET was planted inside the colon. The terminal end of the TET was put proximally to or near the location of the perforation. Then gas and fluid was sucked out through the TET with a syringe every 4 h. RESULTS: Three cases were treated with endoclip closure and colonic TET drainage. Case 1 was caused by urgent immediate perforation during routine colonoscopy, case 2 was delayed perforation after snare resection, and case 3 was ESD-related perforation. All patients got healed, no one transferred to surgery. CONCLUSIONS: A combination of endoclip closure and colonic TET drainage might be an easy and potential method in the dealing with different types of ICP. This study may offer a novel paradigm for addressing endoscopy-related intestinal perforations.

Clinical Benefit, Price, and Uptake for Cancer Biosimilars vs Reference Drugs in China: A Systematic Review and Meta-Analysis.

Importance: The high cost of biologics used to treat cancer has been an increasing burden in the world. In China, the recent approval of cancer biosimilar drugs to resolve this problem is promising, but evidence of clinical benefits, price, and uptake for these drugs is still lacking. Objectives: To compare characteristics of pivotal clinical trials in China and other countries for biosimilars of bevacizumab, rituximab, and trastuzumab and investigate the efficacy or effectiveness, safety, and immunogenicity outcomes of cancer biosimilars compared with reference drugs by meta-analysis. Data Sources: For this systematic review and meta-analysis, PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov were searched for published studies from database inception to February 1, 2023, using the search topics (cancers) AND (biosimilars). Study Selection: Randomized clinical trials and cohort studies that included patients with cancer were included. Data Extraction and Synthesis: Two authors independently extracted the outcome estimates and characteristics for each study. A random-effects meta-analysis was performed to summarize the relative estimates with 95% CIs. This study was performed following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline. Main Outcomes and Measures: Clinical trial characteristics were collected for biosimilars of bevacizumab, rituximab, and trastuzumab. The relative estimates of efficacy or effectiveness (objective response rate, progression-free survival, and overall survival), safety, and immunogenicity outcomes were analyzed for biosimilars vs reference drugs. The weighted average price and uptake rate were evaluated for biosimilars relative to their reference drugs between 2015 and 2022. Results: A total of 39 RCTs (involving 18 791 patients) and 10 cohort studies (involving 1998 patients) were included. The biosimilars of bevacizumab (16 RCTs; risk ratio [RR], 0.97; 95% CI, 0.93-1.01; P = .17), rituximab (12 RCTs; RR, 1.03; 95% CI, 0.98-1.08; P = .70), and trastuzumab (9 RCTs: RR, 1.04; 95% CI, 0.97-1.12; P = .29) met equivalence with reference biologics in regard to the objective response rate. The results summarized from cohort studies were consistent with those from RCTs. In 2022, cancer biosimilars were priced at 69% to 90% of the costs for the reference drugs, and their uptake reached 54% to 83% in China. Conclusions and Relevance: This systematic review and meta-analysis indicated that cancer biosimilars provided comparable clinical benefits at lower prices compared with reference drugs. These findings suggest the potential feasibility of expediting the transition from reference drugs to biosimilars to benefit more patients with cancer.

Presence of diabetes further heightens hepatocellular carcinoma risk in patients with hepatitis B or hepatitis C virus-related cirrhosis: A meta-analysis.

Objective: Impact of diabetes mellitus on the development of hepatocellular carcinoma (HCC) remained controversial in cirrhotic patients. This meta-analysis aimed to investigate the association of diabetes and the occurrence of HCC in patients with hepatitis B or hepatitis C virus-related cirrhosis. Methods: Two authors comprehensively searched PubMed and Embase databases until June 22, 2023, to identify studies that evaluated the association of diabetes with the occurrence of HCC in patients with hepatitis B or hepatitis C virus-related cirrhosis. Results: Sixteen retrospective/prospective cohort studies reporting on 15 articles (5357 cirrhotic patients) were included. The prevalence of diabetes in hepatitis B and hepatitis C virus-related cirrhosis patients ranged from 4 to 46%. Diabetes was associated with higher risk of HCC (risk ratio [RR] 1.74; 95% confidence intervals [CI] 1.24-2.45) in patients with hepatitis C virus-related cirrhosis. However, no significant relationship of diabetes with the occurrence of HCC was present in studies with less than 48-month follow-up among patients with hepatitis C virus-related cirrhosis (RR 1.28; 95% CI 0.68-2.43). Moreover, diabetes also conferred an increased risk of HCC (RR 2.67; 95% CI 2.03-3.51) in patients with hepatitis B virus-related cirrhosis. Conclusion: Presence of diabetes significantly predicted the occurrence of HCC in patients with hepatitis B or hepatitis C virus-related cirrhosis.

The regulation of Tfh cell differentiation by ß-hydroxybutyrylation modification of transcription factor Bcl6.

Transcriptional repressor B cell lymphoma 6 (Bcl6) is a major transcription factor involved in Tfh cell differentiation and germinal center response, which is regulated by a variety of biological processes. However, the functional impact of post-translational modifications, particularly lysine ß-hydroxybutyrylation (Kbhb), on Bcl6 remains elusive. In this study, we revealed that Bcl6 is modified by Kbhb to affect Tfh cell differentiation, resulting in the decrease of cell population and cytokine IL-21. Furthermore, the modification sites are identified from enzymatic reactions to be lysine residues at positions 376, 377, and 379 by mass spectrometry, which is confirmed by site-directed mutagenesis and functional analyses. Collectively, our present study provides evidence on the Kbhb modification of Bcl6 and also generates new insights into the regulation of Tfh cell differentiation, which is a starting point for a thorough understanding of the functional involvement of Kbhb modification in the differentiations of Tfh and other T cells.

Roxadustat, a Hypoxia-Inducible Factor 1α Activator, Attenuates Both Long- and Short-Term Alcohol-Induced Alcoholic Liver Disease.

Alcoholic liver disease (ALD) is a worldwide healthcare problem featured by inflammation, reactive oxygen species (ROS), and lipid dysregulation. Roxadustat is used for chronic kidney disease anemia treatment. As a specific inhibitor of prolyl hydroxylase, it can maintain high levels of hypoxia-inducible factor 1α (HIF-1α), through which it can further influence many important pathways, including the three featured in ALD. However, its effects on ALD remain to be elucidated. In this study, we used chronic and acute ALD mouse models to investigate the protective effects of roxadustat in vivo. Our results showed that long- and short-term alcohol exposure caused rising activities of serum transaminases, liver lipid accumulation, and morphology changes, which were reversed by roxadustat. Roxadustat-reduced fatty liver was mainly contributed by the reducing sterol-responsive element-binding protein 1c (SREBP1c) pathway, and enhancing ß-oxidation through inducing peroxisome proliferator-activated receptor α (PPARα) and carnitine palmitoyltransferase 1A (CPT1A) expression. Long-term alcohol treatment induced the infiltration of monocytes/macrophages to hepatocytes, as well as inflammatory cytokine expression, which were also blocked by roxadustat. Moreover, roxadustat attenuated alcohol caused ROS generation in the liver of those two mouse models mainly by reducing cytochrome P450 2E1 (CYP2E1) and enhancing superoxidase dismutase 1 (SOD1) expression. In vitro, we found roxadustat reduced inflammation and lipid accumulation mainly via HIF-1α regulation. Taken together, our study demonstrates that activation of HIF-1α can ameliorate ALD, which is contributed by reduced hepatic lipid synthesis, inflammation, and oxidative stress. This study suggested that roxadustat could be a potential drug for ALD treatment.

The impact of online education on carbon emissions in the context of the COVID-19 pandemic - Taking Chinese universities as examples.

While the COVID-19 pandemic has had various impacts on economic and social development, it may have partially reduced human energy use, thereby helping achieve the goals of reducing carbon emissions and promoting carbon neutrality. During the pandemic, online education was widely used to replace traditional education all over the world. There is a lack of empirical studies on whether and to what extent the change of education model can reduce carbon emissions. Taking Chinese universities as cases, this study, concentrating on two main elements - transportation and electricity consumption - constructs a model and calculates the impact of online education on carbon emissions. The results show that online education can significantly reduce energy consumption and lower carbon emissions. In the field of higher education alone, the carbon emissions reduction caused by online education in half a year is equivalent to the total carbon emissions reduction of college students caused by online education during the half-year is equivalent to the total carbon emissions in 1.296 h in China, 2.688 h in the United States, 5.544 h in India, 12 h in Japan and 3.864 h in European countries of OECD. Therefore, this study suggests that the impact of online education on carbon emissions should be further studied, online education should be promoted through legislation and other systemic measures, and the goals of carbon emissions and carbon neutrality should be explored further within the field of education.

Propofol Inhibits Proliferation and Invasion of Stomach Cancer Cells by Regulating miR-205/YAP1 Axis.

BACKGROUND: Propofol is a common clinical intravenous anesthetic. In the last few years, studies have revealed that propofol not only has good anesthetic effect but also has certain anticancer effect. However, its role in stomach cancer (SC) and related mechanisms are still under investigation. OBJECTIVE: This study was designed to determine the effect of propofol on SC and its related mechanisms. METHODS: Purchased SC cells were treated with propofol at different concentrations (5, 10, and 20 µg/mL), miR-205 overexpression, and YAP1 inhibition. Then, the Cell Counting Kit-8 (CCK8), Transwell, and flow cytometry were carried out to determine the biological behavior changes of treated cells and the expression of miR-205 and YAP1 after treatment. RESULTS: Propofol (10 µg/mL and 20 µg/mL) inhibited the growth of SC cells and promoted their apoptosis, and overexpressing miR-205 or inhibiting YAP1 can exert the same effects. In addition, propofol (10µg/mL and 20µg/mL) up-regulated miR-205 in SC cells. The dual-luciferase reporter assay revealed that YAP1 could be targeted and regulated by miR-205, and the rescue assay revealed that inhibiting miR-205 or overexpressing YAP1 could weaken the effect of propofol on the biological behaviors of SC cells. CONCLUSION: Propofol can strongly suppress the proliferation and invasion of SC cells and induce their apoptosis via the miR-205/YAP1 axis.

Prominent effect of platelet on improvement of liver cirrhosis.

Thrombopoietin (TPO) can improve liver regeneration and fibrosis. We report on a patient with liver cirrhosis who received treatment with TPO to improve liver function. An 82-year-old male had liver cirrhosis with ascites due to hepatitis C virus infection. The Child-Pugh classification was Child B. The patient received human recombinant TPO for 12 months. The platelet counts increased and were maintained at 60-80×109/L. The liver function improved, the ascites resolved, and the liver volume increased. These results indicate that the novel treatment with recombinant human TPO (rhTPO) may be effective for improving liver function in patients with liver cirrhosis.

Promotion of miR-221-5p on the Sensitivity of Gastric Cancer Cells to Cisplatin and Its Effects on Cell Proliferation and Apoptosis by Regulating DDR1.

PURPOSE: This research aimed to explore the role of miR-221-5p on the sensitivity of gastric cancer cells to cisplatin, and the proliferation and invasion of gastric cancer cells by regulating DDR1. PATIENTS AND METHODS: Altogether 69 patients who treated with radical gastrectomy from January 2014 to January 2016 were collected. With the agree of the patients, 69 gastric carcinoma and 69 adjacent tissues were taken, respectively, during the operation, and gastric carcinoma and human gastric mucosa cells were purchased. RT-PCR was used for detection of the expression level of miR-221-5p and DDR1. Wound healing assay and CCK-8 assay were used for exploration of the cell migration and viability. Western blot and double luciferase reporter gene were performed to determine the target gene of miR-221-5p. RESULTS: It was showed that miR-221-5p expression was decreased in GC tissues and cell lines. The high expression of miR-221-5p reduced the resistance of GC cells to cisplatin and inhibited the proliferation and migration of gastric cancer cells. The high expression of miR-221-5p promoted the proliferation, invasion and migration of GC cells. In addition, we found that DDR1 was a direct target gene of miR-221-5p in GC cells. We found that DDR1 expression increased in gastric carcinoma. Moreover, there was a negative correlation of DDR1 with the expression level of miR-221-5p. The increase of miR-221-5p increased the chemosensitivity of GC cells to cisplatin, and inhibited the proliferation, invasion, migration and EMT of GC cells by targeting DDR1. CONCLUSION: The above research indicated that miR-221-5p may be a target for enhancing cisplatin chemotherapy sensitivity in gastric cancer patients.

SP1-induced lncRNA TINCR overexpression contributes to colorectal cancer progression by sponging miR-7-5p.

Mounting evidences have indicated that long noncoding RNAs (lncRNAs) play pivotal roles in human diseases, especially in cancers. Recently, TINCR was proposed to be involved in tumor progression. However, its role in colorectal cancer (CRC) remains elusive. In our study, we found that SP1-induced TINCR was significantly upregulated in CRC tissues and cell lines. Moreover, cox multivariate survival analysis revealed that high TINCR was an independent predictor of poor overall survival (OS). Functionally, knockdown of TINCR obviously suppressed CRC cells proliferation, migration and invasion in vitro, and inhibited CRC cells growth and metastasis in vivo. Mechanistically, we identified TINCR could act as a miR-7-5p sponge using RNA pull down, luciferase reporter and RIP assays. Furthermore, we showed that TINCR might promote CRC progression via miR-7-5p-mediated PI3K/Akt/mTOR signaling pathway. Lastly, we revealed that plasma TINCR expression was upregulated in CRC when compared to healthy controls and could be a promising diagnostic biomarker for CRC. Based on above results, our data indicated that TINCR might serve as a potential diagnostic and prognostic biomarker for CRC.

Identification of diagnostic utility and molecular mechanisms of circulating miR-551b-5p in gastric cancer.

BACKGROUND: Gastric cancer (GC) is one of the most common cancers globally leading to 850,000 deaths each year. GC patients are often diagnosed at advanced stages which results in poor prognosis. This study aimed to identify a novel circulating miRNA as the diagnostic biomarker of GC and further explore its regulatory mechanisms in GC. MATERIALS AND METHODS: First, the candidate serum miRNA was selected after analysis of microarray data. Then, the levels of candidate miRNA in the serum of GC patients were validated in an independent cohort. The diagnostic utility of miRNA was evaluated by using receiver operating characteristic curve (ROC) analysis. The functional and pathways enrichment analysis of targets of candidate miRNA were explored by online tool DAVID. RESULTS: After comprehensive analysis of Gene Expression Omnibus (GEO) dataset, miR-551b-5p was selected as candidate due to its highest differential fold-change. Another independent cohort showed that serum miR-551b-5p could differentiate GC patients from healthy controls (HCs) with area under the curve (AUC) of 0.84 (95%CI: 0.75-0.93). The functional and pathways enrichment analysis revealed that targets of miR-551b-5p mainly located in cytoplasm and significantly associated with regulation of ubiquitin-dependent protein catabolic process, cell division, and mRNA stability. CONCLUSIONS: Circulating miR-551b-5p was a novel promising biomarker for the detection of GC and exploration of the molecular mechanisms of miR-551b-5p is useful to search for new therapeutic strategies of GC.

Long non­coding RNA PVT1 promotes epithelial­mesenchymal transition via the TGF­ß/Smad pathway in pancreatic cancer cells.

Recent studies have revealed that overexpression of long non­coding RNA (lncRNA) PVT1 is correlated with several types of cancer. However, its role in pancreatic cancer development remains to be clarified. In the present study, we found that PVT1 promoted the growth and the epithelial­mesenchymal transition (EMT) of pancreatic cancer cells. We first determined that PVT1 was upregulated in pancreatic cancer tissues compared with adjacent normal tissues. Knockdown of PVT1 inhibited viability, adhesion, migration and invasion. Furthermore, PVT1 knockdown reduced the expression of mesenchymal markers including Snail, Slug, ß­catenin, N­cadherin and vimentin, while it increased epithelial marker expression of E­cadherin. Finally, knockdown of PVT1 inhibited the TGF­ß/Smad signaling, including p­Smad2/3 and TGF­ß1 but enhanced the expression of Smad4. In contrast, overexpression of PVT1 reversed the process. These findings revealed that PVT1 acts as an oncogene in pancreatic cancer, possibly through the regulation of EMT via the TGF­ß/Smad pathway and PVT1 may serve as a potential target for diagnostics and therapeutics in pancreatic cancer.

TGF-ß1-miR-200a-PTEN induces epithelial-mesenchymal transition and fibrosis of pancreatic stellate cells.

Although the function of miR-200a has been discussed in many cancers and fibrotic diseases, its role in pancreatic fibrosis is still poorly understood. In this study, we for the first time confirm that miR-200a attenuates TGF-ß1-induced pancreatic stellate cells activation and extracellular matrix formation. First, we find that TGF-ß1 induces activation and extracellular matrix (ECM) formation in PSCs, and the effects are blocked by the inhibitor of PI3K (LY294002). Furthermore, we identify that miR-200a is down-regulated in TGF-ß1-activated PSCs, and up-regulation of miR-200a inhibits PSCs activation induced by TGF-ß1. Meanwhile, TGF-ß1 inhibits the expression of the epithelial marker E-cadherin, and increases the expression of mesenchymal markers vimentin, and the expression of ECM proteins a-SMA and collagen I, while miR-200a mimic reversed the above effects in PSCs, indicating that miR-200a inhibits TGF-ß1-induced activation and epithelial-mesenchymal transition (EMT). In addition, overexpression of miR-200a promotes the expression of PTEN and decreases the expression of matrix proteins and attenuates phosphorylation of Akt and mTOR. Taken together, our study uncovers a novel mechanism that miR-200a attenuates TGF-ß1-induced pancreatic stellate cells activation and ECM formation through inhibiting PTEN /Akt/mTOR pathway.

Sonic hedgehog-glioma associated oncogene homolog 1 signaling enhances drug resistance in CD44(+)/Musashi-1(+) gastric cancer stem cells.

Drug resistance in gastric cancer largely results from the gastric cancer stem cells (GCSCs), which could be targeted to improve the efficacy of chemotherapy. In this study, we identified a subpopulation of GCSCs enriched in holoclones that expressed CD44(+)/Musashi-1(+) stem cell biomarkers, capable of self-renewal and proliferation. Enriched CD44(+)/Musashi-1(+) GCSCs demonstrated elevated expression of sonic hedgehog (SHH) and glioma-associated oncogene homolog 1 (GLI1), the well-known signaling pathway molecules involved in the drug resistance. Further, CD44(+)/Musashi-1(+) cells exhibited high drug efflux bump activity and were resistant to doxorubicin (Dox)-induced apoptosis, and unregulated the ATP-binding cassette sub-family G member 2 (ABCG2) expression,. The above effects on apoptosis were reversed in the presence of GLI inhibitors, GANT61 and GDC-0449, or by the knockdown of GLI1/SHH. Upon knockdown of GLI1, expression of ABCG2 was downregulated the antitumor effects were significantly improved as observed in the gastric cancer xenograft. Collectively, our study revealed that co-expression of CD44(+)/Musashi-1(+) could be used to identify GCSCs, which also accounts for the drug resistance in gastric cancer. SHH-GLI and its downstream effector ABCG2 could be better targeted to possibly improve the efficacy of chemotherapy in drug-resistant gastric cancers.

Regulation of glucose homeostasis and lipid metabolism by PPP1R3G-mediated hepatic glycogenesis.

Liver glycogen metabolism plays an important role in glucose homeostasis. Glycogen synthesis is mainly regulated by glycogen synthase that is dephosphorylated and activated by protein phosphatase 1 (PP1) in combination with glycogen-targeting subunits or G subunits. There are seven G subunits (PPP1R3A to G) that control glycogenesis in different organs. PPP1R3G is a recently discovered G subunit whose expression is changed along the fasting-feeding cycle and is proposed to play a role in postprandial glucose homeostasis. In this study, we analyzed the physiological function of PPP1R3G using a mouse model with liver-specific overexpression of PPP1R3G. PPP1R3G overexpression increases hepatic glycogen accumulation, stimulates glycogen synthase activity, elevates fasting blood glucose level, and accelerates postprandial blood glucose clearance. In addition, the transgenic mice have a reduced fat composition, together with decreased hepatic triglyceride level. Fasting-induced hepatic steatosis is relieved by PPP1R3G overexpression. In addition, PPP1R3G overexpression is able to elevate glycogenesis in primary hepatocytes. The glycogen-binding domain is indispensable for the physiological activities of PPP1R3G on glucose metabolism and triglyceride accumulation in the liver. Cumulatively, these data indicate that PPP1R3G plays a critical role in postprandial glucose homeostasis and liver triglyceride metabolism via its regulation on hepatic glycogenesis.

[miR-15a and miR-16 modulate drug resistance by targeting bcl-2 in human colon cancer cells].

OBJECTIVE: To investigate the reversal effect of targeted modulation of bcl-2 expression by miR-15a and miR-16 on drug resistance of human colon cancer cells. METHODS: Mimics or inhibitors of miR-15a and miR-16 were transfected into HCT8 or HCT8/VCR cells with the help of Lipofectamine 2000. The expressions of miR-15a and miR-16 mRNA were detected by RT-qPCR. The levels of bcl-2 and P-gp proteins were measured by Western blot. The inhibitory effects of VCR on growth of HCT8 and HCT8/VCR cells were detected by CCK8. RESULTS: After transfection of the mimics, the expression of miR-15a in the blank control group, negative control group and miR-15a mimic group was 1.00, 0.87 ± 0.24, and 223.44 ± 59.07, respectively, and miR-15a was increased significantly (P < 0.001). The expression of miR-16 in the blank control group, negative control group and miR-16 mimic group was 1.00, 0.66 ± 0.19, and 107.32 ± 22.58, respectively, and miR-16 expression was increased significantly (P < 0.001). The Western blot assay showed that the relative expressions of bcl-2 protein in the blank control group, negative control group, miR-15a mimic group and miR-16 mimic group were 1.00, 0.97 ± 0.02, 0.51 ± 0.06, and 0.65 ± 0.03, respectively, and the expression of bcl-2 protein was decreased significantly (P < 0.05), however, the expressions of P-gp protein showed no significant difference. The CCK8 test showed that at 1, 5, 25 and 125 µg/ml concentration of VCR, the survival rates of HCT8/VCR cells were basically the same in the blank control group, negative control group, miR-15a mimic group and miR-16 mimic group, but the survival rate of HCT8/VCR cells was significantly decreased after transfection of mimics (P < 0.05). After transfection of the inhibitors, the expressions of both miR-15a and miR-16 were decreased significantly (P < 0.001). The Western blot showed that the expression of bcl-2 protein was increased (P < 0.05), while the expression of P-gp protein showed no significant difference. The CCK8 test showed that the survival rate of HCT8 cells which were transfected with inhibitors was significantly higher than that of the blank control group (P < 0.05). CONCLUSIONS: miR-15a and miR-16 may reverse the drug resistance in human colon cancer cells. A possible mechanism is regulating the expression of bcl-2.

Tollip, an intracellular trafficking protein, is a novel modulator of the transforming growth factor-ß signaling pathway.

Upon activation, TGF-ß type I receptor (TßRI) undergoes active ubiquitination via recruitment of E3 ligases to the receptor complex by Smad7. However, how ubiquitination of TßRI is coupled to intracellular trafficking, and protein degradation remains unclear. We report here that Tollip, an adaptor protein that contains both ubiquitin-associated domains and endosome-targeting domain, plays an important role in modulating trafficking and degradation of TßRI. Tollip was previously demonstrated to possess a functional role in modulating the signaling of interleukin-1 and Toll-like receptors. We identify here that Tollip interacts with Smad7, a major modulatory protein involved in the negative regulation of TGF-ß signaling. Overexpression of Tollip antagonizes TGF-ß-stimulated transcriptional response, Smad2 phosphorylation, and epithelial-mesenchymal transition. Tollip also interacts with ubiquitinated TßRI, and such interaction requires ubiquitin-associated domains of Tollip. The interaction and intracellular colocalization of Tollip with TßRI is enhanced by Smad7. Overexpression of Tollip accelerates protein degradation of activated TßRI. In addition, Tollip alters subcellular compartmentalization and endosomal trafficking of activated TßRI. Collectively, our studies reveal that Tollip cooperates with Smad7 to modulate intracellular trafficking and degradation of ubiquitinated TßRI, whereby negatively regulates TGF-ß signaling pathway.

A role for protein inhibitor of activated STAT1 (PIAS1) in lipogenic regulation through SUMOylation-independent suppression of liver X receptors.

Liver X receptors (LXRs) are nuclear receptors that function to modulate lipid metabolism as well as immune and inflammatory responses. Upon activation by their ligands, LXRs up-regulate a spectrum of gene transcription programs involved in cholesterol and fatty acid homeostasis. However, the mechanisms by which LXR-mediated transcriptional activation is regulated remain incompletely understood. Here, we show that PIAS1, a member of the protein inhibitor of the activated STAT family of proteins with small ubiquitin-like modifier (SUMO) E3 ligase activity, acts to suppress LXR ligand-dependent transcriptional activation of the lipogenic program in hepatocytes. We found that liver mRNA expression levels of Pias1 and Pias3 were inversely associated with those of genes involved in lipogenesis in mouse models with diet-induced or genetic obesity. Overexpression of PIAS1 in primary hepatocytes resulted in a reduction of LXR ligand-induced fatty acid synthesis and suppression of the expression of lipogenic genes, including Srebp1c and Fas. Moreover, PIAS1 was able to interact with LXRß and repress its transcriptional activity upon ligand stimulation, which did not require PIAS1-promoted SUMO modification of LXRß. In addition, PIAS1 could also interact with PGC-1ß and attenuate its association with LXRß, blunting the ability of PGC-1ß to co-activate LXRß. Importantly, PIAS1 impaired LXRß binding to its target DNA sequence. Taken together, our results suggest that PIAS1 may serve as a lipogenic regulator by negatively modulating LXRs in a SUMOylation-independent manner.

PAQR10 and PAQR11 mediate Ras signaling in the Golgi apparatus.

Ras plays a pivotal role in many cellular activities, and its subcellular compartmentalization provides spatial and temporal selectivity. Here we report a mode of spatial regulation of Ras signaling in the Golgi apparatus by two highly homologous proteins PAQR10 and PAQR11 of the progestin and AdipoQ receptors family. PAQR10 and PAQR11 are exclusively localized in the Golgi apparatus. Overexpression of PAQR10/PAQR11 stimulates basal and EGF-induced ERK phosphorylation and increases the expression of ERK target genes in a dose-dependent manner. Overexpression of PAQR10/PAQR11 markedly elevates Golgi localization of HRas, NRas and KRas4A, but not KRas4B. PAQR10 and PAQR11 can also interact with HRas, NRas and KRas4A, but not KRas4B. The increased Ras protein at the Golgi apparatus by overexpression of PAQR10/PAQR11 is in an active state. Consistently, knockdown of PAQR10 and PAQR11 reduces EGF-stimulated ERK phosphorylation and Ras activation at the Golgi apparatus. Intriguingly, PAQR10 and PAQR11 are able to interact with RasGRP1, a guanine nucleotide exchange protein of Ras, and increase Golgi localization of RasGRP1. The C1 domain of RasGRP1 is both necessary and sufficient for the interaction of RasGRP1 with PAQR10/PAQR11. The simulation of ERK phosphorylation by overexpressed PAQR10/PAQR11 is abrogated by downregulation of RasGRP1. Furthermore, differentiation of PC12 cells is significantly enhanced by overexpression of PAQR10/PAQR11. Collectively, this study uncovers a new paradigm of spatial regulation of Ras signaling in the Golgi apparatus by PAQR10 and PAQR11.

Fasting-induced protein phosphatase 1 regulatory subunit contributes to postprandial blood glucose homeostasis via regulation of hepatic glycogenesis.

OBJECTIVE: Most animals experience fasting-feeding cycles throughout their lives. It is well known that the liver plays a central role in regulating glycogen metabolism. However, how hepatic glycogenesis is coordinated with the fasting-feeding cycle to control postprandial glucose homeostasis remains largely unknown. This study determines the molecular mechanism underlying the coupling of hepatic glycogenesis with the fasting-feeding cycle. RESEARCH DESIGN AND METHODS: Through a series of molecular, cellular, and animal studies, we investigated how PPP1R3G, a glycogen-targeting regulatory subunit of protein phosphatase 1 (PP1), is implicated in regulating hepatic glycogenesis and glucose homeostasis in a manner tightly orchestrated with the fasting-feeding cycle. RESULTS: PPP1R3G in the liver is upregulated during fasting and downregulated after feeding. PPP1R3G associates with glycogen pellet, interacts with the catalytic subunit of PP1, and regulates glycogen synthase (GS) activity. Fasting glucose level is reduced when PPP1R3G is overexpressed in the liver. Hepatic knockdown of PPP1R3G reduces postprandial elevation of GS activity, decreases postprandial accumulation of liver glycogen, and decelerates postprandial clearance of blood glucose. Other glycogen-targeting regulatory subunits of PP1, such as PPP1R3B, PPP1R3C, and PPP1R3D, are downregulated by fasting and increased by feeding in the liver. CONCLUSIONS: We propose that the opposite expression pattern of PPP1R3G versus other PP1 regulatory subunits comprise an intricate regulatory machinery to control hepatic glycogenesis during the fasting-feeding cycle. Because of its unique expression pattern, PPP1R3G plays a major role to control postprandial glucose homeostasis during the fasting-feeding transition via its regulation on liver glycogenesis.